Acceleration in thinning rate on western Svalbard glaciers

Geodetic measurements indicate that a number of glaciers in western Svalbard ranging in size from 5 1000 km 2 are losing mass at an accelerating rate. The average thinning rate for Midtre Lovenbreen, the glacier with the best data coverage, has increased steadily since 1936. Thinning rates for 2003-2005 are more than 4 times the average for the first measurement period 1936-1962 and are significantly greater than presented previously. On Slakbreen, thinning rates for the latest measurement period 1990-2003 are more than 4 times that of the period 1961-1977. Thinning of several glaciers along a previously measured airborne lidar profile in Wedel Jarls Land has also increased, doubling between the period 1990-1996 and 1996-2002. Our results imply an increased sea level contribution from Svalbard. In addition, the mass loss is an important influence on measured rates of rebound on western Svalbard and should be factored into analysis of GRACE results.