Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 5 Discussions The Cryosphere C, on average, from ◦ , J. K. Malmros 4 to the ocean. Local glaciers pe- , J. C. Yde ff 3 462 461 5 , W. H. Lipscomb 2 , and B. Hasholt 5 , N. T. Knudsen 1 This discussion paper is/has beenPlease under refer review to for the the journal corresponding final The paper Cryosphere in (TC). TC if available. Climate, Ocean, and Sea Ice Modeling Group, Computational Physics andDepartment Methods, of Geology, Aarhus University, 8000Climate, Aarhus, Ocean, Denmark and Sea Ice Modeling Group, Fluid Dynamics andCenter Solid for Mechanics, Geomicrobiology, Aarhus University, 8000Department Aarhus, of Denmark Geography and Geology, University of Copenhagen, sea-level rise (Dowdeswell, 2006; Meier etet al., al. 2007; 2009; van Mernild den Broeke, et 2009; al., Dyugerow 2010). Recent mass-balance estimates for Greenland have land’s local glaciers under ongoing climate warming. 1 Introduction Greenland has warmed significantly duringatures the in past Greenland’s two coastal decades. areas increased Summer1991 by air to an temper- 2006 estimated 1.7 (Comiso 2006).smaller Mass glaciers loss and from ice the Greenland caps Ice is Sheet making (GrIS) a and significant from and growing contribution to global mately 70% of itsclimate current changes. area and Temperature records 80%suggest from of that coastal its recent stations volume MG indicative even mass Southeast of in losses Greenland glacier the are changes absence notMG in of merely therefore the provide further a unique broader local documentation region. of phenomenon, the but Mass-balance general are retreat observations of in- for Southeast Green- the out of equilibrium with2009/2010 present-day for climate. the Mittivakkat Glacier Here,land (henceforth we for MG), document the which record only thereand local mass glacier glacier exist loss front in long-term in fluctuations. Green- We observations(June–August) attribute of this and mass both higher-than-average loss the to winterto record surface lower-than-average (September–May) high mass mean winter temperatures summer balance precipitation.record and to Also, estimate present-day weWe and use show equilibrium the that accumulation-area 15-year the ratios mass-balance glacier for the is MG. significantly out of balance and will likely lose approxi- Warming in theand Arctic retreat, during resulting the inripheral past increased to several freshwater the decades runo iceavailable has to sheet caused quantify are glaciers that also retreat to retreating, and thin but determine the few extent mass-balance to observations which are these glaciers are Abstract The Cryosphere Discuss., 5, 461–477,www.the-cryosphere-discuss.net/5/461/2011/ 2011 doi:10.5194/tcd-5-461-2011 © Author(s) 2011. CC Attribution 3.0 License. 1 Los Alamos National2 Laboratory, Los Alamos, New Mexico 87545,3 USA Los Alamos National4 Laboratory, Los Alamos, New Mexico 87545,5 USA 1350 Copenhagen, Denmark Received: 22 January 2011 – Accepted:Correspondence 25 to: January 2011 S. – H. Published: Mernild 4 ([email protected]) FebruaryPublished 2011 by Copernicus Publications on behalf of the European Geosciences Union. Record mass loss from Greenland’s best-observed local glacier S. H. Mernild B. H. Jakobsen 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ff (Allison 1 − erence between ff 48 W) is an excep- ´ c and Hock, 2010)), ◦ , comparable to that from 1 culties, few reliable long- − ffi 41 N, 37 ◦ ; 65 2 1 mm yr ∼ C above the 1971–2000 baseline, with the 464 463 ◦ en et al., 2008), surface mass loss, and freshwater runo ff 15% for the entire glacier. Larger errors may occur locally, particularly ∼ Meteorological conditions at the MG have been recorded since 1995 at an automated The annual surface mass balance of the MG has been recorded since 1995/1996. Comparable estimates are not available for glaciers and ice caps (GIC) peripheral line (the average altitude where the net surface mass balance is zero). Long-term using cross-glacier stake lineseach at line separations were 200–250 of m apart, approximatelystakes. and 500 End-of-winter m. measurements snow density were was The obtainedpits measured at stakes vertically at a in at total 250, 25 of 500, cm 30–40 depth andcurate intervals to 750 in m within a.s.l. Thein observed crevassed mass areas. balance is considered to be ac- weather station operated byof the Copenhagen, Department located of on a Geography and small Geology, nunatak