WP5–Action5.3–Finalreport  Thermalandgeomorphicpermafrost responsetopresentandfutureclimate changeintheEuropeanAlps  



  Editors: AndreasKellererͲPirklbauer,GerhardKarlLieb, PhilippeSchoeneich,PhilipDelineandPaoloPogliotti Graz,2011     WP5–Action5.3–Finalreport  Thermalandgeomorphicpermafrost responsetopresentandfutureclimate changeintheEuropeanAlps  

   Citationreference KellererͲPirklbauer A., Lieb G.K., Schoeneich P., Deline P., Pogliotti P. eds (2011). Thermal and geomorphic permafrost response to present and future climate change in the European Alps. PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,177pp. Downladableon:www.permanetͲalpinespace.eu  Editors Andreas KellererͲPirklbauer and Gerhard Karl Lieb, Institute of Geography and Regional Science, UniversityofGraz,Austria(IGRS) PhilippeSchoeneich,InstitutdeGéographieAlpine,UniversitédeGrenoble,France(IGAͲPACTE) PhilipDeline,EDYTEM,UniversitédeSavoie,France(EDYTEM) PaoloPogliotti,Regional AgencyfortheEnvironmentalProtectionoftheAostaValley,Italy(ARPA VdA)  Projectreference The PermaNET – Permafrost long term monitoring network (2008Ͳ2011) project is part of the EuropeanTerritorialCooperationandcoͲfundedbytheEuropeanRegionalDevelopmentFund(ERDF) inthescopeoftheAlpineSpaceProgrammewww.alpineͲspace.eu  PermaNET–Permafrostresponsetoclimatechange

Authors Baroni,Carlo UniversityofPisa(Italy) Bodin,Xavier UniversityJosephFourier,Grenoble(France) Cagnati,Anselmo RegionalAgencyfortheEnvironmentalProtectionofVeneto(Italy) Carollo,Federico E.P.C.EuropeanProjectConsultingS.r.l.(Italy) Coviello,Velio NationalCenterforScientificResearchEDYTEM,Grenoble(France) Cremonese,Edoardo RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) Crepaz,Andrea RegionalAgencyfortheEnvironmentalProtectionofVeneto(Italy) Dall’Amico,Matteo MountainͲeeringsrl(Italy) Defendi,Valentina RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) Deline,Philip NationalCenterforScientificResearchEDYTEM,Grenoble(France) Drenkelfluss,Anja UniversityofBonn(Germany) Galuppo,Anna RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) Gruber,Stephan UniversityofZurich(Switzerland) KellererͲPirklbauer, UniversityofGraz(Austria) Andreas Kemna,Andreas UniversityofBonn(Germany) Klee,Alexander CentralInstituteforMeteorologyandGeodynamics(Austria) Krainer,Karl UniversityofInnsbruck(Austria) Krautblatter,Michael UniversityofBonn(Germany) Kroisleinter,Christine CentralInstituteforMeteorologyandGeodynamics(Austria) Krysiecki,JeanͲMichel UniversityJosephFourier,Grenoble(France) LeRoux,Olivier Associationpourledéveloppementdelarecherchesurlesglissementsdeterrain (France) Lieb,GerhardKarl UniversityofGraz(Austria) Lorier,Lionel Associationpourledéveloppementdelarecherchesurlesglissementsdeterrain (France) Magnabosco,Laura RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) Magnin,Florence NationalCenterforScientificResearchEDYTEM,Grenoble(France) Mair,Volkmar AutomousProvinceofBolzano(Italy) Malet,Emmanuel NationalCenterforScientificResearchEDYTEM,Grenoble(France) Marinoni,Francesco Freelancer(Italy) MorradiCella,Umberto RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) Noetzli,Jeanette UniversityofZurich(Switzerland) Pogliotti,Paolo RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) Ravanel,Ludovic NationalCenterforScientificResearchEDYTEM,Grenoble(France) Reisenhofer,Stefan CentralInstituteforMeteorologyandGeodynamics(Austria) Riedl,Claudia CentralInstituteforMeteorologyandGeodynamics(Austria) Rigon,Riccardo UniversityofTrento(Italy) Schoeneich,Philippe UniversityJosephFourier,Grenoble(France) Schöner,Wolfgang CentralInstituteforMeteorologyandGeodynamics(Austria) Seppi,Roberto UniversityofPavia(Italy) Vallon,Michel UniversityJosephFourier,Grenoble(France) Zampedri,Giorgio GeologicalSurvey,AutonomousProvinceofTrento(Italy) Zischg,Andreas AbenisAlpinexpertGmbH/srl(Italy) Zumiani,Matteo Geologist(Italy)    ADRAͲAssociationpourladiffusiondelarecherchealpine 14bisav.MarieͲReynoard, FͲ38100Grenoble ISBN978Ͳ2Ͳ903095Ͳ58Ͳ1     Contentsandlistforchapterpublications  1.PermafrostResponsetoClimateChange SchoeneichP.,LiebG.K.,KellererͲPirklbauerA.,DelineP.,PogliottiP.(2011).Chapter1:Permafrost Response to Climate Change. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.4Ͳ15.  2.ClimateChangeintheEuropeanAlps KroisleitnerCh.,ReisenhoferS.,SchönerW.(2011).Chapter2:ClimateChangeintheEuropeanAlps. InKellererͲPirklbauerA.etal.(eds):Thermaland geomorphic permafrostresponse topresentand future climate change in the European Alps. PermaNET project, final report of Action 5.3. OnͲline publicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.16Ͳ27.  3.CasestudiesintheEuropeanAlps 3.1Overviewoncasestudies KellererͲPirklbauerA,LiebG.K.(2011).Chapter3.1:CasestudiesintheEuropeanAlps–Overviewon casestudies.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.28Ͳ34.

3.2Hochreichart,EasternAustrianAlps KellererͲPirklbauerA(2011).Chapter3.2:CasestudiesintheEuropeanAlps–Hochreichart,Eastern AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.35Ͳ44.

3.3DösenValley,CentralAustrianAlps KellererͲPirklbauerA(2011).Chapter3.3:CasestudiesintheEuropeanAlps–DösenValley,Central AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.45Ͳ58.

3.4HoherSonnblick,CentralAustrianAlps KleeA,RiedlC.(2011).Chapter3.4:CasestudiesintheEuropeanAlps–HoherSonnblick,Central AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.59Ͳ65.

 1 PermaNET–Permafrostresponsetoclimatechange

3.5RockGlacierHochebenkar,WesternAustrianAlps Krainer K. (2011). Chapter 3.5: Case studies in the European Alps – Rock Glacier Hochebenkar, Western Austrian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost responsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreport ofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.66Ͳ76.

3.6RockGlacierLaurichard,NorthernFrenchAlps SchoeneichP.,BodinX.,KrysieckiJ.ͲM.(2011).Chapter3.6:CasestudiesintheEuropeanAlps–Rock Glacier Laurichard, Northern French Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost response to present and future climate change in the European Alps. PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.77Ͳ86.

3.7RockGlacierBellecombes,NorthernFrenchAlps SchoeneichP.,KrysieckiJ.ͲM.,LeRouxO.,LorierL.,VallonM.(2011).Chapter3.7:Casestudiesinthe European Alps – Rock Glacier Bellecombes, Northern French Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost response to present and future climate change in the EuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ 58Ͳ1,p.87Ͳ96.

3.8AiguilleduMidi,MontBlancmassif,FrenchAlps DelineP.,CremoneseE.,DrenkelflussA.,GruberS.,KemnaA.,KrautblatterM.,MagninF.,MaletE., MorradiCellaU.,NoetzliJ.,PogliottiP.,RavanelL.(2011).Chapter3.8:CasestudiesintheEuropean Alps–AiguilleduMidi,MontBlancmassif,FrenchAlps.InKellererͲPirklbauerA.etal.(eds):Thermal and geomorphic permafrost response to present and future climate change in the European Alps. PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.97Ͳ108.

3.9RockfallsintheMontBlancmassif, DelineP.,RavanelL.(2011).Chapter3.9:CasestudiesintheEuropeanAlps–RockfallsintheMont Blanc massif, FrenchͲItalian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.109Ͳ118.

3.10CimeBianchePass,ItalianAlps PogliottiP,CremoneseE.,MorradiCellaU.(2011).Chapter3.10:CasestudiesintheEuropeanAlps– Cime Bianche Pass, Italian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.119Ͳ128.

3.11Maroccarorockglacier,ValdiGenova,ItalianAlps SeppiR.,BaroniC.CartonA.,Dall’AmicoM.,RigonR.,ZampedriG.,ZumianiM.(2011).Chapter3.11: CasestudiesintheEuropeanAlps–Maroccarorockglacier,ValdiGenova,ItalianAlps.InKellererͲ PirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimate changeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN 978Ͳ2Ͳ903095Ͳ58Ͳ1,p.129Ͳ139.

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3.12Amolarockglacier,Vald’Amola,ItalianAlps SeppiR.,BaroniC.CartonA.,Dall’AmicoM.,RigonR.,ZampedriG.,ZumianiM.(2011).Chapter3.12: Case studies in the European Alps – Amola rock glacier, Val d’Amola, Italian Alps. In KellererͲ PirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimate changeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.ISBN978Ͳ2Ͳ903095Ͳ58Ͳ1, p.140Ͳ150.

3.13PizBoèrockglacier,Dolomites,EasternItalianAlps A. Crepaz A., Cagnati A., Galuppo A., Carollo F., Marinoni F., Magnabosco L., Defendi V. (2011). Chapter 3.13: Case studies in the European Alps – Piz Boè rock glacier, Dolomites, Eastern Italian Alps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresent andfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲline publicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.151Ͳ158.

3.14UpperSuldenValley,OrtlerMountains,ItalianAlps ZischgA., MairV.(2011).Chapter3.14:CasestudiesintheEuropeanAlps–UpperSuldenValley, Ortler Mountains, Italian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.159Ͳ169.  4.SynthesisofCaseStudies LiebG.K.,KellererͲPirklbauerA.(2011).Chapter4:Synthesisofcasestudies.InKellererͲPirklbauerA. etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimatechangein the European Alps. PermaNET project, final report of Action 5.3. OnͲline publication ISBN 978Ͳ2Ͳ 903095Ͳ58Ͳ1,p.170Ͳ177.  

 3 PermaNET–Permafrostresponsetoclimatechange

 1. PermafrostResponsetoClimateChange  

  Citationreference SchoeneichP.,LiebG.K.,KellererͲPirklbauerA.,DelineP.,PogliottiP.(2011).Chapter1:Permafrost Response to Climate Change. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.4Ͳ15.  Authors Coordination:PhilippeSchoeneich Involvedprojectpartnersandcontributors: Ͳ Institut de Géographie Alpine, Université de Grenoble, France (IGAͲPACTE) – Philippe Schoeneich Ͳ Institute of Geography and Regional Science, University of Graz, Austria (IGRS) – Andreas KellererͲPirklbauer,GerhardKarlLieb Ͳ EDYTEM,UniversitédeSavoie,France(EDYTEM)–PhilipDeline Ͳ Regional Agency for the Environmental Protection of the Aosta Valley, Italy (ARPA VdA) – PaoloPogliotti  Content Summary 1. Introduction 2. Thermalpermafrostresponse 3. Geomorphicpermafrostresponse 4. Finalremarks References

 4 PermaNETͲPermafrostResponsetoClimateChange

Summary   Permafrost is defined as subsurface material that remains below 0°C also during the summer. Thuspermafrostisathermalphenomenonwhosecharacteristicslargelydependontheclimatic conditions. This means that a changing climate also affects the thermal regime of the underground. The interactions between the atmosphere and the surface as well as the subsurfacetemperaturesyetarehighlycomplexdependingonseveralenvironmentalfactorslike e.g. the substrate itself (coarseͲgrained blocky material, fineͲgrained material, bedrock), the characteroftherelief(e.g.depressionvs.ridge),theexposurerelativetothesunorthesnow cover characteristics (onset and disappearance date, length of snow cover period, thickness, dynamics). Inthischaptertheoccurrencetypesoffrostandtheiraltitudinaldistributionisdescribedfirst. Thenpermafrostreactionstoclimatechangearediscussedundertwoaspects–thethermaland thegeomorphiconeaccordingtothealreadyexistingknowledge. Mainthermalreactionsare:(a)increasinggroundtemperatureandhencepermafrostwarming, (b)thawingofpermafrostleadingtoreductioninitsspatialextent,activelayerthickeningand changing groundͲwater circulation, (c) changes in the number of freezeͲthaw cycles and magnitudeoffreezingandthawingperiods. Maingeomorphicreactionsare:(a)changesintherateofrockglacierdisplacement,(b)changes in the displacement mode of rock glaciers, (c) changes in solifluction rates, (d) changes in cryogenicweathering,(e)changesinthevolumeandextentofunstablematerials,(f)changesin frequency and magnitude of mass movement events, and (g) surface instabilities caused by thermokarstprocesses/meltingofpermafrostice.Someofthesegeomorphicreactionsarealso truefornonͲpermafrostperiglacialareas,meaningalpineandsubalpineenvironmentsatlower elevations. Summingupitisshownherequitewellthatongoingclimatechangehasanumberofcomplex influencesonthegroundtemperaturebutalsogroundstabilityonthemountainpermafrostof theEuropeanAlps.

5 PermaNET–Permafrostresponsetoclimatechange

1. Introduction Permafrost is an effect of frost and negative temperatures and results from a negative energy balance at the ground surface. The energy balance mainly depends on the direct incoming solar radiationandonthesensibleheatflux.ThusitisencounteredintheAlpsathighelevations,where airtemperature(controllingthesensibleheatflux)islow.Permafrostismoreextensiveandoccursat lower altitudes on north facing than on south facing slopes, because of a reduced incoming solar radiationduetoslopeangleandshadowingeffects.  1.1Theoccurrencetypesoffrost Permafrostisnottheonlyeffectoffrost.FrostoccursatallaltitudinallevelsintheAlps,withvarious intensityandduration.Oneusuallydistinguishesthefollowingoccurrencesoffrost: x DiurnalfreezeͲthawcyclesconsistofthefreezingandsubsequentthawingofmaterialduring anightͲdaycycleorseveralconsecutivedaysorweeks.Theyaredrivenbyairtemperature cycles. Climatologists define frost days (FD) as days where the minimum temperature is negative,andicedays (ID)asdayswherethemaximumtemperatureremainsbelowzero, henceinducingfreezeconditionsoveratatleastoneday.FreezeͲthawdays(FTD)aredefined asdayswithnegativeminimumandpositivemaximumtemperature.Insoilandrock,freezeͲ thawcycleshavetobedistinguishedaccordingtotheirduration,intensityandpenetration depth. Diurnal frost is usually of moderate intensity and has a limited penetration depth, whereasperiodsofconsecutiveverycoldicedayshavethehighestpenetrationdepthand intensity. FreezeͲthaw cycles induce frost shattering of rocks and are the main controlling factor of debris production. To be efficient, the frost must have a minimal intensity and duration. Diurnal frost cycles have only a limited impact. Cycles of several days reaching temperaturesofͲ5°Candlessareconsideredtobemostefficient. x SeasonalfrostdefinesmaterialthatexperiencesoneannualfreezeͲthawcycle,ofaduration ofatleastseveralweeksuptoseveralmonths,butwithatotalthawingduringthewarm season.Frostdurationanddepthdependmoreonthemeantemperaturethanonindividual cycles.Seasonalfrostinducesgeomorphicprocesseslikesolifluctionandsimilarshallowsoil creepingphenomena. x Permafrostisdefinedformallyasasubsurfacematerial(rock,debrisorsoil)thatremainsata temperature belowzeroduringthewholeyear.Itconsistsoftwoparts:thesurfacelayer, called active layer that thaws seasonally and refreezes during the cold season, and the permafrostsensustrictuthatremainsconstantlybelowzero.Fromtheclimaticpointofview, permafrostoccurswheretheannualheatbalanceisnegative.Duetosomecharacteristicsof thesurfacelayers(knownasthethermaloffset),thisdoesnotoccuratthe0°Cisotherm,but at a mean annual air temperature ofͲ1 toͲ2°C. Permafrost is usually subdivided into continuous,discontinuous,sporadicandisolatedpermafrost,accordingtothepercentageof theareacoveredbypermafrost.Theusualthresholdsarethefollowingonesbutpartlyvary betweenauthors(cf.French2007): o isolated:lessthan10%ofthesurfaceaffectedbypermafrost o sporadic:between10and50%ofthesurfaceaffectedbypermafrost o discontinuous:between50and90%ofthesurfaceaffectedbypermafrost o continuous:morethan90%ofthesurfaceaffectedbypermafrost. Furthermore,someauthorsdistinguish: o coldpermafrost,withameangroundtemperaturebelowͲ1°C o temperateorwarmpermafrost,withagroundtemperaturecloseto0°C(typicallyͲ 0.1toͲ0.2°C).

 6 PermaNETͲPermafrostResponsetoClimateChange

Thispointraisesthequestionofthemeltingpointtemperatureinpermafrost,especiallyin aniceͲdebrismixture.  1.2Altitudinaldistribution The various occurrences of frost show an altitudinal distribution, controlled by the altitudinal gradientsofthecontrollingclimatefactors. x DiurnalfreezeͲthawcyclesoccurinwinteratlowaltitudes,inspringandautumnatmiddle altitudes and in summer at high altitudes. Their maximal frequency is observed at middle altitudes.IntensityanddurationofthefreezeͲthawcyclesincreasewithaltitude. x Seasonal frost occurs at middle altitudes and its duration and penetration depth increase withaltitude.Itpassestopermafrostathighaltitudes. x Permafrost occurs sporadically at middle altitudes. At high altitudes discontinuous permafrostoccurs,withaprogressivetransitiontomorecontinuouscoveragewithincreasing altitude.  Thisaltitudinaldistributionoffrostoccurrencesisassociatedwithanaltitudinaldistributionoffrost relatedprocessesandlandforms: x FrostshatteringandtalusproductionarerelatedtofreezeͲthawcycles. x Shallowsolifluctionprocessesarerelatedtoseasonalfrost. x Deepcreepprocesses(rockglaciers)arerelatedtopermafrost.  This altitudinal morphoͲclimatic distribution has been described by several authors, especially Chardon(1984,1989)whodistinguishesthefollowingbelts: x The infraͲperiglacial belt is concerned by freezeͲthaw cycles and seasonal frost, and processesaredominatedbytalusproductionandsolifluction. x The periglacial belt sensu stricto is concerned by discontinuous permafrost, and processes aredominatedbysolifluctionandrockglaciers. x ThesupraͲperiglacialbeltisconcernedbycontinuouspermafrost.IntheAlpsitcoversmainly rockfacesandprocessesaredominatedbyepisodicrockfallsandglaciers.

 2. Thermalpermafrostresponse Climatewarminginducesanincreaseofairtemperature,henceanincreaseofthesensibleheatflux. Thustheenergybalanceshouldbecomelessnegative.Ageneralwarmingofgroundtemperatures canthereforebeexpected. However, climate warming will will most probably neither change solar radiation nor altitudinal gradients, so that the overall altitudinal distribution of frost types and effects will remain, but is expectedtoshifttowardshigheraltitudes. Heat transfers from both solar radiation and heat flux to the ground are influenced by the snow cover.Thustheevolutionofthegroundtemperaturewillnotonlydependontheevolutionofthe temperature, but also on the amount and type of winter precipitation and subsequently of the distribution,durationandthicknessofthewintersnowcover.

7 PermaNET–Permafrostresponsetoclimatechange

 2.1Migrationofpermafrostbelts Temperaturechangeswillaffectallphenomenarelatedtofrost:diurnalfreezeͲthawcycles,seasonal frostaswellaspermafrost.Ingeneral,aclimatewarmingshouldinduceamigrationofallclimate relatedlimitsandbeltstowardshigheraltitudes.Thefollowingmainchangescanbeexpected: x ConcerningfreezeͲthawcycles: o Lowerfrequencyandintensityatmiddlealtitudes o Migrationofmaximalfrequencyandintensitytowardshigheraltitudes o Seasonalshiftofcyclefrequencytowardsearlier/laterseason o Increaseoffrequencyathighaltitudes x Concerningseasonalfrost: o Decreaseoffrequencyanddepthatmiddlealtitudes o Decreaseofdepthanddurationathigheraltitudes o Replacementofpermafrostbyseasonalfrostatthelowerpermafrostlimit x Concerningpermafrost: o Disappearanceofsporadicpermafrostatmiddlealtitudes o Migrationofthelowerpermafrostlimittowardshigheraltitudes o Replacementofcontinuousbydiscontinuouspermafrost 

 Fig. 1 ͲProcesses  which may occur within permafrost shown as a process of degradation (from Dobinski2011).

 8 PermaNETͲPermafrostResponsetoClimateChange

2.2Changesinthermalprofilesoftheground TemperaturechangeswillaffectpermafrostmainlybythefollowingprocessesvisualisedalsoinFig. 1:(a)thickeningoftheactivelayer,(b)warmingofthepermafrosttemperature,(c)reductionofthe permafrostthickness,and(d)decreaseoftheicecontent.  Increaseofactivelayerthickness Thefirsteffectofclimatewarmingwillbetheincreaseoftheactivelayerthickness.Thisresponds directly to interannual variations. It depends both on the thermal state acquired during the precedingwinterandonthesummertemperature. On rock glaciers there is often a strong contrast between the coarse blocky active layer and the underlyingiceͲrichandfinergrainedpermafrost.Insuchcases,anincreaseoftheactivelayerwill inducealossoficeatthepermafrosttableandageneralloweringofthesurface. Ifthethawingofpermafrostgetsdeeperthantheseasonalfrostdepth,thisseasonalfreezingwillnot beabletorefreezetheentirethawedlayer,andatalik(=unfrozenlayer)willremainduringwinter between the seasonally frozen surface layer and the residual deeper permafrost. This situation occurs when the permafrost warms up, and stops to be cooled from the surface. It can be transitional (after a particularly warm year) or permanent (inactivation of permafrost). Such situationsarelikelytooccurinthefutureatthelowerlimitsofdiscontinuouspermafrost.  Warmingofthepermafrost Due to a low thermal conductivity of the ground, the heat transfer towards depth is very slow, especiallyiniceͲrichpermafrost.Itthereforecantakeyearstopropagatethroughtheprofile.The permafrosttemperatureisthereforeexpectedtoreactrathertodecadaltrendsthantointerannual variations. Thedownprofilepropagationofheatwavescanalreadybeinterpretedfromsomeboreholeprofiles, where the minimal temperature is registered at a greater depth than the ZAA (zero annual amplitude).Withtime,areductionofthecoolingfromthesurfacewillalsoallowawarmingfromthe bottomupwards,duetothegeothermalheatflux.  Theroleofthesnowcover All above mentioned evolutions postulate a linear response of ground temperature to air temperature. However, ground surface temperature monitoring series show that the link is not straightforward. The snow cover plays an important role through its insulation capacity, and can inducesignificantdeviationsfromtheairtemperaturetrends. The onset and thickness of the snow cover in early winter plays the major role: in November to January,thedaysaretheshortestandthedirectradiationataminimum,whereasairtemperatures reachalreadyverylowvalues.Ifthereisnosnowcover,thesoilwilldrasticallycooldown.Ashallow snow cover may even increase the heat loss. On the contrary, an early and thick snow cover will preventthesoilfromcoolingand“keep”theaccumulatedheatoftheprevioussummerandautumn. The snow cover history in early winter will thus largely determine the winter ground surface temperature, and the winter equilibrium temperature (WEqT), i.e. the mean ground surface temperatureinFebruaryandMarch.Onareasofseasonalfrost,itwilldeterminethefreezingorno freezingofthesoil,aswellasthefrostdepth.

9 PermaNET–Permafrostresponsetoclimatechange

The thicknessofthesnowcoverduringthewinterhasofcoursealsoagreatimportance.A thick cover (at least ca. 0.8Ͳ1 m) insulates the ground from air temperature variations, and keeps the thermalstateacquiredduringautumnandearlywinter.Ashallowordiscontinuous(throughwind deflation)snowcoverallowsacontinuedcoolingofthegroundduringthewholewinter. Thedurationofthesnowcoverinspringhasaninverseeffectthaninearlywinter.Alatesnowmelt preventsthesoilfromthedirectsolarradiation,inaperiodwhereitisatamaximum,andprotectsit fromthesensibleheatflux.Onthecontrary,anearlysnowmeltwillallowanearlierwarmingofthe soil.Thus,thewintercoolingeffectofashallowsnowcovercanbecompensatedbyanearliersnow melt. Theeffectofthesnowcoveriswellvisibleontheinterannualtemperaturevariability.Itcaninduce significant departures from the atmospheric temperature variations, e.g. cooling during rather moderate winters, or warming despite of cool winters. Its real influence on middle to long term temperaturetrendsremainsanopenquestion.Temperaturerecordsinboreholesatca10mdepth showadistinctwarmingtrendfrom1987to1994,andthenastabilisation(PERMOS2009),butno realcooling,unlikethesurfacetemperatures. Thethermalevolutionofpermafrost,andmoregenerallyofgroundtemperatures,willthusdepend on both air temperature and snow cover. Most climate models predict an increase of winter precipitations.Ifthisoccursassnowfall,itcanhavevariouseffects,dependingonitsseasonality: x Earlysnowfallswouldincreasewarming x Athickhighwintersnowcoverwillratherincreasewarming x Alatesnowmeltwouldpreventgroundfromwarming. Thesnowcoveronlyimpactsareasofmoderateslopeswhereathicksnowcovercandevelopand stayduringwinter.Onsteeprockfacesthesnowcoverhasnoinfluence.  2.3Ratesofchange Asmentionedabove,theheattransfertowardsdepthisveryslow,especiallyiniceͲrichpermafrost. It therefore can take years to propagate through the profile. The permafrost temperature is therefore rather expected to react to decadal trends than to interannual variations. Model calculations show that it takes decades to reach a new equilibrium at depths of 20 to 30 m. In bedrock,theheatpropagationcanbemuchfaster.  Theroleoficecontent Thepropagationoftemperaturechangesintothesoilisstronglydependentfromtheicecontent. Due to the high amount of latent heat needed to melt ice, high ice content strongly reduces the thermalconductivityoftheground.Onedimensionalheattransfermodelsshowthatanicecontent of 60% almost totally blocks the propagation of seasonal temperature variations, and that the meltingoftheicebodymayneedseveraldecades. Fromthethermalpointofview,iceͲrichpermafrostisthereforelesssensitivetoclimatechangethan “dry”permafrost.Ontheotherhand,thehighicecontentcanleadtosubsidenceandthermokarst phenomena,duetovolumeloss.InflatterrainthethawingoficeͲrichpermafrostthereforeleadsto greaterdisturbanceanddamagethanthethawingof“dry”permafrost.  

 10 PermaNETͲPermafrostResponsetoClimateChange

3. Geomorphicpermafrostresponse Climate change will affect both spatial distribution and intensity of frost related processes. As mentionedabove,thermaleffectsoffrostshowaclearaltitudinaldistribution.Thus,thefrostrelated geomorphicprocessesandlandformsshouldmigratetohigheraltitudes,togetherwiththeirdriving climate parameters. This however will mainly happen through changes in magnitude (intensity, duration,frequency)oftheseprocesses.Inadditiontothealtitudinalshift,someparticularoreven so far unknown phenomena may occur, due to transient states of ground conditions that are not usuallyobservedunderclimaticallystableconditions.  3.1Frostshatteringanddebrisproduction FrostshatteringanddebrisproductionarecontrolledbyfreezeͲthawcycles,anditisusuallyadmitted thatthemaximaldebrisproductionoccursataltitudesofmaximalcyclefrequency,correspondingto spring and autumn cycles. This altitudinal range has been defined as the talus window (Hales & Roering2005). Thetaluswindowisthusexpectedtomovetowardshigheraltitudes.Somestudiesalreadyshowa decreaseoftalusproductionintheuppersubalpinebelt(Arquès2005,Corona2007),aswellasa decreaseofthetorrentialactivityontalussuppliedtorrents(Garitte2006).Thisevolutioncouldlead to an overall decrease of geomorphic activity in middle altitudes, and favour the reͲvegetation of screeslopes. Ontheupperend,thenormalstateofhighaltitudinalrockwallsinthecontinuouspermafrostbeltis ahighstabilityofrockfaces,withonlylimitedsporadicdebrissupplyfromoccasionalrockfalls.These slopes where freezeͲthaw cycles were yet limited to the summer season could experience an increaseoftalusproduction.Departurezonesofrockfallsarefrequentlyconcentratedinthelower partsofthecontinuouspermafrostbelt.Bothrockfallsanddebrisproductionareclearlyrelatedto warmperiodsduringsummermonths,inducingadeepeningoftheheatpenetrationinrockfaces (Deline&Ravanel2011). Regardingdebrisproductionfromcliffsandrockfaces,climatewarmingwillinducesignificanteffects ontwodifferentaltitudinallevels: x Thetaluswindowcanbeexpectedtoshifttowardshigheraltitudes.Asaconsequence,talus productionshoulddecreaseinthelowerparts,andincreaseintheupperpartsofthebelt. Thisbeltischaracterizedbyaregularproductionofsmalldebris. x Anewbeltofincreaseddebrisproductionisdevelopingatthelowerlimitofthecontinuous permafrostbelt.Thisbeltischaracterizedbyasporadicproductionofcoarsedebris,upto largeorevenverylargerockfalls.Duetooftenhighandsteepslopes,theseprocessescan impactzonessituatedfarlowerdownslope. Indirecteffectsonotherprocessescanbeexpected: x Rockglaciersareusuallysituatedintheupperpartofthetaluswindow.Anincreaseofthe talusproductionatthislevelcouldthereforeinduceanincreaseofthedebrissupplytorock glaciers. On a much longer time scale, the increase in volume of some talus bodies could induce the formation of new rock glaciers. However, fast climate warming and hence permafrostdegradationwillmaketheformationofnewrockglaciersmoredifficult. x Accumulationzonesofglaciersareoftensituatedatthefootofhighaltituderockwalls.An increase of sporadic debris supply from these rock walls will induce an increase of debris coveranddebriscontentoftheglaciers,andconsequentlyanincreaseoftheextentofdebris coveronglaciers.ThisimpactthedynamicoftheseglaciersasforinstancetheMiageGlacier

11 PermaNET–Permafrostresponsetoclimatechange

inItaly(Deline&Orombelli2005)orthePasterzeGlacierinAustria(KellererͲPirklbaueretal. 2008).  3.2Solifluctionandseasonalfrost Solifluctionphenomenaarerelatedtoseasonalfrostandneedasufficientfrostdepthinorderto allow a waterͲsaturated thawed layer to form in spring over astill frozen impermeable soil. After completethawing,thesoildrainsandsolifluctionprocessesstop.Adecreaseoftheseasonalfrost depthwillthereforeinduceashorteningoftheactivityperiodandhenceadecreaseofmovement rates.ForamoredetailedclassificationofsolifluctiontypesrefertoMatsuoka(2001). Inaddition,someprocesseslikeboundedsolifluctionareconnectedwithfinegrainedsoilsandwith thepresenceofavegetationcover.Theupwardsmigrationofsuchphenomenawilldependonthe presenceoffinegrainedmaterialandonthedevelopmentofalpinemeadows.Solifluctionprocesses areverydifficulttostudyandonlyfewlongͲtermmonitoringsitesareknownintheAlps(e.g.Stingl etal.2010).Ingeneral,thereisalackofdataonseasonalfrostandonrelatedprocesses.  3.3Rockglaciers ThemostprominentfeaturesofAlpinepermafrostarerockglaciers.Theyarealsothemostmobile ones.Thepossibleevolutionscenariosofrockglacierdynamicsarethereforeacentralconcernfor Alpinemountainregions.Displacementtimeseriesandreconstructionsofadozenofrockglaciers throughouttheAlps,indicatedifferenttypesofbehaviouratvarioustimescales. Attheinterannualtimescale(Delaloyeetal.2008,Bodinetal.2009,KellererͲPirklbauer&Lieb2011): x Mostrockglaciersshowinterannualvelocityvariations,andthusreacttoclimatevariability. x Thesevelocityvariationsarebestcorrelatedwitha12monthrunningmeanoftheground surfacetemperature. x Thevelocityvariationsshowatimelagofca1yeartowardsairandgroundtemperature. x Thesevariationsarereversiblewithwarmingleadingtoavelocityincreaseandcoolingtoa velocitydecrease.Thevelocityratesremainintherangeof0.1toafewm/yͲ1). Somerockglaciershaveshownadistinctchangeindynamicbehaviourduringthelastdecadesor years,withastrongincreaseofvelocitiesonpartsorthewholeoftherockglacier(e.g.Avianetal. 2005).Severaltypesofbehaviourscanbedistinguished(seePermaNETreport6.2forstudycases andmoredetail): x Strong acceleration with opening of crevasses. The velocities increase by an order of magnitude,uptoseveralm.yͲ1.Crevassesshowthatthedeformationratesexceedtheflow capacityoftheice. x Ruptureanddislocationofthelowerpartoftherockglacier.Inthesecases,adistinctrupture withascarpappearsintherockglacierandseparatesthelower,fastpart,fromtheupper, “normal”movingpart. x Totalcollapseofthelowerpart.Onlyonecaseisknownyet,wherethelowerparttotally collapsedintoamudflow(Krysieckietal.2008). x Extremeaccelerationoftherockglacier.Onecaseisknown,withvelocitiesofseveraltensof m.yͲ1(Delaloyeetal.2010). All these evolutions are apparently not reversible, but observation times are not yet sufficient to knowtheendofthestory.Theacceleratedlowerpartstendtodislocate,whereastheupperparts possiblyformanewrockglacierfront.Severalquestionsarise:

 12 PermaNETͲPermafrostResponsetoClimateChange x Interannual variations are hard to explain. One possible explanation could be a higher plasticityoficewithhighertemperature.However,themaindeformationratesoccurinthe basallayerofrockglaciers,asshownbythefewexistinginclinometerprofiles.Thethermal conductivityoficeͲrockmixturesisverylow,anditisunlikelythatinterannualtemperature variationsreachthebottomoftheiceͲrichbody.Anotherexplanationcouldbeanincreased presenceofinterstitialwater,facilitatinginternalmovementsbetweenicegrains. x Theveryhighvelocityincreaseobservedonacceleratingrockglaciers(someauthorseven talkabout“surging”rockglaciers)impliesachangeofdisplacementmode.Rockglaciersare usuallyconsideredtomoveatthesamewayascoldbasedglaciers,bydeformationoficeand shearofthebasalicelayer.Velocitiesofseveralm/yͲ1andevenmoreseemtoindicatethe onsetofabasalsliding.Thiswouldmeanthattheserockglaciershavechangedfroma“cold glacier” to a “temperate glacier” displacement mode. The latter point is crucial for future development,andhastoberelatedtothequestionofthemeltingpointtemperature. x Theconditionsthatleadarockglaciertoaccelerateornotareunknownyet.Thepresenceof aconvexslopeseemstobenecessaryfortheonsetofstrongaccelerationsofthelowerpart (e.g.Avianetal.2005).Thetotalcollapseoccurredonarockglaciermadeoffinematerial, andispossiblyunlikelytohappenonacoarseblockyrockglacier. Fromtheseconsiderations,thefollowingmostprobableevolutionscenarioscanbeproposed: x Interannualvariationswillcontinue.Velocityincreasesareexpectedtohappenmainlyafter very hot summers associated with snow rich winters. Such episodes may occur more frequentlyandonanincreasingnumberofrockglaciers. x Strongaccelerationsarelikelytooccuronanincreasingnumberofrockglaciers. x Acceleration episodesareatransient state,andwilllastonlyaslongasthe ice contentis sufficient to allow creeping. After ice loss is sufficient and the permafrost is no longer supersaturatedwithice,movementsshouldslowdownandstop. x Totalcollapseorextremeaccelerationswillpossiblyremainexceptionalcases,butabetter knowledgeisrequestedinordertobeabletoevaluatetheirprobability.  3.4Thermokarstphenomena Ifpermafrostissupersaturatedinice,themeltingoficeduetopermafrostdegradationinduceda volume loss of the substrate affected which leads to instabilities at the surface and finally to settlementofthesurface.Theseprocessescanespeciallybeobservedinareaswithlowinclinations wheretheycreateamoreruggedtopographythanithasexistedbefore.Ifthereisanimpermeable layerbeneath(e.g.thepermafrosttableitself)thermokarstlakesmaygetformed. Settlementprocessesdonotonlylowerthesurfaceandchangeitstopographybutarealsoofspecial significance for buildings and other infrastructures because they create the need to adapt the constructionsinordertoavoiddamage.   4. Finalremarks Table1givesanoverviewofthethermalandgeomorphicreactionsofpermafrosttoclimatechange astheycanbeexpectedaccordingtoconsiderationsgiveninthepreviousparagraphs.Thechanges listedinthetableservedasguidelinesforcarryingoutthecasestudiesinChapter3andinterpreting theresultswhicharesummarizedinChapter4.

13 PermaNET–Permafrostresponsetoclimatechange

Table1ͲPossiblethermalandgeomorphicpermafrostreactionsrelevantforPermaNET.

Possiblethermalpermafrostreactions Increasinggroundtemperature(inbedrock,fineandcoarsesediments)andhencepermafrostwarming Thawingofpermafrostwiththreeeffects:(1)reductioninthespatialextentofpermafrost,(2)activelayerthickening,and (3)increasinggroundͲwatercirculationandpressure ChangesinthenumberoffreezeͲthawcyclesandmagnitude(durationandintensity)offreezingandthawingperiods

Possiblegeomorphicpermafrostreactions Changesintherateofrockglacierdisplacement(verticallyandhorizontally) Changesindisplacementmodeofrockglaciers(initiationofbasalsliding,collapse) Changesinsolifluctionrates* Changesincryogenicweathering(freezeͲthawcycles,icesegregation)* Changesinthevolumeandextentofunstable/unconsolidatedmaterials Changesinfrequencyandmagnitudeofmassmovementevents(e.g.rockfall,rockslide,debrisflow)* Surfaceinstabilitiescausedbythermokarstprocesses/meltingofpermafrostice*

*notstrictlyrelatedtoonlypermafrostbuttoperiglacialenvironmentsingeneral  Monitoring of permafrost temperature is performed on three different kinds of permafrost sites primarilyusingminiaturetemperaturedataloggers(MTD)orthermistorͲchainslocatedinboreholes (fromveryshallowtodeep): x Permafrostandactivelayerinbedrock(fromnearͲverticalrockwallstoflatmorphologies) x Permafrostandactivelayerinfinegrainedmaterial(ratherflatmorphology) x Permafrost and active layer in coarse grained and blocky material (scree slopes, rock glaciers; fromsteepslopestoratherflatmorphologies) Climate conditions at permafrost sites are monitored by meteorological stations. Monitoring of dynamic conditions in permafrost environments is carried out by geodetic, photogrammetric, terrestrial laserscanning (LiDAR or TLS), differential SAR interferometry (DINSAR) and DGPS techniquesaswellasvisualobservationsandcalculations.Thismonitoringfocuseson: x Massmovement(e.g.rockfall)frequencyandmagnitude x Rateofrockglacierdisplacement(verticallyandhorizontally) x Physicalweathering(freezeͲthawcycles)  TosumupAction5.3usesawiderangeofmethodsintheassessmentofthethermalanddynamic reaction scenariosof different permafrost typologies. Research in this action is carried out in two steps:(i)Establishmentoftherelationshipbetweenmeasured climatedataandobservedthermal and geomorphic permafrost reactions (Table 1) using available datasets collected during the last years and decades (cf. Chapter 3). (ii) Combining the established relationships with data from the climatescenariofortheyear2050presentedinChapter2formsthebasisforestimationsoffuture changesinpermafrostdistribution(verticallyandhorizontally),intheactivelayerthicknessorinthe ratesofrockglacierdisplacement.  References: ArquèsS.,2005:GéodynamiqueetbiodiversitédesversantsasylvatiquesdumassifdelaGrandeChartreuse. Evolutionliéeauréchauffementclimatiqueetproblèmedegestion.ThèseUniversitéJosephFourier, Grenoble. AvianM.,KaufmannV.&LiebG.K.,2005:RecentandHolocenedynamicsofarockglaciersystem:Theexample ofHinteresLangtalkar(CentralAlps,Austria).NorwegianJournalofGeography,59,149Ͳ156.

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BodinX.,ThibertE.,FabreD.,RiboliniA,SchoeneichP.,FrancouB.,Reynaudl.&FortM.,2009:Twodecadesof responses (1986–2006) to climate by the Laurichard rock glacier, French Alps. Permafrost and PeriglacialProcesses,20,331Ͳ344. ChardonM.,1984:Montagneethautemontagnealpine,critèresetlimitesmorphologiquesremarquablesen hautemontagne.RevuedeGéographieAlpine72(2Ͳ4):213Ͳ224. ChardonM.,1989:Essaid'approchedelaspécificitédesmilieuxdelamontagnealpine.RevuedeGéographie Alpine77(1Ͳ3):15Ͳ18. Corona C., 2007: Evolution biostasique du paysage, géodynamique nivéoͲpériglaciaire et fluctuations climatiquesrécentesdanslahautevalléedelaRomanche(AlpesduNord,France).ThèseUniversité JosephFourier,Grenoble. DelineP.&OrombelliG.,2005:GlacierfluctuationsinthewesternAlpsduringtheNeoglacial,asindicatedby theMiagemorainicamphitheatre(MontBlancmassif,Italy).Boreas,34:456–467. DelineP.&RavanelL.(2011).Chapter3.9:CasestudiesintheEuropeanAlps–RockfallsintheMontBlanc massif,FrenchͲItalianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrost responsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportof Action5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1. Delaloye R., Perruchoud E., Avian M., Kaufmann V., Bodin X., Hausmann H., Ikeda A., Kääb A., KellererͲ PirklbauerA.,KrainerK.LambielC.,MihajlovicD.,StaubB.,RoerI.,ThibertE,.2008:Recentinterannual variations of rockglacier creep in the European Alps. 9th International Conference on Permafrost, Fairbanks,UniversityofAlaska:343–348. DelaloyeR.,MORARDS.,AbbetD.,HilbichC.,2010.TheSlumpoftheGrabenguferRockGlacier(SwissAlps). 3rdEuropeanConferenceonPermafrost(EUCOPIII),Svalbard,Norway:157. DobinskiW.,2011:Permafrost.EarthͲScienceReviews108:158–169. FrenchHM.,2007:ThePeriglacialEnvironment.3rdedition.WestSussex:JohnWileyandSons,458pp. Garitte G., 2006: Les torrents de la vallée de la Clarée (Htes Alpes, France). Approche géographique et contribution à la gestion du risque torrentiel dans une vallée de montagne. Thèse Université scientifiqueettechniquedeLille. Hales TC, Roering JJ., 2005: ClimateͲcontrolled variations in scree production, Southern Alps, New Zealand. Geology33:701Ͳ704. KellererͲPirklbauerA.&LiebG.K.,2011:Recentrockglaciervelocitybehaviourandrelatednaturalhazardsin the Hohe Tauern Range, central Austria. PermaNET Project Report Ͳ Contribution of IGRS to Action 6.2/Group1–Rockglacier. KellererͲPirklbauerA.,LiebG.K.,AvianM.&GspurningJ.2008:TheresponseofpartiallydebrisͲcoveredvalley glacierstoclimatechange:TheExampleofthePasterzeGlacier(Austria)intheperiod1964to2006. GeografiskaAnnaler,90A(4):269Ͳ285. Krysiecki,J.M.,Bodin,X.,Schoeneich,P.,2008.CollapseoftheBérardRockGlacier(SouthernFrenchAlps).9th InternationalConferenceonPermafrost,Fairbanks,UniversityofAlaska:153–154. Matsuoka N., 2001: Solifluction rates, processes and landforms: a global review. Earth Science Reviews, 55, 107Ͳ134. PERMOS 2009: Permafrost in Switzerland 2004/2005 and 2005/2006. Nötzli J., Naegeli B., Vonder Mühll D. (eds). Glaciological Report Permafrost N° 6/7, Cryospheric Commission of the Swiss Academy of Sciences. Stingl,H.,Garleff,K.,Höfner,T.,Huwe,B.,Jaesche,P.,John,B.andVeit,H.,2010:Grundfragendesalpinen PeriglazialsͲErgebnisse,ProblemeundPerspektivenperiglazialmorphologischerUntersuchungenim Langzeitprojekt„GlorerHütte“inderSüdlichenGlocknerͲ/NördlichenSchobergruppe(SüdlicheHohe Tauern,Osttirol).SalzburgerGeographischeArbeiten,15Ͳ42.

