The mass balance of circum-Arctic glaciers and recent climate change

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 km(2) of both the widely glacierized archipelagos of the Canadian, Norwegian, and Russian High Arctic and the area north of about 60 degrees 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(-1) to global sea-level rise. (C) 1997 University of Washington.