Glaciers and Ice Caps
(outside Greenland)
M. Sharp1 and G. Wolken2
1University of Alberta, Department of Earth and Atmospheric Sciences
2Alaska Division of Geological & Geophysical Surveys
With data contributions from
D. Burgess, A. Arendt, S. Luthcke, L. Copland, and D. Mueller
November 23, 2011
Highlights
- Warm summer temperatures caused negative mass balances on glaciers in Arctic Canada in the 2009-2010 balance year, extending a period of extremely negative balances in the region that began in 2005. These are nested in a longer period of very negative balances that began in 1987.
- The recent series of warm summers in Arctic Canada has also been associated with continued break-up of the floating ice shelves that fringe northern Ellesmere Island. They are now 54% of their 2005 total area.
- Climatic conditions during the 2010-2011 balance year suggest negative balances on most glaciers and ice caps in the Arctic, and especially on those within a broad region extending from southwest Greenland, the Canadian Arctic Islands and the eastern Russian Arctic.
Mountain glaciers and ice caps in the Arctic, with an area of over 400,000 km2, are a significant contributor to global sea level change (Meier et al. 2007; Gardner et al. 2011). They lose mass by iceberg calving, and by surface melt and runoff. The net surface mass balance (Bn, the difference between annual snow accumulation and annual runoff) is a widely used measure of how they respond to climate variability and change. Variability in mean summer temperature accounts for much of the inter-annual variability in Bn in cold, dry regions like the Canadian high Arctic while, in more maritime regions like Iceland and southern Alaska, variability in winter precipitation is also a factor.
Measurements of Bn of 20 Arctic glaciers have been published for 2008-2009 (World Glacier Monitoring Service 2011). These are located in Alaska (three glaciers), Arctic Canada (four glaciers), Iceland (nine glaciers) and Svalbard (four glaciers) (Table HTC1). All but one of these glaciers (Dyngjujokull in Iceland) had a negative annual balance. The measured mass balances of the Alaskan glaciers for 2008-2009 were all very negative, and the 2008-2009 regional annual Bn for all glaciers in the Gulf of Alaska region (measured by GRACE satellite gravimetry) was -151±17 Gt yr-1, the most negative annual value in the GRACE record for this region (A. Arendt and S. Luthcke, pers. comm.). Mass balances of glaciers in Iceland were less negative than in 2007-2008, while those of Svalbard glaciers were more negative.
Table HTC1. Measured annual net surface mass balance of glaciers in Alaska, the Canadian Arctic, Iceland and Svalbard for 2008-2009 and 2009-2010. Mass balance data for glaciers in Alaska, Svalbard and Iceland are from the World Glacier Monitoring Service (2011); those for the Canadian Arctic were supplied by D. Burgess and J. G. Cogley. The mass balance of all Gulf of Alaska glaciers is derived from GRACE satellite gravity measurements (S. Luthcke and A. Arendt, pers. comm.). |
| Region | Glacier | Net Balance 2008-9 (kg m-2 yr-1) |
Net Balance 2009-10 (kg m-2 yr-1) |
GRACE 2008-2009 (Gt yr-1) |
| Alaska | ||||
| Gulf of Alaska glaciers | -151± 17 | |||
| Wolverine | -1780 | |||
| Lemon Creek | -700 | |||
| Gulkana | -720 | |||
| Arctic Canada | ||||
| Devon Ice Cap | -523 | -112 | ||
| Meighen Ice Cap | -676 | -118 | ||
| Melville S. Ice Cap | -351 | -211 | ||
| White | -580 | -188 | ||
| Iceland | ||||
| Langjökull S. Dome | -362 | |||
| Hofsjökull E | -170 | |||
| Hofsjökull N | -350 | |||
| Hofsjökull SW | -350 | |||
| Köldukvislarjökull | -134 | |||
| Tungnaarjökull | -809 | |||
| Dyngjujökull | 227 | |||
| Brúarjökull | -122 | |||
| Eyjabakkajökull | -507 | |||
| Svalbard | ||||
| Midre Lovenbreen | -138 | |||
| Austre Broggerbreen | -246 | |||
| Kongsvegen | -78 | |||
| Hansbreen | -138 |
Measurements of Bn for the 2009-2010 balance year for the 4 glaciers in Arctic Canada were all negative (Table HTC1; D. Burgess and J.G. Cogley, pers. comm.), though less so than the 2008-2009 net balances. Nevertheless, they extend a period of very negative balances in the region that began in 1987. Of the total mass lost from the 4 glaciers monitored since 1963, 30-48% has occurred since 2005. The mean rate of mass loss from these 4 glaciers between 2005 and 2009 (-493 kg m-2 yr-1) was nearly 5 times greater than the 1963-2004 average. In 2007 and 2008, it was 7 times greater (-698 kg m-2 yr-1) (Sharp et al. 2011).
