TheThe ConsequencesConsequences ofof aa WarmingWarming Arctic:Arctic: AnAn OverviewOverview ofof thethe ResultsResults ofof thethe ArcticArctic ClimateClimate ImpactImpact AssessmentAssessment (ACIA)(ACIA)

Michael MacCracken Chief Scientist for Climate Change Programs Climate Institute, Washington DC, and Member, ACIA Synthesis Team The basic conclusion of the Arctic Climate Impact Assessment is that it is time to take a last look at the Arctic as we know it Public discussion has focused on global warming of 0.8ºC, with land areas warming more rapidly than the oceans

Source: NOAA/NCDC through 2005 HowAnalysis well of theare multi the-decadal models changes depicting and “forcings” the over the 20th century indicate that human activitieslast are 100 playing years? an increasing role

(Black) (Blue) NaturalNatural PlusPlus Anthropogenic (Red) Anthropogenic

NaturalNatural OnlyOnly

NCAR Climate Simulations Warming in the Arctic has been larger than for the globe, nearly 2ºC (3.5 º F) since about 1900

The early 20th century warming was mainly in the North Atlantic basin

It is important to understand that “Global Warming” will be experienced in distinct ways in each region, and we must look at impacts regionally to gain a sense of their influences on both the region’s and the world’s environment and society. The Arctic is one of the most vulnerable regions! With their world changing so rapidly, the people of the Arctic wanted and needed more information about the changes and how best to prepare and adapt-- leading to the undertaking of the Arctic Climate Impact Assessment (ACIA) Mandated by the The Arctic Council has eight national8-nation Arctic members Council; carried out by about 300 scientists The Arctic Council also includes six councils of Indigenous Peoples

• Aleut International Association • Arctic Athabaskan Council • Gwich’in Council International • Inuit Circumpolar Conference • Russian Association of Indigenous Peoples of the North • Saami Council “Nowadays“Nowadays snowssnows meltmelt earlierearlier inin thethe springtime.springtime. Lakes,Lakes, rivers,rivers, andand bogsbogs freezefreeze muchmuch laterlater inin thethe autumn.autumn. ReindeerReindeer herdingherding becomesbecomes moremore diffidifficultcult asas thethe iceice isis weakweak andand maymay givegive way…way… AllAll sortssorts ofof unusualunusual eventsevents havehave takentaken place.place. NowadaysNowadays thethe winterswinters areare muchmuch warmerwarmer thanthan theythey usedused toto be.be. OccasionallyOccasionally duringduring winterwinter timetime itit rains.rains. WeWe nevernever expectedexpected this;this; wewe couldcould notnot bebe readyready forfor this.this. ItIt isis veryvery strange…strange… TheThe cyclecycle ofof thethe yearlyyearly calendarcalendar hashas beenbeen disturbeddisturbed greatlygreatly andand thisthis affectsaffects thethe reindeerreindeer herdingherding negativelynegatively forfor sure…”sure…” AnAn observationobservation byby LarisaLarisa Avdeyeva,Avdeyeva, anan elderelder fromfrom Lovozero,Lovozero, RussiaRussia inin 2002,2002,

ACIAACIA’’ss TenTen KeyKey FindingsFindings

1. Arctic climate is now warming rapidly and much larger changes are projected; 2. Arctic warming and its consequences have worldwide implications; 3. Arctic vegetation zones are very likely to shift, causing wide-ranging impacts; 4. Animal species' diversity, ranges, and distribution will change; 5. Many coastal communities and facilities face increasing exposure to storms; 6. Reduced sea ice is very likely to increase marine transport and access to resources; 7. Thawing ground will disrupt transportation, buildings, and other infrastructure; 8. Indigenous communities are facing major economic and cultural impacts; 9. Elevated ultraviolet radiation levels will affect people, plants, and animals; and 10. Multiple influences interact to cause impacts to people and ecosystems. WarmingWarming hashas occurredoccurred inin allall fourfour seasonsseasons overover thethe pastpast 5050 years,years, especiallyespecially inin thethe ArcticArctic

Source: Hansen et al.