15     2. TemperatureChangeintheEuropeanAlps   

  Citationreference KroisleitnerCh.,ReisenhoferS.,SchönerW.(2011).Chapter2:ClimateChangeintheEuropeanAlps. InKellererͲPirklbauerA.etal.(eds):Thermaland geomorphic permafrostresponse topresentand future climate change in the European Alps. PermaNET project, final report of Action 5.3. OnͲline publicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.16Ͳ27.  Authors Coordination:ChristineKroisleitner Involvedprojectpartnersandcontributors: Ͳ CentralInstituteforMeteorologyandGeodynamics(ZAMG)–ChristineKroisleinter,Stefan Reisenhofer,WolfgangSchöner  Content Summaryfordecisionmakers 1. Temperaturechangeintherecentpast 2. Projectedtemperaturechangeuntil2050 References

 16 PermaNET–ClimateChangeintheEuropeanAlps

Summary  TheairtemperatureintheEuropeanAlpshasincreasedbyabout2°Csincethelate19thcentury. The warming was particularly pronounced since the beginning of the 1980s. The temperature increasewasassociatedwithdegradationoftheAlpinepermafrost.Thispapersummarizesthe observedchangesofairtemperatureandusesresultsfromclimatemodelsimulationstoderive future scenarios of air temperature in the Alps for the period 2021Ͳ2050. In order to provide morerelevantinformationonthermalresponseofpermafrostthepaperusesanempiricalmodel torelateairtemperaturedatatonumberoffrostdays,numberoficedaysandnumberoffreezeͲ thawdaysfortheAlpsataltitudesabove1800ma.s.l.forboththepresentclimate(reference period 1961Ͳ90) and for a future climate 2021Ͳ2050. The model results show that highest numbersoffreezeͲthawdaysaresimulatedforaltitudesof1800ma.s.l.(evenhighervaluesare modeledforlowerelevations)withabout100daysperyearanddecreasingnumberoffreezeͲ thawdayswithincreasingelevation.Moreover,themodelshowsthatthenumberoffreezeͲthaw dayswillgenerallyincreaseforaltitudesabove1800ma.s.l.byvaluesupto4daysayearuntil 2021Ͳ2050,thusincreasingtheweatheringatallelevationsabove1800ma.s.l.

17 PermaNET–Permafrostresponsetoclimatechange

1. Temperaturechangeintherecentpast The Alps as one of the major topographic forms in Europe influences the atmospheric circulation overawiderangeofscales.Theconsequencesofthisfactareavarietyofdifferentclimates,from maritimetocontinentalandfromlowlandtomountainous.InaclimateanalysisoftheGreaterAlpine Region(GAR)Brunettietal.(2009)highlightedanaverageGARwarmingtrendofabout1.3°Cover thecommonperiodcoveredbyalltheclimatevariables(1886Ͳ2005),1.4°CforthereferenceIPCCͲ period(1906Ͳ2005)whichisawarmingabouttwiceaslargeastheglobaltrendreferredtobyIPCC (2007).Furthermore,Brunettietal.(2009)foundout,thatfortheGARregionthemajorityofthe warmestyearsintheperiod1774Ͳ2005weremeasuredinthepast15to20years.Themostextreme summerwasfoundfor2003,whereasthemostextremesummercoldeventhappenedin1816after thevolcaniceruptionsofTambora.Itisworthnoticingthatthe2003summertemperaturewas4.2 standarddeviationsabovethecorresponding2003summernormalvalue,butthe1816coldextreme was only 2.6 standard deviations lower than the summer normal value corresponding to summer 1816. The20thcenturyclimateinEuropevariednotonlyintime,butalsofromlocationtolocation.1900to 1940, the mean annual air temperature (MAAT) increased in western and northern Europe, while mostoftheremainingpartofthecontinentexperiencedonlysmallchanges.From1940to1975was aperiodofcoolinginthearctic,butincontinentalEuropejustthenorthernpartwasaffectedbythis trend.TheeasternpartofEuropeexperiencedaslightwarmingduringthattimeandthesouthern part kept nearly constant. In the period 1975Ͳ2000 widespread climate warming in Europe was recorded.GenerallytheSouthͲWestofEuropeandScandinaviaweremostaffected,butseasonally therewerelargeregionaldeviationsfromthisannualtrend.Inwinterthetemperatureinnorthern andwesternEuropewasincreasing,whereasinspringthetemperatureroseespeciallyinthecentral andsouthͲwesternparts.SummertemperatureswerecharacterizedbyanincreasealloverEurope, mostpronouncedinthesouthernpart.Autumn’stemperaturewasmainlycharacterizedbyitsspatial variability(Harrisetal.,2009). Climatechangeinthepast250yearsintheAlpshasbeenextensivelystudiedintheprojectHISTALP (Auer et al., 2007). The HISTALP database covers the Greater Alpine Region (GAR) with monthly homogenised records of temperature, pressure, precipitation, sunshine and cloudiness for times datingbackto1760fortemperatureand1800forprecipitation.ThelongͲtermwarmingtrendvisible intheseasonalandannualmeantemperaturetimeseriesofGARcouldnotbeconfirmedforother climateparameters,likeprecipitation,forwhichAueretal.(2005)detectedtwoantagonistictrends, awettingtrendintheNorthͲwestoftheAlps(sincethe1860s)andadryingtrendintheSouthͲeast (since 1800). Remarkably, even the highest mountain observatories within the Alps such as Sonnblick,JungfraujochandZugspitzeshowthesametemperaturetrendsasMunich,Vienna,Milano orSarajevo.TheglobalmeantemperatureseriesshowonlyhalfofthelongͲtermwarmingoftheAlps sincethemidͲ19thcentury.  2. Projectedtemperaturechangesuntil2050 2.1Introduction Asinthepast,theAlpswillalsoinfuturebeexposedtoastrongerwarmingthantheearthingeneral. AccordingtotheIPCC(2007)scenarios,thetemperatureforwholeEuropewillrisefor3.3°,whereas theAlpswillhavetofaceatemperatureriseof3.9°Cuntiltheendofthe21stcentury(Figure1).In thehighͲmountainareasabove1500ma.s.l.thewarmingfromclimatemodelprojectionscouldbe evenhigher(4.2°C;EEAReportNo.8,2009). 

 18 PermaNET–ClimateChangeintheEuropeanAlps

 Fig.1–Temperatureanomaly1860to2100fortheGreaterAlpineRegion(GAR)relativetotheWMO normalperiod1961Ͳ1990derivedfromtheIPCCͲAR4AOGCMMultimodelEnsemble(anthropogenic andnaturalforcingpriorto2001,anthropogenicforcingonlyfrom2001Ͳ2100).Thegreenlineshows measuredtemperatureanomaliesfromtheHISTALPͲproject.(Source:Schöneretal.,2011). 

 2.2 Experimentaldesign Althoughpermafrostinthehighmountainareasisnotverywellknownyet,itisobviousthatthereis arelationshiptoclimaticelements.However,ifthisrelationshipwouldbeeasytodescribe,itwould have been done decades ago. The relationship of nearͲsurface permafrost temperatures and air temperature is strongly affected by snow thickness and duration, which are themselves driven by atmospheric conditions (Harris et al., 2009). This investigation does not focus on change in the permafrostͲdistribution, but on the change in atmospheric frostͲbehaviour. The presence of frost above the earth’s surface is crucial for the existence of permafrost, but furthermore for the developmentandconservationofasnowcover. The core of this investigation is the comparison of frostͲ, iceͲ, and freezeͲthaw days between the climateperiods1961Ͳ90and2021Ͳ2050.Adaybecomesclassifiedasfrostday(FD),whenthedaily minimumtemperatureisbelowzero.Ifalsothedailymaximumtemperatureisbelowthefreezing point, the day is classified as ice day (ID). The difference between ice days and frost days, which meansalldayswithadailyminimumtemperaturebelow0°Candadailymaximumabovethislimit, get classified as freezeͲthaw days (FTD). It is obvious from future climate scenarios, that frost frequencywillgetless. Accordingtotheclimatictrend,severalAlpineregionsexperiencedadecreaseinfrostfrequency(FF) andanextensionofthefrostͲfreeseason(Aueretal.2005).InAustriaobservationsindicate,that duringthe20thcenturyareductionofthefrostseasonby17daysintheflateasternregion(Vienna) and by 22 days in the high Alpine region around the mountain peak station of Sonnblick (3100m a.s.l.)hashappened.

19 PermaNET–Permafrostresponsetoclimatechange

Incanbeassumed,thatinawarmerclimatetheintensityoffrostweatheringchanges,causedbythe spreadingofthefreezeͲthawͲcyclesͲzonetohigher altitudes.Howthischangecouldhappeninan A1B climate scenario was investigated for the high mountainous zone of the entire Alps above 1800ma.s.l.  2.3 Empiricalapproachtoestimatefrostdays,icedaysandfreezeͲthawdays Auer et al. (2005) found an empirical relationship of a tangens hyperbolicus function to estimate frostfrequency(FF)frommonthlymeanairtemperature.FFisdefinedbythenumberoffrostdays dividedbythenumberofdayswithintheconsideredmonth.ThetanhͲfunctionwascalculatedusing temperature data from 363 climate stations in Austria including the high alpine station Sonnblick (3105ma.s.l.).Aueretal.(2005)calculatedatleast66%FF(20.5FD)forJanuaryinAustriaforall stations.InApriltheFFcoveredawidespectrum,from100%(30FD)atthemountainpeakstation Sonnblicktonearlynofrostinthelowlands.InJulyonlyatthemountainstationSonnblickfrostdays were registered. Hence, without taking into account highͲelevation mountain stations it would be impossibletoreceiverobustcoefficientsforthemodel.Overall,thetanhͲmodelwasabletoexplain abound55%ofthethevarianceofFFdatafromairtemperaturedata.Validationofthemodelwith datafromtheentireGARshowedthatthereisalmostnodifferenceintheperformanceifthemodels arecalibratedonAustriandataorondatafortheentireGAR(seeAueretal.,2005,fordetails). IncontrarytoAueretal.(2005)inourstudyweused30Ͳyearsclimatenormals(1961Ͳ90)torelate annualfrostdaystoannualairtemperaturemeans,whichsignificantlyincreasedtheperformanceof statisticalrelationships.Thisapproachismotivatedfromtheaimofthisstudytocomparepresent meanclimatewithafutureclimatemeanscenarioforbothfrostdaysandicedays.Consequently, the frequency of ice days (as the number of ice days divided by the number of days within the consideredmonth)wererelatedinasamemannertomeanannualairtemperatureusingatanhͲfit forthereferenceperiod1961Ͳ90.ThestatisticsofthederivedtanhͲmodelsareshowninTables1and 2.InafinalstepthefreezeͲthawdayswerecalculatedfromthedifferencebetweenicedaysandfrost days.  Table1–Statisticalmodel(generalmodel,coefficientsandgoodnessoffit)inordertocomputeannualfrostday frequency(f(x))fromannualairtemperature(x)forthereferenceperiod1961Ͳ90

Coefficients Generalmodel Goodnessoffit (with95%confidencebounds) 

SSE:3530 a=Ͳ0.09316(Ͳ0.0947,Ͳ0.09163) RͲsquare:0.9847 f(x)=50+(50*tanh(a*x+b)) b=0.3437(0.3328,0.3546) AdjustedRͲsquare:0.9847  RMSE:2.77 

 

 20 PermaNET–ClimateChangeintheEuropeanAlps

MeanAnnualAiremperature(°C)   Fig.2–RatiofrostdaystototaldaysversusmeanannualairtemperatureinAustriausingdatafrom 363climatestationsinAustriafortheperiod1961Ͳ90.TheredlineisatanhͲfit.Statisticalmeasures ofthefitareshowninTable1.

MeanAnnualAiremperature(°C)   Fig.3–RatioicedaystototaldaysversusmeanannualairtemperatureinAustriausingdatafrom 363climatestationsinAustriafortheperiod1961Ͳ90.TheredlineisatanhͲfit.Statisticalmeasures ofthefitareshowninTable2.

21 PermaNET–Permafrostresponsetoclimatechange

 Table2–Statisticalmodel(generalmodel,coefficientsandgoodnessoffit)inordertocomputeannualiceday frequency(f(x))fromannualairtemperature(x)forthereferenceperiod1961Ͳ90

Coefficients Generalmodel Goodnessoffit (with95%confidencebounds) 

SSE:1323

a=Ͳ0.1248(Ͳ0.1259,Ͳ0.1236) RͲsquare:0.9951 f(x)=50+(50*tanh(a*x+b)) b=Ͳ0.3573(Ͳ0.3638,Ͳ0.3507) AdjustedRͲsquare:0.995 RMSE:1.696

 2.4 Empiricalapproachtoestimatefrostdays,icedaysandfreezeͲthawdaysfortheentireAlps WeusedthespatiallyhighͲresolutiontemperatureclimatologyofHiebletal.(2009)tocomputethe numberoffrostdays,thenumberoficedaysandthenumberoffreezeͲthawdaysfortheAlpine region for both the present climate and the future climate 2021Ͳ2050. However, our study was restrictedtotheAlpineareaabove1800ma.s.l.asthezonemostrelevantforpermafrost.Inafirst stepthe~1kmresolutionGARmonthlytemperatureclimatology(1961Ͳ90)wasdownscaledusingthe ~30mͲresolution ASTER GDEM for the high mountain area of the Alps. The temperatureͲgrid was recalculatedaccordingtotheapproachofHiebletal.(2009),whichheusedforthedevelopmentof the~1kmspatialresolutionGARͲclimatologybasedon1961Ͳ1990climatenormals.TheworkofHiebl etal.(2009)isbasedonastationnetworkof1,726climatestationsfortheGreaterAlpineRegion, whichwerecarefullyqualitycheckedandhomogenized.

AccordingtoHiebletal.(2009)weusedseveralgeographicalvariablestocomputeairtemperature bymeansofamultilinearregressionapproach: x Thelongitudinalgradientstakeintoaccounttheunderlyingoceanictocontinentaltransition, whichoccursfromthewesterntotheeasternedgeoftheGAR.However,thevarianceof temperatureexplainedfromlongitudeislimitedto1%oftheannualvariance. x Onthecontrarytothissmallamount,latitudeexplained19%ofthevarianceofannualair temperaturebymainlycapturingtheeffectoftheSouthͲNorthsolarradiationgradienton temperature. x Asexpected,thelargestpartoftemperaturevariancecouldbeexplainedbyelevation.The verticalregressionmodelexplainsasmuchas69%ofthetemperaturevariancefortheyearly averages,althoughduringwinterduetostableatmosphericlayeringthevaluedecreasesto around45%. x For considering different temperature behaviours at low altitude areas and high altitude areasHiebletal.(2009)introduceda3verticallayersͲmodel.Thelowestlayerrangesfrom 600minthesouthernpartsupto800minthewesternpartsoftheGAR.Thehighelevation layersverticalextentbeginsat1800ma.s.l.Betweenthetwolayersthetemperatureswere simplyinterpolated.Inourstudyweusedonlythehighest(above1800ma.s.l.)layer. x Slopes got implemented in the model by using an analysis of Auer & Böhm (2003) which systematicallyanalyseddatafrom85Austriansiteswithdetailedsitedescription.Theyfound

 22 PermaNET–ClimateChangeintheEuropeanAlps

monthlydeviationsfromthemeanforNorthͲandSouthͲfacingslopesrangingfromͲ0.2to 1.0°C. x Maritimeinfluencewastakenintoaccountbyestablishingatopographicallyweightedfield of distances from the coast. Hiebl et al. (2009) found a surprisingly strong dependency of temperature on distance from the coast. At a yearly average the distance to the coast variableexplained41%ofthetemperaturevariance.

 The30yearhighͲalpinemonthlymeantemperatureswerecalculatedfromthefollowingregression equation:  t01=9.412932+Ͳ0.190362*[lon_1]+Ͳ0.035543*[lat_1]+Ͳ0.005002*[DEM]+Ͳ0.003347*[coast]  [lon_1]Ælongitude [lat_1]Ælatitude [DEM]Ædigitalelevationmodel [coast]Æcoastdistancegrid  As shown by Hiebl et al. (2009), considering longitude, latitude and the distance from the coasts besides elevation reduced the average monthly standard error to 0.79°C per month. Furthermore Hiebl et al. (2009) used the GTOPO30ͲDEM with a spatial resolution of 30 arc seconds, which corresponds to about 1km. GTOPO30 has a root mean square error of about 18m. Applied on monthlylapseratemodels,theDEMinaccuracyleadstoatemperatureerrorof0.09°Conaverage. In this study we used the empirical temperature model of Hiebl et al. (2009) but replaced the GTOPO30ͲDEMbytheASTERGDEM,thusrefiningthespatialresolutionoftemperaturegridto1arc second(~30m).ComparedtoGTOPO,withanerrorofsurfaceelevationofabout18m,theASTER GDEM has an overall root mean square error of 10.87m. The error of surface elevation can be assumedtobeapproximately20mataconfidencelevelof95%. Based on the refined climatology (climate normal 1961Ͳ90) of annual air temperature and the empiricalmodelsforfrostdays(Tab.1andFig.2)andforicedays(Tab.2andFig.3)30mͲrasterdata ofclimatenormals(referenceperiod1961Ͳ90)offrostdaysandicedaysfortheAlpineregionwere computed.  2.5 Estimationoffuturefrost,iceandfreezeͲthawͲcyclesdaysscenariosfortheperiod2021Ͳ2050 For projecting the temperature of the Alps for the future period 2021Ͳ2050 we used the regional climate model experiment of Hollweg et al. (2008) which dynamically downscaled the ECHAM5Ͳ MPIOMͲA1B scenario (Röckner et al., 2003) by means of the regional climate model CLM. The performance of this CLM model run for the GAR was extensively tested in Schöner et al. (2011). Particularly,itwasshownbySchöneretal.(2011)thatcomparedtoanensemblessimulationforthe Alpineregion(usedfromthePRUDENCEensembles;seeFreietal.,2006)theusedCLMsimulation showsatemperaturechangewhichliesclosetotheensemblesmedian.Thespatialpatternofthe temperaturechangefor2021Ͳ2050relativeto1976Ͳ2007derivedfromtheCLMsimulationisshown inFigure4.ThespatialresolutionoftheCLMgridis18x18km. 

23 PermaNET–Permafrostresponsetoclimatechange

 Fig. 4 Ͳ Change of seasonal mean temperature (left: winter season, right: summer season) for the GreaterAlpineRegionfor2021Ͳ2050relativeto1976Ͳ2007(fromSchöneretal.,2011,sourceforCLM data:Hollwegetal.,2008).  The spatial distributions of the number of frost days, the number of ice days and the number of freezeͲthawdaysfortheclimatereferenceperiod1961Ͳ90fortheregionoftheEuropeanAlpswith elevationshigher1800ma.s.l.areshowninFigures5,6and7.ThehighestnumberoffreezeͲthaw dayswerecomputedforlowestelevationscloseto1800ma.s.l.Withhigherelevationsthenumber offreezeͲthawdaysdecreasesfromabout100daysat1800ma.s.l.tolessthan15daysathighest elevationsoftheAlps.Changesinthenumberoffrostdays,thenumberoficedaysandthenumber offreezeͲthawdaysaredisplayedinFigures8,9and10fortheperiod2021Ͳ2050relativeto1961Ͳ90 based on the temperature change from the CLM simulations. Temperature increase will generally increasethenumberoffreezeͲthawdaysbynumbersupto4daysperyear,thusincreasingalsothe frostweathering.   Acknowledgements.–ThedigitalelevationmodelwascontributedbyMETIandNASAtotheGlobal EarthObservationSytemofSystems(GEOSS)andwasdownloadedfromtheEarthRemoteSensing DataAnalysisCenter(ERDSAC)ofJapanandNASA`sLandProcessDistributedActiveArchiveCenter (LP DAAC) http://asterweb.jpl.nasa.gov/gdem.asp. Climate model results of CLM regional climate model were provided by Deutsches Klimarechenzentrum within the frame of the project AnpassungsstrategienandenKlimawandelfürÖsterreichsWasserwirtschaft. 

 24 PermaNET–ClimateChangeintheEuropeanAlps

Fig.5–Frostdays(1961Ͳ90)intheAlpsforthesubregionwithelevationabove1800ma.s.l.

Fig.6–Icedays(1961Ͳ90)intheAlpsforthesubregionwithelevationabove1800ma.s.l.

 Fig.7–FreezeͲthawdays(1961Ͳ90)intheAlpsforthesubregionwithelevationsabove1800ma.s.l.

25 PermaNET–Permafrostresponsetoclimatechange

 Fig.8–Estimateddifferenceinfrostdaysbetween1961Ͳ90and2021Ͳ2050forthesubregionwith elevationsabove1800ma.s.l.

 Fig. 9 – Estimated difference in ice days between 1961Ͳ90 and 2021Ͳ2050 for the subregion with elevationsabove1800ma.s.l.

 Fig.10–EstimateddifferenceinfreezeͲthawdaysbetween1961Ͳ90and2021Ͳ2050forthesubregion withelevationsabove1800ma.s.l.

 26 PermaNET–ClimateChangeintheEuropeanAlps

References: ASTER GDEM Validation Team, 2009: METI/ERSDAC, NASA/LPDAAC, USGS/EROS, (2009): ASTER GlobalDEMValidationSummaryReport,June2009 Auer I. & Böhm R., 2003: Jahresmittel der Lufttemperatur. Hydrologischer Atlas Österreichs. ÖsterreichischerKunstͲundKulturverlag,Vienna,MapSheet1.6. AuerI.,MatullaC.,BöhmR.,UngersböckM.,MaugeriM.,NanniR.,PastorelliR.,2005:Sensitivityof frostoccurrencetotemperaturevariabilityintheEuropeanAlps.Int.JournalofClimatology, 25,1749Ͳ1766. AuerI.,BöhmR.,JurkovicA.,LipaW.,OrlikA.,PotzmannR.,SchönerW.,UngersböckM.,MatullaCh., BriffaK.,JonesP.,EfthymiadisD.,BrunettiM.,NanniT.,MaugeriM.,MercalliL.,MestreO., MoisselinJ.ͲM.,BegertM.,MüllerͲWestermeierG.,KvetonV.,BochnicekO.,StastnyP.,Lapin M.,SzalaiS.,SzentimreyT.,CegnarT.,DolinarM.,GajicͲCapkaM.,ZaninovicK.,MajstorovicZ. &NieplovaE.2007:HISTALP–Historicalinstrumentalclimatologicalsurfacetimeseriesof theGreaterAlpineRegion1760Ͳ2003.InternationalJournalofClimatology,27,17Ͳ46. BrunettiM.,LentiniG.,MaugeriM.,NanniR.,AuerI.,BöhmR.,SchönerW.,2009:Climatevariability andchangeintheGreaterAlpineRegionoverthelasttwocenturiesbasedonmultiͲvariable analysis.Int.JournalofClimatology,Vol.29,Issue15,2197Ͳ2225DOI:10.1002/joc.1857 EEAReportNo.8,2009:Regionalclimatechangeandadaptation.TheAlpsfacingthechallengeof changingwaterresources.EuropeanEnvironmentAgency,Copenhagen,143pp. FreiC.,SchöllR.,FukutomeS.,SchmidliJ.,VidaleP.L.,2006:Futurechangeofprecipitationextremes inEurope:Intercomparisonofscenariosfromregionalclimatemodels.JournalofGeophysical Research,111:D06105 HarrisC.,ArensonL.U.,ChristiansenH.H.,EtzelmüllerB.,FrauenfelderR.,GruberS.,HaeberliW., Hauck C., Hölzle M., Humlum O., Isaksen K., Kääb A., KernͲLütschg A.M., Lehning M., MatsoukaN.,MuronJ.B.,MötzliJ.,PhilipsM.,RossN.,SeppäläM.,SpringmanS.M.,Vonder Mühll D., 2009: Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphologicalandgeotechnicalresponses.EarthͲScienceReviews,92,117Ͳ171. HieblJ.,AuerI.,BöhmR.,SchönerW.,MaugeriM.,LentiniG.,SpinoniJ.,BrunettiM.,NanniT.,Tadiđ PerēecM.,BihariZ.,DolinarM.,MüllerͲWestermeierG.,2009:AhighͲresolution1961Ͳ1990 monthlytemperatureclimatologyfortheGreaterAlpineRegion.MeteorologischeZeitschrift, 18,507Ͳ530. HollwegH.D.,BöhmU.,FastI.,HennemuthB.,KeulerK.,KeupͲThielE.,LautenschlagerM.,Legutke S., Radtke K., Rockel B., Schubert M., Will A., Woldt M., Wunram C., 2008: Ensemble simulationsoverEuropewiththeregionalclimatemodelCLMforcedwithIPCCAR4Global Scenarios.M&DTechnicalReport,3,2008. IPCC,2007:ClimateChange2007:ThePhysicalScienceBasis.ContributionfromtheWorkingGroupI to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. CambridgeUniversityPress:Cambridge,UnitedKingdomandNewYork,NY,USA,996pp. RöcknerE.,BäumlG.,BonaventuraL.,BrokopfR.,EschM.,GiorgettaM.,HagemannS.,KirchnerI., Kornblueh L., Manzini E., Rhodin A., Schlese U., Schulzweida U., Tompkins A., 2003: The atmospheric general circulation model ECHAMͲ5, Part I: Model description. MaxͲ PlanckͲ InstitutfürMeteorologie,Report349. Schöner W., Böhm R., Haslinger K., 2011: Klimaänderung in Österreich – hydrologisch relevante Klimaelemente.Österr.WasserͲundAbfallwirtschaft1Ͳ2/2011,11Ͳ20

27     3. CasestudiesintheEuropeanAlps   3.1 Overviewoncasestudies   

  Citationreference KellererͲPirklbauerA,LiebG.K.(2011).Chapter3.1:CasestudiesintheEuropeanAlps–Overviewon casestudies.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.28Ͳ34.  Authors Coordination:AndreasKellererͲPirklbauer Involvedprojectpartnersandcontributors: Ͳ Institute of Geography and Regional Science, University of Graz, Austria (IGRS) – Andreas KellererͲPirklbauer,GerhardKarlLieb   Content Summary 1. Theregionaldistributionofthecasestudies 2. Projectpartnersandresearchactivities 3. Structureofthecasestudies References

 28 PermafrostResponsetoClimateChange

Summary  Thecasestudiesprovideinformationrelevantofthereactionsofpermafrosttoclimatechange from study sites which are distributed between 47°22’ and 44°59’N and between 06°10’ and 14°41’E,respectively,coveringagreatpartoftheAlpineArc.Fromaspatialpointofview,the resultsthuscanbeconsideredsufficientlyrepresentativefortheentireAlps.Themethodology usedcoversabroadspectrumoftechniquesmakingtheresultswellreliable. Alltheactivitieswerecarriedoutbyscientificinstitutionswhicharewellprovidedwithbestlocal field experience and in many cases with regional actor networks. All the case studies have a similarconceptualstructurebeginningwithashortpresentationofthesite,thengivingconcise informationonthemethodsusedandtheresultselaborated. Eachcasestudyfinallyprovidessomeassumptionsonthefuturedevelopmentofpermafrostin therespectiveareatakingintoaccounttheclimatescenariopresentedinChapter2.

29 PermaNET–Permafrostresponsetoclimatechange

1. Theregionaldistributionofthecasestudies Theassessmentofthermalanddynamicreactionscenariosofdifferentpermafrostsitesiscarriedout at13siteswithintheEuropeanAlps.Figures1and2depictthelocationofthestudysiteswithinthe AlpineArcaswellasvisualimpressionsofthestudysites.Table1givesanoverviewforeachofthese study sites. The study sites are distributed between 47°22’ and 44°59’ N and between 6°10’ and 14°41’ E, respectively, with Hochreichart (A) being the northernmost and easternmost and Bellecombes (F) the westernmost and southernmost site. Thus the sites cover a great part of the AlpineArcwiththeexceptionoftheSwissAlps(whicharemissingduethecompositionoftheproject staff).ThesitesalsocoverthemostimportantgeologicalunitsoftheAlps(e.g.metamorphicrocksof theCentralZoneoftheEasternAlpsandlimestonesoftheSouthernAlpsaswellasgranitesofthe CentralMassivesoftheWesternAlps).Thus,intermsofthegeographicaldistribution,theresultscan beconsideredsufficientlyrepresentativefortheentireAlps. 

 Fig.1–Locationofthe13PermaNETstudysitesrelevantfortheassessmentofthermalanddynamic reactionscenariosofdifferentpermafrostsitesintheEuropeanAlps.   2. Projectpartnersandresearchactivities Table 1 gives an overview on the study sites containing for each one its name, country, location, elevation, studied landform and processes, research initiation, type of permafrost monitoring site and the institution which has responsibly coordinated the documentation of the respective case study. All persons involved in elaborating the case studies are kindly acknowledged and listed in Table2.Informationontherelevanceofthecharacterofthedifferentpermafrostmonitoringsitesas wellaslandformsandprocessesisgiveninChapter4. 

 30 PermafrostResponsetoClimateChange

 Fig.2–Visualimpressionsof9ofthe13PermaNETstudysitesrelevantfortheassessmentofthermal anddynamicreactionscenarios.ThenumbersinbracketsrefertothenumbersinFig.1.Thestudy sitesrangefromjustbelow2000ma.s.l.(studysiteHochreichart)toabout4000ma.s.l.(studysites intheAiguilleduMidì).Allphotographsprovidedbytheauthors.

31 PermaNET–Permafrostresponsetoclimatechange

  Table 1 – Overview of the study sites investigated in order to assess the thermal and dynamic reaction of permafrost to climate change in the Alps within action 5.3 of the project PermaNET. The different types of permafrost monitoring sites are: PFͲbedrock=Permafrost in bedrock (from nearͲvertical rockwalls to flat morphologies);PFͲfine=PermafrostinfineͲgrainedmaterial(flatmorphology);PFͲcoarse=PermafrostincoarseͲ grained and blocky material (scree slopes, rock glaciers; from slopes to rather flat morphologies). Project partners and collaborators: ARPA VdA=Regional Agency for the Environmental Protection of Valle d'Aosta, Aosta,Italy;ARPAV=EnvironmentProtectionRegionalAgencyofVeneto;UIBK=InstituteofGeology,University ofInnsbruck,Innsbruck,Austria;IGRS=InstituteofGeographyandRegionalScience,UniversityofGraz,Graz, Austria;ZAMG=CentralInstituteforMeteorologyandGeodynamics,Vienna,andRegionalOfficeforSalzburg andUpperAustria,Salzburg,Austria;IGAͲPACTE=InstitutdeGéographieAlpine,UniversityofGrenoble,France; EDYTEM=EDYTEMLab,UniversitédeSavoie;UniPavia=EarthScienceDepartment,UniversityofPavia,Pavia, Italy;Abenis=AbenisAlpinexpertGmbh/srl,Bozen/Bolzano,Italy.  Elevation Main ReͲ Permafrost Nameofstudysite range/ studied search Coordinator’ Con. Latitude Longitude monitoring (codeseeFig.1) max. landform or initiaͲ sinstitution site (ma.s.l.) process tion rock glacier, PFͲbedrock Hochreichart(1) A 47°22’N 14°41’E 1920Ͳ2415 rock wall, 2004 IGRS PFͲcoarse detritus PFͲbedrock rock glacier, DösenValley(2) A 46°59’N 13°17’E 2400Ͳ3000 1995 PFͲfine IGRS rockwall PFͲcoarse bedrock, PFͲbedrock HoherSonnblick(3) A 47°03’N 12°57’E 3105 2007 ZAMG detritus PFͲcoarse OuterHocheben A 46°50’ 11°01’ 2360Ͳ2840 rockglacier 1938 PFͲcoarse UIBK Cirque(4) Combe du F 45°56’N 06°24’E 2450Ͳ2630 rockglacier 1979 PFͲcoarse IGAͲPACTE Laurichard(5) Bellecombes(6) F 44°59’N 06°10’E 2600Ͳ2800 rockglacier 2007 PFͲcoarse IGAͲPACTE Aiguille du Midì* nearͲvertical (Mont Blanc Massif) F 45°53’N 06°53’E 3840 2005 PFͲbedrock EDYTEM rockwalls (7) MontBlancMassif nearͲvertical F 45°50’N 06°52’E 3000Ͳ4000 2006 PFͲbedrock EDYTEM (othersitesas*)(8) rockwalls Cime Bianche Pass bedrock, PFͲbedrock I 45°55’N 07°41’E 3100 2005 ARPAVdA (9) detritus PFͲcoarse ValdiGenova(10) I 46°13’N 10°34’E 2750Ͳ2860 rockglacier 2001 PFͲcoarse UniPavia Vald’Amola(11) I 46°12’N 10°42’E 2330Ͳ2480 rockglacier 2001 PFͲcoarse UniPavia PFͲcoarse PizBoè(12) I 46°30’N 11°50’E 2900Ͳ2950 rockglacier 2005 ARPAV PFͲbedrock UpperSuldenValley PFͲcoarse Abenis I 46°30’N 10°37’E 2600Ͳ3150 detritus 1992 (13) PFͲfine Alpinexpert

 32 PermafrostResponsetoClimateChange

Table2–PersonsinvolvedinelaboratingthecasestudiesofAction5.3andtheiraffiliations.

Casestudy Name Institution (Chapter) Baroni,Carlo UniversityofPisa(Italy) 3.11.,3.12. Bodin,Xavier UniversityJosephFourier,Grenoble(France) 3.6. Cagnati,Anselmo RegionalAgencyfortheEnvironmentalProtectionofVeneto(Italy) 3.13. Carollo,Federico E.P.C.EuropeanProjectConsultingS.r.l.(Italy) 3.13. Coviello,Velio NationalCenterforScientificResearchEDYTEM,Grenoble(France) 3.8. Cremonese, RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) 3.8.,3.10. Edoardo Crepaz,Andrea RegionalAgencyfortheEnvironmentalProtectionofVeneto(Italy) 3.13. Dall’Amico,Matteo MountainͲeeringsrl(Italy) 3.11.,3.12. Defendi,Valentina RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) 3.13. Deline,Philip NationalCenterforScientificResearchEDYTEM,Grenoble(France) editor, 3.8., 3.9. Drenkelfluss,Anja UniversityofBonn(Germany) 3.8. Galuppo,Anna RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) 3.13. Gruber,Stephan UniversityofZurich(Switzerland) 3.8. KellererͲPirklbauer, UniversityofGraz(Austria) editor,3.2,3.3 Andreas Kemna,Andreas UniversityofBonn(Germany) 3.8. Klee,Alexander CentralInstituteforMeteorologyandGeodynamics(Austria) 3.4. Krainer,Karl UniversityofInnsbruck(Austria) 3.5. Krautblatter, UniversityofBonn(Germany) 3.8. Michael Krysiecki,JeanͲ UniversityJosephFourier,Grenoble(France) 3.6. Michel LeRoux,Olivier Associationpourledéveloppementdelarecherchesurlesglissementsde 3.7. terrain(France) Lieb,GerhardKarl UniversityofGraz(Austria) editor,3.2,3.3 Lorier,Lionel Associationpourledéveloppementdelarecherchesurlesglissementsde 3.7. terrain(France) Magnabosco,Laura RegioneVeneto,DirezioneGeologiaeGeorisorse,ServizioGeologico(Italy) 3.13. Magnin,Florence NationalCenterforScientificResearchEDYTEM,Grenoble(France) 3.8. Mair,Volkmar AutomousProvinceofBolzano(Italy) 3.14. Malet,Emmanuel NationalCenterforScientificResearchEDYTEM,Grenoble(France) 3.8. Marinoni, Freelancer(Italy) 3.13. Francesco MorradiCella, RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) 3.8.,3.10. Umberto Noetzli,Jeanette UniversityofZurich(Switzerland) 3.8. Pogliotti,Paolo RegionalAgencyfortheEnvironmentalProtectionoftheAostaValley(Italy) editor, 3.8., 3.10. Ravanel,Ludovic NationalCenterforScientificResearchEDYTEM,Grenoble(France) 3.8.,3.9. Riedl,Claudia CentralInstituteforMeteorologyandGeodynamics(Austria) 3.4. Rigon,Riccardo UniversityofTrento(Italy) 3.11.,3.12. Schöner,Wolfgang CentralInstituteforMeteorologyandGeodynamics(Austria) editor, 3.6., 3.7. Seppi,Roberto UniversityofPavia(Italy) 3.11. Vallon,Michel UniversityJosephFourier,Grenoble(France) 3.7. Zampedri,Giorgio GeologicalSurvey,AutonomousProvinceofTrento(Italy) 3.11.,3.12. Zischg,Andreas AbenisAlpinexpertGmbH/srl(Italy) 3.14. Zumiani,Matteo Geologist(Italy) 3.11.,3.12. 

33 PermaNET–Permafrostresponsetoclimatechange

3. Structureofthecasestudies Inordertofacilitatethecomparisonbetweenthedifferentcasestudiesallofthemusemoreorless thesamestructureasfollows: x Summary x Short introduction into the case study site and the relevant landform (in most cases with detailedmapsandphotographs) x Methodology (in most cases a set of different methods has been used, see discussion in Chapter4) x Recentthermaland/orgeomorphicevolutionoftherelevantlandform(s)(inmostcaseswith graphs,forthecoveredtimespansseediscussioninChapter4) x Assumptionsonpossiblefuturethermal/geomorphicresponseofthislandformtopredicted climatechange(takingintoaccounttheclimatescenariopresentedinChapter2) x Referencelist. 

 34     3. CasestudiesintheEuropeanAlps   3.2 Hochreichart,EasternAustrianAlps   

  Citationreference KellererͲPirklbauerA(2011).Chapter3.2:CasestudiesintheEuropeanAlps–Hochreichart,Eastern AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.35Ͳ44.  Authors Coordination:AndreasKellererͲPirklbauer Involvedprojectpartnersandcontributors: Ͳ Institute of Geography and Regional Science, University of Graz, Austria (IGRS) – Andreas KellererͲPirklbauer  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

 35 PermaNET–CasestudiesintheEuropeanAlps

Summary  Knowledge regarding marginal permafrost zones in the European Alps is fairly limited. A permafrost research project in the Seckauer Tauern, focusing particularly on the Mt. HochreichartͲReichart Cirque area (47°22’N, 14°41’E), Austria, was initiated in 2004 by the author.Since2006,theresearchactivitieswerecarriedoutwithintheprojectsALPCHANGEand PermaNET. Based on geomorphic mapping, numerical permafrost modelling, multiͲannual measurementsofthebottomtemperatureofthesnowcover(BTS),continuousmeasurementsof groundsurface,neargroundsurfaceandairtemperaturesbyminiaturetemperaturedataloggers (MTD), geoelectrics and optical snowͲcover monitoring by a remote digital camera (RDC) the existence of permafrost was proven. Patches of permafrost are strongly related to elevation, aspect,grainsizeofthesediments,andcharacteristicsofwintersnowcover.Therefore,thestudy site is the most easterly evidence of existing permafrost found in the entire European Alps at 14°41’Einelevationsaslowas1900masl.Predictingclimatewarmingwillsubstantiallyinfluence the permafrost distribution and geomorphic dynamics in the study area HochreichartͲReichart Cirque.By2050,permafrostwillbealmostcompletelythawedapartfromfewhighͲelevatedsites where the substrate material (coarseͲblocky material) and topoclimatic conditions (radiation, snowcover)stillallowsmallpatchesofpermafrost.

 36 PermafrostResponsetoClimateChange

1. Introductionandstudyarea Mountain permafrost is a widespread phenomenon in alpine regions in the European Alps. For instance,some2000km²or4%oftheAustrianAlpsareunderlainbypermafrost(Lieb1998).Upto recent times most research on permafrost issues in Austria focused on the central and highest sectionoftheAustrianAlps.Bycontrast,knowledgeconcerningmarginalpermafrostzonesisfairly limitedsofar. ToincreaseknowledgeabouttheeasternmostlimitofpermafrostintheEuropeanAlps,aresearch projectfocusingontheSeckauerTauernMountains(14°30’Eto15°00’E)andparticularlyontheMt. Hochreichartarea(47°22’N,14°41’E) wasinitiatedin2004 by theauthor(Fig.1).Firstpermafrost resultswerepublishedinKellererͲPirklbauer(2005).Theresearchactivitieswerecontinuedbetween 2006and2010withintheprojectALPCHANGEandsince2008withinPermaNET.  

 Fig.1–LocationofthestudyregionSeckauerTauernMountainsandthestudyareaMt.Hochreichart  TheSeckauerTauernMountainsaretheeasternmostmountainsoftheTauernRangewhichcovers almost9,500km²inAustriaandItaly.TheSeckauerTauerhaveaspatialextentof626km²andits highest peak is Mt. Geierhaupt reaching 2417 m asl (KellererͲPirklbauer 2008). Research in the SeckauerTauernMountainsfocusesspatiallyonthesummitareaofMt.Hochreichart(2416masl) andthenorthͲeastfacingReichartCirque. The study area covers about 1 km² in total, ranging in elevation from about 1800 to 2416 m asl. Bedrock is predominantly quartzite and gneiss. The Reichart Cirque is covered by a large relict polymorphicrockglacierwithaverticalextentofc.450mrangingfromabout1500maslto1950m aslattheuppermostpartoftherootingzone(Fig.2A). Thehigherelevationsofthestudyareawereexposedtointensiveperiglacialweatheringduringthe coldperiodsinthePleistocenecausingtheformationofcoarseͲgrainedautochthonousblockfields (mountainͲtopdetritus)andrectilinearslopeswithsolifluctionlandforms,partlywithmaterialsorting byfrostaction(Fig2B).AccordingtoownairtemperaturemeasurementsbetweenSept.2008and August2009,themeanannualairtemperature(MAAT)atthesummitat2416masl(AT1)isͲ1.4°C,in thecirqueat1920masl(AT2)isabout+2.2°C,revealingameanlapserateof0.0072°C/m.

37 PermaNET–CasestudiesintheEuropeanAlps



 Fig. 2 – (A) Mt. Hochreichart (2416 m asl) and Reichart Cirque with the uppermost part of a polymorphic quasiͲrelict (i.e. contains small patches of permafrost) rock glacier. Locations of the miniaturetemperaturedataloggers/MTDwheregroundsurfacetemperature(GST,blackdots)andair temperature(AT,greydots)aremeasuredandtheprofilewheregeoelectricalmeasurementswere carried out in 2008 (blue and white line) are indicated. (B) Summit of Hochreichart with coarseͲ grainedautochthonousblockfieldswithmaterialsortingbyfrostaction(notethevegetationpatchin frontoftheperson).PhotographsbyA.KellererͲPirklbauer(A)22.09.2007and(B)22.08.2007.  

 Fig. 3 – The study area HochreichartͲReichart Cirque: The distribution of the modelled potential discontinuous permafrost, areas of rock glacier depositis, location of air (AT) and ground surface temperature(GST)measurementsites,andthelocationofthegeoelectricprofileareindicated.

 38 PermafrostResponsetoClimateChange

2. Permafrostindicatorsandrecentthermalevolution 2.1Methods Since2004asuiteofmethodshasbeenappliedsuchasgeomorphicmapping,numericalpermafrost modelling, multiͲannual measurements of the bottom temperature of the snow cover (BTS), continuousmeasurementsofgroundsurface,neargroundsurfaceandairtemperaturesbyminiature temperaturedataloggers(MTD),geoelectricsandopticalsnowͲcovermonitoringbyaremotedigital camera(RDC). Thespatialdistributionofpotentialdiscontinuouspermafrostinthestudyareawasmodelledbyan adaptation of the program PERMAKART (Keller 1992), using GIS ArcView and ArcInfo. Details and resultsofthismodellingapproachwerepublishedinKellererͲPirklbauer(2005). MTDswereusedatninelocationsduringdifferentperiods.Theresultsfromthreesites(Fig.1)with groundsurfacetemperature(GST)measurementsloggedat1hintervalarepresentedhere.Theused loggersareproducedbyGeoPrecision,ModelMͲLog1withPT1000temperaturesensors(accuracy +/Ͳ0.05°C, rangeͲ40 to +100°C, calibration drift <0.01°C/yr). Data of continuous measurements of groundsurfacetemperatureatthethreesitesGST1toGST3wereavailableforthe47Ͳmonthperiod 09.10.2006 to 21.09.2010. At site GST3 malfunction of the logger caused a data gap between 18.05.2007and12.08.2007.InordertoallowcomparisonbetweenthesitesaswellasallowingfullͲ year data analysis, the three fullͲyear periods 01.11.2006Ͳ31.10.2007, 01.11.2007Ͳ31.10.2008 and 01.11.2008Ͳ31.10.2009,wereanalysed.AtGST3,onlythesecondandthirdyearwasconsidered.The dataanalysisfocusedonfrostday(FD),iceday(ID),freezeͲthawday(FTD)andfrostͲfreeday(FFD).A day got classified as FD, when the daily minimum temperature is below zero. If also the daily maximum temperature is among the freezing point, the day got classified as ice day ID. The differencebetweenicedaysandfrostdays,whichmeansalldayswithadailyminimumtemperature below0°Candadailymaximumabovethislimit,gotclassifiedasFTD.Finally,adaywithpositive minimumtemperaturegotclassifiedasFFD. BTSwasmeasuredatReichartCirqueannuallybetweenwinter2004and2009usingathermocouple probePT100(1/3DINclassB)fixedtothebottomofa3mlongsteelrod(SystemKRONEIS,Vienna). BTSisknowntobeagoodindicatoroftheoccurrenceorabsenceofpermafrost.ThemeasuredBTS valuesindicate:BTS>Ͳ2°C:permafrostunlikely;BTSͲ2toͲ3°C:permafrostpossible;BTS<Ͳ3°C: permafrostprobable(Haeberli1973).However,theinterpretationofmeasuredBTSvaluesshouldbe madeverycarefullyandinterannualvariationatagivensitemightvarysubstantialfromoneyearto thenext. In order to verify the temperature data and to extend the spatial knowledge about permafrost distributionbeyondpointinformation,ageoelectricalsurveywascarriedoutattheendofAugust 2008 by applying the electrical resistivity tomography (ERT) method along a 120 m long profile coveringtheupperpartoftherootingzoneofa(moreͲorͲless)relictrockglacierandthetalusslope above.ForthissurveythetwoͲdimensional(2D)electricalsurveyswasperformedusingtheWennerͲ Alfaconfigurationwith2.5mspacingandanLGMͲLippmann4ͲPunktlighthpresistivityͲmeter.The ERTmeasurementswerecarriedoutbyB.Kühnast(KNGeoelektrik)jointlywithE.Niesner(University ofLeoben)(KellererͲPirklbauer&Kühnast2009). Finally,aRDCsystemwassetupatanearbymountain(Feistererhorn2081masl.)tomonitorthe snowcoverdynamicsinthecirqueandsummitareofMt.Hochreichart.ThecorepartsoftheRDC system are a standard handͲheld digital camera (Nikon Coolpix), a remote control, a water proof casingwithatransparentopening,a12V/25Ahbatteryandsolarpanelswithachargecontroller.   2.2Resultsoncurrentpermafrostdistribution

39 PermaNET–CasestudiesintheEuropeanAlps

Permafrostmodelling Permafrostdistributionaccordingtothisthechosenmodellingapproachrevealedthatpermafrostis verylikelyatnorthͲfacingaspectsathighestelevations,butnotoccurringataltitudesbelow2270m asl.Accordingtothismodelresult,theentireReichartCirqueispermafrostfree(Fig.3).  Thermalregimebasedonminiaturetemperaturedatalogger ResultsofthecontinuousmeasurementsofgroundsurfacetemperatureatthethreesitesGST1to GST3areshowninFig.4.Themeanvaluesforthethreeyearperiodatthehighestsite(GST1,FD 235)forFDis15dayshighercomparedtothesite116mlowerinelevation(GST2,FD220).ForID, thedifferenceismoresubstantialwith19days,whereasthenumberofFTDisslightlyhigheratthe lowerofthetwosites.Thelowestofthethreesites(GST3)experiencessubstantiallylessFDbutonly slightlylessFTDcomparedtoGST2.Regardinginterannualvariations,thenumberofFDatallthree sitesisrelativelystable,whereasthenumberofIDaswellasofFTDvariesabitmore. 