This recent series of warm summers in Arctic Canada (Sharp et al. 2011) has also been associated with the break-up of the floating ice shelves that fringe northern Ellesmere Island. The total area of these ice shelves is now 563 km2, 54% of what it was in August 2005 (L. Copland and D. Mueller, pers. comm.). In summer 2011, the areas of the two remaining sections of the Serson Ice Shelf (which in 2008 were 42 km2 (Serson A) and 35 km2 (Serson B)) were reduced to 25 km2 and 7 km2 respectively. The Ward Hunt Ice Shelf, which had an area of 340 km2 in 2010, split into two separate pieces with areas of 227 km2 and 74 km2.
To provide a direct measure of summer conditions over glaciers across the Arctic in summer 2011, we use the MODIS MOD11A2 land surface temperature (LST) product (2000-2011; ORNL DAAC 2010) (Table HTC2; Fig. HTC6). In the Canadian Arctic, summer mean 2011 LST anomalies ranged from -0.12°C in South Baffin to +2.68°C on the Agassiz Ice Cap, Ellesmere Island. Summer mean LSTs in 2011 were the warmest in the 12 year record on northern Ellesmere and Axel Heiberg islands, and the second warmest on the Devon, Sydkap (southern Ellesmere Island), and Barnes (northern Baffin Island) ice caps. Elsewhere in the Arctic, 2011 summer mean LSTs were also the warmest on record on Severnaya Zemlya and Franz Josef Land (anomalies of +1.74°C and +1.14°C respectively), and the second warmest in Svalbard and southwest Alaska (Table HTC1). Data for Novaya Zemlya and Iceland were not available at the time of writing as the melt season had not ended in those regions. By contrast, 2011 summer mean LSTs were only the 8th warmest on record on the Penny ice cap (southern Baffin Island; anomaly of -0.12°C) and the 9th warmest in southeast Alaska (anomaly of -0.11°C).
