CHANGES IN THE LENGTH AND VOLUME OF RABOTS GLACIÄR, SWEDEN, 2003-2011 BASED ON GEODETIC METHODS

Terminus geometry and surface elevations on Rabots glaciär were measured using differential GPS during Summer 2011 and compared with those similarly measured in 2003. Ice retreat over the eight years was ~105 m corresponding to 13 m a^-1, a rate consistent with changes in the glacier’s length over the last several decades. Measured changes in ice surface elevations suggest that between 2003 and 2011 the glacier lost ~ 27.6 x 10⁶ m³, or 3.5 x 10⁶ m³ a^-1. The rate of volume loss appears to have significantly increased after 2003, being substantially greater than rates determined for the intervals 1959-80, 1980-89, and 1989-2003. A volume-area scaling provided an estimate of volume change between the onset of retreat in 1910 and 1959. Using this estimate, cumulative volume loss since retreat began is 192.0 x 10⁶ m³ based on post-1959 changes in ice surface elevations, or as much as 213.3 x 10⁶ m³ using a composite mass-balance record. Rabots glaciär never completed its response to a ~1°C warming that occurred ca. 1900, and thus the current marked increase rate of ice loss might reflect the effect of recent, or accelerated regional warming that occurred during the last decade superimposed on its continued response to that earlier warming.