 Fig.4–ThermalregimeatthethreesitesGST1toGST3betweenNov.2006andOctober2009.Numberoffrost days(includingicedays),icedays,freezeͲthawdaysandfrostͲfree.Resultsofsingleyearsandthemeanforthe entireperiodareshown.  Fig.5showsthemeanannualgroundsurfacetemperature(MAGST)aswellastheelevationofthe computedͲzerodegreeisothermbasedonalapserateof0.0065°C/m.Thisgraphclearlydepictsthat theMAGSTvaluesatsiteGST1andGST2areallnegativeindicatingpermafrost,whereasatthelow elevation site GST3 the temperature at the ground surface is at around +2°C. However, GST3 is locatedoncoarseͲgrainedblockymaterialintherootingzoneofarockglacier.Duetothethermal behaviourofsoilmaterial(inparticularcoarseͲgrainedblockymaterialwithopenvoidsinbetween), thetemperatureatthegroundsurface(i.e.MAGST)iswarmercomparedtothetemperatureatthe topofpermafrost(TTOP),possiblyuptoseveraldegrees(“thermaloffset”;SmithandRiseborough 2002). Therefore, despite the fact that positive MAGST are measured at the surface, permafrost mightstillexistintheground. The diagram showing the computedͲzero degree isotherm for the three sites indicates that in general, the lowest computed zeroͲdegree isotherm was calculated for site GST3, whereas the highestcomputedzeroͲdegreeisothermwascalculatedforthehighestsiteGST1.Explanationforthis isthedifferentbufferingeffectofthewintersnowcover.AtsiteGST1,snowcoverisofsubstantially less importance (summit site, small local depression) compared to site GST3 (footͲslope position, rootingzoneofrockglacierwithmoreefficientsnowaccumulationandlonglyingsnowcover).This clearlyhighlightstheimportanceofsnowinfluencingthethermalregime oftheground(cf.“nival offset”;SmithandRiseborough2002) 

 40 PermafrostResponsetoClimateChange

 Fig.5–Meanannualgroundsurfacetemperature(MAGST)andcomputedzeroͲdegreeisotherm(usingalapse rateof0.0065°C/m)atthethreesites.Resultsofsingleyearsandtheentireperiodareshown.  Figure 6 shows the results of two BTSͲcampaigns in the Reichart cirque. The maps show that the general pattern is the same, but BTS values in 2008 were cooler. In 2008 more measurement locations were within the possible (Ͳ2 toͲ3°C) and probable (<Ͳ3°C) permafrost classes. BTS measurementsindicatethatpatchypermafrostprobablyexistsinthecirqueattwodifferenttypesof topographicalpositions:(i)anorthtonorthͲeastfacingfootslope,and(ii)atthefootofasteepnorth to northͲwest facing rockface at elevations as low as 1850 m asl. According to this method, the uppermostpartoftherockglacierincludingtherootzonearepresumablyunderlainbypatchesof permafrost. 

 Fig.6–BTSmeasurementsinlatewinter2007and2008intheReichartCirque.Themeasurementsin2008 indicate substantial cooler ground temperatures. Note the pronounced morphology of the relict rock glacier (Orthophotographkindlyprovidedby©GISSteiermark).  Geoelectricalmeasurements TheERTresults(Fig.7)indicateanactivelayerof2to4munderlainbyapermafrostbodyalong3/4 oftheentireprofilewithresistivityvaluesbetween50to100kOhm.mandextendingtoadepthof 10to15m.Thepermafrostbodyissubstantiallythickeratthelowerpartoftheprofile(rockglacier; first50mofprofile)comparedtomostoftheupperpart(talusslope).Focusingonthetalusslope, thepermafrostbodyisthickestonthecentralsectionoftheprofile(~5Ͳ6mthickness).Incontrast,at

41 PermaNET–CasestudiesintheEuropeanAlps thelowerpartofthetalusslopethepermafrostbodyismostlikelyverythin(lessthan1m)whereas attheuppermostpartpermafrostisabsent. 

 Fig.7–Electricalresistivitytomography(ERT)ofthe120mlongprofilemeasuredintheReichartCirque(see Fig.2forlocation).MeasurementscarriedoutbyKNGeoelektrik   2.3Summaryofcurrentpermafrostdistribution Based on the permafrost research carried out so far, one can conclude that the existence of permafrostisproveninthestudyareaMt.Hochreichart.Themountainpermafrostoccursaspatches inthelowerpartsasforinstanceintherootingzoneoftheofapseudoͲrelictrockglacierwherethe substrat consists of coarseͲgrained sediments. This cooling effect of coarse blocks has been recognised since decades (cf. Gruber & Hoelzle 2008).In higher elevations, permafrost is more widespreadaffectingtheentiresummitarea.MAGSTnear0°Catelevationshigherca.2300masl indicatethatpermafrostisthinandingeneralwarm.Theredistributionofsnowandcharacteristics of the winter snow cover as well as the type of substrat (bedrock, fine material, coarseͲgrained blockymaterial)arethedominantlocalfactorforpresenceorabsenceofpermafrost. Fig.8depictsthesnowcoversituationinthestudyareaMt.HochreichartinNovember2006,2007, 2008and2009basedontheownRDCsystem.Thesefourimagesexemplarilyshowthatsnowcover variessubstantiallyfromyeartoyearduringsimilarperiods.Earlysnowfallinautumnproducinga protectingsnowcoverinhibitsgroundcooling.Incontrast,longlyingsnow(e.g.footslopepositionin cirque)inhibitsgroundwarminginspring.Regardingsubstrat,siteswithratherthicklayers(several meters)ofcoarseͲgrainedblockymaterialintheuppermostpartoftheReichartCirque(talusand rooting zone of the rock glacier) are more likely underlain by permafrost as shown by the ERT measurements.Summarising,thissiteisthemosteasterlyevidenceofexistingpermafrostfoundin theentireEuropeanAlpsat14°41’Eatelevationsaslowas1900masl.

 42 PermafrostResponsetoClimateChange



 Fig.8–SnowcoverdistributioninthecirqueandinthesummitareaofMt.HochreichartinNovember2006, 2007,2008and2009.cf.Fig.2.  3. Possiblefuturethermalresponsetopredictedclimatechange Aspresentedabove,permafrostinthestudyareaHochreichartͲReichartCirqueisrestrictedtothe highestelevationsandtolocations,wherethesnowcoverregimeand/orthecharacteristicsofthe substrat material is favourable for permafrost existence. Climate change with the predicted temperatureincreasefortheGreaterAlpineRegion(GAR)byusingtherelativelyoptimisticCLMA1B scenarioindicatesatemperatureincreaseofaround2°Cby2050(seeChapter2.) Theestimatesforfrostday(FD),iceday(ID)and(FTD)forthe periods1961Ͳ1990and2021Ͳ2050 basedonairtemperaturedatarevealforthestudyareaHochreichartͲReichartCirquethefollowing results:ThenumberofFDwilldecreaseby13to14daysperyear.Forthesummitarea,thiswould mean207Ͳ227FDinsteadof221Ͳ240FDhenceareductionofFDbyupto6.3%.ThenumberofIDwill decrease also by some 13 to 14 days per year, which means 127Ͳ147 ID instead of 141Ͳ160. In relativenumber,thisisalmost10%.Incontrast,thenumberofFTDwillpresumablyremainmoreor lessatthesamelevelwithasmallincreaseby0.1to2daysperyear. ThepredictedwarmingbasedontheCLMA1BscenariocausingthemodelledchangesinFD,IDand FTDwillseverelyinfluencethepermafrostdistributionandgeomorphicdynamicsinthestudyarea HochreichartͲReichartCirque.By2050,permafrostinthestudyareawillberestrictedtofewhigh elevated locations in the summit area where the substrat and the snow cover conditions will still allowtheexistenceofpermafrost.Incontrast,permafrostinthecirquewillbecompletelythawed despitethefactoflargeareasofcoarseͲgrainedsediments.  

43 PermaNET–CasestudiesintheEuropeanAlps

Acknowledgements. – This study was partly carried out within the framework of the projects ALPCHANGE,financedbytheAustrianScienceFund(FWF)throughprojectno.FWFP18304ͲN10,and PermaNET.ThePermaNETprojectispartoftheEuropeanTerritorialCooperationandcoͲfundedby the European Regional Development Fund (ERDF) in the scope of the Alpine Space Programme www.alpinespace.eu  References:  GruberS.&HoelzleM.,2008:Thecoolingeffectofcoarseblocksrevisited:amodelingstudyofa purely conductive mechanism. Proceedings of the Ninth International Conference on Permafrost(NICOP),UniversityofAlaska,Fairbanks,June29–July3,2008,557Ͳ561. HaeberliW.,1973:DieBasisͲTemperaturderwinterlichenSchneedeckealsmöglicherIndikatorfür die Verbreitung von Permafrost in den Alpen. Zeitschrift für Gletscherkunde und Glazialgeologie,9,221Ͳ227. KellerF.,1992:AutomatedmappingofmountainpermafrostusingtheprogramPERMAKARTwithin the Geographical Information System ARC/INFO. Permafrost and Periglacial Processes, 3, 133Ͳ138. KellererͲPirklbauerA.,2005:Alpinepermafrostoccurrenceatitsspatiallimits:Firstresultsfromthe easternmarginoftheEuropeanAlps,Austria.NorskGeografiskTidsskriftͲNorwegianJournal ofGeography,59,184Ͳ193. KellererͲPirklbauerA.,2008:Aspectsofglacial,paraglacialandperiglacialprocessesandlandformsof theTauernRange,Austria.UnpublishedPhDͲThesis,UniversityofGraz,200p. KellererͲPirklbauer A. & Kühnast B., 2009: Permafrost at its limits: The most easterly evidence of existing permafrost in the European Alps as indicated by ground temperature and geoelectricalmeasurements.GeophysicalResearchAbstracts11:EGU2009Ͳ2779. Lieb G.K., 1998: HighͲmountain permafrost in the Austrian Alps (Europe). Proceedings of the 7th International Permafrost Conference (Yellowknife, 23–27 June 1998), Collection Nordicana 57,663–668.Centred’étudesnordiques,UniversitéLaval,Québec. Smith M.W. & Riseborough D.W., 2002: Climate and the limits of permafrost: a zonal analysis. PermafrostandPeriglacialProcesses,13,1Ͳ15.

 44     3. CasestudiesintheEuropeanAlps   3.3 DösenValley,CentralAustrianAlps   

  Citationreference KellererͲPirklbauerA(2011).Chapter3.3:CasestudiesintheEuropeanAlps–DösenValley,Central AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.45Ͳ58.  Authors Coordination:AndreasKellererͲPirklbauer Involvedprojectpartnersandcontributors: Ͳ Institute of Geography and Regional Science, University of Graz, Austria (IGRS) – Andreas KellererͲPirklbauer  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

 45 PermaNET–CasestudiesintheEuropeanAlps

Summary  Permafrost research in the Dösen Valley (46°59’N and 13°17’E), Hohe Tauern Range, Central Austriawasinitiatedinthe1990s.Sincethen,anumberofdifferentmethodshavebeenapplied tounderstandpermafrostdistributionandrockglacierdynamics.Resultsshowthatatpresent permafrost exists at permafrost favourable sites (northͲexposed, well sheltered, coarseͲblocky material) at elevations down to 2200 m asl. In contrast, on southͲexposed slopes covered by coarseͲblockymaterialthelowerlimitisataround2600masl.Localconditionssuchassubstrate material(i.e.fine/coarsesediments,thick/thinsediments,bedrock)andtopoclimaticconditions (radiation sheltered, timing and characteristics of snow cover) alter the general pattern of decreasing ground surface temperature with increasing elevation substantially and makes the permafrostdistributionpatterninthestudyareacomplex.Rockglaciervelocitiesseemtoreact quickerafteracoolperiodwithdeceleration.Incontrast,rockglaciersseemtoneedmoretime to react after warmer periods with movement acceleration indicating the inertia of the rock glaciersystemtowardsgroundwarmingandvelocitychanges.By2050,southͲfacingslopesnot coveredbycoarseͲblockymaterialwillbepermafrostfree.OnlythehighestnorthͲfacingslopes willstillbeinfluencedbywidespreadpermafrost.Theroleofsubstratematerialandsnowcover dynamicswillbeevenmoreimportantfortheremainingpermafrostthantoday.Temperature increasewilleventuallyleadtoinactivationofallpresentlyactiverockglaciersinthestudyarea.

 46 PermafrostResponsetoClimateChange

1. Introductionandstudyarea PermafrostresearchintheHoheTauernRangeinCentralAustriawasinitiatedinthe1990s.Oneof themainstudyareasforpermafrostresearchistheDösenValleynearMallnitz(Fig.1A).Sincethen, differentmethodshavebeenappliedinordertounderstandpermafrostdistributionandrockglacier dynamicsinthisvalley(Table1).Presentpermafrostresearchinthisstudyareaiscarriedoutwithin the framework of the projects ALPCHANGE (2006Ͳ2010), PermaNET (2008Ͳ2011) and permAfrost (2010Ͳ2012)byresearchersfromtheUniversityofGraz,theGrazUniversityofTechnologyaswellas theUniversityofLeoben.  Table1–AppliedmethodsandpublicationsatthestudyareaDösenValley

Method initiated/carriedout Publications Geodeticsurveys 1995 Photogrammetricsurveys 1954 Buck&Kaufmann2008 Geophysical campaigns (seismics, geomagnetics Delaloyeetal.2008 1994 andgeoradar/GPR) Kaufmann & Ladstädter 2007 Kaufmann Geomorphologicalmappingandobservations 1994 etal.2007 Meteorologicalmonitoring 2006 KellererͲPirklbauer2008 Monitoring of snow cover dynamics in the 2006 KellererͲPirklbaueretal.2008a,2008b rootingzonebyautomaticdigitalcameras 1995 Kenyi&Kaufmann2003 Groundtemperaturemonitoring (continuoussince2006) Kienast&Kaufmann2004 NearͲsurfacegroundtemperaturemonitoring 1995 Lieb1991,1996,1998 (continuoussince2006) Schmöller&Fruhwirth1996 Relativedatingofrockglaciersurface 2007  ThestudyareaissituatedintheAnkogelMountainsattheinnerpartoftheglaciallyshaped,EͲW trendingDösenValleyataboutN46°59´andE13°17.Theelevationofthestudyarearangesbetween 2270maslatthecirquethresholdneartheArthurͲvonͲSchmidHuttoslightlymorethan3000masl atthenearbySäuleckpeak.Thispartofthevalleyischaracterisedbyanumberofrockglaciersand distinctterminalmorainesinrelativelyflatparts,acirquefloorwithatarnlake,slopescoveredby coarse debris and steep rock faces partly acting as debris supply areas for the rock glaciers. Geologically, the study area is located within the central gneiss complex of the Hochalm/Ankogel area with predominantly westͲdipping biotite gneiss (Lieb 1996). (Fig. 1B). The moraines were presumablyformedduringtheEgesenͲmaximumadvanceandarethusofearlyYoungerDryas(YD) age(Lieb1996).InAustria,theearlyYDis10BeͲdatedtoaround12.3–12.4ka(Kerschner&IvyͲOchs 2007).Atpresent,onlysomeperennialsnowpatchesarefoundinthestudyarea. TheninerockglaciersintheDösenValleydepictedinFig.1Bpredominantlyconsistofgraniticgneiss (Kaufmannetal.2007)andwereformedafterdeglaciationintheLateglacialandHoloceneperiod. Accordingtothe“RockGlacierInventoryofCentralandEasternAustria”(Liebetal.2010,KellererͲ Pirklbaueretal.2010),threeoftheserockglaciers(mo236,mo239.1,mo239.2)areconsideredtobe relictandsixareregardedasintactstillcontainingpermafrost(mo237,mo237.1,mo238,mo238.1, mo238.2, mo239). Previous permafrost research – including velocity measurements – focused particularlyontherockglaciermo238(fordetailsseeLieb1996orKaufmannetal.2007).Thisrock glacierischaracterisedbyanaltitudinalrangeof2355Ͳ2650masl,alengthof950m,awidthof250 mandanareaof0.19km².TherockglacierisanactivemonomorphictongueͲshapedrockglacier situatedattheendoftheinnerDoesenvalleywithpresentmeansurfacevelocityratesofaround15Ͳ 25cmperyear(Fig.2).  

47 PermaNET–CasestudiesintheEuropeanAlps

According to air temperature measurements by the own meteorological station located at the surface of rock glacier mo238 (for location see Fig. 1) in the 4Ͳyears period September 2006 to August 2010, the mean annual air temperature (MAAT) at the 2603 m asl isͲ1.7°C. The coldest monthisJanuarywithamonthlyvalueofuptoͲ11.8°CwhereasthewarmestmonthisAugustwitha monthlymeanvalueofupto7.8°C. 

 Fig. 1 – Study area Dösen Valley and its location within Austria. The distribution of rock glaciers, terminal moraines of Late Glacial age (Younger Dryas), modelled potential discontinuous permafrost, location of the meteorological station (MS)as well as the location of six miniature temperature datalogger (MTD) used for ground surface temperature (GST) measurements are indicated. Code of the rock glacier is according to the “RockGlacierInventoryofCentralandEasternAustria”(Liebetal.2010,KellererͲPirklbaueretal.2010). 

 Fig.2–ThestudyareaDösenValleywithfourintactrockglaciers:(A)viewtowardsE,(B)viewtowardsSE. Note the widespread steep rock faces acting as debris supply areas, the perennial snow fields, the flowing structureoftherockglaciersandwidespreadvegetation(indicatorforabsenceofalpinepermafrost).Locations ofthesixminiaturetemperaturedataloggers/MTDwheregroundsurfacetemperature(GST)ismeasuredand the site of the meteorological station (MS) are indicated. Code of the rock glacier is according to the “Rock GlacierInventoryofCentralandEasternAustria”(Liebetal.2010,KellererͲPirklbaueretal.2010).Photographs byA.KellererͲPirklbauer. 

 48 PermafrostResponsetoClimateChange

In this paper, the present situation and the evolution of the ground surface temperature in the recentpast(2006Ͳ2010)anditssignificanceforpermafrostdistributionarehighlighted.Furthermore, theresultsoftherockglaciermonitoringprogramfortheperiod1954to2010anditsrelationshipto climaticconditionsandclimatechangearediscussed.  2. Permafrostindicatorsandrecentthermalevolution 2.1Methods Since1994asuiteofmethodshasbeenappliedaslistedaboveinTable1.Inthispaper,resultsbased onnumericalpermafrostmodelling,climatemonitoringbyusingameteorologicalstationaswellas continuous measurements of ground surface temperature by using miniature temperature dataloggers(MTD)andphotogrammetricandgeodeticrockglacierdisplacementmeasurementsare presented. Thespatialdistributionofpotentialdiscontinuouspermafrostinthestudyareawasmodelledbyan adaptationoftheprogramPERMAKART(Keller1992)usingGISArcViewandArcInfo.Forthissimple modellingapproach,theempiricalvaluesofthelowerlimitofdiscontinuouspermafrostforcentral Austriawereused(Lieb1998). Themeteorologicalstationhasbeeninstalledin2006atonelargeblockonthesurfaceoftherock glaciermo238withintheALPCHANGEproject.Atthisstation,climatedataincludingairtemperature, airhumidity,windspeed,winddirectionandglobalradiationarecontinuouslyloggedanddataare availablefortheperiod01.09.2006to17.08.2010. MTDswereusedatatotalof11locationsduringdifferentperiods.Theresultsfromsixsiteswith groundsurfacetemperature(GST)measurementsloggedat1hintervalarepresentedhere(Figs.1& 2).TheusedloggersareproducedbyGeoPrecision,ModelMͲLog1withPT1000temperaturesensors (accuracy+/Ͳ0.05°C,rangeͲ40to+100°C,calibrationdrift<0.01°C/yr).Ateachofthesixsites,the temperaturesensorisshelteredfromdirectsolarradiationbyaplatyrock.SitesGST1andGST2are locatedoncoarseͲblockyslopes.GST2islocatedbetweenalargeboulderandbedrock. All three sites form a vertical profile on southͲfacing slopes. In contrast, sites GST4 to GST6 are locatedonthesurfaceofthemainactiverockglacierinthevalley(mo238)andfromaverticalprofile on northͲfacing slopes. Data of continuous measurements of ground surface temperature at the threesitesGST1ͲGST4andGST6wereavailableforthec.48Ͳmonthperiod01.09.2006to17.08.2010. AtsiteGST5thetimeseriesendson05.09.2009.Toallowcomparisonbetweenthesixsitesaswellas to allow fullͲyear data analysis, the four fullͲyear periods 01.09.2006Ͳ31.08.2007, 01.09.2007Ͳ 31.08.2008, 01.09.2008Ͳ31.08.2009 and 01.09.2009Ͳ17.08.2010 were analysed. Furthermore, the zeroͲdegree isotherm was computed for each site using a vertical temperature gradient of 0.0065°C/m.Table2summariseskeyparametersofthesixGSTsites. Temperaturedata(airandground)analysesfocusedonfrostday(FD),iceday(ID),freezeͲthawday (FTD)andfrostͲfreeday(FFD).AdaygotclassifiedasFD,whenthedailyminimumtemperatureis belowzero.Ifalsothedailymaximumtemperatureisamongthefreezingpoint,thedaygotclassified as ice day ID. The difference between ice days and frost days, which means all days with a daily minimumtemperaturebelow0°Candadailymaximumabovethislimit,gotclassifiedasFTD.Finally, adaywithpositiveminimumtemperaturegotclassifiedasFFD.    

49 PermaNET–CasestudiesintheEuropeanAlps

Table 2 – Summary of the sites where ground surface temperature (GST) is monitored by using miniature temperaturedataloggers(MTD).LocationoftheGSTͲsitesinindicatedinFigs.1and2.Theelevationofthe computed zeroͲdegree isotherm was computed by using a vertical temperature gradient of 0.0065°C/m. MAGST=meanannualgroundsurfacetemperature.

Computed Elevation zeroͲdegree GSTͲsite Exposition Dataperiod MAGST(°C) (masl) isotherm (masl) GST1 South 2489 4years:1.09.2006to17.08.2010 2.0 2797 GST2 South 2586 4years:1.09.2006to17.08.2010 1.2 2771 GST3 South 3002 4years:1.09.2006to17.08.2010Ͳ2.6 2602 GST4 North 2626 4years:1.09.2006to17.08.2010Ͳ0.9 2488 GST5 North 2501 3years:1.09.2006to05.09.2009Ͳ1.5 2270 GST6 North 2407 4years:1.09.2006to17.08.2010Ͳ1.3 2207  Surface displacement measurements of the rock glacier mo238 is carried out since 1954 by using aerialphotogrammetryandsince1995byusingterrestrialgeodeticsurvey(Kaufmann&Ladstädter 2007,Kaufmannetal.2007).Thegeodeticmeasurementsusingatotalstationareannuallycarried out in the middle of August following a proven scheme. Since 1995, the measurements were repeatedapartfrom2003duetolackoffunding.TheannualcampaignsareledbyV.Kaufmann,TU Graz. In addition to the geodetic measurements satellite based radar interferometry (Kenyi & Kaufmann 2003) and photogrammetric displacement measurements based on aerial photographs (1954,1969,1975,1983,1993,1997and1998)werecarriedout(Kaufmannetal.2007,Kaufmann& Ladstädter2007)previously. Finally,aRDCsystemwassetupinSeptember2006inordertomonitorthesnowcoverdynamicsat therootingzoneoftherockglaciermo238.ThecorepartsoftheRDCsystemareastandardhandͲ held digital camera (Nikon Coolpix), a remote control, a water proof casing with a transparent opening,a12V/25Ahbatteryandsolarpanelswithachargecontroller.  2.2Resultsoncurrentpermafrostdistribution Permafrostmodelling Thelowerlimitofpotentialdiscontinuouspermafrostaccordingtothechosenregionalpermafrost modellingapproachindicatespermafrostonslopesbetween2500masl(northͲfacing)and2900m asl.(southͲfacing)andonfootslopepositionsbetween2410masl(northͲfacing)and2690m(southͲ facing).Themodellingresultsshowthatonlythelargeintactrockglaciermo238aswellasthetwo smaller ones slightly to the west (mo238.1 and mo238.1) as well as the southͲfacing rock glacier mo237.1arepredominantlyinpermafrostareaswhichisinaccordancetothefreshappearanceof thefourrockglaciers(Fig.2).  Airtemperatureregimebasedonthemeteorologicalstation Themeteorologicalstationislocatedat2603maslintheupperpartoftherockglacier(Figs.1&2). Resultsfromthisstationshow,thatthenumberoffrostdays(FD),icedays(ID),freezeͲthawdays (FTD)andfrostͲfreedays(FFD)wasrelativelystableinthe4yearperiod2006to2010(Fig.3).The meanvalueofFDis246meaningthatduring2/3oftheyearfrostoccursat2600masl.inthestudy area. In contrast, the mean annual air temperature values indicate a substantially warmer year

 50 PermafrostResponsetoClimateChange

2006/07,twocomparableyears2007/08and2008/09andasubstantiallycooleryear2009/10(Fig.3) yieldingameanvalueofͲ1.7°C.TheelevationofthezeroͲdegreeisothermis2340masl.ifusinga verticallapserateof0.0065°C/m.  

 Fig.3–Airtemperatureregimeatthemeteorologicalstationattherockglaciermo238.(A)Numberoffrost days(includingicedays),icedays,freezeͲthawdaysandfrostͲfree;(B)meanannualairtemperature(MAAT); bothforthesingleyearsandthemeanoftheentire4Ͳyearsperiod.   Groundthermalregimebasedonminiaturetemperaturedatalogger ResultsofthecontinuousmeasurementsofgroundsurfacetemperatureatthesixsitesGST1toGST6 areshowninFigs.4and5.Fig.4showsthenumberoffrostdays(includingicedays),icedays,freezeͲ thawdaysandfrostͲfreedays.Ingeneral,thelowestvaluesinFDandIDweremeasuredinwinter 2006/07. Incontrast, the highest values of FTD were measured generally in winter 2006/07 apart fromthesnowrichsiteGST5.Atallsixsites,thenumberofFFDwasagainhighestinwinter2006/07, atsiteGST1theFFDvaluewasevenhigherthantheFDvalue. ThemeanvalueofFDislowestatthesouthexposedsiteGST1withonly198days,followedbyGST2 with208days.Incontrast,atsiteGST3at3000masl,themeanvalueofFDdaysisalmost270.The FDvalueforthenorthexposedsitesGST4toGST6isquitesimilaratallthreesiteswith237to245. Regardinginterannualvariation,thenumberofFDduringthefouryearperiodvariedonlyby15days betweenthehighestandcoldestsiteGST3.Incontrast,atsouthexposedandwarmersiteGST1the numberofFDvariedduringthesameperiodby60days(168FDin2006/07vs.228FDin2007/08). Consideringthefactthatthewinter2006/07wasexceptionallywarmandthewinter2007/08was relatively“normal”,theseresultssupposethatpermafrostsitesatlowerlocationinthestudyarea DösenValleyaremoresusceptibletoclimatewarming. Regardingicedays,thelowestIDvaluesareagainfoundatthesouthfacingsitesGST1andGST2with about 170 days. The coldest site with the highest number of ID is site GST5 with 234 days. This maximuminIDatthissiteisattributedtolocaltopoclimaticconditions(smalldepressiononnorth facingslopefavouringgroundcooling) andlongsnowcoverduration(delayingroundwarmingin springtomidsummer).SimilarIDvaluesarefoundatthehighestsiteGST3andthetwonorthfacing sites GST4 and GST6. The interannual variation of the number of ID during the four year measurementperiodvariedsubstantiallyby36(GST4)to73days(GST1). ThemeanvalueofthefreezeͲthawdaysisgenerallylowrangingfrombetween11atthesnowrich siteGST5to37atthewarmsiteGST2,but50atthehighestsiteGST3.AtsiteGST5,theFTDvalue was even only five in the winter 2007/08 related to the longͲlasting snow cover at this site. In contrast, at site GST3 the number of FTD value reached 70 in the warm winter 2006/07. The differencesinthenumberofFTDatthesitesalsoindicatethatfrostweatheringcausedbyfreezeͲ

51 PermaNET–CasestudiesintheEuropeanAlps thawactionisimportantatthesouthͲexposedsitesGST1,GST2andinparticularGST3.Incontrast,at thecoolerandsnowrichersitesthisweatheringprocessislessactiveatpresentclimateconditions. Finally,frostͲfreedaysishighestatthewarmsitesGST1andGST2,comparableatthethreenorthͲ exposedsitesGST4toGST6andsubstantiallylowestatsiteGST3.  

 Fig.4–GroundthermalRegimeatthesixsitesGST1toGST6betweenSeptember2006andAugust2010with numberoffrostdays(includingicedays),icedays,freezeͲthawdaysandfrostͲfreedays.Resultsofsingleyears andthemeanfortheentireperiodareshown.  Fig.5showsthemeanannualgroundsurfacetemperature(MAGST)aswellastheelevationofthe computedͲzero degree isotherm based on a lapse rate of 0.0065°C/m for all six sites. Results are shownforthesinglemeasurementyearsbetween2006and2010aswellasthemeanoftheentire period. Results show that the northͲfacing slopes are cooler than the southͲfacing slopes at comparableelevation.OnthesouthͲexposedslopes,theverticaltemperaturegradientforthefour yearperiodis0.0082°C/m(betweenGST1undGST2)und0.0091°C/m(betweenGST2undGST3).In contrast, on the northͲexposed slopes the situation is more complex due to local topoclimatic conditions also influencing the characteristics of the winter snow cover (duration, thickness). A negativegradientofͲ0.0048°C/mwascalculatedbetweenthesitesGST4andGST5,whereasaslight positivegradientof0.0021°C/mwascalculatedbetweenthesitesGST5andGST6 Fig.5clearlydepictsthattheMAGSTatsitesGST1andGST2arepositivewithmeanvaluesof+1.2°C (GST2)to+2.0°C(GST1)indicatingabsenceofpermafrost.However,siteGST1islocatedonblocky material.Duetothethermalbehaviourofsoilmaterial(inparticularcoarseͲgrainedblockymaterial withopenvoidsinbetween;Gruber&Hoelzle2008),the temperatureat thegroundsurface(i.e. MAGST) is warmer compared to the temperature at the top of permafrost (TTOP), possibly up to several degrees (“thermal offset”; Smith and Riseborough 2002). Therefore, despite the fact that positiveMAGSTaremeasuredatthesurface,permafrostmightstillexistinthegroundatoraround thesiteGST1.Incontrast,theMAGSTvaluesattheotherfoursitesGST3toGST6areclearlynegative

 52 PermafrostResponsetoClimateChange

(apartfrom2006/07atsiteGST6)withmeanvaluesofͲ0.9°CatsiteGST4toͲ2.6°Catthe3000ͲmͲ siteGST3indicatingatthesefoursitespresenceofpermafrost. 

 Fig.5–Meanannualgroundsurfacetemperature(MAGST)andcomputedzeroͲdegreeisotherm(usingalapse rateof0.0065°C/m)atthesixsitesGST1toGST6.Resultsofsingleyearsandthemeanfortheentireperiodare shown.TheelevationrangeofthecomputedzeroͲdegreeisothermduringthefouryearsisindicated.  ThediagramshowingthecomputedͲzerodegreeisothermforthesixsitesindicatesthatthelowest computedzeroͲdegreeisothermwascalculatedforthenorthͲfacingandlowelevatedsiteGST6with a mean value of 2207 m asl. In contrast, the highest computed zeroͲdegree isotherms were calculatedforthetwosouthͲfacingsitesGST1(2797masl)andGST2(2771masl).Explanationfor thisisthelocaltopoclimaticconditionandthebufferingeffectofthewintersnowcoveratagiven site.AtsitesGST1,GST2,GST3andGST6)snowcoverisofminorimportance(windexposedsites with little/minor snow cover) compared to sites GST4 and GST5 (footͲslope position with more efficientsnowaccumulationandlonglyingsnowcover).Thisalsohighlightstheimportanceofsnow influencingthethermalregimeoftheground(“nivaloffset”;SmithandRiseborough2002).Basedon thecalculations,thezerodegreeisothermatthegroundsurfaceonnorthͲexposedslopesislocated between about 2200 and 2500 m asl, on southͲfacing slopes between 2600 and 2800 m asl. The computedͲzero degree isotherm varied during the four years between 177 m (GST4) and 472 m (GST6) indicating substantial interannual changes. Single years such as the warm winter 2006/07 causeasubstantiallyincreaseofthisisothermby80to260m. Summarising,onemightexpectpermafrostinthestudyareaonnorthͲexposedslopescoveredby coarseͲblockymaterialatelevationsof2200Ͳ2300masl,onsouthͲexposedslopesat2600Ͳ2750m asl.  Rockglacierkinematic Active rock glaciers are creeping phenomena of continuous or discontinuous permafrost. Their movement mode is strongly related to climatic conditions and as a consequence to ground temperatures(Kääbetal.2007).Fig.6depictstheevolutionofthemeanannualhorizontalsurface velocity at the Dösen rock glacier mo238 between 1954 and 2010 based on geodetic and photogrammetricmeasurements.Notethatthemeanannualvaluesintheperiodbefore1995are generallylowercomparedtotheyearsafter1995indicatinggenerallylowerdisplacementratesin theperiod1954to1995.However,singleyearswithdisplacementratescomparabletothevaluesof

53 PermaNET–CasestudiesintheEuropeanAlps the postͲ1995 period are conceivable. Furthermore, note the maximum in the movement rates between 2002 and 2004, the following deceleration until 2008 followed by a remarkable new acceleration during the last two measurement yeas. This movement pattern over the last 1.5 decadescorrelateswithothermonitoredrockglaciersintheHoheTauernRange(KellererͲPirklbauer & Lieb 2011) and in the entire Alpine Arc (Delaloye et al. 2008). This circumstance confirms the assumption that climatic conditions and changes in the European Alps are the dominant steering factorsforrockglaciermovement. 

 Fig.6–Changeofmeanannualhorizontalsurfacevelocity(cmaͲ1)attheDösenrockglaciermo238between 1954and2010basedongeodeticandphotogrammetricmeasurements.Meanof11measurementpoints(Pt. 10Ͳ17,21Ͳ23).DatasourceKaufmannetal.(2007)andunpublisheddata.  Relationshipbetweenrockglacierkinematicandclimate Theownmeteorologicalstationattherockglaciermo238wasusedtocollectairtemperaturedata fortheperiodOctober2006toAugust2010.Meanmonthlyairtemperaturedatawerecalculatedfor theperiodJanuary1990toSeptember2006fortheDösensitebyapplyingcorrelationanalysiswith theairtemperaturedatafromthemeteorologicalobservatorySonnblick,about24kmWNWofthe DösenValley.Fig.7depictstherelationshipbetweenthegeodeticmeasurementsatmo238andthe mean annual air temperature/MAAT (running 12Ͳmont mean). This graph shows that the warm MAATvaluesattheendof1994/beginningof1995causedanincreaseinsurfacedisplacementinthe years1997to1999.Incontrast,thecoolerMAATvaluesbetweenendof1996andmid1997caused lower velocities in 1999Ͳ2000. The MAAT values in the period 1999 to 2004 were generally high causingasteadyincreaseofthevelocityratespeakingin2003Ͳ2004.Thiswaspreviouslyexplained byconstantwarmingandanincreaseofliquidwaterinthepermafrostbodyoftherockglacier(Buck &Kaufmann2008).Accordingtotheseauthors,therockglaciervelocityexperiencedinthisperioda selfͲreinforcingdynamicleadingtoafurtherincreaseinvelocity.TheMAATvaluesdecreasedafter 2004causingrockglacierdecelerationuntil2007Ͳ2008.TheextremeincreaseoftheMAATbetween early2007tomidof2008causedanewaccelerationintheperiod2008to2010.  

 54 PermafrostResponsetoClimateChange

 Fig.7–Meanannualairtemperature/MAAT(running12Ͳmonthmean)andhorizontalsurfacevelocitiesatthe Dösenrockglaciermo238duringtheperiod1990to2010.DatasourceofvelocityvaluesKaufmannetal.(2007) andunpublisheddata.Data   2.3Summaryofcurrentpermafrostdistributionanddynamics Basedonthepermafrostresearchcarriedoutsofar,wecanconcludethatpermafrostinthestudy areaDösenValleyexistsatextremesites(northͲexposedslopes,wellshelteredfromsolarradiation, andcoarseͲblockymaterial)atelevationsdownto2200masl.Incontrast,onsouthͲexposedslopes coveredbycoarseͲblockymaterialthelowerlimitisataround2600masl.Animportantroleplays thewintersnowcoverinthelocalpermafrostdistributionparticularlyatsuchcoarseͲblockysites.On theonehand,snowpoorsitesinradiationshelteredlocations(suchasGST6)allowefficientground coolinginautumnaccompaniedbymoderatewarminginspring.Ontheotherhand,snowrichsites atfootslopepositionsinradiationshelteredlocations(suchasGST5)reduceefficientgroundcooling butshelterthegroundfromwarminginspringandevensummer. OnslopesnotcoveredbycoarseͲblockymaterial,thelowerlimitofpermafrostissubstantiallyhigher at elevations of between 2500 m asl. (northͲfacing) to 2900 m asl. (southͲfacing). At footslope positionsinfluencedbylonglastingsnow,thepermafrostlimitseemstobeataround2400masl (northͲfacing) to 2700 masl (southͲfacing). These results clearly show that local conditions influencingsolarradiation,degreeofgroundcooling,thermalregimeofthegroundsurfaceandnear groundsurfaceaswellaswintersnowcoverconditionshaveamajorimpactonthedistributionof permafrost in the study area. This impact alters the general pattern of decreasing ground surface temperaturewithincreasingelevationsubstantiallyandmakesthepermafrostdistributionpatternin thestudyarea(andatcomparablesitesintheneighbouringarea)complexatelevationsbetween 2200mand2900masl. Thebehaviourofthe monitoredrock glacier mo238intheinnerDösenValleyisinaccordance to othermonitoredrockglaciersintheHoheTauernRangeandtheentireAlpineArc.Duringthelast1.5 decades,twopeaksofhighsurfacedisplacementratesweredetectedat2003Ͳ2004and2008Ͳ2010 withratesexceeding30cmperyear.Therockglaciervelocitypatternindicatesthattherockglacier mo238reactsquickerafteracoolperiodwithdeceleration.Incontrast,therockglacierneedsmore timetoreacttowarmerperiodswithaccelerationofthemovementindicatingtheinertiaoftherock glaciersystemtowardsgroundwarmingandvelocitychanges. 

55 PermaNET–CasestudiesintheEuropeanAlps

3. Possiblefuturethermalresponsetopredictedclimatechange Aspresentedabove,permafrostinthestudyareaDösenValleyplaysanimportantroleandcovers presumably about 1/3 of the area above 2270 m asl. Besides the sole existence of permafrost in bedrock and in slope deposits, permafrost in the study area is also important for geomorphic periglacialprocessessuchascreepingoftheactiverockglaciers(inparticularrockglaciermo238)or rockfallscausedbyfrostweatheringobservedfrequentlyduringeachfieldcampaign. Climate change with the predicted temperature increase for the Greater Alpine Region (GAR) by usingtherelativelyoptimisticCLMA1Bscenarioindicatesatemperatureincreaseofaround2°Cby 2050 (see Chapter 3). The air temperature at the meteorological station in the study area Dösen Valleywouldbeslightlypositivewitharound+0.3°C.Ifusingalapserateof0.0065°C/mandtheair temperatureincreaseof+2°C,theelevationofthezeroͲdegreeisothermwouldshiftbyabout310m frompresently2340maslto2650maslcausingsubstantialpermafrostdegradationinthebedrock (fasterreaction)andintheintactrockglaciers(slowerreactionwithalongertimelag). Theestimatesforfrostday(FD),iceday(ID)and(FTD)forthe periods1961Ͳ1990and2021Ͳ2050 based on air temperature data reveal for the study area Dösen Valley the following results: The numberofFDwilldecreaseby14to15daysperyear.Forthesummitarea,thiswouldmean246Ͳ266 FDinsteadof261Ͳ280FD.Fortheelevationaroundtheactiverockglaciermo238(2350Ͳ2650,this wouldyield226Ͳ246FDinsteadof241Ͳ260FD,henceareductionofFDbyupto5.7%.Thenumberof IDwilldecreasealsobysome15to16daysperyear,henceareductionfrom201Ͳ220to185Ͳ205ID inthesummitareasand,respectively,from161Ͳ180to145Ͳ165atelevationsataround2350to2650 masl,henceareductionofIDbyupto10%.Incontrast,thenumberofFTDwillpresumablyincrease slightlyby0.1to2daysperyear.Intheperiod1961Ͳ1990,thenumberofFTDinthesummitareasis about 70Ͳ80, at elevations at around 2350 to 2650 m asl about 80Ͳ90. Based on the own air temperaturemeasurementsatthemeteorologicalstationat2603maslatthesurfaceofmo238,the mean number of FD during the four year period September 2006 to August 2010 was 246. Furthermore, 165 ID and 82 FTD were measured. This suggests that the modelling results for the standardperiod1961Ͳ1990appliedfortheGARareinaccordancewiththemeasurementsof2006Ͳ 2010attheDösenValley.However,onehastokeepinmindthatMAATatthenearbymeteorological observatorySonnblickwasaboutͲ1.3°Ccoolerduringthenormalperiod1961Ͳ1990comparedtothe periodSeptember2006toAugust2010.ThisdifferenceintheMAATvaluesduringthetwoperiods certainlyinfluencesthenumberofFD,IDandFTD.Therefore,thiscircumstanceclearlyshowsthat comparinglocaldatawithregionalmodellingresultsisnottrivial. RegardingrockglaciervelocityandclimaticconditionsintheDösenValley,onecanexpectthatan increase of ground temperatures in the active rock glaciers will cause permafrost warming and eventuallypartialthawingofthepermafrost.Thiswillleadtoanincreaseofliquidwaterintherock glacierwhichitselfmightincreasethemobilityandhencesurfacevelocityoftherockglacier.Further permafrost warmingandthawingwilllead toincreasingfrictionwithin the rockglacier due toice loss,tocompletepermafrostdegradationandfinallytotheformationofaninactiveorevenrelict rockglacierwithlittletonopermafrostice. Thepredictedclimatechangeuntil2050willsubstantiallydecreasethearealextentofpermafrostin thestudyareaDösenValleyaccompainedbydestabilisationofbedrockandslopedepositsaswellas changesinfrostweatheringconditionsandconsequentlyrockfallactivity.SouthͲfacingslopesnot covered by coarseͲblocky material will be permafrost free in the entire study area and only the highestnorthͲfacingslopeswillstillbeinfluencedbywidespreadpermafrost.Theroleofsubstrate material (coarse, fine, bedrock) and snow cover dynamics will be even more important for the remainingpermafrostthantoday.Furthermore,temperatureincreasewillpresumablycausefirstan increaseofthecreepvelocitiesofcurrentlymovingrockglacier.Inalaterstage,however,thiswill leadtoinactivationofallpresentlyactiverockglaciersinthestudyareaDösenValley. 

