Glaciers outside Greenland

M. Sharp and G. Wolken

Department of Earth and Atmospheric Sciences, University of Alberta

August 26, 2009

Glacier shrinkage is a major contributor to global sea level change, and mountain glaciers and ice caps may account for up to 60% of the total glacier contribution to sea level rise since the 1990’s (Meier et al., 2007; Cazenave et al., 2009). Since the Arctic (including Alaska) contains nearly 50% of the total global mountain glacier and ice cap area, it has accounted for a large fraction of this contribution (50-60% in the 1961-2004 period) (Kaser et al., 2006).

Surface mass balance (annual net balance and its summer/winter components) measures how climate affects the health of Arctic glaciers. Measurements of this quantity on Arctic glaciers and ice caps suggest accelerating rates of mass loss since the early 1990’s (Kaser et al., 2006). As most 2007-8 measurements are not yet available, we report results for the 2006-2007 balance year (Svalbard: 4 glaciers, Iceland: 6, Alaska:3, Arctic Canada:4). Annual surface balances were negative for 14 glaciers, positive for 2 (1 each in Iceland and Alaska) and zero for one (in Svalbard) (WGMS, 2009). The 2006-2007 annual surface balances were among the five most negative balances in the > 40-year long records from the four Canadian Arctic sites. These results suggest a continuation of the longer term trend of overall mass loss.

Summer (JJA 2008) 700 hPa air temperature and winter (September 2007-May 2008) precipitation data from the NCEP/NCAR Reanalysis serve as climatic indices for regions centered over each of the Arctic’s major glaciated regions (excluding Greenland). Correlations between the 1948-2008 NCEP summer temperature series from 16 discrete regions form 4 groups (Alaska, Arctic Canada, Iceland, and the Eurasian Arctic). Measurements from glaciers in these regions suggest that inter-annual variability in the annual net balance arises primarily from variability in the summer balance (Arctic Canada), the winter balance (southern Alaska, Iceland) or both (Eurasian Arctic, with greater influence from the summer balance). The climatic indices therefore suggest that the annual mass balance was likely extremely negative in Arctic Canada, due to unusually warm summer air temperatures, and positive in Alaska due to strong positive winter precipitation anomalies (confirmed by GRACE satellite gravimetry; pers. comm. from S. Luthcke, 2009). Annual balance was likely near zero or slightly positive in the Eurasian Arctic (relatively cool summers and generally high winter precipitation) and negative in Iceland (warmer than average summer temperatures and below average winter precipitation).

Melt onset and freeze-up dates and 2008 melt season duration were determined from temporal backscatter variations measured by QuikScat’s SeaWinds scatterometer (Table G1; Figure G1). In Arctic Canada, melt duration anomalies (relative to 2000-2004 climatology) on the N Ellesmere, Agassiz, and Axel Heiberg ice caps ranged from +17.6 to +22.5 days, largely due to late freeze-up (Table 1). Here, summer 2008 was the longest melt season in the 2000-2008 record. Melt duration anomalies were also strongly positive on northern Prince of Wales Icefield and Severnaya Zemlya, and positive in the southern Queen Elizabeth Islands and Baffin Island (Arctic Canada), Franz Josef Land, and Iceland. The melt season in southwest Alaska was the shortest in the nine-year record, with strongly negative melt duration anomalies, mostly due to early freeze-up.

Figure G1. 2008 standardised melt duration anomalies derived from QuikScat for glaciers and ice caps in (a) Iceland, (b) the Eurasian Arctic, (c) the Queen Elizabeth Islands, (d) Baffin and Bylot Islands, and (e) Alaska. (f) Anomalies in JJA 2008 mean air temperature (degrees Celsius) at 700 hPa relative to 1948-2008 climatology from the NCEP/NCAR Reanalysis

Table G1. Melt onset and freeze-up dates

The total ice shelf area in Arctic Canada decreased by 23% in summer 2008 (Mueller et al., 2008). The Markham ice shelf disappeared completely and the Serson ice shelf lost 60% of its area. 90% of Arctic ice shelf area has been lost in the past century. Several fjords on the north coast of Ellesmere Island are now ice-free for the first time in 3000-5500 years (England et al., 2008).

Acknowledgements

References

Cazenave, A., Dominh, K., Guinehut, S., Berthier, E., Llovel, W., Ramillien, G., Ablain, M., and Larnicol, G. 2009. Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo. Global and Planetary Change, 65, 83–88.

England, J., Lakeman, T.R., Lemmen, D.S., Bednarski, J.M., Stewart, T.G., and Evans, D.J.A. 2008. A millennial-scale record of Arctic Ocean sea ice variability and the demise of the Ellesmere Island ice shelves. Geophysical Research Letters, 35, L19502, doi:10.1029/2008GL034470.

Kaser, G., J.G. Cogley, M.B. Dyurgerov, M.F. Meier, and A. Ohmura, 2006: Mass balance of glaciers and ice caps: Consensus estimates for 1961–2004. Geophys. Res. Lett., 33, L19501, doi:10.1029/2006GL027511.

Meier, M.F., Dyurgerov, M.B., Rick, U.K., O’Neel, S., Pfeffer, W.T., Anderson, R.S., Anderson, S.P., and Glazovsky, A.F. 2007. Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century. Science 317, 1064-1067.

Mueller, D.R., Copland, L., Hamilton, A., and Stern, D. 2008: Examining Arctic Ice Shelves Prior to the 2008 Breakup. EOS, Transactions of the American Geophysical Union, 89, 502-503.

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