RECENT INCREASED VOLUME LOSS OF RABOTS GLACIÄR, NORTHERN SWEDEN, LINKED TO MORE NEGATIVE SUMMER MASS BALANCES

Terminus geometry, ice margins, and surface elevations on Rabots glaciär were measured using differential GPS during summer 2011 and compared with those similarly measured in 2003. Glacier length over the eight years decreased by ~105 m corresponding to 13 m a^-1, a rate consistent with ice recession over the last several decades. Measured changes in surface elevations show that between 2003 and 2011 the glacier’s volume decreased by ~ 27.6 ± 2.6 x 10⁶ m³, or 3.5 ± 0.3 x 10⁶ m³ a^-1. This compares favorably with an estimate of -28.1 ± 2.6 x 10⁶ m³ based on a mass-balance approach. The rate of volume loss appears, however, to have significantly increased after 2003, being substantially greater than rates determined for the intervals 1959-80, 1980-89, and 1989-2003. Correlation between the rate of volume loss and mean winter and summer balances allowed the effect of variations of the latter to be examined individually and suggests the recent increased volume loss can be attributed almost entirely to persistent more negative summer balances (with respect to the mean). This interval of sustained and extraordinary negative summer balances most probably reflects accelerated regional warming that occurred during the last decade.