 56 PermafrostResponsetoClimateChange

Acknowledgements. – This study was mainly carried out within the framework of the projects ALPCHANGE,financedbytheAustrianScienceFund(FWF)throughprojectno.FWFP18304ͲN10,and PermaNET.ThePermaNETprojectispartoftheEuropeanTerritorialCooperationandcoͲfundedby the European Regional Development Fund (ERDF) in the scope of the Alpine Space Programme www.alpinespace.eu. Viktor Kaufmann is thanked for providing unpublished data on rock glacier velocities.TheCentralInstituteforMeteorologyandGeodynamics(ZAMG)isthankedforproviding temperaturedatafromthemeteorologicalobservatorySonnblick.  References:  BuckS.&KaufmannV.,2008:Theinfluenceofairtemperatureonthecreepbehaviourofthreerockglaciersin theHoheTauern.GrazerSchriftenderGeographieundRaumforschung,45,159Ͳ169. Delaloye R., Perruchoud E., Avian M., Kaufmann V., Bodin X., Hausmann H., Ikeda A., Kääb A., KellererͲ Pirklbauer A., Krainer K., Lambiel Ch., Mihajlovic D., Staub B., Roer I. & Thibert E. (2008): Recent interannual variations of rock glacier creep in the European Alps. Proceedings of the Ninth International Conference on Permafrost (NICOP), University of Alaska, Fairbanks, June 29 – July 3, 2008,343Ͳ348. Gruber S. & Hoelzle M., 2008: The Cooling effect of coarse blocks revisited: a modeling study of a purely conductive mechanism. Proceedings of the Ninth International Conference on Permafrost (NICOP), UniversityofAlaska,Fairbanks,June29–July3,2008,557Ͳ561. KääbA.,FrauenfelderR.&RoerI.,2007:Ontheresponseofrockglaciercreeptosurfacetemperatureincrease. GlobalandPlanetaryChange,56,1Ͳ2:172Ͳ187. KaufmannV.&LadstädterR.,2007:Mappingofthe3DsurfacemotionfieldofDoesenrockglacier(Ankogel group, Austria) and its spatioͲtemporal change (1954Ͳ1998) by means of digital photogrammetry. GrazerSchriftenderGeographieundRaumforschung,43,127Ͳ144. KaufmannV.,LadstädterR.& Kienast G.,2007: 10 years of monitoring of the Doesen rockglacier (Ankogel group,Austria)–Areviewoftheresearchactivitiesforthetimeperiod1995Ͳ2005.Proceedings,5th MountainCartographyWorkshop,29MarchͲ1April2006,Bohinj,Slovenia,129Ͳ144. Keller F., 1992: Automated mapping of mountain permafrost using the program PERMAKART within the GeographicalInformationSystemARC/INFO.PermafrostandPeriglacialProcesses,3,133Ͳ138. KellererͲPirklbauer A., 2008: The SchmidtͲhammer as a Relative Age Dating Tool for Rock Glacier Surfaces: Examples from Northern and Central Europe. Proceedings of the Ninth International Conference on Permafrost(NICOP),UniversityofAlaska,Fairbanks,June29–July3,2008,913Ͳ918. KellererͲPirklbauerA.&LiebG.K.,2011:Recentrockglaciervelocitybehaviourandrelatednaturalhazardsin the Hohe Tauern Range, central Austria. PermaNET Project Report Ͳ Contribution of IGRS to Action 6.2/Group1–Rockglacier. KellererͲPirklbauerA.,AvianM.,LiebG.K.&RieckhM.,2008a:TemperaturesinAlpineRockwallsduringthe Warm Winter 2006/2007 in Austria and their Significance for Mountain Permafrost: Preliminary Results. Extended Abstracts, Ninth International Conference on Permafrost (NICOP), University of Alaska,Fairbanks,June29–July3,2008,131Ͳ132. KellererͲPirklbauerA.,AvianM.,LiebG.K.&PilzA.,2008b:AutomaticDigitalPhotographyforMonitoringSnow Cover Distribution, Redistribution and Duration in alpine Areas (Hinteres Langtal Cirque, Austria). GeophysicalResearchAbstracts10:EGU2008ͲAͲ11359. KellererͲPirklbauerA.,LiebG.K.&KleinferchnerH.,2010:Anewrockglacierinventoryattheeasternmarginof theEuropeanAlps.GeophysicalResearchAbstracts12:EGU2010Ͳ13110. Kenyi L.M. & Kaufmann V., 2003: Measuring rock glacier surface deformation using SAR interferometry. Proceedingsofthe8thInternationalConferenceonPermafrost,Zurich,Switzerland,537Ͳ541.

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Kerschner H. & IvyͲOchs S., 2007: Palaeoclimate from glaciers: Examples from the Eastern Alps during the AlpineLateglacialandearlyHolocene.GlobalandPlanetaryChange,60,58Ͳ71. Kienast G. & Kaufmann V., 2004: Geodetic measurements on glaciers and rock glaciers in the Hohe Tauern National Park (Austria). Proceedings, 4th ICA Mountain Cartography Workshop, 30 September Ͳ2  October 2004, Vall de Núria, Catalonia, Spain, Monografies tècniques 8, Institut Cartogràfic de Catalunya,Barcelona,101Ͳ108. LiebG.K.,1991:DiehorizontaleundvertikaleVerteilungderBlockgletscherindenHohenTauern(Österreich). ZeitschriftfürGeomorphologieN.F.,35,345Ͳ365. Lieb G.K., 1996: Permafrost und Blockgletscher in den östlichen österreichischen Alpen. Arbeiten aus dem InstitutfürGeographiederKarlͲFranzensͲUniversitätGraz,33,9Ͳ125. LiebG.K.,1998:HighͲmountainpermafrostintheAustrianAlps(Europe).Proceedingsofthe7thInternational ConferenceonPermafrost,Yellowknife,663Ͳ668. LiebG.K.,KellererͲPirklbauerA.&KleinferchnerH.,2010:BlockgletscherinventarvonZentralundOstösterreich erstelltimRahmendesProjektesPermaNET.InstitutsfürGeographieundRaumforschung,Graz SchmöllerR.&FruhwirthR.K.,1996:KomplexgeophysikalischeUntersuchungaufdemDösenerBlockgletscher (Hohe Tauern, Österreich). Arbeiten aus dem Institut für Geographie der KarlͲFranzensͲUniversität Graz,33,165Ͳ190. SmithM.W.&RiseboroughD.W.,2002:Climateandthelimitsofpermafrost:azonalanalysis.Permafrostand PeriglacialProcesses,13,1Ͳ15.

 58     3. CasestudiesintheEuropeanAlps   3.4 HoherSonnblick,CentralAustria   

  Citationreference KleeA,RiedlC.(2011).Chapter3.4:CasestudiesintheEuropeanAlps–HoherSonnblick,Central AustrianAlps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponseto presentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3. OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.59Ͳ65.  Authors Coordination:AlexanderKlee Involvedprojectpartnersandcontributors: Ͳ CentralInstituteforMeteorologyandGeodynamics(ZAMG)–AlexanderKlee,ClaudiaRiedl  Content Summary 1. Introductionandstudyarea 2. Measurementsandresults 3. Possiblefuturethermalresponsetopredictedclimatechange References

 59 PermaNET–CasestudiesintheEuropeanAlps

Summary  Climate change in the Alps is not only related to the retreat of glaciers, but rather to the permafrost distribution. Indices for the permafrost retreat in the higher mountain area, e. g. erosion, frost shattering or instabilities of the infrastructure are observable. The relevance of permafrostlongͲtermmonitoringiswidelyspread.Theknowledgeaboutpermafrostinteraction, influencesonpermafrostandthetemporalbehaviourofpermafrostisveryimportantforseveral kindsofinfrastructure,e.g.cablelifts,liftstationsormountainhuts.Furthermorethisknowledge is the basis for measuring the drinking water reservoirs of permafrost in the higher mountain areas,itsqualityanditsusageforthefuture.DetaileddataabouttheglacierͲretreatisavailable. But the permafrost distribution Ͳincluding  its thickness and spatial dimension Ͳ is largely unknown. On the top of Hoher Sonnblick (3.105 m asl) in the Hohe Tauern (Austria) three boreholeshavebeeninstalledtomeasurerocktemperaturesdownto20munderthesurface. Thisdataabouttemperature,geophysicalandgeodeticalmeasurements(availablesince2007)is a first approach for the documentation of permafrost behaviour in the Alps. Furthermore the summitregionofHoherSonnblickwillbemodelledwiththeaimtocomputethebehaviourof permafrostinthefuturewithdifferentscenariosinclimatechange.

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1. Introductionandstudyarea ThetopofHoherSonnblick(3.105ma.s.l.)islocatedintherangeoftheEasternAlpsintheregionof HoheTauern(Austria).NeighbouringmountainsofHoherSonnblickreachsimilarelevationsofabout 3.000ma.s.l..ThenorthslopeofHoherSonnblickischaracterizedbyaverydeepandsteepnorth face.Tothesouththeslopeismoderatewithabout30°downtotheuppermarginoftheglacier Goldbergkees.Fig.1showsthesummitareaofHoherSonnblick. InthevicinityofHoherSonnblickarethreeglaciers.Thelargestglacierisofthethreeistheglacier Goldbergkees.ThetwosmalleronesareKleinfleißkeesandPilatuskeesbothwithoutatypicalglacier tongue.Glaciericeoccurrencedowntoabout2.500ma.s.l..Therockintheregionconsistsmainlyof biotitͲgneiss(Exner,1964).Thethicknessofthedebrislayermantlingthebedrockinthesummitarea (wherethethreeboreholesweredrilled;Fig.1)isupto2m. 

 Fig.1–ThesummitofHoherSonnblick(3105ma.s.l.)withthelocationofthethreeboreholes.Totheright Zittelhausandtothelefttheobservatorium.ThesummitinthebackgroundisMt.Hocharn(3254ma.s.l.)  The observatory was built at the end of 19th century and a mountain hut, the Zittelhaus, is also locatedontopofthesummit.In2001astudyobservedthatfissuringofthecrestdemandsforthe necessity of a geological stabilization of the steep north face to protect the observatory. This reͲ development was done from 2003 to 2007. The main reason for the fissuring is the change in meteorological conditions in the 20th century. Higher temperatures and more liquid precipitation advance the physical weathering process of the rock. Higher temperature contrasts causes frost shattering,whichismoreactivethaninpasttimes.

61 PermaNET–CasestudiesintheEuropeanAlps

Climatologicalmeasurements,especiallyoftemperature,startedin1886.Actually,eachyearcounts 310 freezing days (daily minimum below 0° C) and 239 ice days (daily maximum below 0° C). All valuesrefertotheperiodbetween1971and2000.Uptonowanunbrokentemperaturerowexists. Next to temperature measurements and measurements of other meteorological parameters, the Sonnblickobservatoryisacentreofseveralscientificactivities.E.g.measurementsinatmospheric chemistry,snowchemicalmeasurements,massbalancemeasurementsofthesurroundingglaciers, avalanche reports, of course the permafrost longͲterm monitoring since 2007 and many more researchactivitiesactuallytakeplaceatHoherSonnblick.  2. Measurementsandresults Tomeasurethebehaviourofpermafrostandtheinfluencesofclimatechangeforpermafrostontop ofHoherSonnblick,three20mdeepboreholesweredrilledon14thand15thSeptember2005.At theendofAugust2006theboreholeswereequippedwithtemperaturesensorsindifferentdepths (Fig. 2). Additionally, a 10 m deep borehole next to borehole 2 was drilled and equipped with extensometers. Daily actualized measurements of temperature data and extensometer data are availableonlineatwww.sonnblick.net.Allboreholesarelocatedonthesouthernslope(seeFig.1). Themeanslopebetweenborehole1and3is27°andthetotalelevationdifferenceis34m.Borehole 1isdirectlylocatedtotheSonnblickobservatory,borehole3isadjacenttoacontinuoussnowfield andborehole2islocatedinbetween. Notonlymeasurementsintheboreholesareavailable.InOctober200635miniaturetemperature datalogger/MTD(20ofthetypeUTLͲ1andUTLͲ2and15ofthetypeHOBOTidbiT)wereinstalledto measure the basic temperature of the snow cover in wintertime and the ground surface temperaturesduringsummer.The20loggeroftypeUTLͲ1andUTLͲ2wereinstalledonmoderate slope on the southern side of the summit. In the steep north face, the 15 HOBO TidbiTs were installed. Furthermore, the air temperature change in the past since 1886 is also available. Fig. 3 shows an example of temporal variability of the temperature with increasing depth for the hydrological year in 2008. Measurements of the boreholes show that the summerly temperature amplitudeisobservabledownto15mwithadelayofabout6to7months. Thecoolingfromthewinterseasoniseffectiveto5mwithadelayofabout4months.Thethickness oftheactivelayerinsummertimewasaboutinborehole1in20081mand70cmin2009.Inthe boreholes2and3theactivelayerislessthan1m.There,theactivelayerwasabout60cmin2008. In 2009 there are no data available for borehole 2 and 3. Naturally, in the upper layers of the boreholesthedifferencesbetweensummerandwinterseasonsarelargerthanindeeperlevels.Itis also interesting to compare yearly average temperatures as it is done in Fig. 4. On the xͲaxis the temperature is assigned and on the yͲaxis the depth of the borehole. The figure shows the temperature of borehole 1 in 2008 (blue line) and in 2009 (red line). Down to about9mthetemperatureprofilein2008ismuchwarmerthanin2009.In3mthereisadifference of0.7°C.Inautumn2009thesummitregionwassnowlessorwithonlyathinsnowcoverforalong timewhichcausedthesedifferences. 

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Fig. 2 Ͳ Construction of measurement chain in the boreholes with depths of the temperature sensors and geophones.Additionally,theentranceofoneboreholeisshown. 

63 PermaNET–CasestudiesintheEuropeanAlps

 Fig 3 – Temporal temperature variability with increasing depth for borehole 1 during the hydrological year 2007/2008. 

 Fig.4–Meantemperaturesofborehole1in2008(blueline)and2009(redline). 

 64 PermafrostResponsetoClimateChange

Inwinter2008/09anearlyandthicksnowcoverexistedsothecoldnesscouldnotpenetrateintothe ground.Thisfactcausesthehighermeantemperatureintheupperlayersin2009.Anotherfactis illustrated in Fig. 4. Below 10 m the temperature of the years 2008 and 2009 are similar. One explanationcouldbethatthepenetrationdepthofseasonallytemperatureonlyreachesadepthof 15m.ThisbehaviourisalsoillustratedinFig.3.Below15mtherearenearlynotemporalfluctuations andbetween10and15mthefluctuationsareverysmall. Asitwasmentionedabove,nexttoborehole2isanothermoreshallowborehole,whichwasdrilled down to 10 m and is equipped with extensometers. Measurements show that in autumn the extensometersmeasurenegativevalues,whichcanbeidentifiedwithcompression.Notenoughdata are available yet for late spring and summer, but a first guess would be stretching with positive values.Thishypothesiswillbetestedinsummer2011,whenwinterseasonisgone.  3. Possiblefuturethermalresponsetopredictedclimatechange Because measurements exist only since 2007 it is not possible to make statements concerning permafrostretreatinthepastclimatewarmingatSonnblickuntilnow.Butwiththehelpofclimate models which are able to compute temperature development in the future with different assumptions,itisachievabletoproducepossiblefuturescenarios.Asitisdescribedinsection3.1, above1.800ma.s.l.iceandfrostdayswillbereducedbyabout14daysperyearbetween2021and 2050 and also freezeͲthaw days will increase about 3 to 5 days per year in this timeͲperiod (the referenceintervalis1961to1990).ActuallyonHoherSonnblick310freezingdayswillbereducedto 296and239icedayswillbereducedtoabout225dayswithdailymaximumbelow0°C.Underthese scenariospermafrostinhighermountainareaswillretreat.Especiallyupperrocklayerswillreactfast to the warming of the air. In deep layers, where the temperature change during one year is not observable,warmingwillbeslower.TheincreaseoffreezeͲthawdayswillbenefitweathering,frost shattering and fissuring. In regions with permafrost existence higher activity in rockfall will affect humaninfrastructure,mountainclimbersandchangeofthelandscape.  Acknowledgement.ThisworkwaspartlygrantedbytheprojectPermafrostinAustriabytheAustrian AcademyofScience.  References: ExnerCh.,1964.ErläuterungenzurgeologischenKartederSonnblickgruppe1:50.000.Geol.B.ͲA.168 S.,Vienna.

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 3. CasestudiesintheEuropeanAlps   3.5 RockGlacierHochebenkar,WesternAustria   

  Citationreference Krainer K. (2011). Chapter 3.5: Case studies in the European Alps – Rock Glacier Hochebenkar, Western Austrian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost responsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreport ofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.66Ͳ76.  Authors Coordination:KarlKrainer Involvedprojectpartnersandcontributors: Ͳ InstituteofGeologyandPaleontology,UniversityofInnsbruck(UIBK)–KarlKrainer  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentgeomorphicevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

 66 PermafrostResponsetoClimateChange

Summary  Rock glacier Hochebenkar is a tongueͲshaped active rock glacier located in a small Northwest facingcirqueintheÖtztalAlps(Austria;46°50´14´´N,11°00´46´´E).Morphologyandhighsurface flowvelocitiesindicatethattherockglaciercontainsamassiveicecoreandthuspointtoaglacial origin.Duringwinter,thetemperatureatthebaseofthesnowcover(BTS)issignificantlylower ontherockglacierthanonpermafrostͲfreegroundadjacenttotherockglacier.Dischargeofthe rockglacierischaracterizedbystrongseasonalanddiurnalvariationsandisstronglycontrolled by the local weather conditions, particularly the amount of snow and rainfall events. Water temperature of the rock glacier springs remains constantly low, mostly below 1°C during the entiremeltseason.Duringthelastdecadeschangesinthevelocityoftherockglaciershowa closecorrelationwithchangesinthemeanannualairtemperatureofnearbyweatherstations. Thestrongdecreaseinthicknessinthelowermost,steeppartoftherockglacieriscausedby increasedmeltingoficeandindicatesthepresenceofamassiveicecore.Ifincreasedmeltingwill continueduringthenextdecadesflowvelocitywilldecreaseandtheactiverockglacierwillpass intoaninactiveone.

67 PermaNET–Permafrostresponsetoclimatechange

1. Introductionandstudyarea PermafrostiswidespreadintheAlpswhichisdocumentedbythelargenumberofrockglaciersthat havebeenmappedintheeasternpartoftheAlps,particularlyinthecentralmountainranges(e.g. ÖtztalandStubaiAlps).AspermafrosttemperaturesintheAlpsarejustslightlybelow0°Candthe frozencoreofrockglaciersisthin,rarelyexceeding25m,permafrostintheAlps,particularlyactive and inactive rock glaciers, are very sensitive to climate change. Studies on Alpine permafrost, particularlyonactiverockglaciers,advancedrapidlyduringthelasttwodecades(seesummaryby Haeberlietal.2006).IntheAustrianAlpsseveralrockglaciershavebeenstudiedindetailinrecent years(e.g.Lieb,1986,1987,1991,1996;Lieb&Slupetzky1993;Kaufmann,1996a,b,Kaufmann& Ladstädter2002,2003,KellererͲPirklbauer2007,2008,Bergeretal.2004,Krainer&Mostler,2000, 2001,2002,2004,2006,Kraineretal.2002,2007,Hausmannetal.,2007). Hochebenkar rock glacier is located in Äußeres Hochebenkar, a Northwest oriented cirque in the southernÖtztalAlps,about4.3kmSSWofObergurgl,Ötztal(Tyrol,Austria).AlthoughHochebenkar rock glacier has been studied concerning flow velocities for more than 70 years (see below), only littleinformationisavailableaboutcomposition,thickness,hydrologyandthermalconditions. 



Fig.1–RockglacierHochebenkarwithlocationofsprings,gaugingstationsandtemperatureloggers (fromAbermannetal.2011). 

 68 PermafrostResponsetoClimateChange

Hochebenkarrockglacieristongueshapedandextendsfromanaltitudeof2840m(rootingzone)to 2360m (front). The maximum length of this active, NWͲfacing rock glacier is 1550m. The width rangesfrom160mnearthefrontto335minthemiddleandupto470mintheupperpart.Therock glaciercoversanareaof0.4km²,thedrainageareacomprises1km². ThesurfacelayeriscoarseͲgrainedwithvaryinggrainsizeandlocallywelldevelopedtransverseand longitudinalfurrowsandridges.Adepressionisdevelopedinthewesternpartoftherootingzone. The front is steep and bare of vegetation. The highest peaks surrounding the rock glacier are Hangerer(3021m)ontheeasternsideandtheHochebenkammwithitshighestpointat3149mon the southern side, separated by the Hochebenscharte (2895m). The debris of the rock glacier is derivedfromthesteeprockwallsoftheHochebenkamm. Bedrockinthedrainageareaoftherockglacieriscomposedofparagneissandmicaschistsofthe ÖtztalͲStubaicomplex.AtHochebenkammthebedrockiscutbynumeroussteepfaultsalongwhich highamountsofdebrisareproducedbyfrostweathering,particularlyduringbreakͲupinspringand earlysummer. TheaimofthiscasestudycontributionistopresentsomepreliminarydataonthedynamicsofRock GlacierHochebenkar,oneofthelargestandmostactiverockglaciersoftheAustrianAlps.  



Fig.2:Viewtothesteep,activefrontofHochebenkarrockglacier(viewtowardsSW)

69 PermaNET–Permafrostresponsetoclimatechange

 2. Permafrostindicatorsandrecentgeomorphicevolution 2.1Previousstudies Hochebenkar rock glacier is one of the largest and most active rock glaciers in the Austrian Alps, whichalsoshowstheworldwidelongestrecordofflowvelocities.Pillewizerstartedtomeasureflow velocitiesonHochebenkarrockglacierin1938.Sincethattime,i.e.overaperiodofmorethan70 years,flowvelocitiesonthisrockglacierhavebeenmeasuredbyterrestrialphotogrammetry,since 1951 by terrestrial geodetic methods (Theodolite) and since 2008 by differential GPS (Pillewizer 1938,1957;Vietoris1958,1972;Haeberli&Patzelt1982;Kaufmann1996;Schneider&Schneider 2001;Kaufmann&Ladstädter2002,2003;Ladstädter&Kaufmann2005).Haeberli&Patzelt(1982) measuredthebasaltemperaturesofthewintersnowcoverinFebruary1975,1976and1977,and the water temperature of rock glacier springs during summer. They also carried out refractionͲ seismicmeasurementsalong11transectsonfrozenandunfrozenground.  2.2Rockglacierdynamicsandthermalregime DuringthelastyearsintensiveinvestigationshavebeencarriedoutonHochebenkarrockglacierto studythedynamics.Theseinvestigationsincludefieldmappingofthebedrockandsedimentsand geomorphologic features, grainͲsize analysis of the debris layer, BTS measurements, hydrology, georadarandflowvelocitymeasurements(detailsinAbermannetal.2011).  

 Fig.3:GrainͲsizedistributionofthreesitesonHochebenkarrockglacier.Greenbars:coarseͲgrained, bluebars:mediumͲgrained,redbars:fineͲgrined. 

 70 PermafrostResponsetoClimateChange

Grainsizeofrockglacier ThesurfacedebrislayerofHochebenkarrockglacieriscoarseͲgrainedwithanaveragegrainsize(aͲ axis)measuring35cmonfinergrainedareasand58cmoncoarsergrainedareasinthemiddlepart (Fig.3).Locallyblocksuptoafewmindiameteroccuronthesurface.Similarvaluesarerecorded fromotherrockglacierscomposedofdebrisderivedfromgneissesandschists(Bergeretal.2004, KrainerandMostler2001,2004). The coarseͲgrained debris layer has a maximum thickness of 1.5m and is underlain by debris containinghigheramountsofsandandsilt(Fig.4)displayingpoortoverypoorsortingwithvaluesof 2.96Ͳ3.23Phi (inclusive graphic standard deviation after Folk & Ward, 1957). Similar values have been reported from other rock glaciers (Barsch et al. 1979, Giardino & Vick 1987, Haeberli 1985, Krainer&Mostler2000,2004,Bergeretal.2004)andtills. 

 Fig.4:CumulativecurvesoftwosamplestakenatthesteepfrontofHochebenkarrockglacier.Both samplesshowasimilartrendindicatingpoorsorting.  Thermalregimeofground BTSmeasurementsperformedbyHaeberli&Patzelt(1982)inFebruary1975,1976and1977yielded meanvaluesrangingbetweenͲ4.8andͲ7°C.SimilartemperatureswererecordedinMarch2010. Duringwinter2006/2007eighttemperatureloggerswereinstalledwhichrecordedthetemperature atthebaseofthesnowcoveratanintervaloftwohours.Resultsshowthatthetemperatureatthe base of the snow cover on permafrostͲfree ground near the gauging station remained constantly between 0 andͲ1°C from November until May. From December until April temperatures varied betweenͲ3andͲ4°CatthewesternmarginandbetweenͲ2andͲ4°Cattheeasternmarginofthe rockglacier.BTStemperaturesweresignificantlydeeperinthecentralpartoftherockglacierranging betweenͲ5andͲ9.3°Cwithonlyminorvariations.Thedeepesttemperature(Ͳ9.9°C)wasobservedin earlyJanuary.SnowmeltstartedduringthefirsthalfofMay.

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SimilarBTStemperaturepatternswererecordedonotheractiverockglaciersintheÖtztalandStubai Alps(Ölgruberockglacier–Bergeretal.2004,Reichenkarrockglacier –Krainer&Mostler2000, Sulzkarrockglacier–Krainer&Mostler2004)andSchoberMountains(Krainer&Mostler2001).  Thermalregime,dischargeandelectricalconductivityofwatersprings Watertemperatureoftherockglacierspringsremainedalmostcontinuously<1°Cduringsummer. Even after heavy thunderstorms in summer with rather “warm” rainfall causing peak floods in dischargeoftherockglacierthewatertemperaturedidnotchange. AtHochebenkarrockglaciermostofthemeltwaterisreleasedfromspringsatthefront(Fig.1).A minoramount(ca.30%)ofmeltwaterisreleasedfromtwospringsontheeasternsideoftherock glacieratanaltitudeof2575m(Fig.1).About95mdownstreamagaugingstationwasinstalledin spring2007atanaltitudeof2555minordertorecordthewaterdepthversustimeduringthemelt season.Waterdepthofthemeltwaterstreamiscontinuouslyrecordedbyapressuretransducerat intervalsof1hour. The discharge of the rock glacier is mainly controlled by water derived from snowmelt, summer thunderstormsand/orsnowfallduringsummerandthusdisplayspronouncedseasonalanddiurnal variationsindischarge.Runoffin2009startedduringAprildisplayingfloodswithmaximumflowpeak duringMayandJunecausedbyfairweatherperiodswithintensemeltingofsnowandice(Fig.5).A rapiddeclineindischargewasrecordedafewhoursafterinfluxofcoldair whichsometimeswas accompanied by snowfall. ShortͲterm floods with peakflows >100l/s are triggered by summer thunderstorms with heavy rainfall. From July until September discharge decreased and was interruptedbysinglepeakflowscausedbyrainfallevents.

 Fig.5–Hydrograph(waterheights,blueline)ofthemeltwaterstreamreleasedfromHochebenkar rockglacier(springsattheeasternsideoftherockglacier)fortheperiodApriltoSeptember2009. Redlineindicateswatertemperatureatthegaugingstation(locationseeFig.1). Thevaluesforelectricalconductivityofthewaterdischargedfromtherockglaciervarysignificantly overtheseason.AtHochebenkarrockglaciersignificantlyhighervaluesofelectricalconductivityare recordedatthetwospringsontheeasternsidethanatthemainspringatthefront.

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AtspringswhichoccuratthebaseofthesteepfrontelectricalconductivityisextremelylowinMay andJune(20Ͳ30µS/cm)andincreasesslightlyreachingvaluesof40µS/cmbytheendofAugustand 60µS/cmatthebeginningofOctober.Thewatertemperatureatthesespringsrangesfrom0.6to 1.4°C. Atthetwospringsontheeasternsideoftherockglacierthevaluesofelectricalconductivityare significantly higher with 100Ͳ200µS/cm in June, increasing to 400µS/cm during August and to 570µS/cmduringSeptember.Watertemperatureisverylowwith0.2Ͳ0.4°C.Theseasonalvariation inelectricalconductivityresultsfromthedifferentmixingratiooflowmineralizedprecipitationand highermineralizedgroundwater(Krainer&Mostler2001,2002,Kraineretal.2007).  Rockglacierdynamics Fortheperiod1938Ͳ1953Pillewizer(1957)documentedamaximumflowvelocityintheupperpart (profile B) of 75cm/a, and 85 cm/a for the period 1953Ͳ1955. Profile 2 yielded flow velocities of 1.61mfortheperiod1951Ͳ1952,1.84mfortheperiod1952Ͳ1953and1.53mfortheperiod1953Ͳ 1955(Pillewizer1957,Vietoris1958). Significantly higher flow velocities (average 3.9m/a, maximum6.6 m/a) were recorded between 1954 and 1972, whereas between 1973 and 1995 flow velocities were lower (average 1.15m/a, maximum2m/a).Flowvelocitiesagainincreasedsince1995reachingthehighestvaluesin2003,and thendecreasedagain(seeAbermannetal.2011).  Recentmorphologicalchanges From1936to1997thefrontoftherockglacieradvancedfor165m(Schneider&Schneider2001). AccordingtoKaufmann(1996)thefrontofHochebenkarrockglacieradvancedfor148mduring50 years,indicatingameanflowvelocityof3m/aforthatperiod.Thelowermostprofile1yieldedthe highestflowvelocitiesof3.57m/a(1953Ͳ1955)whichincreasedto5m/a(Vietoris1972).Since1995 asignificantdecreaseinthicknesswasobservedinthelowermost,steeppartoftherockglacier.  2.3DiscussionandConclusion Morphologyanddebrispropertiesoftheactivelayerareverysimilartootherrockglacierscomposed ofdebrisderivedfrommetamorphicrocks,particularlygneissandschist(Bergeretal.2004;Krainer &Mostler2000,2001,2004).BasedongrainͲsizeofthesurfacelayerHochebenkarrockglacierisa typicalboulderrockglacieraccordingtoIkedaandMatsuoka(2006).Temperaturesatthebaseofthe wintersnowcover(BTS)aretypicalforactiverockglaciersandsimilartothoserecordedfromother activerockglaciersintheAustrianAlps(Bergeretal.2004;Krainer&Mostler2000,2001,2004).The pronounced seasonal and diurnal variations in discharge are strongly controlled by the weather conditions.Waterreleasedattherockglacierspringsismainlyderivedfromsnowmeltandsummer rainfall,subordinatelyfrommeltingofpermafrosticeandgroundwater.Floodpeaksarecausedby intensivesnowmeltonwarm,sunnydaysduringlatespringandearlysummerandbyrainfallevents. Thewatertemperatureoftherockglacierspringswhichremainspermanentlybelow1.5°C,mostly below1°C,indicatesthatthewaterflowsthroughtherockglacierindirectcontactwithpermafrost ice(Krainer&Mostler2002,Kraineretal.2007).Extremelyhighvaluesoftheelectricalconductivity atthespringontheeasternsideoftherockglacierindicateamuchlongerresidencetimeofthe watercomparedtothewaterreleasedatthespringsatthesteepfrontwhichischaracterizedbyvery lowvaluesindicatingthattheresidencetimeisshortandthatthewaterisderivedfrommeltingof iceandsnowandrainfall.

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Thedepressionintherootingzoneandthepronounceddecreaseinthicknessinthelowermostpart duringthelastyearsindicatemeltingofmassiveiceandwesuggestthatHochebenkarrockglacier hasaglacialoriginsimilartoReichenkarrockglacier(Krainer&Mostler2000,Kraineretal.2002, Hausmann et al. 2007). High iceͲcontent is also indicated by annual flow velocities which are significantly higher than those of most other active rock glaciers with typical values of 0.1Ͳ1m. Schneider&Schneider(2001)showedthatthevariationsinflowvelocitycorrelatewiththemean annual air temperature values. Higher flow rates during warmer periods are probably caused by higher amounts of meltwater within the rock glacier and near the base, probably also to slightly highericetemperatures. Hochebenkar rock glacier most likely developed from a debrisͲcovered cirque glacier due to the inefficiencyofsedimenttransferfromglaciericetomeltwater,amodelproposedbyShroderetal. (2000)basedonstudiesintheNangaParbatHimalaya.  3. Possiblefuturethermalresponsetopredictedclimatechange Inhighalpinemountain environmentspermafrostiswarm(Ͳ2to0°C)andthushighlysensitiveto temperaturechanges.WhereaswarmingofpermafrostwasobservedinthenorthernpartsofEurope of0.5Ͳ1°Cduringtheperiod1998Ͳ2008,noclearwarmingtrendwasrecordedintheAlpsforthis periodduetohighannualvariationsresultingparticularlyfromvaryingthicknessesofthesnowcover (GärtnerͲRoer et al. 2011). However, field observations show that many rock glaciers in the Alps alreadyreactedonthewarmingtrendduringthelastdecade.AsmostrockglaciersintheAlpsare located near the lower boundary of discontinuous permafrost, which is thin and rather “warm”, theserockglaciersareexpectedtoreactmorerapidlytoevenslighttemperaturechangescompared torockglaciersofcolderregions. AtHochebenkarrockglacierasignificantdecreaseinthicknesswasobservedduringthelast15years in the steep lower part indicating increased melting of permafrost ice. This already resulted in a decreaseofflowrates.Ifthetrendofglobalwarmingwillcontinue,meltingofpermafrosticewill continue, particularly in the lower part of the rock glacier which is close to the lower limit of permafrost,resultinginadecreaseinflowvelocity. Butevenintheupperpartoftherockglacierincreasedmeltingofpermafrosticeisexpected.Thus Hochebenkarrockglacierwilltransformfromahighlyactiverockglacierintoaninactiverockglacier duringthenextdecades.Asaconsequence,vegetationwillstarttogrowonthefineͲgrained,steep frontalpartoftherockglacier,whichisstillbareofvegetation. Changes of total rock glacier discharge will depend on changes of annual precipitation. Increased melting of permafrost ice will slightly increase the amount of meltwater derived from ice, which constitutes only a small part (<10%) of the total discharge. Warming will change the discharge patternofrockglaciers:themeltingseasonwillstartearlier(inAprilinsteadofearlyMay),andsnow is expected to melt more rapidly within a shorter period during May and June causing high peak flows.Thesepeakflowsmaybeoverprintedbysinglerainfalleventsresultinginextremepeakflows. Heightofpeakflowandlengthofthepeakflowperiodwilldependonthesnowheightswhichalso maychange.SuchadischargepatternwithonsetofthemeltperiodinAprilandextremepeakflows duetointensivesnowmeltduringMayandearlyJunewasalreadyrecordedintheextremewarm summerof2003.LowdischargeisexpectedforJulyuntiltheendofthemeltperiod,interruptedby singlepeakflowscausedbyrainfallevents.  Acknowledgements:MonitoringofHochebenkarrockglacierisfundedbytheAustrianAcademyof Sciences(project“ImpactofClimateChangeonAlpinePermafrost”).

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 References:  Abermann,J.,Fischer,A.,Krainer,K.,Nickus,U.,Schneider,H.,&Span,N.,2011:Resultsofrecentresearchon RockGlacierÄußeresHochebenkar.ZeitschriftfürGletscherkundeundGlazialgeologie(submitted). BarschD.,FierzH.&HaeberliW.,1979:Shallowcoredrillingandboreholemeasurementsinpermafrostofan activerockglacierneartheGrubengletscher,Wallis,SwissAlps.ArcticandAlpineResearch,11,215Ͳ 228. BergerJ.,KrainerK.&MostlerW.,2004:Dynamicsofanactiverockglacier(ÖtztalAlps,Austria).Quaternary Research,62,233Ͳ242. FolkR.L.&WardW.C.,1957:BrazosRiverBar:Astudyinthesignificanceofgrainsoilparameters.Journalof SedimentaryPetrology,27,3Ͳ26. GärtnerͲRoerI.,ChristiansenH.H.,EtzelmüllerB.,FarbotH.,GruberS.,IsaksenK.,KellererͲPirklbauerA.,Krainer K.&NoetzliJ.,2011:Permafrost.In:T.Voigt&H.M.Füssel(eds),Impactsofclimatechangeonsnow, ice,andpermafrostinEurope:Observedtrends,futureprojections,andsocioeconomicrelevance:66Ͳ 76. GiardinoJ.R.&VickS.G.,1987:Geologicengeneeringaspectsofrockglaciers.RockGlaciers,Allen&Unwin, London,265Ͳ287. Haeberli W., 1985: Creep of mountain permafrost: Internal structures and flow of alpine rock glaciers. MitteilungenderVersuchsanstaltfürWasserbau,HydrologieundGlaziologieETHZürich,77,1Ͳ142. HaeberliW.&PatzeltG.,1982:PermafrostkartierungimGebietderHochebenkarͲBlockgletscher,Obergurgl, ÖtztalerAlpen,ZeitschriftfürGletscherkundeundGlazialgeologie,18,127Ͳ150. Haeberli W., Hallet B., Arenson L., Elconin R., Humlum O., Kääb A., Kaufmann V., Ladanyi B., Matsuoka N., SpringmanS.&VonderMühllD.,2006:PermafrostCreepandRockGlacierDynamics.Permafrostand PeriglacialProcesses,17,189Ͳ214. HausmannH.,KrainerK.,BrücklE.&MostlerW.,2007:InternalStructureandIceContentofReichenkarRock Glacier (Stubai Alps, Austria) Assessed by Geophysical Investigations. Permafrost and Periglacial Processes,18,351Ͳ367. IkedaA.&MatsuokaN.,2006:Pebblyversusboulderrockglaciers:Morphology,structureandprocesses.– Geomorphology,73,279Ͳ296. KaufmannV.,1996a:DerDösenerBlockgletscher–StudienkartenundBewegungsmessungen.Arb.Inst.Geogr. Univ.Graz,33,141Ͳ162.  KaufmannV.,1996b:GeomorphometricmonitoringofactiverockglaciersintheAustrianAlps.4th International SymposiumonHighMountainRemoteSensingCartography.Karlstad,Kiruna,Tromso,August19Ͳ29, 1996,97Ͳ113. KaufmannV.&LadstädterR.,2002:SpatioͲtemporalanalysisofthedynamicbehaviouroftheHochebenkar rockglaciers(OetztalAlps,Austria)bymeansofdigitalphotogrammetricmethods.GrazerSchriftender GeographieundRaumforschung,37,119Ͳ140. Kaufmann V. & Ladstädter R., 2003: Quantitative analysis of rock glacier creep by means of digital

photogrammetry using  multiͲtemporal aerial photographs: two case studies in the Austrian Alps. Proceedingsofthe8th InternationalConferenceonPermafrost,21Ͳ25July2003,Zurich,Switzerland,1, 525Ͳ530. KellererͲPirklbauer A. 2007: Lithology and the distribution of rock glaciers: Niedere Tauern Range, Styria, Austria.Z.Gemorph.N.F.,51/2,17Ͳ38. KellererͲPirklbauer A., 2008: The SchmidtͲhammer as a Relative Age Dating Tool for Rock Glacier Surfaces: Examples from Northern and Central Europe. Proceedings of the Ninth International Conference on Permafrost(NICOP),UniversityofAlaska,Fairbanks,June29–July3,2008,913Ͳ918.

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KrainerK.&MostlerW.,2000:ReichenkarRockGlacier:aGlacierDerivedDebrisͲIceSystemintheWestern StubaiAlps,Austria.PermafrostandPeriglacialProcesses,11,267Ͳ275. KrainerK.&MostlerW.,2001:DeraktiveBlockgletscherimHinterenLangtalKar,Gößnitztal(Schobergruppe, NationalparkHoheTauern,Österreich).Wiss.Mitt.NationalparkHoheTauern,6,139Ͳ168. Krainer K. & Mostler W., 2002: Hydrology of Active Rock Glaciers: Examples from the Austrian Alps. Arctic, Antarctic,andAlpineResearch,34,142Ͳ149. Krainer K. & Mostler W., 2004: Aufbau und Entstehung des aktiven Blockgletschers im Sulzkar, westliche StubaierAlpen.Geo.Alp,1,37Ͳ55. KrainerK.&MostlerW.,2006:FlowVelocitiesofActiveRockGlaciersintheAustrianAlps.GeografiskaAnnaler, 88A,267Ͳ280. KrainerK.,MostlerW.&SpanN.,2002:AglacierͲderived,iceͲcoredrockglacierintheWesternStubaiAlps (Austria): Evidence from ice exposures and ground penetrating radar investigation. Zeitschrift für GletscherkundeundGlazialgeologie,38,21Ͳ34. Krainer K., Mostler W. & Spötl C., 2007:Discharge fromactive rock glaciers, Austrian Alps: a stable isotope approach.AustrianJournalofEarthSciences,100,102Ͳ112. LadstädterR.&KaufmannV.,2005:StudyingthemovementoftheOuterHochebenkarrockglacier:Aerialvs. groundͲbased photogrammetric methods. Second European Conference on Permafrost, Potsdam, Germany,TerraNostra2005(2),97. LiebG.K.,1986:DieBlockgletscherderöstlichenSchobergruppe(HoheTauern,Kärnten).Arb.Inst.Geogr.Univ. Graz,27,123Ͳ132. LiebG.K.,1987:ZurspätglazialenGletscherͲundBlockgletscehrgeschichteimVergleichzwischendenHohen undNiederenTauern.Mitt.Österr.Geogr.Ges.,129,5Ͳ27. LiebG.K.,1991:DiehorizontaleundvertikaleVerteilungderBlockgletscherindenHohenTauern(Österreich). Z.Geomorph.N.F.,35,345Ͳ365. LiebG.K.,1996:PermafrostundBlockgletscherindenöstlichenösterreichischenAlpen.Arb.Inst.Geogr.Univ. Graz,33,9Ͳ125. LiebG.K.&SlupetzkyH.,1993:DerTauernfelckͲBlockgletscherimHollersbachtal(Venedigergruppe,Salzburg, Österreich).Wiss.Mitt.NationalparkHoheTauern,1,138Ͳ146. Pillewizer W., 1938: Photogrammetrische Gletscheruntersuchungen im Sommer 1938. Zeitschrift der GesellschaftfürErdkunde,1938(9/19),367Ͳ372. PillewizerW.,1957:UntersuchungenanBlockströmenderÖtztalerAlpen.GeomorphologischeAbhandlungen desGeographischenInstitutesderFUBerlin(OttoͲMaullͲFestschrift),5,37Ͳ50. SchneiderB.&SchneiderH.,2001:Zur60jährigenMessreihederkurzfristigenGeschwindigkeitsschwankungen amBlockgletscherimÄusserenHochebenkar,ÖtztalerAlpen,Tirol.ZeitschriftfürGletscherkundeund Glazialgeologie,37(1),1Ͳ33. ShroderJ.F.,BishopM.P.,CoplandL.&SloanV.F.,2000.DebrisͲcoveredglaciersandrockglaciersintheNanga ParbatHimalaya,Pakistan.GeografiskaAnnaler,82:17Ͳ31. VietorisL.,1958:DerBlockgletscherdesäußerenHochebenkares.GurglerBerichte,1,41Ͳ45. Vietoris L., 1972: Über die Blockgletscher des Äußeren Hochebenkars. Zeitschrift für Gletscherkunde und Glazialgeologie,8,169Ͳ188.

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 3. CasestudiesintheEuropeanAlps   3.6 RockGlacierLaurichard,NorthernFrenchAlps   

  Citationreference SchoeneichP.,BodinX.,KrysieckiJ.ͲM.(2011).Chapter3.6:CasestudiesintheEuropeanAlps–Rock Glacier Laurichard, Northern French Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost response to present and future climate change in the European Alps. PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.77Ͳ86.  Authors Coordination:PhilippeSchoeneich Involvedprojectpartnersandcontributors: Ͳ Institut de Géographie Alpine, Université de Grenoble, France (IGAͲPACTE) – Philippe Schoeneich,XavierBodin,JeanͲMichelKrysiecki  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentgeomorphicandthermalevolution 3. Possiblefuturethermalanddynamicresponsetopredictedclimatechange References

77 PermaNET–CasestudiesintheEuropeanAlps

Summary  The Laurichard rock glacier in the French Alps is monitored for surface displacements and repeated geoelectrical soundings and tomographies since the 1980’s. The 25 years velocity record,togetherwiththerepeatedgeoelectricalsurveysandgroundsurfacetemperaturerecord, allows to draw some essential conclusions on the influence of climate on the behaviour and evolutionofrockglaciers.Rockglaciersreacttoclimateandshowinterannualvelocityvariations. Theirreactiontimeisthusmuchshorterthanpreviouslyassumed.Velocityvariationsarelinked totemperaturevariations–anincreaseintemperatureinducesanincreaseinvelocity.Theair temperature only partly explains the observed ground surface temperature and velocity variations.Thegroundsurfacetemperatureshowsthebestlinkwithvelocityvariations,witha time lag of around one year. The snow cover explains most of the difference between air temperatureandgroundsurfacetemperature,andthusappearsasthemaindrivingfactorboth for ground surface temperatures and for velocity variations. Thus, the evolution of the permafrostwillnotonlydependontheairtemperature,butwillbestronglyinfluencedbythe evolutionofthesnowcover,especiallyitsearlyorlateonsetinautumn.Alateonsetofthesnow covercanatleastpartiallycompensateariseinairtemperature.

