Change in geometry of a high Arctic glacier from 1948 to 2013 (Austre Lovenbreen, Svalbard)

The change of Austre Lovenbreen, a 4.5km(2) land-based glacier along the west coast of Spitsbergen, is investigated using geodetic methods and mass balance measurements over 1948-2013. For 2008-2013, annual mass balances computed on 36-stake measurements were obtained, in addition to annual mass balances reconstructed from the neighbouring glaciers, Midtre Lovenbreen (1968-2007) and Austre BrOggerbreen (1963-1967). The mean rate of glacier retreat for 1948-2013 is -16.7 +/- 0.3ma(-1). Fluctuations in area (1948-2013 mean, -0.027 +/- 0.002km(2)a(-1)) showed a slowing as the glacier recedes within its valley from 1990 to 1995. For 1962-2013, the average volume loss calculated by digital elevation model subtraction of -0.441 +/- 0.062m w.e.a(-1) (or -0.54 +/- 0.07% a(-1)) is similar to the average annual mass balance (-0.451 +/- 0.007m w.e.a(-1)), demonstrating a good agreement between the loss rates computed by both methods over 1962-2013. When divided in two periods (1962-1995 and 1995-2013), an increase in the rate of ice mass loss is statistically significant for the glacier volume change. The 0 degrees C isotherm elevation (based on mean May-September air temperatures) is estimated to have risen by about 250m up to the upper parts of the glacier between 1948 and 2013. The glacier area exposed to melting during May to September almost increased by 1.8-fold while the area reduced by a third since 1948. Within a few years, the glacier area exposed to melting will decrease, leading the upper glacier parts under the 0 degrees C isotherm while the snout will keep on retreating.