University at 515 m a.s.l., close to the equilibrium May) and summer massserved. balance Net (ablation mass measured balance atThe data stake the method from end – 1995/1996–2009/2010 also of are knownman, August) as 1991) illustrated were the – in “direct was ob- Fig. glaciological used to method” 3a. ice determine (Østrem extent annual and and variations Brug- and ice possible volume. trends in Snow snow accumulation and and snow/ice ablation were measured intervals since 1931, supplementedtrated by more Figs. 1 recently and by 2,In the topographic 1995 glacier the surveys. terminus observing has program As retreatednual was by surface-mass-balance illus- expanded about measurements with 1300 and m an the since automatedThese initiation 1931. glacier measurements of climate are continuous program. supplemented and by an- of meteorological Tasiilaq, data 15 km from to the coastal the town southeast. In 10 out of 15 years, both winter mass balance (accumulation measured at the end of As a resultterm of observations harsh of mass climateglaciers. loss and conditions The retreat MG and are intion. available logistical Southeast for Greenland di This Greenland’s (17.6 remote glacier km local and the surrounding landscape have been photographed at regular 2 Methods and results the Greenland and Antarctic ice sheetsThis combined (Meier study et al., provides 2007;2009) information Velicogna, 2009). – about the Mittivakkat theservations Glacier only of in both local SE the Greenland surface glacier(since mass – in balance 1931). for (since which Greenland We 1995) there estimate and (WGMS, to exist glacier accumulation-area which front long-term ratios the fluctuations ob- for glacier is thecent out MG MG of to mass balance losses quantify with are the present-daychanges. not climate, extent merely and a we local suggest phenomenon that but re- are indicative of regional to the main ice4.4 sheet. cm sea-level Although equivalent for GIC Greenlandthey have and a 60 are cm relatively globally sensitive small (Radi changes total to on mass surface-mass-balance time (an changes scales estimated sulting of and from a GIC can retreat few has equilibrate decades. been to estimated The to rate climate be of global mean sea-level rise re- conditions in 2007, when2007; high Tedesco, summer 2007; temperatures Ste led(Mernild to and increased Hasholt, melting 2009).have (Mote, As accelerated the and thinned, climate and hasannual accumulation the warmed, and surface Greenland’s ablation) mass outlet has balance become glaciers years more (the the negative. GrIS di During is estimated the to pastet have several al., lost 2009). mass at a rate of more than 200 Gt yr Greenland experienced record-setting surfaceto melt a extent relatively andrecorded warm, glacier temperatures dry area were loss winterlargest due 0.6 followed anomalies by to in the an 2.4 west,servations exceptionally where began warm melt in rates summer. 1990 were (Box the et highest Mean al., since systematic 2010). ob- Greenland last experienced comparable focused on the main ice sheet (Hanna et al., 2008; Ettema et al., 2009). In 2010, 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 C − ◦ C, respec- 0.65 m yr ◦ ± 2.0 − C at Tasiilaq. Win- ◦ C and ◦ is the level of significance) 3.4 p − C, respectively, above the 1995– is the explained variance) and at ◦ 2 r 01, where C, and the mean temperature at Tasiilaq . ◦ 0 40%) below the 15-year average (Fig. 3b). C and 1.4 ◦ ∼ 466 465 C at the MG and by 1.8 p < 01, where ◦ . 0 C (Station Tasiilaq), respectively. Figure 3a shows 230 mm w.eq., although this change is within the ◦ ∼ p < 260 mm w.eq. ( 10) (Fig. 4). These data suggest that recent MG mass losses, C above average. Uncorrected winter precipitation at Tasiilaq ∼ . ◦ 0 1.9 m w.eq., or 11% of the total ice volume determined in 1994 ± p < 1000 mm w.eq.) and mean summer temperatures of 4.2 and 6.1 > 42, . 