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1. Introductionandstudyarea TheLaurichardrockglacierRGL1issituatedinthegraniticCombeynotmassifonaNorthfacingslope. Itisawelldevelopedboulderyrockglacierwithdistinctcompressionridgesandasteepfrontaland lateralslope(Fig.1).TheRGL1extendsfromtherootingzone(2650ma.s.l.)atthecontactwiththe rockfaceto2450ma.s.l.atitsfrontandisadvancingontoHoloceneglacialandperiglacialdeposits. Itis490mlong,between80and200mwide,andhasanapparentthickness(basedonthevertical heightofthesidesandfront)of20Ͳ30m.Therockglacierhasathreesteppedlongitudinalprofile, with moderate slopes in the upper part, a steep median part, and again a moderate slope in the frontalpart.Itdisplaysmorphologicalfeaturestypicalofanactivelandform:longitudinalridgesinthe centralsteeppartandasuccessionoftransverseridgesandfurrowsinthecompressivepartofthe tongue(Table1). 

 Fig.1–TheLaurichardrockglacier.PhotographbyX.Bodin.  Table1–CharacteristicsoftheLaurichardrockglacier

Method initiated/carriedout Latitude N45.0181° Longitude E06.3997° Elevation[ma.s.l.] 2440Ͳ2650m Slope Variable:moderateontopandtoe,steep(50%)inmiddlepart Aspect North Typeofrockglacier talus;lobatetotongueshaped;active Evidenceofpermafrost Observationofgroundice,groundsurfacetemperature,geoelectric Evidenceofmovement Aerialphotograph,geodetic,Lidar Typologyofmovement Velocitiychanges Meanvelocityrange From0.3to1.6m/yr Changeinvelocity 20%increase2000Ͳ2004,decrease2004Ͳ2006 Yearoffirstdata (1979)1985

79 PermaNET–CasestudiesintheEuropeanAlps

2. Permafrostindicatorsandrecentgeomorphicandthermalevolution 2.1Methods Movementshavebeenmeasuredsince1979andregularlyrepeatedsince1985.Thusitrepresents oneofthelongestdisplacementmeasurementrecordonarockglacierintheAlps.Classicalgeodetic measurementsaremadeundersupervisionoftheParcNationaldesEcrinsonatransverseandona longitudinallineofpoints,withaclassicaltotalstation.Thesurveywascarriedouteverytwotothree yearsfrom1979to1999andsubsequentlyeveryyear.Fourmarkedblockswereaddedattheupper end part of the longitudinal profile in 1999. Annual velocity (downslope, vertical and horizontal), actual vertical change after removing total displacement of the block downslope and variation in interͲblockdistancecanbecalculatedfromthesedata(Bodinetal.2009).Measuredvelocitiesrange from0.2to1.6m/a.Thehighestvelocitiesaremeasuredinthesteepmedianpart(Fig.2).Compared toothersurveyedrockglaciers,itcanbeconsideredasaratherfastmovingrockglacier. 

 Fig.2–DownslopemeanannualsurfacevelocitiesoftheLaurichardrockglacieralonglongitudinal profile line L (1986Ͳ2006 or 2000Ͳ06). Grey band represents one standard deviation for each measurementlocation(fromBodinetal.2009).  Geophysical investigations have been repeated regularly since 1986. In total 12 vertical electrical soundings(VES)andsixelectricalresistivitytomography(ERT)profileshavebeenundertakenonthe rockglaciertoinvestigateitsinternalstructure:twoVESin1986(Francou&Reynaud,1992),fiveVES in1998(V.Jomelli&D.Fabre,unpublishedwork),fourVESandtwoERTin2004,andoneVESin 2006. All of the VES were carried out using the Schlumberger configuration and the results were interpretedwithtwoorthreeͲlayeredresistivitymodels,whereasapoleͲdipoleconfigurationproved tobethebestforERT.ThetwoERTprofilesweremeasuredagainin2007and2009.Theserepeated measurementsallowsomeinterpretationsontheevolutionoftheicecontent. Ground surface temperature (GST) measurements have been performed on the Laurichard rock glaciersince2003,withsevenUTLminidataloggersburiedjustbelowtheblockysurfacetoprotect themfromdirectsolarradiation.OneloggerisplacedoutsidetherockglacierinanonͲpermafrost area,whereasthesixothersaredistributedoverthesurfaceofthelandform.Anautomatedweather stationhasbeeninstalledin2004besidetherockglacier.Meteorologicaldatafromnearbystations canbeusedinaddition 

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2.2Rockglaciervelocityvariation OneofthetypicalcaractristicsoftheLaurichardrockglacierRGL1aresignificantvelocityvariations all over the 25 years observation period. The rock glacier showed an increasing trend in flow velocitiesfrom1985to1999,oscillationsaroundahighvelocityratefrom2000to2004,adecrease from2004to2006,andagainamoderateincreasesince2007.Previousto2000,thevelocitychanges aremoredifficulttointerpret,duetothenonͲannualmeasurements.Meanvelocitiesonperiodsof2 to3yearsdonotshowsignificantchanges,butthemeasurementintervalinducesasmoothingofthe valuesthatpossiblyhidesmoresignificantinterannualvariations. Thevelocitychangescanbecomparedtothemeanannualairtemperature(MAAT)usingthenearby stationofMonêtierͲlesͲBains(MeteoͲFrance),usinga12monthrunningmean(Fig.3).Theoverall picture shows a correspondence between the increasing temperature trend and the increasing velocitytrendfrom1985to1999,thehighlevelofbothtemperatureandvelocitybetween2000and 2004, and the decrease in both temperature and velocity since 2004. This shows at least that a generaldependenceofvelocityontemperatureseemstoexist.Whenlookingondetails,however, thecorrespondenceappearstobelessevident.Before2000strongtemperaturevariationsarenot expressedinthevelocitychanges,butasmentionnedabove,thiscouldbepartlyduetoasmoothing ofthevelocitycurvebythemeasurementinterval.Between2000and2004,somevelocityvariations appeartobeinvertedcomparedtotemperaturevariations.Thiscouldindicateeitheratimelagor theinfluenceofotherparameters. 

 Fig.3–MeansurfacevelocityoftheLaurichardrockglacier(RGL1)and1ʍrange(greyband)from 1986Ͳ2006 (based on points L1ͲL3, L5ͲL8, L10ͲL12), and 12Ͳmonths running mean air temperature anomaly(relativetothe1960Ͳ91average)attheMonêtierstation(MeteoFrancedata)(fromBodin etal.2009).  Since2000velocityvariationscanbecomparedonanannualbasiswithgroundsurfacetemperature records(usingadatasetfromValaisfortheperiodbefore2004).Thevelocitychangesshowagood correspondence with the MAGST (mean annual ground surface temperature), averaged over the previous 12 months. This shows that creep rates are strongly dependent on ground surface temperatures,whichappearasthemaincontrollingfactorwithatimelagintheorderof1year(Fig. 4). 

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 Fig. 4 – Ground surface temperatures and rock glacier movement, 2000Ͳ06: mean surface velocity (profileL)oftheLaurichardrockglacier(RGL1),andgroundsurfacetemperaturesonRGL1(2003Ͳ06, 12Ͳmonthsrunningmean,averageoffourdataloggers)andintheValaisregion(2000Ͳ06,12Ͳmonths runningmean;westernSwissAlps;about2500ma.s.l.,datafromDelaloyeetal.,2008)(fromBodinet al.2009).  2.3Evolutionofgroundsurfacetemperature Ground surface temperatures (GST) show some deviations from the air temperature. The main controllingfactorforgroundsurfacetemperatureappearstobethesnowcoverthickness,especially inautumnandearlywinter.ThisiswelldemonstratedbytheGSTmeasurementseriesperformedat Laurichardsince2003(fig.5,Schoeneichetal.2010). Anearlyandsufficientlythicksnowcoverprotectsthegroundsurfacefromcoolingduringthecold andshortdaysofNovemberͲDecember,whereasalateorshallowsnowcoverallowsastrongcooling oftheground.Whenthesubsequentsnowcoveristhickenough,itsinsulationeffectpreservesthe “thermal memory” during the whole winter, as is shown by the winter equilibrium temperatures (WeqT)measuredinMarch. Thusthegroundsurfacecanexperienceanaveragecoolingeveninwarmyears,ifthesnowcover onsetislate,and/orifthesnowcoverremainsthin.Ontheotherhand,thecumulativeeffectofan early snow rich winter preceded or followed by a hot summer is most efficient for inducing a warmingofthegroundsurface.  2.4Evolutionoficecontentandstate Repeatedverticalelectricsoundings(VES)andelectricalresistivitytomography(ERT)profilesshow anevolutionofapparentresistivitiesmeasuredontherockglacierbody.Alldatashowthetypical profile expected on rock glaciers, with a moderately resistant surface layer corresponding to the blockyactivelayer,ahighresistivemainlayercorrespondingtothepermafrostbody,andabasalless resistivelayer.Thediscussionwillthusfocusondifferenceswithtime. FoursuccessiveVESwereperformedonthetongue(1986,1998,2004,2006)andthreeattheroot (1986,1998,2004).Theaccuracyofrelocationofthe1986sitesisjudgedtobeabout5mforthe lower one and 10m for the upper one. There was a general decrease in the maximum apparent resistivity (ramax) at the VES sounding sites located at the root and on the tongue from 1986 to 2004Ͳ06(Fig.6).Attheroot(foraninterͲelectrodespacingAB/2=50m),ramaxdecreasedby35Ͳ50% from8.105ɏ.min1986to3Ͳ4.105ɏ.m18yearslater.Atthetongue,ramaxdecreasedby20Ͳ50%cent from5.104ɏ.min1986(AB/2=30m)to1.5Ͳ4.104ɏ.min2004(AB/2=20m). 

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 Figure 5 – Ground surface temperatures measured on 5 locations on the Laurichard rock glacier (2003Ͳ2009,runningmeanofthe12previousmonths).LA1isoutsideoftherockglacier,theothers areonit.Theeffectofthesnowpoorwinters2004/05and2005/06isclearlyvisible,aswellasthe cumulativeeffectofthehotsummer2006andthesnowrichwinter2006/07.  

 Fig.6–(a)Measuredandmodelledresistivityattheroot(blackcurvesanddots)andtongue(grey curvesanddots)oftheLaurichardrockglacierin1986and2004;(b)invertedmodelsfortheroot (top)andtongue(bottom)in1986and2004(fromBodinetal.2009). 

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Therelativelylargevariationsinresistivityovertheperiod1998Ͳ2006suggestthatitmaybedifficult todistinguishresistivitychangesduetolongͲtermmodificationofthepermafrost(e.g.athickening oftheactivelayer,anincreaseingroundtemperature,adecreaseinicecontent)fromthoserelating to seasonal changes in ground properties (e.g. differing water contents during the sounding campaignsintheactivelayerand/orwithintheicylayer),and/orlocalisedchangesintheinternal structure related to permafrost deformation. Despite these limitations, the diachronic VES measurementscanbeinterpretedusinginversionmodelstodepicthypotheticalverticalchangesin structurescomposedofhomogeneoushorizontallayers(Figure6b).Takingintoaccounttheinfinity ofsolutionsandthewellͲestablishedelectricalpropertiesofsimilargroundmaterials(Fabre&Evin 1990,Hauck2001,Delaloye2004),changesattherootcanbeinterpretedasbeingduetothickening oftheactivelayerfrom1Ͳ2mto2Ͳ3mwithnonoticeablemodificationoftheicylayer.Incontrast, thoseatthetonguecouldrepresentathickeningoftheactivelayerandalowericecontent,and/ora thinningoftheicylayer.Theseresultsarelessreliable,however,duetostronglateralvariationsof theinternalstructurewhicharenotidealforlayeredmodelling.  2.5LessonsfromtheLaurichardcase The25yearsvelocityrecord,togetherwiththerepeatedgeoelectricalsurveysandgroundsurface temperature recordallowstodrawsomeessential conclusions ontheinfluenceofclimateonthe behaviourandevolutionofrockglaciers. x Rockglaciersreacttoclimateandshowinterannualvelocityvariations.Theirreactiontimeis thusmuchshorterthanpreviouslyassumed. x Velocityvariationsarelinkedtotemperaturevariations–anincreaseintemperatureinduces anincreaseinvelocity. x The air temperature only partly explains the observed ground surface temperature and velocityvariations. x Thegroundsurfacetemperatureshowsthebestlinkwithvelocityvariations,withatimelag ofaround1year. x Thesnowcoverexplainsmostofthedifferencebetweenairtemperatureandgroundsurface temperature, and thus appears as the main driving factor both for ground surface temperatureandforvelocityvariations. Thus, the evolution of the permafrost will not only depend on the air temperature, but will be stronglyinfluencedbytheevolutionofthesnowcover,especiallyitsearlyorlateonsetinautumn.A lateonsetofthesnowcovercanatleastpartiallycompensateariseinairtemperature. Severalopenquestionsremain,however.Themainquestionmaybehowtoexplaintheveryrapid responseofvelocitytogroundsurfacetemperature.Therockglaciermovementtakesplaceinthe permafrostbodyandmainlyatitsbase.Thethermalconductivityofthepermafrostislowandthe surfacetemperaturevariationsneedtimetodiffusethroughtheprofileandarestronglyattenuated withdepth.Itseemsunlikelythatthetemperaturevariationsalonearesufficienttoinducestrong velocity variations. Another factor could be the presence of liquid water percolating through the permafrostbodyoratitsbase.Thiswouldmeanthatthevelocityvariationsarecontrolledbythe amountofavailableliquidwater.Thiswouldimplyapermafrosttemperatureclosetothemelting point. Asimilarquestionarisesconcerningtheresistivitymeasurementsontherockglaciertongue.Thelow resistivitymeasuredintheVESareconsideredastypicalforicepoorpermafrost,andERTprofiles suggest a discontinuous and ice poor permafrost body. Such interpretations however are

 84 PermafrostResponsetoClimateChange inconsistentwiththehighvelocityratesmeasuredonthetongue,whichimplyanicesupersaturated permafrostbody.Theexplanationcouldbethepresenceofliquidwaterin“temperate”permafrost. This means that the evolution of rock glacier permafrost with rising temperature could be characterizedbyanincreaseofthepermafrosttemperaturetovaluesclosetothemeltingpoint,and anincreaseofinterstitialliquidwaterduringthemeltingseason.  3. Possiblefuturethermalanddynamicresponsetopredictedclimatechange TheresultsfromtheLaurichardrockglacierandformothersimilarcasesshowthat(i)thedynamic responseofrockglacierswillstronglydependonthethermalevolutionofthepermafrostand(ii) thatthethermalresponsewilldependonthetemperatureevolutionaswellasontheevolutionof winterprecipitationandsnowcoveronsetandduration. Forgroundsurfacetemperature,thedirectinfluenceofthesnowcoveronsetdateandthicknessis welldocumentedatLaurichard,andshowsastronginterannualvariability.Notemperatureprofileis availableatLaurichard,butotherexistinglongtimeseriesshowanoverallwarmingtrendatca10m depth(Permosreports).Sothemostprobablescenarioofthermalresponsecouldbethefollowing: x Warmingtemperatureswillinduceageneralwarmingtrendofthepermafrost. x Astronginterannualvariabilitywillcontinuetoexist,andcoolingperiodsofonetoseveral yearswillcontinuetohappen. x The interannual variability depends mainly on the snow cover. Increased winter precipitationscouldinduceastrongerwarmingofgroundsurfacetemperature,especiallyif increasedprecipitationmeansearlieronsetofthesnowcover. x Anearliersnowmeltduetowarmerspringtemperatureswouldinduceawarmingofground surfacetemperatures. x The thermal effect of increased amounts of melting water due to increased winter precipitationisunknown. Thedynamicresponseoftherockglacierdependsontheicecontent,temperatureandstate.The followingresponsescanbededucedfromtheobservations: x Thedecreaseobservedinelectricalresistivitywillpossiblycontinue,reflectingthepresence ofincreasingamountsofwaterwithintheiceͲrockmixture.Theamountoficeintherock glacierbodyisstillhigh,however,andshouldremainsoforalongtime. x Interannual velocity variations will continue to occur, in relation to ground surface temperaturevariations.Velocityincreasesareexpectedespeciallyafterverywarmsummers associatedwithsnowrichwinters. x ThegeomorphologicalsettingsoftheLaurichardrockglacierarenotfavourabletoastrong acceleration, and a destabilization of the rock glacier is not expected. Due to its already relativelyhighmeanvelocity,thispointhoweverneedstobemonitored.   Acknowledgements. – The study of the Laurichard rock glacier was supported by the Fondation MAIF.TheannualdisplacementmeasurementsareperformedbytheParcNationaldesEcrins.We thankDenisFabreandAdrianoRiboliniforallowingtheuseofgeophysicialdata. 

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References: BodinX.,2007:Géodynamiquedupergélisoldemontagne:fonctionnement,distributionetévolution récente.L’exempledumassifduCombeynot(HautesAlpes).PhDthesis,UniversityofParisͲ DiderotParis7.272pp. BodinX.,ThibertE.,FabreD.,RiboliniA,SchoeneichP.,FrancouB.,Reynaudl.&FortM.,2009:Two decades of responses (1986–2006) to climate by the Laurichard rock glacier, French Alps. PermafrostandPeriglacialProcesses,20,331Ͳ344. DelaloyeR.,2004:Contributionàl’étudedupergélisoldemontagneenzonemarginale.PhDthesis, UniversitédeFribourg.260pp. Delaloye,R.,Perruchoud,E.,Avian,M.,Kaufmann,V.,Bodin,X.,Ikeda,A.,Hausmann,H.,Kääb,A., KellererͲPirklbauer,A.,Krainer,K.,Lambiel,C.,Mihajlovic,D.,Staub,B.,Roer,I.andThibert, E.,2008:RecentInterannualVariationsofRockglaciersCreepintheEuropeanAlps.In:Kane, D.L. and Hinkel, K.M. (eds), Proceedings, Ninth International Conference on Permafrost (NICOP),UniversityofAlaska,Fairbanks,343Ͳ348. Fabre D. & Evin M., 1990: Prospection électrique des milieux à très forte résistivité: le cas du pergélisolalpin.6èmeCongrèsInternationaldeAIGI,Rotterdam. FrancouB.&ReynaudL.,1992:Tenyearsofsurficialvelocitiesonarockglacier(Laurichard,French Alps).PermafrostandPeriglacialProcesses3:209–213. HauckC.,2001:Geophysicalmethodsfordetectingpermafrostinhighmountains.PhDthesis,VAW, Zürich.204pp. SchoeneichP.,BodinX.,KrysieckiJ.ͲM.,DelineP.&RavanelL.,2010:PermafrostinFrance.Report N°1.PermaFrancenetwork,Grenoble,InstitutdeGéographieAlpine.

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 3. CasestudiesintheEuropeanAlps   3.6 RockGlacierBellecombes,NorthernFrenchAlps   

 Citationreference SchoeneichP.,KrysieckiJ.ͲM.,LeRouxO.,LorierL.,VallonM.(2011).Chapter3.7:Casestudiesinthe European Alps – Rock Glacier Bellecombes, Northern French Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrost response to present and future climate change in the EuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ 58Ͳ1,p.87Ͳ96.  Authors Coordination:PhilippeSchoeneich Involvedprojectpartnersandcontributors: Ͳ Institut de Géographie Alpine, Université de Grenoble, France (IGAͲPACTE) – Philippe Schoeneich,JeanͲMichelKrysiecki Ͳ Association pour le développement de la recherche sur les glissements de terrain, France (ADRGT)–LionelLorier,OlivierLeRoux Ͳ Laboratoire de Glaciologie et de Géophysique del'Environnement, Université de Grenoble, France(LGGE)–MichelVallon  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentgeomorphicandthermalevolution 3. Possiblefuturethermalanddynamicresponsetopredictedclimatechange References

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Summary  TherockglacierBellecombesisashallowslowmovingrockglacier.However,surfacemovements associated with settlement due to ice melting are sufficient to induce strong disturbance to a chairliftstationbuiltonitssurface.Twoboreholesweredrilledthroughtherockglacier,revealing atotalthicknessofca9.50m,butwithaveryiceͲrichlayer,6Ͳ7mthick,lyingdirectlyonbedrock. The temperature profiles show a very stable and constant temperature of the iceͲrich layer aroundͲ0.2°C,withalmostnoseasonalvariation.Thegroundsurfacetemperatureshowscold winterequilibriumtemperatures(downtoͲ4°C)andstrongseasonalvariationslimitedtotheiceͲ poorblockysurfacelayer.Thetemperatureprofilearisesthequestionofthestatusoftheice:the icetemperature,verycloseto0°C,couldindicatethattheiceisatthemeltingpointtemperature. Ontheotherhand,veryhighelectricalresistivityvaluesindicatelowliquidwatercontent,and velocities show that no basal sliding is occurring so far. The question of the melting point temperature of an iceͲrock mixture could be crucial for the future dynamic behavior of rock glacierslikeBellecombes.MoreknowledgeisneededonthephysicsoficeͲrockmixtures.One dimensional modelling was run with different scenarios. Results show that the very iceͲrich permafrostbodyseemstobeverystableunderpresentdayconditions,andastrongwarming wouldbenecessarytoinducesignificantchangesiniceͲcontentandtemperature.

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1. Introductionandstudyarea TheBellecombesrockglacierissituatedontheskiresortLesDeuxAlpes,intheEcrinsmassif,French Alps(Table1).Itisashallow,topographicallysmoothrockglacier.ItdevelopsonaNorthoriented slopefromca2800to2600ma.s.l.Thetwolastpylonsandtheupperstationofachairliftarebuilt ontherockglacier.Duringconstructionwork,anicelayerof2Ͳ4mthicknesswasremovedunderthe future chair lift station. Despite this, the chairlift station is subjected to settling movements, indicatingthatthereisstillicebelowit. The site has therefore been monitored since 2007 for ground surface temperature and surface displacements. It has become a reference test site for various geophysical methods (geoelectrical sounding and tomography, refraction and reflexion seismics, surface waves,seismic ground noise, georadar).Twoboreholesweredrilledinautumn2009throughtherockglacierdowntothebedrock andequippedwithsensorchainsfortemperatureprofilemonitoring. 

Fig.1–TheBellecombesrockglacier.PhotographbyPhilippeSchoeneich.  Table1–CharacteristicsoftheBellecombesrockglacier

Method initiated/carriedout Latitude N44.99° Longitude E06.16° Elevation[ma.s.l.] 2710m Slope moderate Aspect North Typeofrockglacier talus;lobatetotongueshaped;active Evidenceofpermafrost Observation of ground ice, ground surface temperature, borehole profile Evidenceofmovement Aerialphotograph,DGPS Typologyofmovement Veryslowmovement Meanvelocityrange From0.03to0.10m/yr Changeinvelocity Nosignificantchange Yearoffirstdata 2007  2. Permafrostindicatorsandrecentgeomorphicandthermalevolution 2.1Groundsurfacetemperatures Ground surface temperatures are monitored since 2007 with 4 UTLͲ1 mini data loggers (3 on the rockglaciersurface,1outsideoftherockglacierinnonͲpermafrostterrain).Inaddition,severalBTSͲ mappingcampaignswereperformedinlatewinter,inordertomapthegroundsurfacetemperature distributionduringwinterequilibriumconditions.

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Fig.2–OrthophotooftheBellcombesrockglacier,andpositionofmonitoringdevices.  Theresultsshow: x Agenerallylowwinterequilibriumtemperatureontherockglaciersurface,withvaluesas lowasͲ4toͲ5°C. x Astrongtemperature contrastwiththenonͲpermafrostareasurrounding therockglacier, whereonlyslightlynegativetemperaturesarerecorded.Thiscontrastappearsontheloggers aswellasontheBTSͲmaps. x TheBTSͲmappingshowsanalmostperfectmatchbetweenlowgroundsurfacetemperature andgeomorphologicalextentoftherockglacier(fig.3). Theseresultsclearlyindicatethepresenceofpermafrostontheentireareaoftherockglacier.

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Fig.3–Groundsurfacetemperaturedistributionatwinterequilibrium,fromBTSͲmappinginMarch 2009(left)andsnowcoverthickness(right).Theleftmapshowsdistinctlimitsofthepermafrostzone, consistentwiththegeomorphologicallimitsoftherockglacier.  2.2Rockglaciervelocity ThesurfacedisplacementsaremeasuredwithDGPSon32pointsdistributedoverthesurfaceofthe rockglacier.Theannualdisplacementvaluesareverylowonmostofthepoints,intheorderofafew cm/a, at the accuracy limit of the measurement method. In addition to horizontal displacements, verticalsettlementsareobservedatthechairliftstationandonthepylons.Thesemovements,inthe orderofseveralmillimeters,aresufficienttoneedperiodiccablealignments.  2.3Icecontentandstratigraphy Verticalresistivitysoudings(VES)andelectricalresisitivitytomography(ERT)wereperformedin2007 and 2009 on four profiles across the rock glacier. No significant changes have been observed between2007and2009.AllERTprofilesshowveryhighresistivityvalues,typicalofhighicecontent. Thishighicecontentwassubsequentlyconfirmedbytwoboreholes. Bothdestructiveboreholesshowasimilarstratigraphy(fig.4): x Ontop,2.1mofdrydebris,correspondingtotheblockyactivelayer. x 7.5mofveryiceͲrich material.Fromtheinterpretationofthepenetrationlogsandofthe cuttings,thislayercanbesubdividedonboreholeSD1intoanuppericeͲrockmixtureand andaloweralmostpureicelayer,whereasinboreholeSD2thewholelayerismadeofaniceͲ rockmixture. x Bedrock was reached in both boreholes at ca 9.5m depth. The iceͲrich layer lies in both boreholesdirectlyonthebedrock.

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Fig.4–BoreholestratigraphyofthetwoboreholesatBellecombesrockglacier.  Theboreholesconfirmedthepresenceofveryhighicecontent,asdeducedfromtheERTprofiles. However,thethicknessinterpretedfromtheERTprovedtobelargelyoverestimated,duetothevery highresistivityvalues.ThisknowndrawbackoftheERTmethodlimitsitsuseforthedeterminationof the thickness of permafrost bodies. Combined tests of several geophysical methods on the same profiles show that only the georadar can possibly help to determine the real thickness of the permafrostbody.  2.4Temperatureprofiles Thetwoboreholeswereequippedwiththermistorchains(PT100sensors)connectedtoaloggerfor temperatureprofilemonitoring.TheresultsofboreholeSD1areshowninfig.5.Theinfluenceofthe icecontentonthetemperaturevariationsappearsveryobviously: x Strongseasonaltemperaturevariationsoccurwithinthe2mthickactivelayerwithalmostno icecontent. x The seasonal temperature variations are drastically attenuated at ca. 2m depth, at the boundarywiththeiceͲrichlayer. x Thezeroannualamplitudecanbesetatthetransitionfromfrozendebristomassiveice. 

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Fig.5–TemperatureprofileofboreholeSD1andevolutionfromNovember2009toJuly2011.  x In the iceͲrich layer, as well as in the bedrock below, temperature variations are almost absentorlimitedtoarangeof±0.1°C. ThetemperatureoftheiceͲrichlayerisveryconstantandstable: x TheabsolutevalueisaroundͲ0.2°C,veryclosetothemeltingpoint. x Itshowsnotrendtowardsdepth,buttheprofileisveryshort(ca13mtotaldepth). x Variationsarelimitedtoaverynarrowrange.  2.5LessonsfromtheBellecombescase TheinvestigationsontheBellecombesrockglaciershowthelimitsofgeophysicalmethodsforthe determinationoficebodythicknessandgeometry.Themostfavourablegeophysicalmethodusedin permafrost, geoelectrical tomography (ERT), proves to strongly overestimate the thickness of the permafrostbodyincaseofaveryhighicecontentinducingveryhighresistivityvalues.Thispointis verycritical,astheknowledgeofthethicknessiscrucialforacorrectmanagementofgeotechnical problemsliketheoneofthechairliftstation.Sofar,boreholesremainthebestmethodtoassessthe stratigraphyofpermafrostbodies. The most interesting aspect of the Bellecombes study case is the temperature profile of the boreholes.Thevery“warm”temperaturesregisteredinthepermafrostbodycontrastwiththelow winterequilibriumtemperaturesregisteredonthesurface.Moreover,thevaluesverycloseto0°C andtheirconstancywithdepthandstabilityintimeraisethequestionofthestatusoftheice: x Theconstancyoftemperatureintimeanddepthsuggeststhattheicecouldbeatthemelting pointtemperature,similarto“temperate”glaciers. x However the values are still negative, and the consistency of the values on both sensor chainsseemtoindicatethattheyarereliableandnotduetoalackofaccuracy. Actually the physics of iceͲrock mixtures is poorly known, and the value of the melting point temperatureinsuchamaterialisunknown.Itcouldbeslightlybelowzero,intherangemeasuredin theBellecombesboreholes.Ontheotherhand,theveryhighresistivityvaluesindicatetheabsence ofliquidwaterintheicebody,andtheverylowdisplacementratesindicatethatnobasalsliding occurs,likeitwouldbeexpectedincaseof“temperate”basalice.Thequestionremainsopenand needsfurtherinvestigations.

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 3. Possiblefuturethermalanddynamicresponsetopredictedclimatechange Theknowledgeofthestratigraphyandofthegeophysicalpropertiesoftherockglacierbodyallowed thecalibrationofathermaldiffusionmodel.Themodelwasrunforvarioustemperatureevolution scenarios.Themodelusedisaonedimensionalmodelthatcalculatestemperatureandicecontentat a spacing of 0.2m, and for time slices of 0.01 days. It uses as input the mean monthly air temperatureandageothermalfluxof0.05watt.mͲ2. 

Fig.6–LogofboreholeSD1andmodelsettingsforstructureandicecontent.  The ice content was estimated from the cuttings and the drilling progression graph, according to figure6.Themodelcharacteristicsweresetwiththevaluesoftable2. Table2–Intrinsicvaluesusedformodelcalculations  Thermalconductivity Specificmass Massicheat Kw.mͲ1.°CͲ1 Ukg.mͲ3 CpJ.kgͲ1.°CͲ1 Snow 0.20 300 2009 Ice 2.10 900 2009 Debris 0.50 1800 900 Bedrock 2.50 2600 900  Themodelneedstosetameanairtemperatureaswellasprecipitation,andusesaclimaticscenario todrivethemodel.Toavoiduncertaintiesrelatedtoaltitudinalgradientextrapolations,initialvalues weretakenfromthemeteorologicalstationofSaintͲSorlin,situatedca20kmNorthofthesite,at almost exactly the same altitude and a similar situation in the Alpine range: the mean annual air temperatureduringtheyears2006Ͳ2009isͲ0.35°C,andthemeanprecipitationduringthelast35 years is between 1 and 2m per year. For the variability, the history of deviations against mean temperature and precipitation values measured at the station Chamonix from October 1959 to September1994wastransferred. Themodelwasrunforvariousscenarios.Themainresultsarethefollowingones:

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x Allscenarioswithameanannualairtemperature<Ͳ3°Candprecipitation>1mperyearlead tothepersistenceofthesnowcoverandtotheformationofaglacier.Intheseconditions, thegroundicevolumedoesn’tchangeanditstemperaturerisestothemeltingpoint.The permafrostunderthepermanentsnowbecomestemperate. x WithameanairtemperatureofͲ0.5°Candaprecipitationof1mperyear,nothinghappens within the first ten years. The snow cover, with a mean thikness of 1m in high winter preventsthesoilfromcooling,andthehighicecontentabsorbstheheatflux.Underpresent conditions,thepermafrostandicebodyseemstobestable. x Totesttheeffectofastrongandbrutalwarming,awarmingof5°Cwassetfromthesecond model year, leading to a mean annual air temperature of 4.5°C. After three years, the ice volumehasnotyetchanged,buthastotallydisappearedafter20years.Thiscorrespondsto themeltingof150to200kg/m2/year.Thethermalequilibriumhoweverisstillnotreached after30years,andthetemperatrureat20Ͳ30mdepthisstillcloseto0°C(figure7).Inthis simulation,thewintersnowcoverisoftenverythin(0to1.5mdependingontheyear). 

      Fig7–BoreholeSD1.Left:initialstate,year1(MAATͲ0.5°C).Right:monthlygeothermsofyear32,10 yearsaftertotaldisappearanceofgroundice,31yearsaftersuddenwarmingof5°C.  Theresultsshowthat: x The high ice content totally explains the damping of seasonal variations at the activeͲ layer/iceͲrich body transition. The latent heat transfer due to ice melting/freezing absorbs almostthetotalheatflux. x Thesiteisstableunderpresentdayconditions. x In case of a progressive temperature rise, the heat flux increase would be almost totally absorbedbylatentheatduringthefirstdecade,andneithericetemperaturewouldrisenor significanticevolumelosswouldoccur.

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x Significant changes would occur only after several decades or in case of a very strong warming. Thus,veryiceͲrichpermafrostcouldshowahighresistancetoclimatechange.However,themodel run considered a melting point at 0°C and does not take into account the effect of possible melt waterflows.  Acknowledgements. – The study of the Bellecombes Rockglacier was supported by the Fondation MAIF.TheboreholeswerecoͲfinancedbytheRegionRhôneͲAlpesthroughtheCIBLE2008program. TheskiresortDeuxͲAlpesfacilitatedtheworkandprovidedhelpforlogistics.   References: Lorier L. et al., 2010: Analyse des risques induits par la dégradation du permafrost alpin. Rapport final,projetFondationMAIF.ADRGT,Gières. SchoeneichP.,BodinX.,KrysieckiJ.ͲM.,DelineP.&RavanelL.,2010:PermafrostinFrance.Report N°1.PermaFrancenetwork,Grenoble,InstitutdeGéographieAlpine.

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 3. CasestudiesintheEuropeanAlps   3.8 AiguilleduMidi,MontBlancMassif,FrenchAlps  

 Citationreference DelineP.,CremoneseE.,DrenkelflussA.,GruberS.,KemnaA.,KrautblatterM.,MagninF.,MaletE., MorradiCellaU.,NoetzliJ.,PogliottiP.,RavanelL.(2011).Chapter3.8:CasestudiesintheEuropean Alps–AiguilleduMidi,MontBlancmassif,FrenchAlps.InKellererͲPirklbauerA.etal.(eds):Thermal and geomorphic permafrost response to present and future climate change in the European Alps. PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.97Ͳ108.  Authors Coordination:PhilipDeline Involvedprojectpartnersandcontributors: Ͳ EDYTEM, Université de Savoie, France (EDYTEM) – Philip Deline, Velio Coviello, Florence Magnin,EmmanuelMalet,LudovicRavanel Ͳ Regional Agency for the Environmental Protection of the Aosta Valley, Italy (ARPA VdA) – EdoardoCremonese,UmbertoMorradiCella,PaoloPogliotti Ͳ UniversityofBonn–AnjaDrenkelfluss,AndreasKemna,MichaelKrautblatter Ͳ UniversityofZurich–StephanGruber,JeanetteNoetzli  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

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Summary  WedevelopinvestigationsattheAiguilleduMidi(3842ma.s.l),whererockwallsareofdiverse aspectsandslopeangles,andgalleriesareaccessibleyearͲround.Intheframeworkoftheproject PermaNET,wemonitortherockthermalregime(i)with9sensorswithonetothreethermistors installeduptoadepthof55cm;(ii)withthree10mdeepboreholesequippedwiththermistor chains; and (iii) by using Electrical Resistivity Tomography (ERT), based on the temperatureͲ resistivityrelationshipofthelocalgranite.Thesemeasurementswerecompletedbytwomobile automatic weather stations. Combined with a 3DͲhighͲresolution DEM made using longͲ and shortͲrangeTerrestrialLaserScanning(forrockwallsandgalleries,respectively),thesedatawill be used for physicallyͲbased model validation or construction of statistical models of rock temperaturedistributionandevolutionintherockwalls.Thesitestartedtobeinstrumentedin 2005,andsomemethodsarestillexperimental.Herewefocusonthethermalmonitoringdevice installedonthesiteandpresentsomefirstresults.

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1. Introductionandstudyarea Starting off in the framework of the EU coͲfunded FrenchͲItalian PERMAdataROC project and presentlyunderdevelopmentwithintheprojectPermaNET,ourinvestigationsattheAiguilleduMidi (N45°52',E6°53')beganinNovember2005.Wechoosethissite(Fig.1)becauseof(i)itselevation (3842m a.s.l.), (ii) its steep rockwalls characterized by differents aspects, slope angles, rock structures,andsnowcovers,and(iii)itsaccessibilitythroughouttheyearfromChamonixbyacable car from 1955 – half a million tourists visit the site each year; rockwalls of the Piton central are accessiblebyabseilingfromtheupperterrace,andgalleriesallowtopenetrateintotherockmass whichisrareinhighmountainareas,andlede.g.toobserveasignificantcirculationofwaterduring thehotSummerof2003,forthefirsttimesincetheopeningofthesite.AiguilleduMidihasbecome amajorsiteforthestudyofrockwallpermafrostintheAlps.   AB    

  CD

 Fig.1TheAiguilleduMidi(3842ma.s.l.):(A)viewfromtheeast.Atthecenter:Pitoncentral;ontheright: Pitonnord,withthecablecarstation.(B)westside(1000ͲmͲhigh).Atitsbottom:GlacierdesBossonsetGlacier Rond;ontheleft,intheshadow:northsideofthegroupoftheAiguilleduMidi,mainlyglaciated.(C)underthe pylon:subverticalnorthwestsideofthePitoncentral(100ͲmͲhigh).(D)Southeastside(200ͲmͲhigh).Ontheleft: beginningoftheArêtedesCosmiques;ontheright:PilastresudͲest.PhotographsbyP.DelineandS.Gruber(A, C,D:11.10.2005;B:30.09.2007) 

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The group of the Aiguille du Midi, at the western end of the Aiguilles de Chamonix, develops asymmetricallyover2kmbetweentheColduMidiandtheColduPlan(Fig.2).Itformsarockyscarp whosewestfaceandnorthface(whichisglaciatedonitsupperhalf)aretoweringtheGlacierdes Bossons(by1000m)andtheGlacierdesPélerins(by1350m)respectively(Fig.1B).However,the backofthisscarpisoccupiedbythewesternbasinofGlacierduGéant,separatedfromwestand northfacesbytherockyArêtedesCosmiquesandthesummitoftheAiguilleduMidi. ThebulkoftherockisgraniteofMontBlanc,amassiverockwithagrainedfaciesthatcontributesto thesteepnessoftheAiguilleduMidifaces–50°forthenorthface,57Ͳ58°forthesoutheast(only 200mhigh)andwestsides.Manyrockwallswithinthesefacesaresubvertical,asthenorthfaceof thePitoncentral(Fig.1C)orthePilastresudͲest(Fig.1D),becauseofthesubverticaldipofthetwo mainfamiliesoffaultswhosedensenetworkcutsacrosstheMontBlancmassif.Becauseofadense secondary fracturing unevenly distributed very massive rockwalls alternate with very densely fracturedones(Fig.1D).OurstudyfocusesonthesummitoftheAiguilleduMidi,between3740and 3842ma.s.l.,heretermed“AiguilleduMidi”. 

 Fig.2GroupoftheAiguilleduMidi.TheinstrumentedsiteisthepeaklabelledAigleduMidi.Detailofthemap Mont Blanc n°1 NordͲAiguille du Midi (IGN, 1952) at 1:10000 (contour interval: 10 m). This extract is 4 km large.  2. Permafrostindicatorsandrecentthermalevolution 2.1Methods Rocktemperaturemonitoring TherocksurfacetemperatureismeasuredeveryhouroverallfacesofthePitoncentralsince2005by severalminiͲdataloggerswiththermistorsplacedatdepthsof3,10,30and55cmbelowthesurface. Three10mdeepboreholeshavealsobeendrilledinSeptember2009(Fig.3),normaltotherock

 100 PermafrostResponsetoClimateChange surfaceof:(i)the northwestface(boreholeat3738ma.s.l.),a verticalrockwallinaverymassive granite;snowcanonlyaccumulateonasmall2mwideterrace;(ii)thesoutheastface(boreholeat 3745ma.s.l.),a55°slopeangleinahighlyfracturedareasnowcoveredduringapartoftheyear;and (iii)thenortheastface(boreholeat3753ma.s.l.),witha65°slopeangleinaveryfracturedcouloir, wheresnowoccursoveralargepartoftheyearduetotheconcavetopography.Theseboreholesare locatedwellbelowthecablecarinfrastructurelevelinordertominimizeitsthermalinfluenceon rock temperature. They are equipped with 10m long chains of 15 thermistors that measure rock temperatureevery3hourssinceDecember2009onthenorthwestandsoutheastfaces,sinceApril 2010onthenortheastface. 

  Fig.3Drillingofa10mdeepboreholeinthesoutheastfaceofPitoncentralinSeptember2009.Photograph byP.Deline17.09.2009  Electricalresistivitytomography ElectricalResistivityTomography(ERT)isincreasinglybeingusedasanonͲinvasiveimagingtoolin alpinepermafroststudies(Krautblatter&Hauck,2007;Krautblatteretal.,2010).Keyobjectivesof thismethodare(i)themappingoftemperaturedistributionsinsidetherocktoinferthepresenceof permafrost, and (ii) the delineation of fracture zones given their influencing role on permafrost dynamics and stability. For the first purpose a preliminary relationship between temperature and resistivity of the rock has been established in laboratory. The imaging of fractures, however, is a notoriously difficult task using conventional ERT approaches which rely on smoothnessͲconstraint regularization.AttheAiguilleduMidi,weinvestigateregularizationschemesforimprovedfracture delineationbymeansofnumericalsimulationsandapplicationtofielddata.

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Since2008,fourERTsurveyswereconductedatthesite.Eachonecomprisedtheacquisitionofmore than10,000normalandreciprocaldipoleͲdipoledataoverthreedifferentarraysofaltogether144 electrodes.TheelectrodesoftwoarrayscouldbeplacedtoalmostsurroundthePitoncentraland thePitonnordinahorizontalplane,offeringafavourabletomographiccoverage.AverticalnorthͲ southtransectacrossthePitoncentralwasinstalledbyabseilingonthenearverticalnorthandsouth faces.TheERTdatawereinvertedusingisotropicsmoothing,anisotropicsmoothing,andafocussing regularization scheme based on the soͲcalled minimumͲgradient support (MGS), and employing a finiteͲelementgridwhichcapturestheirregulargeometryoftherockaswellastheelectrodelayout.  Airtemperaturemonitoring AirtemperatureandrelativehumidityaremeasuredonsouthandnorthfacesbythemeanofminiͲ dataloggersplacedinsideradiationshields.Onthesouthface,meteorologicalparameters(incoming andoutgoingsolarradiationinbothshortwaveandlongwavebands,windspeedanddirection)were measuredduringnearly4years(December2006toOctober2010)byanautomaticweatherstation adaptedandinstalleddirectlyontherockwall.  TerrestrialLaserScanning A DEM is necessary (i) to accurately represent the rock volume, (ii) as a basis for a geological structureanalysis,(iii)torefinethemodelingofrocktemperaturedistribution,and(iv)tostudythe water flow into the rock mass. A highͲresolution DEM was made using longͲ and shortͲrange TerrestrialLaserScanning–forrockwallsandgalleries,respectively(Fig.4). 

 Fig. 4  Triangulated Irregular Network (TIN) model of the rockwalls of the Pitons nord (left) and central, obtainedbylongͲrangeterrestriallaserscanning.

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2.2 Preliminaryresultsaboutrocktemperature All the subͲsurface data are collected mainly for initialization, calibration and validation of rock temperature and permafrost distribution models. However their statistical analysis allows quantifyingthegreatspatialvariabilityofsubͲsurfacetemperaturesinsuchcomplexmorphologies. Preliminaryresults(Table1;Fig.5)showthat:(i)themeanannualgroundsurfacetemperaturecan varyofmorethan6°Cwithinfewmetersofdistance,dependingontheaspect;(ii)freezeͲthawcycles on southern aspect are nearly twice as frequent than in the north but markedly shallower; (iii) a significantthermalͲoffsetprobablyexistsdespitethecompactrockmassandtheabsenceofground covers(e.g.debris,snow)onsouthfaces. 

 Fig.5–MeandailyrocktemperatureonthesouthandnorthfacesofthePitonCentralforthehydrologicalyear 2008Ͳ09atthreedifferentdepthsbelowthesurface.   Table 1 – Rock temperature 55cm below the surface on south and north faces of the Piton Central of the Aiguille du Midi for 2007Ͳ08, 2008Ͳ09, and 2009Ͳ10 hydrological years. MAGT: mean annual ground temperature;MAX/MINabs:absolutelywarmestandcoldesttemperature;DateMAX/MINabs:occurrencedate of MAX/MINabs;ȴTavg/max/min: mean, maximal and minimal amplitude of daily temperatures; ZCD: Zero Crossing Days, i.e. number of days per year where the 0°CͲisotherm is crossed; MAX/MINday: warmest and coldestmeandailytemperature;DateMAX/MINday:occurrencedateofMAX/MINday;DBZ:DaysBelowZero, i.e.numberofdayswithmaximumtemperaturebelow0°C.

