On the net mass balance of the glaciers and ice caps in Svalbard, Norwegian Arctic

The ice masses of Svalbard cover an area of ca. 36 600 km(2), and are thus among the largest glaciated areas in the Arctic. Annual mass balance measurements have been carried out on several Svalbard glaciers over up to 30 yr. However, these glaciers extend over only 0.5% of the total ice-covered area. The measured mean net balance has been negative and no changing trend has been observed. On some glaciers and larger ice caps, the mean net balance has also been measured at different altitudes by detecting radioactive reference layers from nuclear fallouts in 1963 and 1986 in shallow ice cores. The net balance/altitude curves have been estimated for thirteen different regions in Svalbard, and combined with digital elevation models of all Svalbard ice masses used to calculate the net balance in each 100-m altitude interval. The net loss of mass through iceberg calving was estimated and appears to be an important component of the net mass loss from Svalbard ice masses. The overall total net balance is slightly negative, -4.5 +/- 1 km(3) yr(-1), giving a specific net balance of ca. - 120 +/- 30 mm yr(-1) over the archipelago. The contribution of ice caps and glaciers on Svalbard to global sea-level change is, therefore, close to 0.01 mm yr(-1) as an average value over the last 30 years, which is less negative than former estimates.