Table HTC2. Anomalies of summer (June-August) 2011 700 hPa air temperature, winter (September 2010-May 2011) precipitation, and summer 2011 MODIS MOD11A2 Land Surface Temperature (LST) for major glaciated regions of the Arctic (excluding Greenland). Air temperature and precipitation anomalies are relative to 1948-2008 climatology from the NCEP/NCAR R1 Reanalysis. LST anomalies are relative to the mean LST for the period 2000-2010. For ranks, 1 = year with highest summer air or land surface temperature and winter precipitation. Mean summer LST values are calculated from 8 day averages of daytime, clear sky values for a period centered on July 15 of each year. The length of the measurement period varies between regions and is equal to the mean (+ 4 standard deviations) annual melt duration in each region during the period 2000-2009 derived using microwave backscatter measurements from the Seawinds scatterometer on QuikScat. LST is measured for blocks of 1km by 1km cells containing only glacier ice centered on high elevation regions of major ice caps in each region. Block size varies with the size of the ice cap, but is consistent between years. |
| Region | Sub-Region | Latitude (N) | Longitude (E) | 2011 JJA 700 hPa T Anomaly | 2011 Rank | 2010-11 Sep-May Ppt Anomaly | 2010-11 Rank | 2011 MODIS LST Anomaly | 2011 Rank |
| (°C) | (/64) | (mm) | (/63) | (°C) | (/12) | ||||
| Arctic Canada | N. Ellesmere Island | 80.6 - 83.1 | 267.7 - 294.1 | 2.72 | 2 | -6.8 | 38 | 1.52 | 1 |
| Axel Heiberg Island | 78.4 - 80.6 | 265.5 - 271.5 | 2.57 | 1 | 2.4 | 29 | 2.56 | 1 | |
| Agassiz Ice Cap | 79.2 - 81.1 | 278.9 - 290.4 | 2.43 | 2 | 15.7 | 9 | 2.68 | 1 | |
| Prince of Wales Icefield | 77.3 - 79.1 | 278 - 284.9 | 1.96 | 4 | 161.0 | 1 | 1.94 | 1 | |
| Sydkap | 76.5 - 77.1 | 270.7 - 275.8 | 2.01 | 3 | 58.1 | 8 | 1.39 | 2 | |
| Manson Icefield | 76.2 - 77.2 | 278.7 - 282.1 | 1.95 | 4 | 144.6 | 2 | 0.75 | 4 | |
| Devon Ice Cap | 74.5 - 75.8 | 273.4 - 280.3 | 1.50 | 6 | -14.5 | 40 | 0.95 | 2 | |
| North Baffin | 68 - 74 | 278 - 295 | 1.42 | 7 | -9.6 | 38 | 0.47 | 2 | |
| South Baffin | 65 - 68 | 290 - 300 | 1.76 | 3 | 60.9 | 14 | -0.12 | 8 | |
| Eurasian Arctic | Severnaya Zemlya | 76.25 - 81.25 | 88.75 - 111.25 | 1.46 | 7 | 47.6 | 8 | 1.74 | 1 |
| Novaya Zemlya | 68.75 - 78.75 | 48.75 - 71.25 | -0.32 | 40 | 36.8 | 16 | |||
| Franz Josef Land | 80 - 83 | 45 - 65 | 0.78 | 15 | 10.2 | 21 | 1.14 | 1 | |
| Svalbard | 76.25 - 81.25 | 8.75 - 31.25 | 0.62 | 15 | 13.3 | 25 | 0.51 | 2 | |
| Iceland | 63 - 66 | 338 - 346 | -0.70 | 51 | -3.3 | 32 | |||
| Alaska | SW Alaska | 60 - 65 | 210 - 220 | 0.30 | 22 | -33.2 | 37 | 0.40 | 2 |
| SE Alaska | 55 - 60 | 220 - 230 | -0.79 | 51 | -196.5 | 56 | -0.11 | 9 |
 |
Fig. HTC6. Comparison of 2010 (red) and 2011 (blue) summer mean land surface temperature (LST) anomalies (relative to 2000-2010 climatology) for 16 glaciated regions of the Arctic based on the MODIS MOD11A2 LST product. |
Data from the NCEP/NCAR R1 Reanalysis were also used as indicators of climatic conditions over the major glaciated regions of the Arctic during the 2010-2011 mass balance year. Relative to the 1948-2008 mean, winter precipitation (September 2010-May 2011) was significantly above normal in southeastern Ellesmere Island (anomalies of +145 to +161 mm) and in Novaya Zemlya and Severnaya Zemlya (+37 to +48 mm), and below normal in south eastern Alaska (-196.5 mm; Table HTC2; Fig. HTC7e). Summer temperature anomalies (JJA 2011 mean at 700 hPa geopotential height, relative to the 1948-2008 mean) were strongly positive over the Canadian Arctic Islands (including Baffin Island) and Severnaya Zemlya (+1.4 to +2.7°C; Table HTC2, Fig. HTC7d), moderately positive in Svalbard and Franz Josef Land (+0.6 to +0.8°C), and negative over Iceland (-0.7°C) and southeast Alaska (-0.79°C). These patterns of summer air temperature anomalies are broadly consistent with the pattern of summer LST anomalies.
