Recent contributions of glaciers and ice caps to sea level rise
Résumé
Glaciers and ice caps (GICs) are important contributors to present-day global mean sea level rise1, 2, 3, 4. Most previous global mass balance estimates for GICs rely on extrapolation of sparse mass balance measurements1, 2, 4 representing only a small fraction of the GIC area, leaving their overall contribution to sea level rise unclear. Here we show that GICs, excluding the Greenland and Antarctic peripheral GICs, lost mass at a rate of 148 ± 30 Gt yr−1 from January 2003 to December 2010, contributing 0.41 ± 0.08 mm yr−1 to sea level rise. Our results are based on a global, simultaneous inversion of monthly GRACE-derived satellite gravity fields, from which we calculate the mass change over all ice-covered regions greater in area than 100 km2. The GIC rate for 2003-2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period2. The high mountains of Asia, in particular, show a mass loss of only 4 ± 20 Gt yr−1 for 2003-2010, compared with 47-55 Gt yr−1 in previously published estimates2, 5. For completeness, we also estimate that the Greenland and Antarctic ice sheets, including their peripheral GICs, contributed 1.06 ± 0.19 mm yr−1 to sea level rise over the same time period. The total contribution to sea level rise from all ice-covered regions is thus 1.48 ± 0.26 mm −1, which agrees well with independent estimates of sea level rise originating from land ice loss and other terrestrial sources6.