 

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Deeper borehole thermistor chains show a very sharp contrast between the three surveyed faces (Fig.6). A time lag of approximately half a year between minimal and maximal air temperature periods (JanuaryͲFebruary, and July, respectively) and minimal and maximal rock temperature periodsatadepthof10m(JuneͲJuly,andDecemberͲJanuary,respectively;Fig.7).In2010,theactive layerthicknessvariedfrom1.80minthenorthwestfaceto5.20minthesoutheastface. While anisotropic smoothing can be adjusted such as to allow a correct interpretation of the ERT image, inversion with MGSͲbased regularization provides most convincing results in terms of resolvingsharpstructuralfeaturesassociatedwithlithologicalchangessuchasfractures,butatthe sametimepreservingsmoothchangestypicaloftemperaturevariationsintherock.LowͲresistivity zonescouldbedelineatedatthePitonnord,whichseemtocoincidewithwaterͲcontainingfractures causedbyartificialheatsupply;continuationofthesefracturesoutsidetheheatedgalleryindicates permafrost conditions. At the Piton central, resistivity values were below 200000:m in October 2010,whichisquitereasonablewithrespecttothetemperaturerange(Fig.8). Meteorologicaldataontherockwallshowthat:(i)thepeakofSWradiationoccursduringthewinter (>1300W/m2)givingstrongdailytemperatureamplitudesatrocksurface(upto30°C);(ii)thereisa clear prevalence of upslope winds with speeds ranging from 4 to 9m/s; (iii) the mean annual air temperatureisaroundͲ7°Conaverage(Table2),with5to6°Cofdailyamplitudeandanabsolute temperaturerangebetweenͲ25to+12°C.  

 Fig.6Plotsofrocktemperaturefromthesurfaceto10mdepthfortheperiod18.12.2009to21.01.2011at thenorthwestandsoutheastfaces,and13/04/2009to21/01/2011atthenortheastfaceoftheAiguilleduMidi (continuednextpage)    

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 Fig.6continued  

105 PermaNET–CasestudiesintheEuropeanAlps

 Fig.7Timelagbetweenairtemperatureand10mdeeprockatthesoutheast,northeastandnorthwestfaces ofthePitoncentraloftheAiguilleduMidi.   

 Fig.8ElectricalresistivitytomographyinahorizontalplaneatthePitoncentraloftheAiguilleduMidion 22.10.2010.Blackdotsareelectrodelocations;blue/green:unfrozen;yellow:transitionfromunfrozentofrozen; red:frozen;resistivityisintherange102.Ͳ105.0:m.Reliableresultsareonlyinsidethearcthatisenclosedby the48electrodes.

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 Table2–AirTemperatureonthesouthface(A)andnorthface(B)ofthePitonCentraloftheAiguilleduMidifor 2007Ͳ08,2008Ͳ09and2009Ͳ10hydrologicalyears.Meanannualairtemperature(MAAT),frostdays(FD),ice days(ID)andfreezeͲthawdays(FTD)calculatedassuggestedinchapter2.Onthenorthface,hydrologicalyear 2007Ͳ08istheonlyonewithoutmissingdata.  (A) South face 2007-08 2008-09 2009-10 Mean (B) North face 2007-08 MAAT (°C) -6.77 -6.85 -7.33 -6.98 -7.53 FD (d) 352 336 335 341 353 ID (d) 246 241 249 245 275 FTD (d) 106 95 86 96 77   2.3 Outlook AiguilleduMidiisthemostelevatedAlpinesitetostudypermafrostinrockwalls.Duringthenext yearsnumericalmodellingofthetransient3Dsubsurfacetemperaturefields,combiningadistributed energybalancemodelwitha3Dheatconductionscheme,willbeaccomplished(Noetzlietal.,2007; Delineetal.,2009).Severalstatisticalmodelsofdistributionofsurfacetemperaturesoftherockwalls begantobedevelopedfortheMontBlancmassif,butcomparingtemperaturedataattheAiguilledu Midi with one of these models shows some discrepancies: whereas the Piton central north face modeledtemperatureisintherangeofͲ7°toͲ13°C(Fig.9),itsmonitoredaveragetemperatureisca. Ͳ6°C(Table1).

 Fig.9ModeleddistributionofrocksurfacemeanannualtemperatureintheMontBlancmassif(Frenchside) withthemodelTEBAL(viewfromthewest;imagedraping:E.Ployon).ThetemperatureisintherangeͲ1°C (darkorange)toͲ13°C(darkblue);groupoftheAiguilleduMidi(northandwestsides)isdelimited.

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The combination of process understanding, statistical analyses and/or modelling (e.g. numerical modelling of water flow in rock fractures) will help to improve our understanding of the characteristics of the mountain permafrost degradation. Secondly, we are interested in how a reduction in the uncertainty of data, process understanding and models may contribute to our predictive skill of corresponding effects. This longͲterm monitoring and modelling approach at AiguilleduMidiwillbeastrongsupporttotakeintoaccountfuturethermalresponseofrockwall permafrosttopredictedclimatechangeinthenext50yearsanditsgeomorphicconsequences.  3. Possiblefuturethermalresponsetopredictedclimatechange Assuggestedinchapter2,frostdays,icedaysandfreezeͲthawdayshavebeencomputedusingthe availableairtemperaturedatasetofthesouthfaceofAiguilleduMidi(Table2A).Referringtomaps andpredictionsinchapter2,theairtemperaturemeasurementsconductedonbothsouthandnorth facesoftheAiguilleduMidifrom2007to2010areinaccordancewiththemeansoftheperiod1961Ͳ 1990fortheGreatAlpineRegion(GAR).ThatisanumberofIDintherange241Ͳ260andanumberof FDgreaterthan320.OnlythenumberofFTDisabovethemeaninthemeasurements(96vs.70/80 of the mean 1961Ͳ1990), probably because the sensor is placed on a south near vertical rockwall wheredailytemperaturevariationsareverystrong,especiallyduringwinter. Thepredictionsfortheperiod2021Ͳ2050inthestudyareaareadecreaseofIDrangingfromͲ13/Ͳ16 daysperyearthatmeans232Ͳ229IDinsteadof245,andadecreaseofFDrangingfromͲ14/Ͳ15days peryearthatmeans326FDinsteadof341.Applyingthesescenariostothedataofthenorthface (Table2B)thenumberofIDcouldfalltoabout260daysperyearthatmeansconditionsmoresimilar tothoseobservedtodayonthesouthfaces.Thesechangescouldleadtoadoublingoftheactive layerthicknessofthenorthexposedrockwallsoftheAlpsinthefuture,withaconsequentlyincrease ofinstabilitiesandrockfallevents.  Acknowledgements.–CompagnieduMontBlanc,especiallyE.Desvaux,areacknowledgedfortheir assistance to our study at Aiguille du Midi. Participation of Chamonix Alpine guides M. Arizzi, L. Collignon,andS.Frendo,andEDYTEMcolleaguesP.PaccardandM.LeRoy,totheSeptember2009 drillingwascrucialforitssuccess.ManythanksareduetoR.Bölhert,S.Jaillet,A.Rabatel,B.Sadier, S.Verleysdonkfortheirhelpandcontributions.  References:  DelineP.,BölhertR.,CovielloV.,CremoneseE.,GruberS.,KrautblatterM.,JailletS.,MaletE.,MorradiCellaU., NoetzliJ.,PogliottiP.,RabatelA.,RavanelL.,SadierB.,VerleysdonkS.,2009:L’AiguilleduMidi(massif du Mont Blanc): un site remarquable pour l’étude du permafrost des parois d’altitude. Collection EDYTEM,8–CahierdeGéographie,135Ͳ146. KrautblatterM.,Hauck,C.,2007:Electricalresistivitytomographymonitoringofpermafrostinsolidrockwalls. JournalofGeophysicalResearch,112,F02S20,doi:10.1029/2006JF000546. KrautblatterM.,VerleysdonkS.,FloresͲOrozcoA.,KemnaA.,2010:TemperatureͲcalibratedimagingofseasonal changes in permafrost rock walls by quantitative electrical resistivity tomography (Zugspitze, German/AustrianAlps).JournalofGeophysicalResearch,115,F02003. NoetzliJ.,GruberS.,2009:TransientthermaleffectsinAlpinepermafrost.TheCryosphere,3,85Ͳ99. NoetzliJ.,GruberS.,KohlT.,SalzmannN.,HaeberliW.,2007:ThreeͲdimensionaldistributionandevolutionof permafrost temperatures in idealized highͲmountain topography. Journal of Geophysical Research, 112,F02S13.doi:10.1029/2006JF000545:

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 3. CasestudiesintheEuropeanAlps   3.9 RockfallsintheMontBlancmassif,FrenchͲItalianAlps   

  Citationreference DelineP.,RavanelL.(2011).Chapter3.9:CasestudiesintheEuropeanAlps–RockfallsintheMont Blanc massif, FrenchͲItalian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.109Ͳ118.  Authors Coordination:PhilipDeline Involvedprojectpartnersandcontributors: Ͳ EDYTEM,UniversitédeSavoie,France(EDYTEM)–PhilipDeline,LudovicRavanel  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

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Summary  The frequency and volumes of rockfalls as well as their triggering factors remain poorly understoodduetoalackofsystematicobservations.IntheframeworkoftheprojectPermaNET, this study case analyses inventories of rockfalls acquired in the whole Mont Blanc massif by innovative methods in order to characterize the link between climate and rockfalls, and to emphasizetheroleofpermafrost.Intwosectorsofthemassif,thecomparisonofphotographs takensincetheendoftheLittleIceAgeallowedtheidentificationof50rockfalls.Inmostcases these rockfalls occurred during the hottest periods. On another time scale, a network of local observersallowedthedocumentationofthe139rockfallsthatoccurredin2007,2008and2009 in the central area of the Mont Blanc massif. Furthermore, the analyses of a satellite image allowedtheidentificationof182rockfallsinthewholemassifattheendofthe2003summer heat wave. For most of those rockfalls, the permafrost degradation seems to be the main triggeringfactor. 

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1. Introductionandstudyarea Arockfallcorrespondstothesuddencollapseofarockmassfromasteeprockwall,withavolume exceeding 100m3. In the last two decades, many rockfalls and rock avalanches (volume > 0.1Ͳ 1×106m3)occurredfrompermafrostaffectedrockwallsthroughouttheworld(Noetzlietal.2003). RockfallsgenerallyoccurinhardrocksalongpreͲexistingfractures.Inhighmountains,threemajor factors–possiblycombined–cantriggerrockfalls:(i)glacialdebuttressingduetoglacialretreat,(ii) seismic activity, and (iii) permafrost degradation, generating physical changes of the potential interstitialice(Gruber&Haeberli2007). Thecharacterizationofrockfalleventsandtheunderstandingoftheirevolutionareprerequisitesto anyresponseofmanagement.However,dataonrockfallsathighelevationarerareanditisdifficult tointerpretnonͲrepresentativedata(fewisolatedexamples). Started in the framework of the EU coͲfunded FrenchͲItalian PERMAdataROC project, our investigations are presently carried out within the project PermaNET. In this context, we systematicallycollectandprocesshistoricalandcurrentdataonrockfalls(Ravanel2010)inorderto bettercharacterizethisprocess(triggeringconditions,frequency,andvolumes). ThefirstaimofthisstudycaseistoshowthecorrelationexistingbetweenrockfallsintheMontBlanc massifandglobalwarming.Thesecondoneistohighlighttheprobablycrucialroleofthepermafrost degradationontherockfalltrigger.   2. Permafrostindicatorsandrecentthermalevolution 2.1Methods PhotoͲcomparisonapproach Written and oral evidences of rockfalls are not sufficient to accurately reconstruct the recent rockwallmorphodynamics.ThephotoͲinterpretationofaseriesofphotographsisthereforethemost appropriate method. We focus on two areas of the Mont Blanc massif with a rich existing documentation:theWestfaceofthePetitDru(3730ma.s.l.)andthenorthsideoftheAiguillesde Chamonix(3842ma.s.l.fortheAiguilleduMidi).TheproximityofthesepeakswithChamonix,their morphologyandtheirsymbolismallowarichiconographysincetheendoftheLittleIceAge(LIA). Thefirststepconsistsinsettingupdocumentarycorpus,whichisverytimeconsuming.Nearly400 photographsofthetwostudiedareashavebeengatheredbutonlyafewdozencouldfinallybeused. Photographs are compared and interpreted in different steps: (i) delineation of the rockfall scars (Fig.1),(ii)determinationoftheperiodscharacterizedbymorphologicalandcolourchangescaused by rockfalls – it was often necessary to diversify and crossͲcheck information sources in order to precisedatesofcollapse–,and(iii)estimationoftheinvolvedvolumes.50rockfallsoccurredinthe twoareasduringtheperiodfromtheendoftheLIAto2009,involvingrockvolumesrangingfrom 500to265000m3(Fig.2;Ravanel&Deline2008,2011).  Networkofobservers,SPOTͲ5imageandGISanalysis BesidestheinventoriesofpostͲLIArockfalls,itisimportanttocharacterizecurrentrockfalls.Onlya structured network of observation coupled with fieldwork can allow a near completeness of the inventoryofthecurrentrockfalls. 

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 Fig.1Comparisonbetweenphotographsof1862and2009ofthewestfaceoftheGrandsCharmozandthe AiguilleduGrépon,andofthenorthfaceoftheRognondesGrandsCharmoz.Yellowellipsesindicateareas affectedbyrockfallsbetweenthetwodates(Ravanel&Deline2011,slightlymodified).  The network consists of dozens of guides, hut keepers and mountaineers. Initiated in 2005, this observernetworkbecamefullyoperationalin2007.FocusedonthecentralpartoftheMontBlanc massif,theinventoryiscarriedoutwithreportingforms,indicatingthemaincharacteristicsofthe rockfallsandtheconditionsoftheaffectedrockwall.Animportantfieldworkisconductedeveryfall inordertocheckandtocompletethereportedobservations. Meanwhile, in order to compare the data obtained by the network with the exceptional morphodynamicsofthethreemonth2003summerheatwave,the2003rockfallsweresurveyedon thebaseofsupraglacialdepositsthroughtheanalysisofaSPOTͲ5imageoftheentiremassiftakenat theendoftheheatwave(23.08.200,10:50GMT). Characteristicsofeachcollapsearedeterminedusingseveralmethods.Altitudeofscars,slopeangle and orientation of the affected rockwalls, and the deposit areas are calculated in a GIS. Because directmeasurementsofthescarvolumeswerenotpossible,theareaofthedepositswasmultiplied withanestimateoftheirthicknessesinordertoassessthecollapsedvolumes.Geologicalparameters arederivedfromgeologicalmaps,andthepossiblepresenceofpermafrostwasdeterminedfroma modelofmeanannualgroundsurfacetemperature. Thenetworkofobserversallowedthedocumentationof45rockfallsin2007,22in2008and72in 2009(Fig.3),involvingrockvolumesrangingfrom100to33000m3(Delineetal.2008,Ravaneletal. 2010, Ravanel & Deline in press). Furthermore, the analysis of the SPOTͲ5 image allowed the identificationof182rockfallsinthewholemassifattheendofthe2003summerheatwave(Fig.4; Ravaneletal.2011). 

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 Fig.2Locationofthe8scarsofthemain(outlines)andsecondary(stars)rockfallsatthewestfaceoftheDrus.  

113 PermaNET–CasestudiesintheEuropeanAlps



 Fig.3RockfallsoccurredintheMontBlancmassifin2007(reddots),2008(yellowdots)and2009(green dots).  2.2 Linkbetweenclimateandrockfalls Todealwiththerelationshipsbetweenrockfallsandglobalwarming,wecomparedtheoccurrenceof rockfalls at the Drus and the Aiguilles of Chamonix with available climate data – local and reconstructed for the Alps. At the Drus, the climatic factor – especially the thermal one – seems importantinthetriggeringofrockfallswhichoccurredaftertheendoftheLIA,asshownbytheir occurrence during the hottest periods (Fig. 5; Ravanel & Deline 2008). The climate control is also demonstratedbytheanalysisofthe42rockfallsdocumentedonthenorthsideoftheAiguillesde Chamonix during the same period, with a very strong correlation between rockfalls and hottest periods.70%oftherockfallsoccurredduringthepasttwodecades,whichwerecharacterizedbyan acceleration of the global warming. Heat wave periods are particularly prone to rockfalls: the maximum rockfall frequency occurred during the 2003 summer heat wave (Ravanel & Deline in press).  

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 Fig.4Locationofthe182rockfallsthatoccurredduringthehotsummer2003onthepanchromaticSPOTͲ5 satelliteimage051/257ofthe23.08.2003(Ravaneletal.2011,slightlymodified). 

115 PermaNET–CasestudiesintheEuropeanAlps

 Fig.5ChangesinChamonixmeansummertemperature,volumeandelevationofdocumentedrockfallsinthe westfaceoftheDrus(afiveͲyearfilterhasbeenappliedtoremoveinterannualnoise).Dottedquadrilaterals representthedifferentrockfalls.  There is also correspondence between the 2003, 2007, 2008 and 2009 rockfalls and climatic conditions of those years – in particular with temperatures (Fig. 6). 139 rockfalls have been documentedbetween2007and2009inthecentralareaoftheMontBlancmassif,53ofthembeing preciselydated(38%).Amongthem,51rockfalls(96%)occurredbetweenJuneandSeptember,i.e. duringthehottestmonthsoftheyear.The2003summerheatwave,withapositiveMeanDailyAir Temperature (MDAT) located at very high elevation, has generated extremely active morphodynamics.Intheareacoveredbythenetworkofobservers,with152rockfallsreportedin 2003outofthe182observed,2003hasbeenquiteexceptionalintermsofrockfalloccurrence.Some intensestormsduringsummer2003mayhavecausedhighfluidpressureinfracturesthattriggered rockfalls,butthisfactorremainsdifficulttoassess.Finally,itisworthytonotethat38(72%)ofthe 53preciselydatedrockfallsof2007,2008and2009occurredafteraperiodofMDATwarmingofat leasttwodays(Ravanel2010).  2.3 Theprobableroleofpermafrost The role of climate – especially the one of the thermal factor – has been demonstrated by the analysis of the rockfalls documented in the Mont Blanc massif. This relation can only be fully explained by temperatureͲdependent factors: permafrost degradation, glacial debuttressing and evolutionofice/snowcoveronrockwalls(cryosphericfactors).Thetwolastfactorsmayonlyexplain alittlepart oftherockfalls.Furthermore,itissometimesdifficulttodistinguishbetweenrockfalls linked to glacial debuttressing or to ice/snow cover retreat, and rockfalls due to permafrost degradation,asbothfactorsareoftencloselyrelatedandfavouredbysummertemperatures. Secondly, topographic factors are highlighting the importance of permafrost in rockfall triggering. The average rockwalls elevation in the Mont Blanc massif is around 3000m a.s.l., whereas the averageelevationofrockfallscarsof2003and2007Ͳ2009is3335ma.s.l.Althoughrockwallsarevery commonbelow3000ma.s.l.,theyareaffectedbyveryfewcollapses.Themostaffectedaltitudinal beltis3200Ͳ3600ma.s.l.,whichcorrespondstoareasof“warm”permafrost(closeto0°C,withfast degradation).Moreover,observationsareconsistentwithpermafrostdistributionanditsevolution: (i)thehotterthesummer,thehigherthescarelevations;(ii)asharpcontrastinthescarelevations between north and south faces. Rockfalls occur more frequently in context of pillars, spurs and ridges,particularlyaffectedbypermafrostdegradation.

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 Fig.6MeandailyairtemperatureattheAiguilleduMidi(3842ma.s.l.)anddailytotalrainfallatChamonix for the year 2009. Arrows indicate the days when one or several collapses occurred, with the value of temperatureandrainfallforthesedays.  Finally,thepermafrostdegradationappearstobethemostlikelytriggeringfactorforseveralother reasons(Ravanel2010): x Almostalloftherecordedrockfalls(98%)occurredinpossibleorprobablemodelledpermafrost; x Rockfallsoccurprimarilyduringsummertime,whichispronetopermafrostdegradation; x Massiveicewasobservedinatleast22scarsofthe2007Ͳ2009rockfalls; x Summer 2003 rockfalls were unusually numerous and could mainly be explained only by permafrostdegradation(Gruberetal.2004); x For the largest identified rockfalls (e.g. June 2005 at the Drus), the formation of a deep thaw corridorinthepermafrostmayhavepredisposedrockwallstocollapse. WhenrockfallsinhighͲAlpinesteeprockwallsareconsideredindividually,theroleofpermafrostin their triggering is difficult to establish. On the other hand, this role in the Mont Blanc massif is stronglysupportedbytheanalysisof:(i)the50surveyedrockfalls(ranginginvolumefrom500to 265000m3)atthewestfaceoftheDrusandonthenorthsideoftheAiguillesofChamonixsince 1862;(ii)the182surveyedrockfalls(ranginginvolumefrom100to65000m3)inthewholeMont Blancmassifattheendofthe2003summerheatwave;and(iii)the139surveyedrockfallsbetween 2007and2009inthecentralpartofthemassif(ranginginvolumefrom100to33000m3). 

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3. Possiblefuturethermalresponsetopredictedclimatechange Withintheglobalwarmingpredictionforthe21thcentury,rockfallsfromhighͲAlpinesteeprockwalls areexpectedtooccurmorefrequently,withvolumesthatarelikelytoincrease.Thefrequencythatis currentlyincreasingshouldmaintainthesametrendinthenextdecades,duetothedeepeningof theactivelayerasthetemperatureriseabove1800ma.s.l.intheAlpsforthe21thcenturywillbe higher by nearly 1°C than the global one, as reported in chapter 2. Moreover, heat advection by triggeringofwatercirculationatdepthalongthawcorridorswouldincreasethecollapsedvolumes.  Acknowledgements. – Alpine guides and hut keepers from Chamonix and Courmayeur who are involvedintherockfallinventoryoftheMontBlancmassifsince2005arekindlyacknowledged.  References:  DelineP.,KirkbrideM.,RavanelL.,RavelloM.,2008:TheTréͲlaͲTêterockfallontotheglacierdelaLexBlanche (MontͲBlancmassif,Italy)inSeptember2008.GeografiaFisicaeDinamicaQuaternaria,31,251Ͳ254. GruberS.,HoelzleM.,Haeberli,W.,2004:PermafrostthawanddestabilizationofAlpinerockwallsinthehot summerof2003.GeophysicalResearchLetter,31.L13504.doi:10.1029/2004GL020051. GruberS.,HaeberliW.,2007:PermafrostinsteepbedrockslopesanditstemperatureͲrelateddestabilization followingclimatechange.JournalofGeophysicalResearch,112.F02S18.doi:10.1029/2006JF000547. NoetzliJ.,HoelzleM.,HaeberliW.,2003:MountainpermafrostandrecentAlpinerockͲfallevents:aGISͲbased approachtodeterminecriticalfactors.Proceedingsofthe8thInternationalConferenceonPermafrost, Zurich,Switzerland,827Ͳ832. Ravanel L., 2010: Caractérisation, facteurs et dynamiques des écroulements rocheux dans les parois à permafrost du massif du Mont Blanc. Thèse de Doctorat, Université de Savoie, Le Bourget du Lac, France,322pp. RavanelL.,DelineP.,2008:LafaceouestdesDrus(massifduMontͲBlanc):évolutiondel’instabilitéd’uneparoi rocheusedanslahautemontagnealpinedepuislafinduPetitAgeGlaciaire.Géomorphologie,4,261Ͳ 272. RavanelL.,DelineP.,2011:ClimateinfluenceonrockfallsinhighͲAlpinesteeprockwalls:thenorthsideofthe AiguillesdeChamonix(MontBlancmassif)sincetheendoftheLittleIceAge.TheHolocene,21,357Ͳ 365. Ravanel L., Deline P., in press: On the trigger of rockfalls in high alpine mountain. A study of the rockfalls occurredin2009intheMontBlancmassif.ProceedingsoftheRockSlopeStabilityConference,Paris, France. RavanelL.,AllignolF.,DelineP.,GruberS.,RavelloM.,2010:RockfallsintheMontBlancMassifin2007and 2008.Landslides,7,493Ͳ501. RavanelL.,AllignolF.,DelineP.,2011:LesécroulementsrocheuxdanslemassifduMontBlancpendantl’été caniculairede2003.ActesduColloque2009delaSSGm,Olivone,Suisse,245Ͳ261. 

 118     3. CasestudiesintheEuropeanAlps   3.10 CimeBianchePass,ItalianAlps 

  Citationreference PogliottiP,CremoneseE.,MorradiCellaU.(2011).Chapter3.10:CasestudiesintheEuropeanAlps– Cime Bianche Pass, Italian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.119Ͳ128.  Authors Coordination:PaoloPogliotti Involvedprojectpartnersandcontributors: Ͳ Regional Agency for the Environmental Protection of the Aosta Valley, Italy (ARPA VdA) – PaoloPogliotti,EdoardoCremonese,UmbertoMorradiCella  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange Reference

 119 PermafrostResponsetoClimateChange

Summary  Cime Bianche Pass (45°55'N 7°41'E) is located at the head of the Valtournenche Valley in the northeasterncorneroftheAostaValleyRegion(Italy)atanelevationof3100ma.s.l.Twoboreholes ofdifferentdepth(6and41m)drilled30mapartindifferentmorphologicalconditionshavebeen realizedin2005andinstrumentedin2006.TheactivelayerthicknessreflectsthedifferentsnowͲ coverconditionsofthetwoboreholes:inthedeepboreholeitisalmosttwicethevalueobservedin theshallowone.Thetemperatureprofilesofthedeepboreholeallowtoidentifythedepthofzero annual amplitude (ZAA) at ca. 17m. The mean permafrost temperature is aboutͲ1.36°C in this depth. In the next future a probable decrease in the number of ID/year will strongly affect the ground thermal regime leading to a thickening of the active layer, increasing water pressure and permafrost degradation in the study area. All these changes will probably affect the spatial distributionofthehydroͲgeologicalriskinsucharegion.

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1.Introductionandstudyarea Cime Bianche Pass (45°55'N 7°41'E) is located at the head of the Valtournenche Valley in the northeast corner of the Aosta Valley Region at an elevation of 3100m a.s.l. (Fig. 1). The site is characterized by bare fractured bedrock locally mantled by shallow coarseͲdebris deposits. The lithologyismainlyconsistingofgarnetiferousmicaschistsandcalcschistsbelongingtotheupperpart oftheZermattͲSaasophiolitecomplex(DalPiazetal.1992).Severalgelifluctionlobes,terracettes andsortedpolygonsoccuronthedeposits. A            B

 Fig.1–Studyarea:(A)localizationofthestudyarea.(B)Siteoverviewandinstruments;intheforegrounda GSTͲgridarea(fencedbytheyellowflags)andinthebackgroundfromrighttoleft:boreholesdataloggers,GSTͲ grid datalogger, automatic weather station and related dataloggers. SkiͲlifts of the BreuilͲCervinia ValtournencheZermattresortarevisibleinthebackground.

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Thelocalclimatecanbedefinedasslightlycontinentalwithmeanprecipitationaround1000mm/a (meanoftheperiod1931Ͳ1996attheLakeGoilletweatherstation,2540ma.s.l.,1.5kmfar,Fig.1AͲ left).Themeanairtemperature(derivedfromPlateauRosàweatherstation(3480ma.s.l.,2kmfar, Fig.1AͲright)isaboutͲ3.2°Cfortheperiod1951Ͳ2000(Mercallietal.2003).Themeanmonthlyair temperaturesoverthesameperiodgivepositivevaluesonlyfromJunetoSeptember.Februaryisthe coldestmonthandJulyisthehottestone.ThesiteisverywindyandmainlyinfluencedbynortheastͲ northwestairmasses.Thecombinedeffectofirregularmorphologyandstrongwindactionleadtoa highvariabilityofsnowcoverthicknesswithinfewmeters. Thepermafrostmonitoringisperformedby: x Two boreholes of different depth (6 and 41m) drilled 30m apart in different morphological conditions(Fig.1A).Theshallowborehole(SH)isdrilledonaconvexcoarseͲdebrislandͲform highlysubjecttowinderosionwhichusuallyavoidstheformationofthicksnowcovers.Onthe other hand the deep borehole (DP) is located in a depression where the snow tends to accumulate,assuringasnowthicknessalwaysgreaterandmoredurablethanthoseobservedin SH. Temperature measurements in the borehole started in January 2005 for the SH and in August2008forDP. x AsmallGSTͲgridareaequippedwiththepurposetoquantifythespatialvariabilityofsurface temperatureinasmallarea.Thegridhasanextensionof40x10mandisactivesinceJanuary 2005.TheGSTismeasuredat5nodes:4atthegridcornersand1inthecentreofthearea.In each node the ground temperature is measured 2 and 30cm below the surface with hourly frequency.Thesurfaceischaracterizedbycoarseblockymaterialslightlypendingandirregular whichgivesgreatvariabilityofsnowcoveramongthenodes(Fig.1B). The site is equipped with an automatic weather station for the measurement of snowͲdepth, air temperature and relative humidity, wind speed and direction as well as radiation. The site is accessibleallovertheyear,bycablecarandskiinwinterandbyoffͲroadvehicleduringsummer.  2.Permafrostindicatorsandrecentthermalevolution 2.1Meteorologicalrecords Airtemperatureandsnowdeptharetheparametersthatmainlyaffectthegroundthermalregimein permafrost environments (Zhang 2005). On the study site both parameters are measured in correspondenceoftheSHborehole. The Fig. 2A shows monthly air temperature anomalies calculated comparing the monthly means measured at Cime Bianche Pass with longͲterm monthly means (1951Ͳ1998) derived from the Plateau Rosà meteorological station. An extrapolation method based on monthly lapse rates was usedtoshiftͲdownthelongͲtermdatasetfromtheelevationofPlateauRosàtoCimeBianchePass. TheFig.2BshowsthemeansnowdepthoftheperiodNovember15thͲJune15thovertheboreholeSH for3availablehydrologicalyears.  2.2ActiveLayerThickness The active layer thickness reflects the different snowͲcover conditions of the two boreholes. The combinedeffectofmorphologyandwindleadstothicksnowcoverabovetheDPboreholeandathin snow cover above the SH. These morphological differences strongly affect the ground thermal regime:itfollowsthatthethicknessoftheactivelayer(ALT),definedasthemaximumdepthofthe 0°CͲisotherm, in the deep borehole is almost twice the one observed in the shallow one. Table 1 summarizesthevaluesofALTofsomeyearsobtainedbylinearinterpolationamongthemeasured temperaturesatdifferentdepths.

122 PermafrostResponsetoClimateChange

  A              B

 Fig.2–(A):monthlyairtemperaturesfrom2006to2009comparedwithalongtermmean(1951Ͳ1998)derived fromPlateauRosaobservations.Theverticallinesgivethestandarddeviationofthelongtermmonthlymeans. RedlinesarethemonthlymeansmeasuredatCimeBianchePass.(B)meanseasonalsnowdepthabovethe boreholeSHcalculatedovertheperiodNovember15thͲJune15th. 

123 PermafrostResponsetoClimateChange

A          

  B 

 Fig.3–Maximumdailygroundtemperaturevs.timeintheSH(A)andDP(B)boreholes.Theblacklineisthe 0°CͲisotherm.NotethatyͲaxeshavedifferentranges.

124 PermafrostResponsetoClimateChange

 Table1–Valuesofthemaximumactivelayerthickness(ALT)inthetwoboreholesatCimeBianchePassand dayoftheyearinwhichthevaluehasbeenreached.

ActiveLayerThickness(ALT)(m) OccurrencedayofmaximumALT Hydrological Shallow Deep Shallow Deep Year Borehole Borehole Borehole Borehole 2005/2006 3.12 ͲOctober 7th Ͳ 2006/2007 2.36 ͲOctober 11th Ͳ 2007/2008 1.9 3.9 September30th September27th 2008/2009 2.8 4.85 October22th October17th  Comparingthecontourplotsofbothboreholes(Fig.3)withthesnowͲdepthmeasuresofFig.2B,a goodcorrelationbetweenthemeanseasonalsnowdepthandtheactivelayerthicknesscanbeseen. Thedifferenceintheactivelayerthicknessfrom2008to2009inbothboreholesshowsthesame behaviour: 2009 maximum depth has an increase of about 1m compared to 2008, due to the exceptionalsnowfallsofthewinterseason2008/09whichleadtoimportantsnowcoverthroughout thewinteronbothboreholes.  2.3PermafrostTemperature Thetemperatureprofilesofthedeepboreholeallowtoidentifythedepthofzeroannualamplitude (ZAA)ataround17m.ThemeanpermafrosttemperatureatthisdepthisaboutͲ1.36°C(Fig.4A).The thermalͲoffset,definedinaccordancetoRomanovsky&Osterkamp(1995)asthedifferencebetween TTOP (mean annual permafrost surface temperature) and MAGST (mean annual ground surface temperature),seemsquitevariablefromyeartoyear.Theavailablevaluesforbothboreholesare reportedinTable2.  Table 2 – Values of thermalͲoffset in the boreholes. MAGST is calculated using the node atͲ2cm from the groundsurface.TTOPiscalculatedatthedepthofALT(Table1)bylinearinterpolationamongthemeanannual temperaturesofthefirstnodeaboveandfirstnodebelowtheALTvalue.

ShallowBorehole DeepBorehole Hydro.Year MAGST TTOP ThͲOffset MAGST TTOP ThͲOffset (°C) (°C) (°C) (°C) (°C) (°C)㩷 '08Ͳ'09Ͳ0.05Ͳ0.73Ͳ0.67Ͳ0.01Ͳ0.81Ͳ0.8 '09Ͳ'10Ͳ1.1Ͳ1.24Ͳ0.14Ͳ1.17Ͳ1.23Ͳ0.05

 Fig.4showstheboreholetemperatureprofilesatspecificdaysoftheyear.Meandailytemperature profileof1stAprilarerepresentativeofgroundtemperaturesattheendofthewinterseasonwhile thoseof1stOctoberarerepresentativeofgroundtemperaturesattheendofthehydrologicalyear neartheoccurrenceofthemaximumALT. The effect of different snow amount during the winter season is clearly reflected in the 1st April profiles of borehole SH. The profiles differ very much from each other with the colder ones corresponding to the less snowy years. The great differences at the end of the winter are systematicallylevelledduringthespring/summerperiod,indeedthe1stOctoberprofilesdifferless from each other. From the beginning of the measures the hydrological year 2007/08 shows the coldestgroundtemperatureprofilesandshallowerALT(Table1).Thisresultsfromacombinationof

125 PermafrostResponsetoClimateChange scarce snow accumulation and summer air temperature around the mean (Fig. 2). In contrast the seasonswhichshowwarmergroundtemperatureprofilesanddeeperALTarethosewithabundant snowduringthewinterandairtemperatureabovethemeanduringthewinterͲsummerperiod.This ismainlytrueforthehydrologicalyear2008/09whilein2005/06thequitecoldgroundtemperature profile of April is completely overhung by the extremely warm spring/summer 2006. All these considerationssuggestthatevenifwinterconditionsarestronglyfavourabletogroundcoolingthey are often not enough to restrain the effect of very hot springͲsummer conditions on ground temperatures. 

A        

 B 

 Fig.4–GroundtemperatureprofilesovertheSH(A)andDP(B)boreholesatspecificdaysattheendofwinter andsummerseasons.

126 PermafrostResponsetoClimateChange

3.Possiblefuturethermalresponsetopredictedclimatechange As suggested in chapter 2, frost days (FD), ice days (ID) and freezeͲthaw days (FTD) have been computedusingtheairtemperaturedatasetoftheCimeBianchePassovertheavailableyearsof observation(Table3).  Table3–Frostdays(FD),IceDays(ID)andFreezeͲThawDays(FTD)occurrenceattheCimeBianchesiteduring theavailablehydrologicalyears(October1stͲNovember30th).Thelastcolumnreportsthemeanvalueofthe period.

 2006/07 2007/08 2008/09 2009/10 Mean MAAT Ͳ1.73 Ͳ3.01 Ͳ3.4 Ͳ3.75 Ͳ2.97 (°C) FD 275 284 275 282 279 ID 149 202 198 201 187.5 FTD 126 82 77 81 91.5

  Referringtothemapsandpredictionsofchapter2,theairtemperaturemeasurementsconductedat CimeBianchePassfrom2006to2010areinaccordancewiththemeansoftheperiod1961Ͳ1990 computed for the Great Alpine Region (GAR). That is a number of ID in the range of 261Ͳ280, a numberofFDintherangeof181Ͳ200andanumberofFTDintherangeof80Ͳ90.Thepredictionfor the period 2021Ͳ2050 in the study area are a decrease of ID ranging fromͲ15/Ͳ16 days/year that means172IDinsteadof187andadecreaseofFDrangingfromͲ15/Ͳ16days/yearthatmeans264FD insteadof279. Comparing the data of Table 3 and plots of Figure 3 year by year, it is evident that the air temperature is not the only factor controlling the ground temperatures. In fact, as already highlighted,thesnowcoverplaysakeyrole.Despitethis,lookingatthehydrologicalyear2006/07a clear correlation between warmer air temperature and deeper ALT exists. Looking at table 3 it is interesting to note that the number of ID is the most affected value by this anomalous winter. ProbablyafuturedecreaseinthenumberofID/yearwillstronglyaffectthegroundthermalregime leadingtoathickeningoftheALT,increasingwaterpressureandpermafrostdegradation.Allthese changeswillprobablyaffectthespatialdistributionofthehydrogeologicalriskinsucharegion.    References:  DalPiazG.etal.,1992:LeAlpidalMonteBiancoalLagoMaggiore.GuideGeologicheRegionaliacuradella SocietàGeologicaItaliana,3/II,211pp. MercalliL.,CastellanoC.,CatBerroD.,DiNapoliG.,MontuschiS.,MortaraG.,RattiM.&GuindaniN.,2003: AtlanteClimaticodellaValled'Aosta.EditionsSMS,405pp. ZhangT.,2005:Influenceoftheseasonalsnowcoveronthegroundthermalregime:anoverview.Reviewof Geophysics,43:RG4002.

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RomanovskyV.E.&OsterkampT.E.,1995:Interannualvariationsofthethermalregimeoftheactivelayerand nearͲsurfacepermafrostinnorthernAlaska.PermafrostandPeriglacialProcesses,6,313Ͳ335. 

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 3. CasestudiesintheEuropeanAlps   3.11 Maroccarorockglacier,ValdiGenova,ItalianAlps  

 Citationreference SeppiR.,BaroniC.CartonA.,Dall’AmicoM.,RigonR.,ZampedriG.,ZumianiM.(2011).Chapter3.11: CasestudiesintheEuropeanAlps–Maroccarorockglacier,ValdiGenova,ItalianAlps.InKellererͲ PirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimate changeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲlinepublicationISBN 978Ͳ2Ͳ903095Ͳ58Ͳ1,p.129Ͳ139.  Authors Coordination:RobertoSeppi Involvedprojectpartnersandcontributors: Ͳ UniversityofPavia–RobertoSeppi Ͳ UniversityofPisa–CarloBaroni Ͳ MountainͲeeringsrl–MatteoDall’Amico Ͳ UniversityofTrento–RiccardoRigon Ͳ GeologicalSurvey,AutonomousProvinceofTrento–GiorgioZampedri Ͳ Geologist–MatteoZumiani  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalandgeomorphicevolution 3. Possiblefuturethermalandgeomorphicresponsetopredictedclimatechange References

129 PermaNET–CasestudiesintheEuropeanAlps

Summary  In2001westartedatopographicstudyonanactiverockglacier(namedMaroccarorockglacier, acronym MaRG, coordinates: 46° 13’06” N, 10° 34’ 34” E) located in the AdamelloͲPresanella massif(CentralItalianAlps).Since2004,alsothenearͲsurfacegroundtemperaturewasmeasured usingaminiaturedatalogger.Ourdatashowthatineightyears(2001Ͳ2009)MaRGhasmoved downslope with average velocities ranging from 0.02 to 0.21m/year. The velocity reaches a maximuminthemiddleandthelowerpartoftherockglacier,anddecreasestowardstheupper sector,wherethesurveyedbouldersarealmoststationary.Aconsiderabledifferentvelocityfrom year to year has been observed, but no clear trends seem to emerge from the mean annual displacement rate. On the rock glacier the evolution of the ground temperature since 2004 is directlyassociatedwiththeairtemperatureandthesnowconditions,intermsofthicknessand durationofthesnowpack.Thegroundhaswarmedsignificantlybothin2007,afteraverymild and little snowy winter, and in 2009, after a cold but exceptionally snowy winter. The displacement rate of MaRG seems to rapidly react to the ground temperature variations, apparently without any time delay. The exceptionally snowy winter 2008/09 seems to have playedasignificantroleonthedisplacementrate,causingagroundtemperatureincreaseand, probably,anincreaseinvelocity,whichreacheditsmaximuminthatyear. 

 130 PermafrostResponsetoClimateChange

1. Introductionandstudyarea IntheAdamelloͲPresanellaGroup(CentralItalianAlps),anactiverockglacier(MaRG)locatedinVal Genova has been selected for carrying out multitemporal topographic surveys (Fig. 1). The measurements aim at studying its surface displacement rate and its dynamic behaviour. The displacement rates of the rock glacier are compared with the nearͲsurface thermal regime of the groundandwiththemajorclimaticparameters,inordertoinvestigatethepotentialrelationships betweenitsdynamicbehaviourandthelocalclimaticconditions.Thisrockglacierisincludedinan inventory published by Baroni et al. (2004), in which it has the number 41 and is also briefly described.

 Fig.1–GeographicalsettingofthestudyareawithrockglacierMaRGandautomaticweatherstations(AWS)  The topographic measurements started in 2001 and have been repeated in late summer of the followingyears(2002,2004,2006,2007,2008and2009).Ontherockglaciersurface,amonitoring networkof25largebouldersmarkedwithsteelboltshasbeenestablishedandalasertheodolitehas beenusedforperformingthesurveys.FormonitoringthenearͲsurfacetemperatureoftheground,a miniaturetemperaturedatalogger(UTL1,accuracy:±0,25°C;Hoelzleetal.1999)hasbeenplacedin 2004 few centimetres below the surface, in a place were fineͲgrained material outcrops. Detailed meteorologicaldata(i.e.airtemperatureandsnowthickness)coveringthefullmonitoringperiodare available from two highͲaltitude automatic weather stations (AWS) located near the studied rock glacier(CimaPresena,3015ma.s.l.,andCapannaPresena,2730ma.sl.). MaRGisatongueͲshaperockglacier,about280mlongand100mwide.Itfacessouthwestandits lowerpart(topedgeofthefrontalslope)reachesanaltitudeof2760ma.s.l.(Fig.2).Thesurfaceof MaRGdoesn’tdisplaythetypicalmorphologicalfeaturesofactiverockglaciers,suchaslongitudinal andtransversalridges,furrowsandhollows.MaRGiscomposedoftalusmaterialcomingfromthe shatteredrockwallssituatedabove,andnofieldevidencesofLittleIceAgeglaciationarepresentin

131 PermaNET–CasestudiesintheEuropeanAlps its rooting area. It is almost completely covered by large and very angular boulders (from few decimetrestosomemetersindiameter),andfineͲgrainedrockmaterialoutcropsonlyonthesteep frontalandlateralslopes.AccordingtothedefinitiongivenbyBarsch(1996),MaRGcanbedefinedas atalusrockglacier. 

 Fig. 2 – General view of MaRG. The elevation at the front is about 2760m a.s.l., the highest peaks in the backgroundreachelevationsofabout3000ma.s.l.PhotographybyR.Seppi(21.08.2009)  On this rock glacier, BTS measurements carried out in late March 2003 recorded very cold temperatures,consistentwiththepresenceofafrozencoreintothedebrisdeposit.TheBTSvalues rangedbetweenͲ2.1°CandͲ6.1°C(averagevalueof23measurementpoints:Ͳ4.2°C)andtheaverage thicknessofthesnowpackwas230cm.Thetemperatureofaspringemergingfromthebottomof thefrontalslopeisalsoundermeasurementssince2004.Thewatertemperaturemeasuredduring thelatesummerseasonisconstantlybelow1°C,indicatingfurthermorethepresenceofpermafrost intherockglacier.  2. Permafrostindicatorsandrecentthermalandgeomorphicevolution Fig.3showsthetotalhorizontaldisplacementofMaRGinthefullperiodofmeasurements(2001Ͳ 2009).Onthisrockglacier,thetotaldisplacementrangesbetween0.12m(boulder19)and1.67m (boulder2),correspondingtoavelocityof0.02and0.21m/year,respectively(Table1).Thesurveyed boulders moved along the maximum gradient of the slope in a rather homogeneous pattern. The velocity reaches a maximum in the middle and the lower part of the landform, and decreases towardstheuppersector,wheretheslowestboulders(18,19and20)arelocated.Afterthesecond survey(2002)theboulder3felldownfromthefrontalslope.

