Partitioning Recent Greenland Mass Loss

TLDR

Mass budget calculations, validated with GRACE satellite gravity observations, enable quantification of the individual components of recent Greenland mass loss. From 2000–2008 Greenland lost ~1500 Gt (0.46 mm yr⁻¹ sea‑level rise), split evenly between surface runoff/precipitation and ice dynamics; without enhanced snowfall and refreezing, losses would have doubled, and since 2006 summer melt has raised annual loss to 273 Gt yr⁻¹ (0.75 mm yr⁻¹), while the seasonal surface mass balance cycle explains GRACE variations, indicating minimal subannual ice discharge changes.

Abstract

Mass budget calculations, validated with satellite gravity observations [from the Gravity Recovery and Climate Experiment (GRACE) satellites], enable us to quantify the individual components of recent Greenland mass loss. The total 2000-2008 mass loss of approximately 1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics. Without the moderating effects of increased snowfall and refreezing, post-1996 Greenland ice sheet mass losses would have been 100% higher. Since 2006, high summer melt rates have increased Greenland ice sheet mass loss to 273 gigatons per year (0.75 millimeters per year of equivalent sea level rise). The seasonal cycle in surface mass balance fully accounts for detrended GRACE mass variations, confirming insignificant subannual variation in ice sheet discharge.