0 C and 0.5 ◦ values of 0.61–0.91, = 2 2 r r C (Fig. 3b). These values are 1.8 ◦ 440 mm w.eq., or ∼ The accumulation-area ratio (AAR: the ratio of the accumulation area to the area of The long-term record of surface temperature in Tasiilaq is reproduced in Fig. 4, to- The general trend for the MG since 1995 has been toward higher temperatures, less Local meteorological data indicate that higher-than-average temperatures in both Data collected during the past year show that the MG experienced an average sur- period long enough to reduce interannual variability but significantly shorter than the stations ( Summit ( which have been driven largelythe by broader higher region, surface whicheight temperatures, includes other are many glaciers representative hundreds in of of theIsland, local Mittivakkat show region, glaciers. terminus including retreats Observations Sermilik comparablethe to of Fjord MG that and in of Ammassalik size MG. and These elevation glaciers range. are similar to the entire glacier) has been estimated for the MG each year since 1995 (Fig. 3a), a gether with meteorological observations(ranging from in Southeast elevation Greenland’s from coastal 13the stations to Greenland Ice 88 m Sheet a.s.l.), (3208lies and m a.s.l). at from Station Mean-annual-air-temperature the Tasiilaq are (MAAT) Summit anoma- significantly station correlated with at MAAT anomalies the at top other of coastal ative surface mass balance. The(0.01 m two w.eq.) years and with 2002/2003 a (0.34ter slightly m precipitation w.eq.), positive were ( balance, associated 1995/1996 with unusually(Station high Nunatak) win- and 5.6 andthe 7.9 cumulative net massis balance estimated for at 13.0 the(Knudsen MG and since Hasholt, 1999). 1995/1996. Since200 m, 1995 The as the total illustrated glacier by terminus mass the has loss front retreated observations by (Fig. about 1c). snowfall, and a moreperatures negative have glacier increased mass significantlyat ( balance both (Fig. meteorological 3a stationster and by precipitation b). 1.7 has Summer declinedvariability tem- of by the 15-year record (Fig. 3b). In 13 of the last 15 years, the MG had a neg- the west and less so in the northeast (Box et al., 2010). tively, or 1.3 was High summer temperatures favored increasedtion, surface and ablation melt), (evaporation, and sublima- season high due winter to temperatures contributed thewinter to lower snowfall an “cold led early content” to startmer of earlier of snow the exposure the surface; snowpack of melt these (Bøggildal., glacier surfaces et 1995), ice have promoting al., and greater a 2005). of solarconditions lower the absorption were albedo Low previous and observed than increased year’s fresh in melting. sum- snow 2009/2010 Similar (Douville weather throughout et Greenland, more pronounced in son (June through August) theice-free prominence) mean at MG 515 air m a.s.l.,was temperature, 7.8 was recorded 7.5 on a2010 nunatak average. (an During the 2009/2010May), winter mean accumulation season temperatures (September at through the MG and Tasiilaq were ume, from September 2009 throughloss August since 2010. the expansion This of wasrecord the the observing set greatest program in annual in mass 2005 1995,(Fig. 0.34 and 3a). m significantly above the At above previous 4.5 the the to glacier 15-year 5.2 m, terminus average twice the of the observed 15-year 0.87 area-averaged average of melt approximately ratewinter 2.5 and m. ranged summer, along from with somewhatprimarily lower-than-average winter responsible precipitation, for were this record mass loss. During the 2010 summer ablation sea- meteorological station at 44and m located a.s.l., 15 km operated to by thetown. southeast the of the Danish MG Meteorological in the Institute outskirts of Tasiilaq, a small coastal face mass loss of 2.16 m water equivalent (w.eq.), or about 2% of the total glacier vol- (1900–2010) climatic data representative of the region are available from a synoptic 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | is 1 − 0.49 m yr is the expected = of approximately ¨ s onnimann 2009), 36 is an empirical . 0 p m 1 01) gives the relation ), = . 1 0 γ − p < 0.06 implies that the MG will –1, where ± 89, γ r . α 0 , the ratio of the current AAR to 0 = = 0.25 v 2 0. Zero values of AAR are excluded 12% of its volume (a volume loss of = p r r ± = α b AAR/AAR –1 and = 468 467 r r α α = s p . The resulting average AAR of 0.15 is slightly lower is the net mass balance (m yr 1 − b is the fractional volume change, and 0.009 (Dyurgerov et al., 2009). Expected changes in glacier 61 is the AAR when v 0.05, and can be determined as follows. A linear regression . ± p 0 ∼ 0.87 m yr , where = − 0 0 11% of its present area and 85 AAR ) if current climate conditions persist. ± 3 + m b 0.2 km = ± During the past century, mean temperatures at Tasiilaq have been characterized by A similar analysis of glacier AARs has been used to obtain lower bounds for global In several years (1998, 2001, 2005, 2007, and 2010), net ablation was recorded at all 1.5 warming driven mainly by increased fossil fuel