 132 PermafrostResponsetoClimateChange

ThemeandisplacementofMaRGinallthemeasurementintervalsisshowninFig.7(topgraph), where all the surveyed boulders of the rock glacier have been taken into account. The average velocityissignificantlyvariablefromyeartoyear,rangingfromaminimumof0.08m/year(2007Ͳ 2008) to a maximum of 0.17m/year (2008Ͳ2009). No clear trends seems to emerge from the evolution of the mean annual displacement. The interannual variability of the velocity and an acceleratingtrendhavebeenrecentlyreportedforseveralrockglaciersintheEuropeanAlps(Roeret al.2005,Delaloyeetal.2008,PERMOS2009,Bodinetal.2009).  Table1–HorizontaldisplacementsofMaRG.Thefirstsixcolumnsshowthedisplacementforeachperiodof measurements,thecolumnseventhetotaldisplacement,andthecolumneighttheannualdisplacementrate. (*)Measurementperiodoftwoyears;(**)Thebouldernumber3fellfromthefrontalslopeafter2002.

Boulder Horizontaldisplacement(m) 2001Ͳ09 2001Ͳ09 ID total horizontal horizontal displacement 2001Ͳ02 2002Ͳ04(*) 2004Ͳ06(*) 2006Ͳ07 2007Ͳ08 2008Ͳ09 displacement rate (m) (m/yr) 01 0.16 43.2 27.6 0.21 0.08 0.22 1.38 0.17 02 0.21 51.9 34.1 0.24 0.11 0.25 1.67 0.21 03(**) 0.20 . . . . . . . 04 0.18 47.4 29.7 0.20 0.11 0.24 1.50 0.19 05 0.17 43.6 26.2 0.17 0.12 0.23 1.38 0.17 06 0.17 46.6 26.5 0.20 0.09 0.25 1.44 0.18 07 0.16 44.2 25.3 0.18 0.08 0.23 1.34 0.17 08 0.15 35.9 22.0 0.12 0.10 0.18 1.13 0.14 09 0.11 25.9 14.6 0.06 0.06 0.12 0.77 0.10 10 0.17 46.7 24.9 0.18 0.10 0.24 1.41 0.18 11 0.16 45.0 22.9 0.17 0.08 0.21 1.31 0.16 12 0.15 37.1 20.8 0.14 0.08 0.19 1.13 0.14 13 0.16 40.9 23.9 0.16 0.08 0.21 1.26 0.16 14 0.13 27.2 16.3 0.07 0.08 0.15 0.87 0.11 15 0.15 34.0 19.2 0.11 0.08 0.19 1.05 0.13 16 0.13 30.6 16.4 0.11 0.06 0.17 0.94 0.12 17 0.08 12.6 5.4 0.07 0.0 0.07 0.39 0.05 18 0.08 5.6 4.4 0.0 0.04 0.04 0.22 0.03 19 0.07 2.0 1.8 0.01 0.0 0.03 0.12 0.02 20 0.08Ͳ0.5 2.1 0.02 0.0 0.04 0.14 0.02 21 0.05 10.8 8.3 0.06 0.0 0.07 0.35 0.04 22 0.09 19.9 10.6 0.11 0.02 0.09 0.61 0.08 23 0.12 29.7 14.3 0.12 0.06 0.15 0.88 0.11 24 0.15 38.0 20.6 0.16 0.08 0.19 1.17 0.15 25 0.10 21.2 9.0 0.10 0.01 0.10 0.61 0.08  ThenearͲsurfacetemperatureofthegroundrecordedonMaRGfromAugust2004toAugust2009is showninFig.4(bottomgraph).Inthisfigurethegroundtemperature(dailymean)isassociatedto theairtemperature(centralgraph)andtothethicknessofthesnowcover(topgraph),recordedat two meteorological stations located about 1 km from the rock glacier (Cima Presena AWS and CapannaPresenaAWS). Focusingonthegroundthermalregimeduringwinter,thecoldesttemperatureswererecordedin the 2004Ͳ2005 and 2005Ͳ2006 winter seasons. During the first winter, the ground reached a minimumtemperatureofaboutͲ10°CinlateFebruary,andastrongwarmingfollowedinMarchdue

133 PermaNET–CasestudiesintheEuropeanAlps toanearlystartingofthesnowmelt.Inthewinterof2005Ͳ2006,thegroundcooledveryquickly towardstheminimumvaluesofaboutͲ8°C.Thestrongcoolingofthegroundinthesetwowinters maybeduetothecombinedeffectofcoldairtemperatureandrelativelythinsnowpackinautumn andearlywinter.Inthetwofollowingwinters,thegroundtemperaturewaswarmerandreacheda phaseofwinterequilibriumtemperature(WEqT)ofaboutͲ5°C.Thewinter2006Ͳ2007wasverymild and the snowpack was relatively thin until mid winter, while the following winter was colder and snowier.

 Fig.3–Totalhorizontaldisplacement(2001Ͳ2009)ofMaRG. 

 Fig.4–Topandmiddlegraphs:snowthicknessandairtemperatureatCapannaPresenaautomaticweather station; bottom graph: ground nearͲsurface temperature from August 2004 to August 2009 for MaRG. For locationoftemperaturedataloggerrefertoFig.3.

 134 PermafrostResponsetoClimateChange

Withrespecttothepreviousyears,thegroundtemperaturewascomparativelywarmerduringthe 2008Ͳ2009winterseason,andreachedarelativelyshortWEqTofaboutͲ4°C.Althoughinthiswinter theairtemperaturewasnotparticularlymildcomparedtotheprecedingones,thesnowpackalready reached a significant thickness in autumn and early winter, preventing the cooling of the ground. Moreover, the snowpack further thickened in the following winter months. This underlines the strongcontrolofthesnowcoveronthewintertemperatureofthegroundand,consequently,onthe meanannualgroundtemperature. The Ground Freezing Index (GFI), computed as the cumulative value of the negative daily mean groundtemperaturesbetween1stOctoberand30thJune,isshowninFig.5.Thelowestvalueswere recorded in the winter 2005Ͳ2006 and 2007Ͳ2008 (Ͳ1197°Cͼday andͲ1052°Cͼday, respectively). DespiteathinandlateͲappearedsnowcoverinwinter2006Ͳ2007,theGFIwaslessnegativethanthe previousandthefollowingwinter,probablybecauseoftherelativelyhighairtemperature(seeCima PresenaAWSinFig.4).ThehighestGFI(Ͳ471°CͼDay)sincethebeginningofthemeasurementswas recordedinwinter2008Ͳ2009,whenaverythicksnowpackwaspresentontherockglaciersincethe middleofautumn.

 Fig.5–Annualgroundfreezingindex(GFI)atMaRGfrom2004to2009.  TheeffectofthesnowcoveronthegroundtemperaturecanbeobservedinFig.6.Inthegraph,the evolutionofthemeanannualairtemperature(MAAT)atCimaPresenaAWSandtheevolutionofthe mean annual ground temperature at MaRG are compared on the same period of time. The temperaturesaredisplayedas12Ͳmonthsrunningmeans,andthedateonthexͲaxiscorrespondsto the end of the period used for the calculation. The mean ground temperature on MaRG ranged between0°CandͲ2°Cintheperiodofmeasurements(mid2005tomid2009),reachingthehighest valuesin2007andin2009.Thefirstwarmingphase(2007)occurredafterawinterseasonthatwas verymildandwithlittlesnow,whilethesecond(2009)followedanexceptionallysnowywinterwith relativelycoldairtemperature.Onthisrockglacier,theevolutionofthegroundtemperatureseems tobewellcorrelatedwiththeMAAT,atleastuntil2008.Infact,thestrongwarmingoftheground observedin2009ismoreduetoaneffectofthethicksnowcoverofthepreviouswinterthantoa correspondingwarmingintheairtemperature.

135 PermaNET–CasestudiesintheEuropeanAlps

 Fig.6–EvolutionofthemeanannualairtemperatureatCimaPresenaautomaticweatherstation(topgraph) andofthenearͲsurfacegroundtemperatureatMaRg(bottomgraph).Allthetemperaturesaredisplayedas12Ͳ monthsrunningmeans,andthedateonthexͲaxiscorrespondstotheendoftheperiodusedforthecalculation.  InFig.7alltheobservationscarriedoutonMaRGaresummarized.Thetopgraphshowsthemean annualdisplacementsince2001andhasbeendescribedabove.Theintermediategraphshowsthe mean annual nearͲsurface temperature of the ground, and the bottom graph reports the mean annualairtemperatureatCimaPresenaAWS.Inordertoemphasizethecontributionofthewinter seasons,thevaluesofthemeanannualtemperature(bothforthegroundandfortheair)havebeen calculatedtakingintoaccountanannualbasisextendingfromthe15thAugustofthepreviousyearto the14thAugustofthefollowingyear.Forthisreason,anextremelywarmsummerlike2003isnotas wellvisibleinthedatarecordasamildwinterlike2006Ͳ2007. 

 Fig.7–MeandisplacementofMaRG(topgraph)comparedwiththemeanannualgroundtemperature(middle graph)andthemeanannualairtemperatureatCimaPresenaautomaticweatherstation(bottomgraph).

 136 PermafrostResponsetoClimateChange

 

 Fig. 8 – Potential change of frost, ice and freezeͲthaw days for 2020Ͳ2050, as proposed in chapter 2. The locationofMaRGisshown.

137 PermaNET–CasestudiesintheEuropeanAlps

The displacement of the MaRG seems to react rapidly to the ground temperature variations, apparently without any time delay. In the last three years, indeed, higher ground temperatures correspondratherwellwithhigherdisplacementvelocities,asclarifiede.g.intheyear2006Ͳ2007.In thisyear,therockglacierhasmovedfasterthaninthepreviousandinthefollowingyears,inclose relationwiththehighermeantemperatureofthegroundthatwasslightlyabove0°C.Inthelastyear of measurements (2008Ͳ2009) MaRG reached the highest velocity since the beginning of the observations.Thisaccelerationcorrespondswithameangroundtemperaturethatapproachedagain 0°C,buttheeffectseemstobeamplifiedbythesnowcover.Infact,theexceptionallysnowywinter of2008Ͳ2009couldhaveplayedaroleindeterminingthedisplacementrate,probablybecauseofthe longmeltingphaseofthesnowcoverassociatedtothelongzerocurtainphaseofthegroundthat characterizedMaRG(fromearlyMaytolateJuly;seeFig.4,bottomgraph).Thelongmeltingphase couldhaveinducedaprolongedinfiltrationofmeltwaterintotheactivelayerand,possibly,intothe frozencoreoftherockglacier,causingtheobservedacceleration.Asimilareffecthasrecentlybeen observedanddescribedbyIkedaetal.(2008)onarockglacieroftheSwissAlps.   3. Possible future thermal and geomorphic response to predicted climate change Accordingtotheanalysesinchapter2,somespeculationsonthefutureevolutionofMaRGcanbe done.IntheareawhereMaRGislocated,themodelledaveragenumberoffrostdaysintheperiod 1961Ͳ1990rangesbetween280and300peryear,andthepredictedchangefor2021Ͳ2050showsa decreaseof15/16days/year.Inthesameareaandthesameperiod,theaveragenumberoficedays is between 201 and 220 per year, with a predicted decrease of 17/19 days/year for 2021Ͳ2050. RegardingtheaveragenumberoffreezeͲthawdays,ithasbeenmodelledasrangingbetween70and 80peryearinthe30Ͳyearreferenceperiod,andanincreaseof3/4days/yearispredictedfor2021Ͳ 2050.InFig.8thelocationofMaRG(whitedot)onthemapsofthepredictedchangeinfrost,iceand freezeͲthawdaysisdisplayed.SomechangesinthedynamicresponseofMaRGtoclimatechange canbeexpected,becauseofthecloserelationshipbetweenitsbehaviourandtheclimaticvariables. However, an assessment of its future evolution should carefully take into account the future evolution of the precipitation (amount and distribution) and not only the predicted rise in air temperature.  Acknowledgements. – Mauro Degasperi and Franco Crippa (Geological Survey, Autonomous ProvinceofTrento)conductedthetopographicsurveysandprocessedtheroughtopographicdata. FieldcollaborationwasprovidedbyLucaCarturan,StefanoFontanaandDavideTagliavini.Thiswork waspartlyfundedbythePRIN2008project“ClimateChangeeffectsonglaciers,onglacierͲderived waterresourceandonpermafrost:QuantificationoftheongoingvariationsintheItalianAlps”.   References:  BaroniC.,CartonA.&SeppiR.,2004:DistributionandbehaviourofrockglaciersintheAdamelloͲPresanella Massif(ItalianAlps).PermafrostandPeriglacialProcesses,15,243Ͳ259. Barsch D., 1996: Rockglaciers: Indicators for the Present and Former geoecology in High Mountain Environments.Springer,Berlin,331pp.

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Bodin X., Thibert E., Fabre D. Ribolini A., Schoeneich P, Francou B., Louis Reynaud L. & Fort M., 2009: Two DecadesofResponses(1986–2006)toClimatebytheLaurichardRockGlacier,FrenchAlps.Permafrost andPeriglacialProcesses,20,331Ͳ344. Delaloye R., Perruchoud E., Avian M., Kaufmann V., Bodin X., Ikeda A., Hausmann H., Kääb A., KellererͲ Pirklbauer A., Krainer K., Lambiel C., Mihajlovic D., Staub B., Roer I. & Thibert E., 2008: Recent interannualvariationsofrockglacierscreepintheEuropeanAlps.Proceedingsofthe9thInternational ConferenceonPermafrost(NICOP),UniversityofAlaska,Fairbanks,June29ͲJuly3,2008,343Ͳ348. Haeberli W., Hallet B., Arenson L., Elconin R., Humlum O., Kaab A., Kaufmann V., Ladanyi B., Matsuoka N., SpringmanS.&VonderMühllD.,2006:Permafrostcreepandrockglacierdynamics.Permafrostand PeriglacialProcesses,17,189Ͳ214. Hoelzle M., Wegmann M. & Krummenacher B., 1999: Miniature temperature dataloggers for mapping and monitoringofpermafrostinhighmountainareas:firstexperiencefromtheSwissAlps.Permafrostand PeriglacialProcesses,10,113Ͳ124. KääbA.,FrauenfelderR.&RoerI.,2007:Ontheresponseofrockglaciercreeptosurfacetemperatureincrease. GlobalandPlanetaryChange,56,172Ͳ187. IkedaA.,MatsuokaN.&KääbA.,2008:Fastdeformationofperenniallyfrozendebrisinawarmrockglacierin theSwissAlps:Aneffectofliquidwater.JournalofGeophysicalResearch113,F01021. PERMOS, 2009: Permafrost in Switzerland 2004/2005 and 2005/2006. Noetzli, J., Naegeli, B., and Vonder Muehll,D.(eds.),GlaciologicalReportPermafrostNo.6/7oftheCryosphericCommissionoftheSwiss AcademyofSciences,100pp. Roer I., Kääb A. & Dikau R., 2005: Rockglacier acceleration in the Turtmann valley (Swiss Alps) – probable controls.NorwegianJournalofGeography,59,157Ͳ163. 

139 PermaNET–CasestudiesintheEuropeanAlps

 3. CasestudiesintheEuropeanAlps   3.12 Amolarockglacier,Vald’Amola,ItalianAlps  

 Citationreference SeppiR.,BaroniC.CartonA.,Dall’AmicoM.,RigonR.,ZampedriG.,ZumianiM.(2011).Chapter3.12: Case studies in the European Alps – Amola rock glacier, Val d’Amola, Italian Alps. In KellererͲ PirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimate changeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.ISBN978Ͳ2Ͳ903095Ͳ58Ͳ1, p.140Ͳ150.  Authors Coordination:RobertoSeppi Involvedprojectpartnersandcontributors: Ͳ UniversityofPavia–RobertoSeppi Ͳ UniversityofPisa–CarloBaroni Ͳ MountainͲeeringsrl–MatteoDall’Amico Ͳ UniversityofTrento–RiccardoRigon Ͳ GeologicalSurvey,AutonomousProvinceofTrento–GiorgioZampedri Ͳ Geologist–MatteoZumiani  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalandgeomorphicevolution 3. Possiblefuturethermalandgeomorphicresponsetopredictedclimatechange References

 140 PermafrostResponsetoClimateChange

Summary  Topographicmeasurementsareinprogresssince2001onaglacierͲderived,activerockglacier (namedAmolarockglacier,acronymAmRG,coordinates:46°12’09”N,10°42’46”E)locatedin theAdamelloͲPresanellagroup,CentralItalianAlps.Inaddition,dataonthegroundtemperature measured few centimetres below the surface are available since 2004. The displacement data showthatsomeareasoftherockglaciercurrently(2001Ͳ2009)movewithvelocitiesrangingfrom 10 to 20cm/year, while other sectors can be defined as “dynamically inactive”. The average velocityissignificantlyvariablefromyeartoyear,rangingfromaminimumof0.06m/year(2007Ͳ 2008)toamaximumof0.13m/year(2006Ͳ2007),andaslowingtrendhasbeenrecordedinthe lasttwoyears.In2006Ͳ2007ahigherrateofdisplacementseemstoberelatedtoariseinthe mean air temperature that probably caused a corresponding rise in the ground temperature. However,inthelastyearofmeasurements(2008Ͳ2009),anincreaseinthegroundtemperature causedbythelargeamountofsnowoftheprecedingwinter,didnotresultinacorresponding increaseofthedisplacementrate.Thedynamicbehaviourofthisrockglacierreactsveryfastto theexternalforcing,anditsresponseseemstobemodulatedbytheamountandevolutionofthe snowduringwinter,duetoitseffectonthegroundtemperature.Thus,notonlythetemperature but also the projected changes in the amount and distribution of precipitation, especially as snow,shouldbetakenintoaccountinassessingtheresponseofthislandformtofutureclimate change.

141 PermaNET–CasestudiesintheEuropeanAlps

1. Introductionandstudyarea Activerockglaciersoriginatefromthecreepofperenniallyfrozendebris(i.e.permafrost)andmove downslope with typical velocities ranging from few cm to more than 1m per year. The surface displacementofactiverockglaciersismarkedlyvariablefromyeartoyear,andintheEuropeanAlps arecentspeedingͲuptrendhasbeenunderlinedonsomelandforms(Roeretal.2005,Haeberlietal. 2006,Delaloyeetal.2008,PERMOS2009).Theinterannualvariabilityofthesurfacevelocityseems toberelatedtotheclimaticfactorsinfluencinggroundsurfacetemperatureofthedeposits,suchas theairtemperature,thethicknessanddurationofthewintersnowcoverandtheprocessesofwater infiltration(Kääbetal.2007,Ikedaetal.2008;Bodinetal.2009) In 2001 we choose an active rock glacier located in Val d’Amola for performing topographic measurements,inordertostudyitssurfacedisplacementrateandthepotentialvelocityvariations (Fig.1).Thisrockglacierisoneoftheactivelandformsincludedintherockglacierinventoryofthe AdamelloͲPresanella massif (Baroni et al. 2004), where it has the number 51 and is also briefly described. The measurements have been carried out using a laser theodolite and after the first survey have been repeated in the late summer/early autumn of the following years (2002, 2004, 2006,2007,2008,2009).ThesurveyswereconductedeveryyearbetweenearlySeptemberandmid October.Onthesurfaceoftherockglacier,amonitoringnetworkof25largebouldersmarkedwith steelboltshasbeenestablished.

 Fig.1–GeographicalsettingofthestudyareawithrockglacierAmRGandautomaticweatherstations(AWS)  In 2004 we also started to measure the temperature of the ground few centimetres below the surface, using a miniature temperature data logger (UTL1, accuracy: ±0,25°C; Hoelzle et al. 1999) placedinfineͲgraineddebrisonthelowerpartoftherockglacier.Thedataloggerhadamalfunction in 2006 and stopped to collect data between March and August 2006. In order to compare the groundtemperaturewiththeairtemperatureandtheevolutionofthewintersnowcover,weused

 142 PermafrostResponsetoClimateChange themeteorologicaldataoftwohighͲaltitudeautomaticweatherstations/AWS(CimaPresenaAWS, 3015ma.s.l.,andCapannaPresenaAWS,2730ma.sl.)locatedabout10kmfromtherockglacier. AmRG is a tongueͲshape rock glacier located in a north facing glacial cirque, between an upper altitudeof2480ma.s.l.andaloweraltitudeof2360ma.s.l.(topedgeofthefrontalslope)(Fig.2).It isabout530mlongand250mwideandshowsadistinctivesetoflongitudinalandtransversalridges onitssurface.Initsintermediateanduppersector,awidehollowlocatedbetweentwoelongated longitudinalridgesispresent,whilethecompressiveridgescanbemainlyobservedinitslowerarea. TherockglaciersurfaceismostlycomposedofmatrixͲfree,largeandveryangulargraniteboulders (uptosomemetersindiameter),whilethefineͲgrainedmaterialfrequentlyoutcropsnotonlyonthe lateralandfrontalslopes,butalsoonthetopofthelongitudinalandtransverseridges.Intherooting area of the rock glacier, snow patches are present over the whole summer only in the most favourableyears(i.e.withalargeamountsofsnowduringtheprecedingwinter). 

 Fig. 2 – General view of AmRG. The elevation at the front is about 2300m a.s.l., the highest peaks in the backgroundreachelevationsofabout2700ma.s.l.PhotographybyR.Seppi(26.09.2009).  Fieldevidences,confirmedbyhistoricalmaps,showthatacirqueglacierwaspresentintherooting area of the rock glacier during and after the Little Ice Age. This little glacier is still reported in a 1:75.000mapof1903,whileinmorerecentmaps(e.g1:25.000mapof1973)thecirqueisindicated withoutaglacier.Thematerialcomposingthisrockglacierisprobablyofdifferentorigin,butglacial till seems prevailing. Therefore, this landform is developing from glacial deposits and thus can be defined,accordingtothedefinitionofBarsch(1996),asadebrisrockglacier.

143 PermaNET–CasestudiesintheEuropeanAlps

SeveralspringsemergeatthebaseofthefrontalslopeofMaRG.Besidetheotherinvestigations,in 2004westartedtomeasurethetemperatureofthewater,inordertogetadditionalinformationon thepresenceofafrozencorewithintherockglacier.Thewatertemperaturewasmeasuredseveral times during summer using a handͲheld thermometer and continuously from early August to late September2004usingdataloggers(HoboH8Temp,accuracy:±0,4°C).   2. Permafrostindicatorsandrecentthermalandgeomorhicevolution The water temperature that was monitored continuously in late summer 2004 showed very cold values (below 1°C). Therefore, this data support the presence of permafrost in the rock glacier (Fig.3). 

 Fig.3–Watertemperatureofaspring(SLC7)emergingfromAmRGcontinuouslymeasuredbetweenAugust andSeptember2004.ThelocationofthespringisindicatedinFig.4.  The total displacement (2001Ͳ2009) of AmRG ranges between 0.05m (boulder 9) and 1.60m (boulder15),correspondingtoavelocityof0.01and0.20m/year,respectively(Fig.4andTab.1). Thefrontalareaofthisrockglaciershowsaverydifferentbehaviour,withanactivesector(boulders 1to6)closetoasectorthatcanberegardedasdynamicallyinactive(boulders7to11).Similarly,the rightsideoftherockglacier(boulders12to20)ismoreactivethanthemiddleandtheleftsectors (boulders21to25).Thesurveyedboulderslocatedonthelongitudinalridgemovetowardthecentre ofthelandform,whereawidehollowispresent. ThemeandisplacementofAmRGinallintervalofmeasurementsisshowninFigure8(topgraph), where all the surveyed points have been taken into account. The average velocity is significantly variablefromyeartoyear,rangingfromaminimumof0,06m/year(2007Ͳ2008)toamaximumof 0,13m/year(2006Ͳ2007).Aslowingtrendseemstoemergeinthelasttwoyearsofmeasurements. ThenearͲsurfacetemperatureofthegroundrecordedonAmRGfromAugust2004toAugust2009is showninFig.5(bottomgraph).Inthisgraph,thegroundtemperature(dailymean)isassociatedto theairtemperature(centralgraph)andtothethicknessofthesnowcover(topgraph).

 144 PermafrostResponsetoClimateChange

 Table1–HorizontaldisplacementofAmRG.Thefirstsixcolumnsshowthedisplacementforeachperiodof measurements, the column seven the total displacement, and the column eight the displacement rate. (*) Measurementperiodoftwoyears.

Boulder Horizontaldisplacement(m) 2001Ͳ09 2001Ͳ09 ID total horizontal horizontal displacement 2001Ͳ02 2002Ͳ04(*) 2004Ͳ06(*) 2006Ͳ07 2007Ͳ08 2008Ͳ09 displacement rate (m) (m/yr) 01 0.13 40.42 17.83 0.17 0.09 0.10 1.08 0.13 02 0.13 39.59 9.61 0.12 0.08 0.10 0.93 0.12 03 0.15 39.05 13.58 0.14 0.06 0.09 0.97 0.12 04 0.12 34.71 12.50 0.12 0.08 0.06 0.85 0.11 05 0.06 19.33 6.74 0.08 0.06 0.11 0.57 0.07 06 0.05 9.10 3.70 0.07 0.02 0.01 0.28 0.03 07 0.02 10.55 0.00 0.09 0.01 0.00 0.16 0.02 08 0.04 6.08 0.00 0.06 0.00 0.01 0.13 0.02 09 0.04 3.23 0.00 0.07 0.00 0.01 0.05 0.01 10 0.04 14.80 0.87 0.06 0.00 0.06 0.32 0.04 11 0.02 0.00 5.90 0.08 0.00 0.00 0.08 0.01 12 0.07 25.56 10.75 0.13 0.04 0.10 0.71 0.09 13 0.13 36.30 25.13 0.21 0.11 0.17 1.23 0.15 14 0.11 36.44 23.37 0.22 0.13 0.25 1.30 0.16 15 0.16 39.15 39.09 0.36 0.19 0.10 1.60 0.20 16 0.04 15.26 6.88 0.13 0.02 0.00 0.39 0.05 17 0.07 24.13 17.22 0.21 0.05 0.02 0.76 0.10 18 0.04 18.79 5.97 0.16 0.02 0.04 0.51 0.06 19 0.15 32.93 31.83 0.34 0.18 0.00 1.31 0.16 20 0.07 24.89 10.23 0.07 0.05 0.14 0.69 0.09 21 0.08 19.96 8.94 0.13 0.05 0.03 0.58 0.07 22 0.04 12.59 4.91 0.05 0.02 0.07 0.36 0.04 23 0.06 23.01 5.15 0.06 0.05 0.07 0.53 0.07 24 0.04 15.25 0.03 0.10 0.04 0.00 0.29 0.04 25 0.04 13.15 0.00 0.09 0.03 0.00 0.28 0.03  Focusingonthewintersthecoldesttemperatureswererecordedinthe2004Ͳ2005and2005Ͳ2006 seasons.Duringbothwinters,thegroundreachedtemperaturesbelowͲ10°C.Thestrongcoolingof thegroundmaybeduetothecombinedeffectofcoldairtemperatureandrelativelythinsnowpack inautumnandearlywinter.Inthe twofollowingwinters(2006Ͳ2007and2007Ͳ2008),theground temperaturewaswarmer,withamarkedphaseofWEqT(WinterEquilibriumTemperature)ofabout Ͳ5°C. The winter 2006Ͳ2007 was very mild and the snowpack was relatively thin until mid winter, whilethefollowingwinter(2007Ͳ2008)wascolderandsnowier. Thehighestwintertemperatureswererecordedduringthe2008Ͳ2009seasonandreachedaWEqT phaseofaboutͲ3°C.Thiswasmainlyduetothepresenceofaverythicksnowcover,whichappeared earlyinautumnandfurtherincreasedinthefollowingwintermonths.Thesnow,withitsthermal insulatingeffect,preventedthecoolingofthegroundalreadyinthefirstpartofthewinter,whilethe air temperature was not particularly mild compared to the preceding winters. This underlines the strongcontrolofthesnowcoveronthewintertemperatureofthegroundand,consequently,onthe meanannualgroundtemperature.

145 PermaNET–CasestudiesintheEuropeanAlps

 Fig.4–Totalhorizontaldisplacement(2001Ͳ2009)ofAmRG.ThelocationofthespringmentionedinFig.3is indicated.

 Fig.5–Topandmiddlegraphs:snowthicknessandairtemperatureatCapannaPresenaautomaticweather station;bottomgraph:groundnearͲsurfacetemperaturefromAugust2004toAugust2009forAmRG.Thelack ofdatainthefirsthalfof2006wasduetoadataloggerfailure.Forlocationoftemperaturedataloggersee Fig.4.

 146 PermafrostResponsetoClimateChange



 Fig.6–Annualgroundfreezingindex(GFI)atAmRGfrom2004to2009.Nodatawereavailableforthe2005Ͳ 2006period. 

 Fig.7–EvolutionofthemeanannualairtemperatureatCimaPresenaautomaticweatherstation(topgraph) andofthenearͲsurfacegroundtemperatureatAmRG(bottomgraph).Allthetemperaturesaredisplayedas 12Ͳmonths running means, and the date on the xͲaxis corresponds to the end of the period used for the calculation.  ThecoolingofthegroundduringthewinterseasonisalsohighlightedbytheGroundFreezingIndex (GFI),calculatedasthecumulativevalueofthenegativedailymeangroundtemperaturesbetween 1stOctoberand30thJune(Fig.6).Thecoldestwinter(Ͳ1020°Cͼday)wasrecordedin2004Ͳ2005dueto acombinationofverycoldairtemperatureandrelativelythinsnowcover.Theindexwasalsovery

147 PermaNET–CasestudiesintheEuropeanAlps low in the winter 2007Ͳ2008 (Ͳ972°Cͼday), as a result of the strong cooling of the ground at the beginningofthewinterduetocoldairtemperatureduringautumnandearlywinter.AveryhighGFI value (Ͳ360°Cͼday) was recorded in 2008Ͳ2009, mainly due to the very thick snow cover of that winter. TheroleofthewintersnowcoveronthegroundtemperaturecanalsobeobservedinFig.7,where theevolutionofthemeanannualairtemperature(MAAT)atCimaPresenaAWSandtheevolutionof theMAGSTarecomparedonthesameperiodoftime.Thetemperaturesaredisplayedas12Ͳmonths running means, and the date on the xͲaxis corresponds to the end of the period used for the calculation.Groundtemperaturedataaremissingin2006and2007becauseofthefailureofthedata logger.Forexample,astrongwarmingofthegroundin2009(temperaturesabove1°C)andaclear separationbetweenthetemperaturetrendsofsoilandaircanbeobserved.Thisisduemoretothe effect of the thick snow cover of the previous winter than to a corresponding warming of the air temperature. Finally,inFig.8themeanannualdisplacementrateiscomparedwiththemeanannualtemperature ofthegroundandtheair.Inordertoemphasizetheroleofthewinterseasons,thevaluesofthe mean annual temperature (both for the ground and for the air) have been calculated taking into accountanannualbasisextendingfromthe15thAugustofthepreviousyeartothe14thAugustofthe followingyear.Forthisreason,anextremelywarmsummerlike2003isnotaswellperceptibleinthe datarecordasamildwinterlike2006Ͳ2007.Thegroundtemperaturedataaremissingfor2005Ͳ2006 and2006Ͳ2007. 

 Fig.8–MeandisplacementofAmRG(topgraph)comparedwiththemeanannualgroundtemperature(middle graph)andthemeanannualairtemperatureatCimaPresenaautomaticweatherstation(bottomgraph).  In 2006Ͳ2007, an increase in the displacement rate corresponds quite well with a higher air temperaturecomparedtotheprecedingyear.Inthefollowingyear,thedisplacementratedecreased considerably, in good agreement with a lower air temperature. In the last year of measurements (2008Ͳ2009),thedisplacementratewasonlyslightlyhigherandthemeanairtemperaturesomewhat lowerthanintheprecedingyear.Inthesameyear,asignificantincreaseinthegroundtemperature duetothelargeamountofsnow(seeabove)wasrecorded,butthisdoesnotseemtohaveresulted inanincreaseofthedisplacementrate. 

 148 PermafrostResponsetoClimateChange



 Fig. 9 – Potential change of frost, ice and freezeͲthaw days for 2020Ͳ2050, as proposed in chapter 2. The locationofAmRGisshown. 

149 PermaNET–CasestudiesintheEuropeanAlps

3. Possible future thermal and geomorphic response to predicted climate change FutureevolutionandgeomorphicresponseofAmRGtoclimatechangearedifficulttohypothesize. As reported in chapter 2, not only changes in the temperature for the end of the 21st century (a warmingof4.2°Cinthealpineareasabove1800ma.s.l.),butalsosignificantchangesinthenumber offrost,iceandfreezeͲthawdaysfortheperiod2021Ͳ2050canbeexpected.Accordingtothis,inthe areawhereAmRGislocated,weexpectadecreaseinthefrostdaysof15/16days/year,adecreasein theicedaysof15/19days/yearandaslightincreaseinthefreezeͲthawdaysof0/4days/year(Fig.9). As highlighted above, the dynamic response of AmRG seems to be related to the changes in the amountandevolutionofthesnowduringwinter,duetoitseffectonthegroundtemperature.Thus alsothefuturechangesintheamountanddistributionofprecipitations,especiallyassnow,should betakenintoaccountinassessingtheresponseofthislandformtofutureclimatechange.  Acknowledgements. – Mauro Degasperi and Franco Crippa (Geological Survey, Autonomous ProvinceofTrento)conductedthetopographicsurveysandprocessedtheroughtopographicdata. FieldcollaborationwasprovidedbyLucaCarturan,StefanoFontanaandAndreaPaoli.Thisworkwas partlyfundedbythePRIN2008project“ClimateChangeeffectsonglaciers,onglacierͲderivedwater resourceandonpermafrost.QuantificationoftheongoingvariationsintheItalianAlps”.

 References:  BaroniC.,CartonA.&SeppiR.,2004:DistributionandbehaviourofrockglaciersintheAdamelloͲPresanella Massif(ItalianAlps).PermafrostandPeriglacialProcesses,15,243Ͳ259. Barsch D., 1996: Rockglaciers: Indicators for the Present and Former geoecology in High Mountain Environments.Springer,Berlin,331pp. Bodin X., Thibert E., Fabre D. Ribolini A., Schoeneich P, Francou B., Louis Reynaud L. & Fort M., 2009: Two DecadesofResponses(1986–2006)toClimatebytheLaurichardRockGlacier,FrenchAlps.Permafrost andPeriglacialProcesses,20,331Ͳ344. Delaloye R., Perruchoud E., Avian M., Kaufmann V., Bodin X., Ikeda A., Hausmann H., Kääb A., KellererͲ Pirklbauer A., Krainer K., Lambiel C., Mihajlovic D., Staub B., Roer I. & Thibert E., 2008: Recent interannualvariationsofrockglacierscreepintheEuropeanAlps.Proceedingsofthe9thInternational ConferenceonPermafrost(NICOP),UniversityofAlaska,Fairbanks,June29–July3,2008,343Ͳ348. Haeberli W., Hallet B., Arenson L., Elconin R., Humlum O., Kaab A., Kaufmann V., Ladanyi B., Matsuoka N., SpringmanS.&VonderMühllD.,2006:Permafrostcreepandrockglacierdynamics.Permafrostand PeriglacialProcesses,17,189Ͳ214. Hoelzle M., Wegmann M. & Krummenacher B., 1999: Miniature temperature dataloggers for mapping and monitoringofpermafrostinhighmountainareas:firstexperiencefromtheSwissAlps.Permafrostand PeriglacialProcesses,10,113Ͳ124. KääbA.,FrauenfelderR.&RoerI.,2007:Ontheresponseofrockglaciercreeptosurfacetemperatureincrease. GlobalandPlanetaryChange,56,172Ͳ187. IkedaA.,MatsuokaN.&KääbA.,2008:Fastdeformationofperenniallyfrozendebrisinawarmrockglacierin theSwissAlps:Aneffectofliquidwater.JournalofGeophysicalResearch113,F01021. PERMOS, 2009: Permafrost in Switzerland 2004/2005 and 2005/2006. Noetzli, J., Naegeli, B., and Vonder Muehll,D.(eds.),GlaciologicalReportPermafrostNo.6/7oftheCryosphericCommissionoftheSwiss AcademyofSciences,100pp. Roer I., Kääb A. & Dikau R., 2005: Rockglacier acceleration in the Turtmann valley (Swiss Alps) – probable controls.NorwegianJournalofGeography,59,157Ͳ163.



 150 PermafrostResponsetoClimateChange

 3. CasestudiesintheEuropeanAlps   3.13 PizBoèrockglacier,Dolomites,EasternItalianAlps 

 Citationreference A. Crepaz A., Cagnati A., Galuppo A., Carollo F., Marinoni F., Magnabosco L., Defendi V. (2011). Chapter 3.13: Case studies in the European Alps – Piz Boè rock glacier, Dolomites, Eastern Italian Alps.InKellererͲPirklbauerA.etal.(eds):Thermalandgeomorphicpermafrostresponsetopresent andfutureclimatechangeintheEuropeanAlps.PermaNETproject,finalreportofAction5.3.OnͲline publicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.151Ͳ158.  Authors Coordination:AndreaCrepaz Involvedprojectpartnersandcontributors: Ͳ RegionalAgencyfortheEnvironmentalProtectionofVeneto,Italy(ARPAV)–AndreaCrepaz, AnselmoCagnati Ͳ Regione Veneto, Direzione Geologia e Georisorse, Servizio Geologico (GeoVE) – Anna Galuppo,LauraMagnabosco,ValentinaDefendi Ͳ E.P.C.EuropeanProjectConsultingS.r.l.–FedericoCarollo Ͳ Freelancer–FrancescoMarinoni  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References 

151 PermaNET–CasestudiesintheEuropeanAlps

Summary  Recently,ARPAVincollaborationwithGeoVEstartedtomonitortheperiglacialenvironmentof PizBoè(46.51°N,11.83°E),inVenetoregion,atanaltitudeof2900ma.s.l.Inthepast,some preliminarygeoelectricalandgeoseismicsurveyswerecarriedoutontherockglacier,butonlyin the framework of the PermaNET project the characteristics of the permafrost are extensively studied.ContinuousGST(Groundsurfacetemperature)measurementswerecarriedoutinthe winter 2009/2010; a 30m deep borehole was drilled in Dolomite bedrock and an automatic weatherstationwasinstalledinsummer2010.Laterweplannedtocarryoutasecondelectrical resistivitytomography(ERT)campaign(firstonein2005)ontherockglacier.Inthisreportwe presentthefirstresultsonthecomparisonofERTmeasurementscarriedoutin2005and2010. Thedatacomparisondoesnotshowsignificantchangesinthestructureoftheicecoveredwith debrisduringthelastfiveyears.Inparticular,itseemsthatthecoveredicedidneithermodifyits consistencenoritsextent.Duetotheshortmonitoringtimeandthelackofotherexperimental dataonthePizBoèsite,itisverydifficulttoexplainitsfuturebehaviour.ARPAVmanagesalsoa broad weather station network on Veneto mountain region, so the highest station data (Ra Vales)wasusedtomakesomeanalysisofthelastyears.Forthenextcenturyclimatemodels estimate a dramatic increase of air temperature. This condition will directly influence the thickness,theextensionandthedisplacementoftherockglacieratPizBoè.

 152 PermafrostResponsetoClimateChange

1. Introductionandstudyarea The Piz Boè site is located in the NorthͲEast of Italy (46.51°N, 11.83°E; Fig. 1), on the border of Veneto region, at 2900m a.s.l. on the Sella Group, near Piz Boè peak (Fig 2). The Sella Group represents one of the most important massifs of the Dolomites. Its base is constituted by the “DolomiadelloSciliar”Formation(LadinianͲLowerCarnian).ThethicknessofthisnonͲstratifiedcoral reefvariesfrom300to600m.Thetopofthemassifismadeupby“DolomiaPrincipale”(Norian). Thegeologicalboundarybetweenthetwoabovementionedformationsisveryclearandmarkedby layersofmarlsandclaysofthe“RaiblFormation” (Carnian).Thewhite/cleargreyDolomiaPrincipale Formationiswellstratifiedanditsthicknessreachesitsmaximum(300Ͳ350m)atPizBoè,whereitis covered by the most recent “Calcari di Dachstein” (Lias), nodular limestones of the “Rosso Ammonitico”Formation(Jurassic)and“MarnedelPuez”Formation(LowerCretaceous). 

 Fig.1–GeographicalsettingofVenetoregionandPizBoèintheDolomites,EasternItalianAlps  AtNorthͲEastofthepeakPizBoètherewasaglacier,listedin1980’scampaignsurveywithabouta surface of 0.04km2. Nowadays the glaciated area is very limited (about 0.014km2), but a debris coveredglacier(insomemapsitisconsideredarockglacier)hasbeenformedbelowtheglacier.At the bottom of the debris there is a small shallow lake (Lech Dlacé, Fig. 3), which is completely coveredbysnowandiceithemostpartoftheyearover(NovembertoJune). 

153 PermaNET–CasestudiesintheEuropeanAlps

 Fig.2–SellaGroupandPizBoè(3151ma.s.l.)fromEast(Livinallongo).Locationofthestudysiteisindicated withanarrow.PhotographbyBrunoRenon(ARPAV)(30.07.2008). 

Boreholeand weatherstation Dataloggers 2005/2010

2010WͲE

Spring

 Fig.3–ViewtowardsSouthͲWestofthelakeLechDlacéandtherockglacierofPizBoèwiththelocationofthe borehole and the weather station, dataloggers, ERT profiles and the spring. Elevation of the lake is 2833m a.s.l.,elevationofthepeakinthebackground(PizBoè)is3151ma.s.l.NotethewidespreadappearanceoflateͲ lyingsnowpatches.PhotographbyBrunoRenon(ARPAV)(30.07.2008). 

 154 PermafrostResponsetoClimateChange

2. Permafrostindicatorsandrecentthermalevolution 2.1Methods InJuly2010aboreholewasdrilledintothebedrockdowntoadepthof30mandathermistorchain of16sensors(at0.02,0.3,0.6,1.0,1.5,2.0,3.0,3.5,4.5,5.5,10.0,15.0,20.0,25.0,30.0mfromthe surface)wasplacedtomeasurethegroundtemperatures.InSeptember2010aweatherstationwas installedatthelocationindicatedinfig.3;itmeasuesairtemperature,relativehumidity,snowpack height,winddirectionandvelocity,incomingandoutcoming(shortwaveandlongwave)radiation. DuringSummer2010watersampleswerecollectedfromthespringcomingoutfromtherockglacier andfromtheLechDlacéwithatemporalresolutionofabout15days,inordertoevaluatechemical compositionanditsrelativeseasonalchanges;watertemperaturesweremeasuredaswell. SinceOctober2009twodataloggers(HoboProV2U23Ͳ001,OnsetComputerCorp.),loggingevery30 minutes, have been placed near Piz Boè rock glacier in order to measure the ground surface temperature.Thefirstonewasputontherockglacierfrontandthesecondoneoutsideoftherock glacier,belowthefront,wheretheweatherstationwasplannedtobeinstalledinSeptember2010 (see Fig. 3 for location). They were recovered in the melting season in July 2010. At the end of October,onedataloggerwasreplacedinthesameprevioussite,afewcentimetersbelowthesurface oftherockglacier,whiletheotherone,outsideoftherockglacier,wasmovedabout30mtowards SouthͲEast. Duringthesummer2005adetailedtopographicsurveywascarriedoutandinthesummer2010a LaserScannersurveywasperformedbyIRPICNR. The study area was furthermore investigated on 01.09.2010 by performing an electrical resistivity profile(ERT)of124m,usingthedeviceelectrodeWennerͲSchlumbergerwithadistancebetween the electrodes equal to 4m and maximum depth of exploration of 25m. The inversion of geoelectricaltomographicdatawasperformedusingthemethodproposedbyLaBrequeetal.(1996), using a finite element algorithm based on the concept of reverse OCAM'S (Oldenburg, 1994) and implementedinsoftwarePROFILER(Binely,2003).Theconfigurationwascomparabletotheoneof theERTcampaignon04.08.2005,thelengthofwhichwas141m.  2.2Resultsoncurrentpermafrostexistence Fig.4showsthemeasuredtemperaturesduringtheperiod09.10.2009and02.07.2010alsodepicting somesignificantevents.On22ndOctoberthefirstsnowfalloccurred(about5Ͳ10cmoffreshsnow), meltingthefollowingdays.ThenextsignificantsnowfalloccurredatthebeginningofNovemberwith about50Ͳ60cmoffreshsnow;thispartofsnowpackremainedallthewinter,eventhoughatthe endofNovembertheairtemperatureincreasedwithfreezinglevelatabout3200Ͳ3500m.Duringall thewinter,groundsurfacetemperaturesremainedataboutͲ4toͲ2°C.InFebruary,Marchandpart ofAprilGSTwasaboutͲ4°Cinbothsites(winterequilibriumtemperature–WeqT).Attheendof April on the rock glacier zero curtain was reached, while on the monitoring site temperatures remainedbelow0°C,excepton29thAprilwhentemperaturesincreasedupto0°C.On17thMay2010 asnowpitwasdugonthemonitoringsiteandabottomtemperatureofsnowcover(BTS)ofͲ1.5°C wasmeasured(dataloggervalueswerearoundͲ1.7°C).Zerocurtainonthebedrockstartedon11th June, while on the rock glacier snow was already completely melted; at the beginning of July the dataloggeronthebedrockwasburiedinameltingicelayer. Thesetemperatureresultsindicatethepossiblepresenceofpermafrostonthebedrockandonthe debris, where in 2005 ERT measurements were performed, as well. In summer 2010, the ERT measurementswererepeatedalongthesamesectionandtheinvestigationwasextendedtoanew orthogonalWͲEorientedtransect,alongthemaximumslopegradient.Inthisworkwecomparethe profilescarriedoutin2005and2010alongthesamesection.

