The Mass Balance of Circum-Arctic Glaciers and Recent Climate Change

Abstract

The sum of winter accumulation and summer losses of mass from glaciers and ice sheets (net surface mass balance) varies with changing climate. In the Arctic, glaciers and ice caps, excluding the Greenland Ice Sheet, cover about 275,000 km2of both the widely glacierized archipelagos of the Canadian, Norwegian, and Russian High Arctic and the area north of about 60°N in Alaska, Iceland, and Scandinavia. Since the 1940s, surface mass balance time-series of varying length have been acquired from more than 40 Arctic ice caps and glaciers. Most Arctic glaciers have experienced predominantly negative net surface mass balance over the past few decades. There is no uniform recent trend in mass balance for the entire Arctic, although some regional trends occur. Examples are the increasingly negative mass balances for northern Alaska, due to higher summer temperatures, and increasingly positive mass balances for maritime Scandinavia and Iceland, due to increased winter precipitation. The negative mass balance of most Arctic glaciers may be a response to a step-like warming in the early twentieth century at the termination of the cold Little Ice Age. Arctic ice masses outside Greenland are at present contributing about 0.13 mm yr−1to global sea-level rise.

Acceleration in thinning rate on western Svalbard glaciers

“…Surface deformation data from Ny-Å lesund, NW Svalbard as determined from GPS and VLBI data [Sato et al, 2006] indicate a contemporary uplift rate which, if it were attributed solely to elastic uplift in response to mass loss from Svalbard glaciers, would be equivalent to À0.75 m a À1 , in meters water equivalent. Again, this is a greater mass loss than prior estimates [Dowdeswell et al, 1997;Van de Wal and Wild, 2001;Hagen et al, 2003aHagen et al, , 2003b, which are based on assorted mass balance data averaged over variable periods, but roughly from the mid-1960s to 2000. The acceleration in thinning we observe implies a greater contribution from this region to sea level rise, even considering the concurrent reduction in glaciated area, which in western Svalbard amounts to only $0.3% per year for the period 1936 -1990 [Nuth et al, 2007].…”

Possible interactions between bacterial diversity, microbial activity and supraglacial hydrology of cryoconite holes in Svalbard

“…The annual mass-balance monitoring conducted by the Norsk Polar Institutt (Dowdeswell et al, 1997) includes two of the glaciers studied here, with both AB and ML experiencing similar surface meltrates of up to 1-2 m per year (Hagen et al, 2003), and it is likely that surface melt rates would be similar on VB. The upper surfaces of all three glaciers therefore experience ubiquitous melting in their lower reaches during the months of summer.…”

Hydrology and dynamics of a polythermal (mostly cold) High Arctic glacier

“…The issue is especially pertinent in the High Arctic (>75°N) where recent climate models predict exceptional warming over the next century (Manabe et al, 1991;Cattle and Crossley, 1995;Houghton et al, 2001). The many small-to medium-sized glaciers that exist throughout the region (covering c. 275 000 km 2 ) are likely to respond much more rapidly to climate warming than the major ice sheets, and may contribute significantly to eustatic sea level rise over the next century (Prowse, 1990;Dowdeswell et al, 1997;Munro, 2000). However, the coupling between hydrology and dynamics has not been considered adequately in recent models of High Arctic glacier response to climate change (Houghton et al, 2001), owing largely to limited understanding of such coupling in the mostly cold polythermal glaciers that characterize the High Arctic.…”