burning (IPCC, 2007; Chylek et al., eral glaciers, observations ofestimates the of mass future balance glacial of retreat and MG sea-level are rise. relevant toearly-twentieth-century more warming (ETCW) informed from 1900century until the warming 1930s (LTCW) and from late-twentieth- 1970mid-century to cooling the (Fig. present, 4). interrupted(Bahr Similar et by trends al., several have 2009). decades been Both of observed theto ETCW throughout be and the connected the cooling Arctic to during internalwhereas the variability 1960s it and in 1970s is the appear generally North Atlantic accepted Ocean that (Br the LTCW is a regional amplification of global for a global samplelose at of least 86 27% glacierssea of and level) their in ice volume order capsthese (the to 86 was equivalent reestablish glaciers 0.44, of is equilibrium suggestingwell an located under below that in 18 the present-day cm Greenland. global GIC conditions. rise average will Given and in is that None global likely the of to average average be AAR typical for of the many of MG Greenland’s is periph- record mass loss in 2009/2010.face mass In balance: 13 The of two theunusually years last with high 15 a winter slightly years, precipitation. positive the The balanceaccumulation MG MG were area had is associated ratios a significant with suggests negative out that sur- ofits the balance; current glacier an area will analysis and likely of lose 80% approximately of 70% its of volume even insea-level the rise absence of associated furtherpresent-day climate with changes. climate the (Bahr shrinking et of al., GIC 2009). that From are 1997 out through of 2006 the equilibrium average with AAR Local glacier observations in Greenlandland are for rare, and which MG long-termfront is observations the fluctuations only of exist. glacier both inhigher the Green- Since temperatures, surface 1995, less mass the snowfall, balance and general and a trend glacier more for negative the glacier MG mass has balance, been with toward 3 Discussion and conclusions its equilibrium value. (Specifically, fractional area change, constant (Bahr et al., 2009)).0.61, close As to stated the above, global thelose average. MG about The has resulting 75 an AAR ∼ elevations between the summitand (930 m ice a.s.l.) caps and in the equilibriumglobal terminus average with of (180 local m 0.579 climate a.s.l). typicallyarea Glaciers have and an volume AAR can of be 0.5–0.6, derived with from a AAR the slope, and AAR from the regression, since AARtion and occurs mass everywhere balance on aredefined the not as glacier. linearly the Based predicted related on AAR whenyear this during abla- mean a regression, value year the of when averagethan the AAR the mass 15-year is arithmetic balance mean is AARnegative equal of mass to 0.22, balance its which and 15- includes zero several years AAR. of strongly into 100 m bands,rium and the line AAR altitude for (ELA:by a the ablation) given and elevation the year where glacier is annualwith area determined accumulation an above is based and uncertainty below exactly on of thebetween balanced the the ELA. AAR equilib- The and average the AAR surface is mass 0.15, balance ( time scale of adjustment to equilibrium. As shown in Table 1, the glacier is partitioned 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , , 2010. ´ e, C., Lenton, T. M., , 2009. ´ er doi:10.1029/2009JD013060 doi:10.1029/2009GL038110 en, K., Steig, E. J., Visbeck, M., ff , R., Shuman, C., Irvine-Fynn, T., , 2007. ff er, W. T., Anderson, R. S., Anderson, ff ¨ okulhlaups, and suspended sediment load from melt from the Greenland Ice Sheet: a , j ff ff http://www.arctic.noaa.gov/reportcard 470 469 doi:10.1029/2008GL036309 ce of Science, by a Los Alamos National Laboratory (LANL) en, K., Cappelen, J., Hu ff ffi , 2010. doi:10.1126/science.1143906 ths, M.: Increased runo This work was supported by grants from the Climate Change Predic- ffi , N. L., Bindschadler, R. A., Cox, P. 