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12.0

10.0 22/10 5/10 cm Fresh snow Bedrock 8.0 Rock glacier 02-03/11 Snow Height 50/60 cm 6.0 17.05 Snow pit (Snow Height 240 cm) 4.0

2.0 GST (°C)GST

0.0

-2.0

-4.0 Zero curtain on the bedrock -6.0 09/10/2009 24/10/2009 08/11/2009 23/11/2009 08/12/2009 23/12/2009 07/01/2010 22/01/2010 06/02/2010 21/02/2010 08/03/2010 23/03/2010 07/04/2010 22/04/2010 07/05/2010 22/05/2010 06/06/2010 21/06/2010 Date  Fig.4–Evolutionofthegroundsurfacetemperaturebetween09.10.2009and02.07.2010.InredGSTfromthe rockglacier,inbluefromthesiteoftheplannedborehole.  The twoͲdimensional model obtained by inversion of apparent resistivity data (Fig. 5) returns the actualdistributionofvaluesofresistivityinthesubsurface;itishighlightedbothbyisolinesandby colour scale. The first contour has been traced to a value of 5*104ɏ*m. The second isoline is 1*105ɏ*m, while the subsequent ones are placed at intervals of 2*105ɏ*m up to the value of 1*106ɏ*m;forhigherresistivitythespacingbetweentheisoresistivelinesishigher. Highest resistivity values (above 1.5*106ɏ*m) might be related to massive ice; values between 1*105ɏ*m and 1.5*106ɏ*m should correspond to ice mixed with boulders, while lower values (5*104ɏ*m<ʌ<1*105ɏ*m)mightdetecttheactivelayer. Comparingthetwoprofileswecanmakethefollowingobservations.Thegeometryofthebodyat veryhighresistivityissimilarinthetwosections.At2940maltitudea.s.l.,thewidthoftheanomaly resistive(ʌ>1.5x106ɏ*m)isapproximatelyequalto99m.Thesurfacemateriallayer(about2mof boulders mixed to fine grained debris) shows more or less the same thickness in both profiles (ʌ<5*104). Thethicknessoftherockglacierismoreorlessthesame,greaterthan23minbothcases.Inboth profiles the maximum depth of investigation was not sufficient to achieve resistence values attributabletothebedrock.Theanalysisofthetwosectionsalsoshowsthelimiteddifferencesinthe pattern of deeper sections; in the section of the 2005 isoresistive lines remain open on values ranging from 1.5 to 5*106ɏ*m, while in the section of 2010 they reach values close to 2*106ɏ*m.Thesedifferencesarenotsignificantbecausetheslightdiscrepancyinthepositioningof twoprofilesonthegroundandhighdifferenceofresistivityonsurfacelayer,whichmayaffect,in part,theresultsofthereverseprocesses. The section of 2005 showed a difference in the resistive body, with two anomalies at very high resistivity(ʌ>4x106ɏ*m),separatedbyastripwithslightlylowerresistivity(ʌ=1.5x106ɏ*m).The

 156 PermafrostResponsetoClimateChange sectionof2010showsthesetwoanomalies,too,buttheirseparationismoreweakened.Alsothis differencecanbeexplainedinpartwiththeconsiderationslistedabove. Wecanconcludethatthesetwoprofilesareverysimilarandthattheslightdifferencesaremainly attributabletothemethoduncertainty.   (m)  Altitude 2005

Distance(m) (m)  Altitude

2010

Distance(m) Resistivity(ohm*m)

 Fig.5–Resultsoftheelectricaltomography(ERT)campaignson04.08.2005and01.09.2010.   3. Possiblefuturethermalresponsetopredictedclimatechange ThePizBoèrockglacierismonitoredsince2005.From2005to2010noairtemperaturesdataare available because the weather station was not installed before September 2010. However, time series of both air temperature (until 2009) and snow height is available for Ra Vales station, at 2615ma.s.l.,about19kmtotheEastͲNorthͲEastofPizBoè. Takingintoaccountthelasttenyears(Table1);thefirstperiod(2000Ͳ2005)seemstobecolderthan thelastone(2005Ͳ2010).MAATwassignificantloweralltheyears,whileitincreasedinthelastfive years, when values were above 0°C in 2006, 2007 and 2008. The number of frost and ice days decreased in the last years. Snow cover duration is similar during these two periods. A little differencecanbeobservedinJune;inthelastthreeyearssnowcoverdurationwaslongerinthe earlysummer,whilein2000Ͳ2005someyearswerecharacterizedbyatotalabsenceofsnowcover. Winter snow height was not so high in 2005Ͳ2008, while in the last two years snow amount was higher.

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 Table1–DifferenttemperaturederivedparametersfromthemeteorologicalstationRaVales(2615ma.s.l.) 19km to the EastͲNorthͲEast of Biz Poè (DSC=days with snow cover; MAAT=mean annual air temperature; JJA=JuneͲJulyͲAugust).

RaVales 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Frostdays 221 239 238 225 233 229 218 202 215 211 247 Icedays 141 140 131 137 134 133 110 104 120 138 157 Freeze/Thawdays 80 99 107 88 99 96 108 98 95 73 90 DaysofSnowcover 173 255 265 240 166 248 207 231 247 235 266 JuneDSC 0 30 17 0 30 1 12 6 22 20 23 MAATͲ0.38Ͳ0.89Ͳ0.30Ͳ0.14Ͳ0.97Ͳ1.46 0.10 0.94 0.51Ͳ0.06Ͳ2.13 JJAMeanAirTemp 6.10 6.28 6.55 9.08 5.95 5.66 5.99 6.94 7.26 7.23 6.36  Summermeantemperature(JJA)seemstoincreaseduringthelasttenyearswithapeakin2003;this veryhotsummercertainlyinfluencedthemeltingoftheseasonalsnowpackandoftheiceaswell. Thelastyear(2010)wasthecoldestoneofthelasteleven,withaverylongsnowcoverduration;this mighthavesignificantlyinfluencedERTprofileofthe2010.Thismeteorologicalbehaviouralloweda quasiͲsteadysituationforthedebriscoveredglacierofPizBoèinthelastfiveyears. Climate models show a dramatic air temperatures increase for the next century (see chapter 2), especially at high altitudes, and this will certainly influence covered ice. In the next decades, accordingtoSRESA1B,frostandicedayswilldecreasebyabout14Ͳ15days.Coveredicewilllikely meltquicklyduringthenextdecadesandthedisplacementoficewillincrease.Themoreimportant factors that will determine the velocity of melting and displacement, will be the summer temperaturesandsnowcoverdurationintheearlysummer.DuringthenextyearsARPAVisgoingto investigatethefutureevolutionofpermafrostatPizBoè.  Acknowledgements.–TheauthorsthankAbuZeidNasserforhisworkduringfieldcampaign.  References: BinelyA.,2003:2Dinversionofapparentresistivitydatausing“Profiler”.InstituteofEnvironmental andNaturalSciences,LancasterUniversity,LANCASTER,UK.6pp. LaBreque D.J., Miletto M., Daily W., Ramirez A., Owen E., 1996: The effects of noise on Occam’s inversionofresistivitytomographydata.Geophysics,61,538Ͳ548. OldenburgD.,L.Y.,1994:Inversionofinducedpolarizationdata.Geophysics,59,9:1327. 

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 3. CasestudiesintheEuropeanAlps   3.14 UpperSuldenValley,OrtlerMountains,ItalianAlps   

  Citationreference ZischgA., MairV.(2011).Chapter3.14:CasestudiesintheEuropeanAlps–UpperSuldenValley, Ortler Mountains, Italian Alps. In KellererͲPirklbauer A. et al. (eds): Thermal and geomorphic permafrostresponsetopresentandfutureclimatechangeintheEuropeanAlps.PermaNETproject, finalreportofAction5.3.OnͲlinepublicationISBN978Ͳ2Ͳ903095Ͳ58Ͳ1,p.159Ͳ169.  Authors Coordination:AndreasZischg Involvedprojectpartnersandcontributors: Ͳ AbenisAlpinexpertGmbH/srl–AndreasZischg Ͳ Automous Province of Bolzano Ͳ South Tyrol, Office for Geology and Building Materials Testing(GeoLAB)–VolkmarMair  Content Summary 1. Introductionandstudyarea 2. Permafrostindicatorsandrecentthermalandgeomorphicevolution 3. Possiblefuturethermalresponsetopredictedclimatechange References

159 PermaNET–CasestudiesintheEuropeanAlps

Summary  ThecasestudyfromtheUpperSuldenValley(46°29’37.87’’N,10°36’57.31’’E),OrtlerMountains, ItalianAlps,showedthegeomorphicresponseofflatorgentlyinclinedareascoveredbydebrisin a highͲmountain ski resort outside of rock glaciers. The subsidence of the surface due to the melting of the ground ice lies in a dimension of 4m in 11 years (1996Ͳ2006). The measured surfacesubsidenceisaccompaniedwithgeomorphicsignssuchasthermokarstphenomenaor withincreasingsurfacetemperatures. Insteeperareas,geomorphicsignsofslopemovements arefoundinareaswithprobablepresenceofpermafrost.Thesubsidenceofsurfaceisrelevant forskiinfrastructuresandmustbehandledwithsometechnicaleffort.Inthevicinityofthepillar no.12oftheskiliftMadritschjoch,mostprobablythegroundicehasmeltedtotally.Therefore, thesubsidenceprocessofthesurfacenearthepillarisfinished.However,thiscanbeconcluded onlyforthisspecificlocationinthestudyarea.Inotherareaswheregroundiceisstillpresent, thedegradationprocesswillcontinuewiththeexpectedincreaseoftemperatures.

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1. Introductionandstudyarea Thestudyareaissituatedintheskiresort"SuldenͲMadritsch"intheUpperSuldenValley,community of Stilfs/Stelvio, Autonomous Province of Bozen/Bolzano (46°29’37.87’’N, 10°36’57.31’’E,Figs. 1, 2 and3).ThestudyareaissituatedintheOrtlermountainrangeneartheStilfserjochpass.Theextent ofthestudyareaisabout5km2.Theareaismostlyfreeofvegetationandispartiallycoveredby debris. One small rock glacier is situated in the study area. During the period between 1805 and 1850,partsoftheareawerecoveredbyasmallglacier. Intheearly1990s,ateamoftheUniversityofMunichbeganitsfirstpermafrostinvestigationsinthis area(Stötter1994).In1992firstmeasurementsofthetemperaturesatthebottomofthesnowcover (BTS), topographic surveys and geophysical measurements (seismics) for mapping the permafrost distribution had been made. Since 2004, the BTS measurements have been repeated in the years 2004,2006,2007,2008and2009.BTSmeasurementswerecarriedoutatmorethan1100pointsin thestudyarea.Since2006,devicesformeasuringthegroundsurfacetemperatures(UTLdataloggers) wereinstalledon10locationsinthestudyarea. 

 Fig.1–LocationofthestudyareaUpperSuldenValley. 

 Fig. 2 – Overview of the study area Upper Sulden Valley. Photograph taken from the upper station of the "Madritschjoch"skiliftlocatedat3150ma.s.l.PhotographbyA.Zischg(09.03.2007).Thestudyareaistheski resortintheforegroundofthepicture.

161 PermaNET–CasestudiesintheEuropeanAlps

 Fig.3–OverviewofthestudyareaUpperSuldenValley.Theblacklinesindicatethelocationofthechairsliftsof theMadritschskiresort.Orthoimage2008.

 Fig.4.–OverviewofthestudyareaUpperSuldenValley.HillshadeoftheairͲborneLidarͲDEM2006.Thered circleshowsthelocationofthepillarno.12oftheskilift"Madritschjoch"mentionedinthetext.Thegreendots showthelocationoftheGSTmeasurementdevices(UTLdataloggers).

 162 PermafrostResponsetoClimateChange

 2. Permafrostindicatorsandrecentthermalandgeomorphicevolution Themeasurementsofthetemperaturesatthebottomofthesnowcoverin1992and1996showed the main areas with probable presence of permafrost. Geophysical measurements (seismic refraction)andtheconstructionoftheskiliftsprovedtheexistenceofcompacticelensesinthearea aroundthepillarno.12oftheskilift“Madritschjoch”.InAugust1992,massiveicewasfoundduring thefoundationofthispillar(Fig.5). 

 Fig.5–Excavationworksforthefoundationofthepillarno.12oftheskilift"Madritschjoch"inAugust1992. PhotographbyM.Maukisch.Source:Stötteretal.(2003).Groundicewasobservedintheconstructionsiteand underthemoraineattheleftoftheconstructionsite.  Thefirstmeasurementsofthetemperaturesatthebottomofthesnowcover(BTS)intheareawere carriedoutin1992and1996bymeansofmobiledevicesinthemonthsFebruaryandMarch.Since 2004,themeasurementshavebeenrepeated.Duringthewinterhalfyearsbetween2004and2008 themeasurementshavebeenrepeatedonlyinthepartswhereasnowdepthofatminimum60cm wasexistent(Figs.6and7,Table1).  Table1–SummaryofthefiveBTSͲmeasurementcampaignsinthestudyareaUpperSuldenValley.

Measurement NumberofBTSͲ Probable Possible Year Nopermafrost(n) date/period measurements permafrost(n) permafrost(n)

1992 March1992 371 227 58 34 1996 March1996 184 157 19 8 24.02.,03.03., 2004 70 27 9 34 16.03.,07.04. 2006 25.04. 51 4 6 38 09.03.,27.03., 2007 249 133 51 65 29.03. 2008 06.03.,07.03. 236 73 37 89 Allyears1161 621 180 268

163 PermaNET–CasestudiesintheEuropeanAlps





 Fig.6–ResultsoftheassessmentofpermafrostexistenceusingBTSmeasurementsin1992,1996and2004.

 164 PermafrostResponsetoClimateChange

Fig.6–ResultsoftheassessmentofpermafrostexistenceusingBTSmeasurementsin2007,2008andallyears.

165 PermaNET–CasestudiesintheEuropeanAlps

 Since 2006, the ground surface temperatures (GST) have been monitored continuously by 10 miniature temperature dataloggers situated in different parts of the study area (UTL datalogger, logginginterval1hour,forlocationsseeFig.4). ThecomparisonoftheBTSmeasurementsofthedifferentyearsshowedanincreaseoftemperatures at the bottom of the snow cover in the area near the mentioned pillar no. 12 of the ski lift “Madritschjoch”. The GST measurements in this area showed a high interannual variability. Despite this fact the followingpatternscouldbefound:TheupperpartoftheslopeoftheHintereSchöntaufpeakshows constantlynegative temperatures(ca.Ͳ6°C)overallobservedperiods.Thelowestparts ofthehill betweenthebottomandtheupperstationoftheskilift“Madritschjoch”showedanincreaseofthe temperaturesovertheyears. In the years before the construction of the ski lift, topographic surveys had been made. These measurementshavebeenrepeatedregularlysincetheconstructionoftheskilift.Inthistimeperiod between1992and2004,thesurfaceoftheareasinthealignmentoftheskilift“Madritschjoch”that are covered by debris were supposed to subsidence processes. In the vicinity of pillar no. 12, the surfacesaggedfor4m(topographicsurveysbytheskiresortoperator).Thissubsidenceofsurface wasduetothemeltingofgroundice.Inthevicinityofpillarno.12geomorphologicevidencesfor surfacesubsidencehavebeenobserved(Fig.7). 

 Fig.7–Photographofsubsidenceprocessesinthevicinityofpillarno.12oftheskilift"Madritschjoch"inJuly 2006.PhotographbyA.Zischg.  The foundation of the pillar moved sideward and disarranged the position of the pillar no. 12. Therefore,thepillarhadtobeadjustedseveraltimessince1992untilthefoundationofthepillarwas reͲconstructed by means of a deeper foundation reaching the bedrock under the debris cover (Fig.8). 

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 Fig. 8 – Photograph of the reͲadjustment of the position of the pillar no. 12 of the ski lift "Madritschjoch". PhotographbyA.Zischg.  Duringtheconstructionoftheskilift,theridgeofdebrismaterialalongsidetheskilift(Fig.9)had beengrabbedslightlywithanexcavator.In1996,theridgeshowedanoutcropofmassiveiceonits lateralpartexposedtowardstheskilift.Theslope wasnearlyvertical. Inthemeantime theridge slumpeddown.Theslopeexposedtowardsthealignmentoftheskiliftisrecontouredandflattened. Theoutcropoficedisappeared.  

 Fig.9–Photographofthedebrisridgealongtheskilift"Madritschjoch"inJuly2006.PhotographbyA.Zischg. Theredarrowshowsthelocationwithoftheobservedslopedeformation.

167 PermaNET–CasestudiesintheEuropeanAlps

 Inthesteeperpartsoftheareascoveredwithdebris,someevidencesforslopemovementscouldbe observed(Fig.10).Theevidencesformovingdownwardsoftheslopeweremorefrequentlyinthe areasthatareshowingwarmergroundtemperaturesofthemeasurementsduringthelastyears.The geomorphicsignsforslopemovementsinthisareawereobservedforthefirsttimein2006. 

 Fig.10–PhotographofevidencesforslopemovementsintheactivelayerofthesouthͲwesternslopeofthe peakHintereSchöntaufspitzeintheskiresortSuldenͲMadritschinJuly2007.PhotographbyA.Zischg.   3. Possiblefuturethermalresponsetopredictedclimatechange Theobservationsofthesurfacesubsidencearerelevantfortheinfrastructureoftheskiresort.With sometechnicalefforts,theproblemforthestabilityofthefoundationofapillaroftheskiliftdueto thisgeomorphicphenomenonofsubsidencecouldbehandled.Thephenomenonhasacceleratedin theyearsfrom2000to2007.Inthevicinityofthepillarno.12mostprobablythegroundicehas beenmeltedtotally.Therefore,thefurthersubsidenceofthesurfacenearbyofthepillarisfinished. However,thiscanbeconcludedonlyforthisspecificlocationinthestudyarea.Inotherareaswhere groundiceisstillpresent,thedegradationprocesswillcontinuewiththeincreaseoftemperatures. AftertheanalysesprovidedinChapter2,thenumberoffrostdaysintheMadritschskiresortislikely todecreasefor15daysandthenumberoficedayswilldecreasefor17Ͳ19days.ThefreezeͲthaw days will increase about 3Ͳ4 days. This will have consequences for a further continuation of the permafrostdegradationprocess.Themonitoringofthepermafrostdegradationinthisareawillbe continued.Incaseofabeginningsubsidenceprocessinotherpartsofthestudyarea,thecourseof thiseventwillbeobserved.   

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References:  Stötter J., 1994: Veränderungen der Kryosphäre in Vergangenheit und Zukunft sowie Folgeerscheinungen – Untersuchungen in ausgewählten Hochgebirgsräumen im Vinschgau (Südtirol). Habilitationsschrift, München. Stötter J., Fuchs S., Keiler M., Zischg A., 2003: Oberes Suldental. Eine Hochgebirgsregion im Zeichen des Klimawandels. In: E. Steinicke (ed.): Geographischer Exkursionsführer Europaregion Tirol, Südtirol, Trentino. Spezialexkursionen in Südtirol. Innsbrucker Geographische Studien Band 33/3, 239Ͳ281, Innsbruck

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 4. Synthesis     

  Citationreference LiebG.K.,KellererͲPirklbauerA.(2011).Chapter4:Synthesisofcasestudies.InKellererͲPirklbauerA. etal.(eds):Thermalandgeomorphicpermafrostresponsetopresentandfutureclimatechangein the European Alps. PermaNET project, final report of Action 5.3. OnͲline publication ISBN 978Ͳ2Ͳ 903095Ͳ58Ͳ1,p.170Ͳ177.  Authors Coordination:GerhardKarlLieb Involvedprojectpartnersandcontributors: Ͳ InstituteofGeographyandRegionalScience,UniversityofGraz,Austria(IGRS)–GerhardKarl Lieb,AndreasKellererͲPirklbauer Ͳ Institut de Géographie Alpine, Université de Grenoble, France (IGAͲPACTE) – Philippe Schoeneich Ͳ EDYTEM,UniversitédeSavoie,France(EDYTEM)–PhilipDeline Ͳ Regional Agency for the Environmental Protection of the Aosta Valley, Italy (ARPA VdA) – PaoloPogliotti  Content Summary 1. Casestudies:Methodsandoverallresults 2. Thermalpermafrostreactioninthepastandfuture 3. Geomorphicpermafrostreactioninthepastandfuture References

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Summary  In the framework of Action 5.3 of the PermNET projects investigations on the thermal and permafrostresponsetoclimatechangewerecarriedoutin13testsitesdistributednearlyallover the Alps. This research work was based on a great variety of methods ranging from geomorphological mapping over monitoring of ground surface temperature to borholes thus makingtheresultswellreliable.Nearlyallhypothesisestablishedintheinitialphaseofthework could be verified and quantified in at least one of the case studies. From this the following conclusionscanbedrawn: Thermalpermafrostreactions An increase in ground temperatures and hence permafrost warming as a response to climate warmingcanalreadybeobservedandwillcontinueinthefuture.However,thereisalsoastrong controlofsnowcovertothethermal regimeofthegroundthuscomplicatingtherelationship betweenclimatewarmingandpermafrostwarmingordegradation.Air,groundandpermafrost temperaturesaswellassnowcovershouldbemonitoredatasmuchlocationsaspossible. There is already a lot of evidence of thawing of permafrost in the Alps which leads and will increasingly lead to a reduced spatial extent of permafrost and to active layer thickening. However, little is yet not known about the assumed increasing ground water circulation and pressurewhichshouldbeonefocusoffutureresearch. Inspecificaltitudinalbeltsthenumberoffreeze/thawcyclesaswellasthedurationandintensity offreezingandthawingperiodswillchangesignificantly.Thusthesubsequentprocesseslikerock fallswillshifttohigheraltitudesaffectingareaswhicharenotyetpronetotheseprocesses.From thisitisadvisabletomonitorthethermalregimeofthegroundatmanysites. Geomorphicpermafrostreactions Rockglaciersreactwithasurprisinglyshorttimelagonairandgroundtemperaturevariations.It canbeassumedthatmostrockglacierswillcreepfasterinthenextyearstodecadesandthen will become climatically inactive due to permafrost degradation. The surface velocity of rock glaciers should be monitored at least at the sites in which infrastructure is placed on rock glaciers. Thedisplacementmodeofrockglaciersalreadychangesandwillcontinuetochangesignificantly inthenextdecades.Especiallysurfaceloweringcanbeobservedatseveralsitesduetomelting ofthepermafrostice.Inthefuturecollapseoficerichrockglacierswilloccurmorefrequently thus endangering infrastructure. Damage can only be avoided if the internal structure of the permafrostusinggeophysicaltechniquesiswellknown. Volumeandextentofdestabilizedmaterialsincreaseasaresponsetoactivelayerthickeningand decreasingpermafrostextent.Thusthedispositiontogravitativeprocessesincreasesmakingthe reevaluationofexistinghazardprotectingmeasuresnecessary. Increasing frequency and magnitude of mass movement events are clearly evident. A further increaseispossible,ashiftofrockfallscarstohigherelevationsevenveryprobable.Monitoring andmodellingofthesesprocesseswillhelptoreducethehazard. The melting of ice in thawͲsensitive permafrost makes surfaces instable thus leading to subsidenceinflatareasorongentleslopesandtodifferenterosionalprocessesonsteepslopes. Theconsequenceisdamageofinfrastructureiftheinternalstructureofthe permafrostisnot known.

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1. Casestudies:Methodsandoverallresults In the 13 case studies of Action 5.3 high mountain permafrost has been investigated by a great methodologicalvariety(Tab.1)comprisingnearlyalltechniqueswhichareavailable.Thustheresults are well reliable, particularly since all the case studies also provide similar evidences from other study sites situated within and without the Alps (see the respective references). According to the thematicaspectofAction5.3groundsurfacetemperatures(GST)playacrucialroleandthushave been used in all of the case studies. GST is the key parameter in giving information on how the warming of the atmosphere is coupled with the thermal regime of the ground. GST can be easily measuredbycheapandtoughequipment(miniaturedataloggerMDL).Thereforethissimplebutin terms of its relevance for understanding thermal (and subsequently geomorphic) changes in permafrostareasveryefficientmethodcanberecommendedforevenmorewidespreadusageinthe future.  Table1–OverviewofpermafrostrelatedmethodsusedinmorethanoneofthecasestudiesofAction 5.3 (Abbreviations: BTS = Basic temperature of winter snow cover, ERT = electrical resistivity tomography,GPR=groundpenetratingradar,GST=groundsurfacetemperature,MDL=miniature datalogger,TLS=terrestriallaserscanning).Annotations:*Modellingofpermafrostdistributionwas thetaskofAction5.1inthePermaNETproject.**Atthestudysiteswhichwerenotequippedwith automaticweatherstationsmeteorologicaldatafromstationsinthevicinityhavebeenused.***In somestudysitesmeasurementstakeplaceinshallowboreholes(downtodepthsof+/Ͳ1m)which areincludedinthiscategory.****OnlytheseBTSsitesarelistedwherespecialBTScampaignswere carriedout(andBTSvalueswerenotjusttakenfromGSTmeasurements).  Method Casestudy(chapter) Gainedinformation Geomorphologicalmapping 3.2.,3.3.,3.5.,3.7. Geomorphologyofstudyareas Continuousphotographic 3.2.,3.3.,3.8. Snowcover,rockfallevents documentation Numericalpermafrostmodelling* 3.2.,3.3. Spatialdistributionofpermafrost 3.2.,3.3.,3.6.,3.8.,3.9.,3.10., Automaticweatherstation Atmosphericconditions** 3.13. GSTandnearGST***(evidenceof GSTlogging(usingMTD) allcasestudies permafrost) BTSmeasurement**** 3.2.,3.3.,3.5.,3.7.,3.11.,3.14. BTS(evidenceofpermafrost) Spring(water)temperature Watertemperature(evidenceof 3.3.,3.5.,3.11.,3.12.,3.13. measurement permafrost) Dischargemeasurementand Runoffandchemicalpropertiesof 3.5.,3.13. chemicalanalysisofwater water Geodeticmeasurement 3.3.,3.5.,3.6.,3.7.,3.11.,3.12. Displacementofsurface PhotogrammetryandTLS 3.3.,3.5.,3.8.,3.13. Displacementofsurface Geophysicalsoundings(inmost 3.2.,3.3.,3.5.,3.6.,3.7.,3.8.,3.13., Internalstructureand casesgeoelectrics/ERTorGPR) 3.14. temperatureofpermafrost Internalstructureand Borehole 3.4,3.7,3.8.,3.10.,3.13. temperatureofpermafrost  Summarizingtheresultspresentedinthecasestudiesithastobementionedthatwithrespecttothe aimofidentifyingandquantifyingtheresponseofhighmountainpermafrosttoclimatechangeone problemremainsunsolved–itisthelackoflongtermdataconcerningpermafrost.Mostofthesites werenotestablishedbeforearound2005andthereise.g.noGSTrecordlongerthan10yearsinany studysite(withtheexceptionofSonnblickwherethemeteorologicalobservatoryprovidesalsoGST

172 PermafrostResponsetoClimateChange datawhichhavenotbeenconsideredinChapter3.4.).Thuswearefarawayfromhavingsufficient informationonlongtermthermalreactionofpermafrost–astatementwhichcanonlyleadtothe conclusion that is absolutely necessary to establish a long term monitoring network as it was the mainobjectiveofthePermaNETproject. The only aspect showing a record of a few decades for at least some sites (the longest one at Hochebenkarsince1938,cf.Chapter3.5.)isthesurfacevelocityofrockglaciers.Naturalscientists becameawareofcreepingrockmassesalongtimebeforetheywererecognisedasbeingthemost striking features of high mountain permafrost. The results of the existing geodetic and photogrammetricmeasurementswhicharepresentedanddiscussedespeciallyattheexamplesof Doesenrockglacier(Chapter3.3.)andLaurichardrockglacier(Chapter3.6.)clearlyrevealsignificant geomorphodynamicchangesoverthelastdecadeswhichcanonlybeexplainedwithchangesinthe thermalregimeofthepermafrost. Inordertoprovideacloserlooktothe“overallresults”itishelpfultodistinguishbetweendifferent typesofpermafrostenvironmentswhichhavebeeninvestigatedinthestudysites(Tab.2).Mostof theworkhasbeendoneonactiverockglacierswhichhavebecomethemostimportantobjectof permafrostresearchinhighmountains.Thustheprocessestakingplaceinrockglaciersystemsare understoodincreasinglywellalthough,ofcourse,alotquestionsstillremainsopen.However,there are still fewer permafrost investigations outside of rock glaciers leading to a relative lack of informationontheotherenvironmenttypeswhichisregrettableduetothefactthatmostofthe infrastructure–mainlyfortouristicpurposes–isbuiltintheseenvironmentandnotonrockglaciers whoseunfavourableconditionsforconstructionworkisinthemeantimewellknowntotechnicians leadingthemtoavoidrockglaciersurfaceswhereverpossible.  Table 2 – Overview of permafrost environments investigated by the case studies of Action 5.3 (Annotations: Some of the case studies refer to different types of permafrost environments, in the tableonlythemostsignificantonesareindicated).  Typeofpermafrostenvironment Casestudy(chapter) Annotations Debrisortalusderivedrock 3.3.,3.5.,3.6.,3.7.,3.11.,3.12., Activerockglacier glacierswhichareatleastpartly 3.13. active,boulderysurface Slopesoutsideofactiverock Slope 3.2.,3.3.,3.10.,3.14. glaciers,mostlycoveredbyglacial orperiglacialsediments Steeprockfaceswithlittleorno Rockwall 3.8.,3.9. coveragebysediments,snowor ice Summitareasmostlyconsistingof Summitandridge 3.2.,3.4.,3.8.,3.9. heavilyweatheredbedrock,partly withmountaintopdetritus  The general thermal reaction of permafrost to climate change can be described in the way that permafrosttemperaturesincrease,activelayersthickenandpermafrostthusbecomesmoreprone todegradation.Basedonthisthemainstatementsonthefourenvironmentaltypesderivedfromthe resultsofthecasestudiescanbesummarizedasfollows: x Activerockglaciersreactsurprisinglyfastonannualorseasonaltemperaturevariationsin thewaythatwarmerconditionsresultinhighersurfacevelocities.Thisisduetothefactthat deformationratesincreasewithtemperatureaswellastothepresenceofmoreliquidwater intherockglaciersystem.

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x Onslopestheactivelayerthickeninganddegradationofpermafrostleadstodestabilization ofsedimentswhichthenarepronetoerosionalprocessesofdifferentkind(especiallydebris flows)whentheinclinationishigh.Inflatterterrainfrostsettlingandsubsequentsubsidence ofthesurfaceisthemostimportantprocessasfaraspermafrostisthawͲsensitve. x Rock walls free of sediments or cryospheric cover are directly coupled to atmospheric changes which therefore have direct consequences on the thermal regime and thus geomorphicprocessesinrockfaces.Dependingontherocktypeanditsproperties(strata, fracturing,clefts)rockfallsofincreasingfrequencyandmagnitudearelikelytooccur. x On summits and ridges the conditions are similar to that in rock walls. Regardless of the existenceofmountaintopdetritusthetendencyofsummitsandridgestocollapseisgiven.  2. Thermalpermafrostreactioninthepastandfuture 2.1Increasinggroundtemperatureandpermafrostwarming Theentireevidenceavailablesofar–notonlyfromthecasestudiesofAction5.3butalsofromthe literature(Harrisetal.2003)–clearlyshowsthattherisingairtemperaturescausesanincreaseof GSTsundviaheatfluxtothegroundanincreaseofpermafrosttemperatures.Asrecordedinthecase studiesallmeasuredpermafrosttemperaturesarequitecloseto0°C(e.g.Ͳ1.02°Casmeanvaluefor theperiod2008Ͳ10atthepermafrosttableinthedeepboreholeatCimeBianchePass,calculated fromTable2inChapter3.10.).Thismeansthatonlyaslightfurtherincreaseintemperaturewould be sufficient to induce permafrost degradation in vast areas currently underlain by permafrost. A modelapproachonthisaspectisdiscussedinChapter3.7. Ontheotherhandmanyofthecasestudieshaveshownthatthereisobviouslynolinearcorrelation between rising air temperatures and rising permafrost temperatures. Instead of this the characteristics of the substrate as well as the snow cover play a crucial role for the temperature regime in the ground. Especially the latter aspect has been elaborated intensively in all the case studies where high resolution GST measurements using MDL have been carried out. So the conclusionthat“theevolutionofthepermafrostwillnotonlydependontheairtemperature,butwill bestronglyinfluencedbytheevolutionofthesnowcover,especiallyitsearlyorlateonsetinautumn. Alateonsetofthesnowcovercanatleastpartiallycompensateariseinairtemperature”(Chapter 3.6.)canbeappliedtoallthecasestudiesandfinallycanbeconsideredasarulevalidfortheentire Alps.Yetthishastobequalifiedbythefactthattherearehardlyany(andwithinAction5.3noneat all)longtermdataseriesofpermafrosttemperatureavailablesofar.  2.2Thawingofpermafrostwithdifferenteffects ThawingofpermafrostintheAlpswhichhasalreadybeenprovenbyalotofevidenceisassumedto createthefollowingeffects.(i)Thespatialextentofpermafrostisreduced:Thisfactcane.g.beseen attheSuldenValleystudysite(Chapter3.14.)wherethepillarofaskiliftwasoriginallyplacedona buried body of massive ice which in the meantime has disappeared so that the pillar could be reconstructedontheunderlyingbedrock.Unfortunately,duetothelackofknowledgeonprevious permafrostdistribution,thecompletedegradationofpermafrostinrecentyearscanundoubtedlybe provenonlyinalimitednumberofcases.However,thenowavailableinformationontheexistence of permafrost not only at specific sites – as documented e.g. within Action 5.3 – but also for the entire Alps will provide the possibility to observe the (probably accelerated) future degradation processindetail.(ii)Activelayerthickeninghasbeendetectedinsomeofthestudysites,e.g.well documentedbyrepeatedgeoelectricalsoundingsonLaurichardrockglacier(Chapter3.6.).However, alsothisstatementcontainssomeuncertaintiesbecauseofthelackoflongtermdataavailability.It hastobekeptinmindthattheinterannualvariabilityoftheactivelayerdepthisveryhighdepending

174 PermafrostResponsetoClimateChange especiallyonthebeginning,durationandthicknessofthewintersnowcover.Thiscane.g.beseenin the respective graphs from Cime Bianche Pass (Chapter 3.10.) in which the active layer thickness shows a great temporal variation but not yet a trend to increase. (iii) Increasing ground water circulation and pressure has been worked out as a possible contribution to increasing rates of permafrost creep on rock glaciers at several study sites (e.g. Doesen Valley, Chapter 3.3., and Hochebenkar,Chapter3.5.).However,thereisnotyetanyunambiguousproofforthisassumption becauseatleastinthecasestudiesinvestigatedinAction5.3therewasnospecificresearchonthe hydrologicalsystemwithinpermafrostbodies. Summarizingfromtheconsiderationsongroundtemperatures,permafrostwarmingandpermafrost thawing given in this and the previous subchapter the conclusion can be drawn that the thermal regime of permafrost should be monitored more intensively in the future. This means that measurementsofGSTandtemperaturesindifferentdepths(inboreholes)havetobecarriedoutat moresitesthantodayand–aboveall–overlongerperiodsthanithashappeneduntilnow.Afurther focusoffutureresearchshouldbetheinvestigationoftheexistence,dynamicsandsignificanceof liquidwaterinpermafrostareas.  2.3Changesinthenumberoffreeze/thawcyclesandmagnitudeoffreezingandthawingperiods ThebasicinformationonthistopicisgiveninChapter2providingdataonthenumbersoffreeze days,icedaysandfreezeͲthawdaysfortheentireAlpineArc.Theanalysisisbasedontheperiod 1961Ͳ90 and the difference in the number of these days to the period 2021Ͳ2050 is given. E.g. consideringthenumberoffrostdaysadecreaseof9Ͳ18daysperyearbetweentheperiods1961Ͳ90 and 2021Ͳ2050 is expected. The change of freeze/thaw days which are of specific relevance for geomorphicprocesses(e.g.frostweathering,rockfallactivity)isestimatedbetweenͲ4and+5days peryear.Thisdoesnotseemtobeahighvalue,yetonemustkeepinmindthealtitudinalshiftof temperaturebeltsupwards.Asithasbeenpointedoute.g.inthestudyareaMontBlanc(Chapter 3.9.)thesubsequentprocesseslikerockfallswillaffecthigheraltitudeswhicharenotyetproneto theseprocesses.Inanycasealsofromthispointofviewitisadvisabletomonitorthethermalregime ofthegroundatasmanysitesaspossible.  3. Geomorphicpermafrostreactioninthepastandfuture 3.1Changesintherateofrockglacierdisplacement Allthe7casestudiesonrockglaciers(Tab.2)haverevealedthefactthatthedynamicsofrockglacier creepstronglydependsontemperaturevariations.Themeasuredsurfacevelocitiesonrockglaciers react on air temperature and especially on GST variations within a surprisingly short time lag. According to the Action 5.3 studies this time ranges between less than one and a few years. As reportede.g.fromDoesenrockglacier(Chapter3.3.)interannualtemperaturevariationsof1Ͳ2°C can result in velocity changes of approx. +/Ͳ20%. The conclusion for the evidence available on surface velocity changes on rock glaciers can be taken from Chapter 3.6.: “Rock glaciers react to climate and show interannual velocity variations. Their reaction time is thus much shorter than previously assumed. Velocity variations are linked to temperature variations: an increase in temperatureinducesanincreaseinvelocity.Theairtemperatureonlypartlyexplainstheobserved groundsurfacetemperatureandvelocityvariations.Thegroundsurfacetemperatureshowsthebest linkwithvelocityvariations,withatimelagofaround1year.Thesnowcoverexplainsmostofthe differencebetweenairtemperatureandgroundsurfacetemperature,andthusappearsasthemain drivingfactorbothforgroundsurfacetemperatureandforvelocityvariations”. Forthenearfuture(nextyearstodecades)itcanbeassumedthatmostrockglacierwillshowatrend to faster surface velocities although there will be subordinate periods of reduced dynamics as a

175 PermafrostResponsetoClimateChange consequencesofcolderyears.Afterthisphaseofincreaseddynamicspermafrostdegradationwith meltingoftheicewillreducetheicecontentofrockglaciersuntilthesubstrateisnotsupersaturated iniceanymore.Giventhissituationtherockglacierwillfallintothestatusofaclimaticallyinactive one,i.e.themovementwillstopandtheremainingicewillslowlymeltaway.Dependingonthesize andelevationoftherockglacierthiswillprobablylastseveraldecadestocenturies. Verticaldisplacementonrockglaciersurfacesmaybeduetothedynamicbehaviourofrockglaciers (areaswithextendingorcompressing“flow”).However,ifthereisanetloweringoftheentirerock glaciersurfacetherecanbenodoubtthatthereisaniceloss.Suchasituationise.g.describedfor HochebenkarrockglacierinChapter3.5.,butitalsoappliese.g.toDoesenrockglacier(Kaufmann& Ladstädter2007;Kaufmannetal.2007).Ithastobeexpectedthatasurfaceloweringduetomeltingof the ice will occur on most of the alpine rock glaciers in the first phase of acceleration due to permafrostwarmingaswellasinthesecondphaseoficedisappearance. Themeasurementofsurfacedisplacementsonrockglaciersshouldbecontinuedwhereitisalready carried out in order to achieve long term data series. Furthermore such monitoring should be establishedatthefewsiteswhereinfrastructureisplacedonthesurfaceofrockglaciers.  3.2Changesindisplacementmodeofrockglaciers The displacement mode of rock glaciers already changes as it has been described considering the verticalsurfacechangesintheprevioussubchapter.Thesealreadyongoingprocesseswillcontinuein thenextdecadesaccompanyingtheaccelerationandsubsequentlythedeactivationofrockglaciers. Withregardtotheaccelerationbasalslidingofrockglacierscanbetakenintoaccount(Hausmannet al.2007)asaconsequenceofachanginghydrologicalsystem.However,asalreadymentionedabove noempiricalfindingsonthisaspectareavailableinAction5.3. Thusstatementsonlyonsurfaceloweringarepossiblewhichcanbeobservedatseveralsitesdueto melting of the permafrost ice. In the future collapse processes on ice rich rock glaciers will occur morefrequently creating thermokarst structureswhichcanalreadybeobservedonseveralalpine rock glaciers (e.g. Murfreit Rock Glacier, Italy; Krainer & Mussner 2010), but not on the ones investigatedinAction5.3.Collapseofcoursecancausedamagetoinfrastructurewhichcanonlybe avoidediftheinternalstructureofthepermafrostusinggeophysicaltechniquesiswellknown.  3.3Changesinsolifluctionratesandcryogenicweathering NoempiricalevidencehasbeenprovidedonthesetwotopicsbythecasestudiesofAction5.3.  3.4Changesinvolumeandextentofunstable/unconsolidatedmaterials As it has been shown e.g. in the Sulden Valley study site (Chapter 3.14.) volume and extent of destabilizedmaterialsincreaseasaresponsetoactivelayerthickeninganddecreasingpermafrost extent. Because more loose material is present meteorological events like heavy rainfalls can mobilize these sediments. Thus the disposition to gravitative and erosional processes has already increasedatmanylocationsandwillfurtherincreaseinthefutureaffectingmoreandlargerareas.In many cases these changes will certainly make the reͲevaluation of existing hazard protecting measuresnecessary. 

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3.5Changesinfrequencyandmagnitudeofmassmovementevents This aspect has been highlighted in much detail by the Mont Blanc study in Chapter 3.9. even at differenttimescales.Theresultsundoubtedlyrevealthattheincreasingfrequencyandmagnitudeof massmovementeventscanonlybecausedbypermafrostdegradation.Thustheconclusionscanbe takenfromthischapter:“…rockfallsfromhighͲAlpinesteeprockwallsareexpectedtooccurmore frequently,withvolumesthatarelikelytoincrease.Thefrequencythatiscurrentlyincreasingshould maintain the same trend in the next decades, due to the deepening of the active layer as the temperaturerise…intheAlpsforthe21thcenturywillbehigherbynearly1°Cthantheglobalone…. Moreover, heat advection by triggering of water circulation at depth along thaw corridors would increase the collapsed volumes”. Furthermore for purposes one must be aware of the fact that rockfallscarswillshifttohigherelevations.Thereforemoreinitiativesofmonitoringandmodellingof thesesprocessesshouldbecarriedoutinordertoprovideknowledgeforreducingrockfallhazards.  3.6Surfaceinstabilitiescausedbythermokarstprocesses/meltingofpermafrostice Surfaceinstabilitiesareofspecialsignificanceinpermafrostareaswhereinfrastructure–intheAlps in most cases constructions and edifices for touristic needs – is present. Thus the most striking examplesofAction5.3aretheMadritschskiingareainSuldenValley(Chapter3.13)aswellasthe observatoryandtouristhutonthesummitofHoherSonnblick(thoughChapter3.4.doesnotprovide muchinformationonthisaspect).MeltingoficeinthawͲsensitivepermafrost(intheAlpinecontext permafrost supersaturated with ice) makes surfaces instable thus leading to subsidence (ground settling) in flat areas or on gentle slopes. Additionally different erosional processes may occur on steepslopesduetothesameprocess.Theconsequenceisdamagetoinfrastructureiftheinternal structure of the permafrost is not sufficiently known and thus measures to avoid such problems cannotbetakenintime.  Acknowledgements.ThePermaNETprojectispartoftheEuropeanTerritorialCooperationandcoͲ funded by the European Regional Development Fund (ERDF) in the scope of the Alpine Space Programmewww.alpinespace.eu  References: Harris C., Vonder Muhll D., Isaksen K., Haeberli W., Sollid J.L., King L., Holmlund P., Dramis F., GuglielminM.&PalaciosD.,2003:WarmingpermafrostinEuropeanmountains.Globaland PlanetaryChange,39,215Ͳ225.doi:10.1016/j.gloplacha.2003.04.001. Hausmann H., Krainer K., Brückl E. & Mostler W. 2007: Internal Structure and Ice Content of Reichenkar Rock Glacier (Stubai Alps, Austria) Assessed by Geophysical Investigations. PermafrostandPeriglac.Process.18:351Ͳ367. KaufmannV.&LadstädterR.,2007:Mappingofthe3DsurfacemotionfieldofDoesenrockglacier (Ankogel group, Austria) and its spatioͲtemporal change (1954Ͳ1998) by means of digital photogrammetry.GrazerSchriftenderGeographieundRaumforschung43:127Ͳ144. KaufmannV.,LadstädterR.&KienastG.,2007:10yearsofmonitoringoftheDoesenrockglacier (Ankogelgroup,Austria)–Areviewoftheresearchactivitiesforthetimeperiod1995Ͳ2005. Proceedings,5thMountainCartographyWorkshop,29MarchͲ1April2006,Bohinj,Slovenia, 129Ͳ144. Krainer K. & Mussner L., 2010: Blockgletscher und Naturgefahren: Der aktive Blockgletscher 'Murfreit'indernördlichenSellagruppe,Dolomiten.Geo.Alp,7:p.99.

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