OverOver thethe PastPast 3030 Years,Years, thethe ArcticArctic RegionRegion HasHas ExperiencedExperienced MajorMajor ChangesChanges inin itsits ClimateClimate •• IncreasesIncreases inin surfacesurface andand oceanicoceanic temperatures,temperatures, •• LargeLarge reductionsreductions inin seasea iceice andand glacierglacier volume,volume, •• IncreasesIncreases inin riverriver runoffrunoff andand seasea level,level, •• OverallOverall increasesincreases inin precipitation,precipitation, •• TheThe thawingthawing ofof permafrost,permafrost, •• ShiftsShifts inin thethe rangesranges ofof plantplant andand animalanimal species,species, andand •• MajorMajor impactsimpacts onon thethe residentsresidents ofof thethe circumpolarcircumpolar ArcticArctic region.region.

MinimumMinimum ExtentExtent ofof ArcticArctic OceanOcean SeaSea IceIce CoverCover

September 1979 September 2003

The extent of September ice cover has continued to decrease since 2003 Models Project Sharp Reductions in Arctic Sea Ice-- and the Sea Ice is Actually Melting Even More Rapidly (from Sorteberg, cited by J. Eystein--2005)

Melting of the Arctic sea ice will reduce the effectiveness of the Northern Hemisphere’s “air conditioner,” leading to winter and summer warming For the 21st century, even a modest emissions scenario causes global warming of 2-4ºC

--Global average from 1990

ACIA’s analysis focused mostly on the

B2 Emissions Scenario

Arctic

Global The projected increase in global Prather diagram average temperature could result in global temperatures being higher than they have been in tens of millions of years

Source: IPCC TAR, 2001 and M. Prather

Average of Results from the 5 Models Used by ACIA

Minimum Projected Sea Ice Extent (2010-2030)

Blue line gives boundary of minimum extent at present.

White dots give approximate indication of concentration of sea ice

Amplified warming in the Arctic contributes to warming in the middle latitudes

Annual Winter

Average result for end of 21st Century from the 5 models used by ACIA

TheThe GreenlandGreenland IceIce SheetSheet DominatesDominates LandLand IceIce inin thethe ArcticArctic OverOver thethe pastpast twotwo decades,decades, thethe meltmelt areaarea onon thethe GreenlandGreenland iceice sheetsheet hashas increasedincreased onon averageaverage byby aboutabout 0.7%/year0.7%/year (or(or aboutabout 16%16% fromfrom 19791979 toto 2002).2002). ThereThere isis preliminarypreliminary paleoclimaticpaleoclimatic evidenceevidence suggestingsuggesting thethe EemianEemian seasea levellevel riserise ofof aa fewfew metersmeters occurredoccurred overover aa fewfew centuriescenturies with rapid melting of about half with rapid melting of about half Source: Business Week Aug. 2004 ofof thethe GreenlandGreenland iceice SheSheet.et.

Melting glacial ice and increased river runoff may be freshening the North Atlantic Freshening of the North Atlantic could slow the global Thermohaline Circulation

Conversely, Kerry Emanuel argues an increase in the number and intensity of tropical cyclones could alter ocean mixing in the tropics and accelerate the THC The CO2 Concentration, Temperature, and Sea Level The CO Concentration, Temperature, and Sea Level Continue2 to Rise Long after Emissions are Reduced Continue to Rise Long after Emissions are Reduced Time Taken to Reach Equilibrium Sea-level rise due to ice melting several millennia

Sea-level rise due to thermal expansion: Centuries to millennia

Temperature Stabilizations in few centuries

CO2 Stabilization: 100 to 300 Years

CO2 Emissions

100100 yryr 1000y1000y rr Climatic and ecological changes in the Arctic will also affect the habitats of birds, fish, and marine mammals that breed and grow in the Arctic during summer

Marine food chains, most immediately in the Arctic, are likely to be impacted by ocean acidification caused by the rising CO2 concentration itself, which are expected to impact organisms having calcium shells and structures HudsonHudson BayBay AnAn earlyearly indicatorindicator ofof thethe changingchanging climateclimate Sea ice retreat allows storm waves to grow in size and increase coastal damage ManyMany coastalcoastal communitiescommunities AlaskaAlaska andand ChukotkaChukotka areare andand facilitiesfacilities faceface increasingincreasing ParticularlyParticularly atat exposureexposure toto storms.storms. RiskRisk

••SevereSevere coastalcoastal erosionerosion willwill bebe aa growinggrowing problemproblem asas risingrising seasea levelslevels andand aa reductionreduction inin seasea iceice allowallow higherhigher waveswaves andand stormstorm surgessurgesto to reachreach shore.shore.