 |
Fig. HTC7. (a) Summer (JJA) 2011 700 hPa geopotential height anomalies (relative to 1980-2010) over the Arctic from the NCEP/NCAR R1 Reanalysis; (b) Summer (JJA 2011) 700 hPa meridional wind speed anomalies over the Arctic (yellow/red = northward directed anomaly; blue/green = southward directed anomaly) from the NCEP/NCAR R1 Reanalysis; (c) Summer (JJ) 2011 sea surface temperature anomalies over the Arctic from the HADSST1 dataset; (d) Summer (JJA) 2011 700 hPa air temperature anomalies over the Arctic from the NCEP/NCAR R1 Reanalysis; (e) Winter (September 2010-May 2011) precipitation anomalies from the NCEP/NCAR R1 reanalysis. |
The region of strongly positive summer 700 hPa air temperature anomalies in 2011 over west Greenland, Arctic Canada, Svalbard, Franz Josef Land and Severnaya Zemlya (Fig. HTC7d) was associated with a region of anomalously high 700 hPa geopotential height that was centred over the North Pole and extended across the Canadian Arctic Islands, Greenland, Iceland and the Eurasian Arctic Islands (excluding Novaya Zemlya) (Fig. HTC7a). Anomalous air flow associated with this feature resulted in anomalous poleward-directed meridional winds at 700 hPa over Davis Strait, Baffin Bay and northeastern Canada (Fig. HTC7b). These seem to play an important role in transporting heat to west Greenland, the Canadian Arctic Islands and the more northerly of the Eurasian Arctic archipelagos from a region around southern Greenland and eastern Baffin Bay, where sea surface temperature anomalies in June and July 2011 were +1-2°C (Fig. HTC7c). Atmospheric circulation and air temperature are also described in the essays on Temperature & Clouds and Greenland Ice Sheet.
By comparing the 2010-11 winter precipitation and 2011 summer temperature anomaly patterns with the anomaly patterns and measured mass balances from previous years, we predict negative annual mass balances in most regions in 2010-2011. It seems likely that balances will be less negative than 2009-10 in southern Ellesmere and Devon islands, Iceland and southern Alaska, and more negative in northern Ellesmere and Axel Heiberg islands, Svalbard, Franz Josef Land and Severnaya Zemlya.
References
Gardner, A. S., G. Moholdt, B. Wouters, G. J. Wolken, J. G. Cogley, D. O. Burgess, M. J. Sharp, C. Braun, and C. Labine, 2011: Sharply increased mass loss from glaciers and ice caps in the Canadian Arctic Archipelago. Nature, 473, 357-360.
Meier, M. F., M. B. Dyurgerov, U. K. Rick, S. O'Neel, W. T. Pfeffer, R. S. Anderson, S. P. Anderson and A. F. Glazovsky, 2007: Glaciers dominate eustatic sea level rise in the 21st century. Science, 317, 1064-1067.
Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC), 2010: MODIS subsetted land products, Collection 5. Available on-line [http://daac.ornl.gov/MODIS/modis.html] from ORNL DAAC, Oak Ridge, Tennessee, U.S.A. Accessed September 26, 2011.
Sharp, M., D. O. Burgess, J. G. Cogley, M. Ecclestone, C. Labine, and G. J. Wolken, 2011: Extreme melt on Canada's Arctic ice caps in the 21st century. Geophysical Research Letters, 38, L11501, doi:10.1029/2011GL047381.
World Glacier Monitoring Service, 2011: Glacier mass balance data 2008 and 2009. http://www.geo.uzh.ch/microsite/wgms/mbb/sum09.html. Accessed 2 October 2011.