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F.: Sea-level riseBox, from J. glaciers E., and Cappelen, ice J., Decker, caps: D., A Fettweis, X., lower Mote, T., Tedesco, M., and Van de Wal, R. S. Allison, I., Bindo Br Bøggild, C. E., Forsberg, R., and Reeh, N.: Melt water in a transect across the Greenland ice References Acknowledgements. tion Program and ScientificU.S. Discovery Department for of Advanced Energy’sDirector’s Computing O Fellowship, and (SciDAC) by program a within fellowshipPhysics. from the LANL the LANL is Institute operated for underof Geophysics the and the Planetary auspices U.S. of Department theBahr, of National Matthew Energy Hecht, Nuclear under and Security Contract Wilbert Administration Danish No. Weijer DE-AC52-06NA25396. Meteorological for their Institute We insightful for thank comments. providingGreenland David Thanks WMO stations. are synoptic given meteorological to data the from the East in the Mittivakkat regionvolume are losses likely than to are continue projectedthe to complete based melting increase, on of the leading the current to MG average larger and AAR, other area and local and possibly glaciers to of Southeast Greenland. 2010). To the extent that the recent warming is anthropogenic in origin, temperatures 5 5 30 25 20 15 10 15 25 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 2009. doi:10.1029/2009JF001373 , 2007. doi:10.1029/2009GL040222 ) 2 471 472 doi:10.1029/2007GL031976 930 –200 0.00 0.54 1.00 > 800–930700–799600–699500–599400–499300–399 0.77200–299 2.65 0.04 < 3.99 0.19 2.70Total 0.42 3.16 0.56 2.35 0.75 1.44 0.89 0.97 17.6 – MG elevation bands(m a.s.l.) 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Res., 115, F01010, Rapid changes in glacierChange, and a ice Report sheet by and the their US impacts Climate on Change sea Science level, Program in: and the Abrupt Subcommittee Climate on surface mass-balance modeling in11(1), 3–25, a 2010. 131-year perspective 1950–2080, J. Hydrometeorol., Østrem, G. and Brugman, M.: Glacier mass balance measurements, A manual for field and WGMS: Glacier Mass Balance Bulletin, Bulletin No. 10 (2006–2007), edited Table 1. intervals; the middlecolumn column gives gives the estimated the AAR glacier when the area equilibrium located line altitude within falls each within the band; given and band. the right Velicogna, I.: Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets Tedesco, M.: A new record in 2007van for den melting Broeke, in M., Greenland, Bamber, Eos J., Trans. AGU, Ettema, 88(39), J., 383, Rignot, E., Schrama, E., van de Berg, W. J., Ste Mote, T. L.: Greenland surface melt trends 1973–2007,Radi Evidence of a large increase in 2007, Mernild, S. H., Liston, G. E., Hiemstra, C. A., and Christensen, J. H.: Greenland Ice Sheet 5 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | glacier outline with a black square indicating the 474 473 (b) the location of the glacier margin delineated as thick lines for (c) Location of the Mittivakkat Gletscher (red circle) and coastal meteorological stations (above, in black and white) Photographs of the Mittivakkat Gletscher in 1931, when the glacier margin, shown by the arrow,Sermilik was Fjord, and within in 200 background m IrmingerUniversity Sea of of (source: the Cambridge). Licensed coastline. (below, with in permission1500 m of color) The the from Photograph photos Scott of the Polar are the Research coast.Copenhagen). Institute, MG taken The in toward photo 2006, is SSE, when taken and the toward in glacier ESE margin (source: the was Department foreground approximately of is Geography and Geology, University of Fig. 2. Fig. 1. (a) (red diamonds) in Southeastphotographic Greenland; area and anunatak black on circle the showing glacier; the location and of the meteorological station at the 1931, 1943, 1972,estimated 1999, from 2005, aerial 2009, photos,surveys: and and 2010. Kern the Theodolite morebird, The and 2005). recent 1931, GPS-measurements margins 1943, (background were photo: and obtained 1972 DigitalGlobe, from margins Quick- topographic were Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 476 475 Time series (1995–2010) of observed winter precipitation and mean (b) Observed annual mass balance (with 15% error bars), cumulative net mass balance Continued. summer air temperature (June–August,Nunatak ablation period) (515 m from a.s.l.). Tasiilaq The (44statistically m straight a.s.l.) significant. lines are and linear Station fits to the data; the temperature trends are Fig. 3. (a) (with a gray zoneGletscher, 1995–2010. indicating the 15% error), and accumulation-area ratio for the Mittivakkat Fig. 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | values indicate the 2 r 477 Long-term time series of observed mean-annual-air-temperature anomaly from Tasi- Fig. 4. ilaq and other meteorological stations in Southeast Greenland. The correlation between the Tasiilaq anomaly(Ittoqqortoormiit and is anomalies farthest north, from and other Ikerasassuaq stations is shown farthest in south). Fig. 1a