•• AlongAlong somesome ArcticArctic coastlines,coastlines, thawingthawing permafrostpermafrost weweakensakens coastalcoastal lands, lands, addingadding toto theirtheir vulnerability.vulnerability. •• TheThe riskrisk ofof floodingflooding inin coastalcoastal wetlandswetlands isis projectedprojected toto increase,increase, withwith impactimpactss onon societysociety andand naturalnatural ecosystems.ecosystems. •• InIn somesome cases,cases, communitiescommunities andand industrialindustrial facilitiesfacilities inin coastalcoastal zoneszones areare alreadyalready threatenedthreatened oror beingbeing forcedforced toto relocate,relocate, whilewhile othersothers faceface increasingincreasing risksrisks andand costs.costs.

ThawingThawing groundground willwill 200200 DaysDays UseUse ofof AlaskaAlaska 100100 DaysDays IceIce RoadsRoads disruptdisrupt transportation,transportation, buildings,buildings, andand otherother infrastructure.infrastructure. 3030 YearsYears

19701970 20002000 •• TransportationTransportation andand industryindustry onon land,land, includingincluding oiloil andand gasgas extractionextraction andand forestry,forestry, willwill increasinglyincreasingly bebe disrupteddisrupted byby thethe shorteningshortening ofof thethe periodsperiods duringduring whichwhich iceice roadsroads and and tundratundra areare frozenfrozen sufficientlysufficiently toto permitpermit travel.travel. •• AsAs frozenfrozen groundground thaws,thaws, many many existingexisting buildings,buildings, roads,roads, pipelines,pipelines, airports,airports, andand industrialindustrial facilitiesfacilities areare likelylikely toto bebe destabilized,destabilized, requiringrequiring substantialsubstantial rebuilding,rebuilding, maintenance,maintenance, andand investment.investment.

8.8. IndigenousIndigenous communitiescommunities areare facingfacing majormajor economiceconomic andand culturalcultural impacts.impacts.

•• IndigenousIndigenous knowledgeknowledge andand observatioobservationsns provideprovide anan importantimportant sourcesource ofof informationinformation aboutabout climateclimate change.change. ThisThis knowledge,knowledge, consistentconsistent withwith complementarycomplementary informationinformation fromfrom scientificscientific research,research, indicatesindicates thatthat substantialsubstantial changeschanges havehave alreadyalready occurred.occurred. •• ChangesChanges inin species’species’ rangesranges andand availabilitavailability,y, accessaccess toto thesethese species,species, aa perceivedperceived reductionreduction inin weatherweather predictability,predictability, aandnd traveltravel safetysafety inin changingchanging iceice andand weatherweather conditionsconditions presentpresent seriousserious chalchallengeslenges toto humanhuman healthhealth andand foodfood security,security, andand possiblypossibly eveneven thethe survivalsurvival ofof manymany cultures.cultures. •• ManyMany IndigenousIndigenous PeoplesPeoples dependdepend onon hhuntingunting polarpolar bear,bear, walrus,walrus, seals,seals, andand caribou,caribou, herdingherding reindeer,reindeer, fishing,fishing, anandd gathering,gathering, notnot onlyonly forfor foodfood andand toto supportsupport thethe locallocal economy,economy, butbut alsoalso asas thethe basisbasis forfor culturalcultural andand socialsocial identity.identity.

10.10. MultipleMultiple influencesinfluences interactinteract toto causecause impactsimpacts toto humanshumans andand ecosystemsecosystems ClimateClimate changechange occursoccurs inin thethe contextcontext ofof otherother stressesstresses includingincluding chemicalchemical pollution,pollution, oiloil spills,spills, over-fishing,over-fishing, ozoneozone depletion,depletion, andand culturalcultural andand economiceconomic changes.changes. ChangesChanges inin climateclimate oftenoften interactinteract withwith otherother changeschanges inin waysways toto increaseincrease thethe impacts,impacts, suchsuch asas pathwayspathways forfor LongLong rangerange oceanicoceanic andand atmoatmosphericspheric pathwayspathways forfor POPsPOPs pollutants.pollutants. thatthat enterenter thethe ArcticArctic areare inflinfluenceduenced byby changeschanges inin climate.climate.

The Overview volume was published in Available from November 2004 Cambridge University Press and The Foundation on the Web at volume with 18 http://amap.no/ technical workdocs/ chapters was published in 2005