Recent Ice-Sheet Growth in the Interior of Greenland

Abstract

A continuous data set of Greenland Ice Sheet altimeter height from ERS-1 and ERS-2 satellites, 1992 to 2003, has been analyzed. An increase of 6.4 ± 0.2 centimeters per year is found in the vast interior areas above 1500 meters, in contrast to previous reports of high-elevation balance. Below 1500 meters, the elevation-change rate is -2.0 ± 0.9 cm/year, in qualitative agreement with reported thinning in the ice-sheet margins. The spatially averaged increase is 5.4 ± 0.2 cm/year, or ~60 cm over 11 years, or ~54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation.

Acceleration of Greenland ice mass loss in spring 2004

“…Regional climate models, supported by in situ observations, suggest that both accumulation and melting have increased during the past decade, with melting increasing faster than accumulation 5 . These surface mass balance estimates are consistent with radar altimeter measurements during 1992-2003 that show interior growth 6,7 , and with laser altimeter observations that show thinning in the 1990s at low elevations 8 where increased melting is probably more important than increased accumulation. Laser altimeter and satellite radar imaging observations over the last decade have shown accelerated glacial mass loss at the ice sheet margins 2-4,9,10 .…”

Ice-sheet contributions to future sea-level change

“…The imbalance is caused by a combination of changes in all the terms. From previous sections, we would expect twentieth-century climatic warming to have led to greater R, exceeding the accompanying increase in S for the ice sheet as a whole, although in the interior the accumulation increase should produce a thickening, which has been confirmed for 1992-2003 from satellite altimetry (Johannessen et al 2005).…”

Tipping elements in the Earth's climate system

“…These changes include melting and thinning of the coastal margins (30) and surging of outlet glaciers (29,31), which may be contributed to by the intrusion of warming ocean waters (32). This is partly compensated by some mass gain in the interior (33). There is a lack of knowledge of natural GIS variability, and Greenland temperature changes have differed from the global trend (26), so interpretation of recent observations remains uncertain.…”