Increasing rates of ice mass loss from the Greenlandand Antarctic ice sheets revealed by GRACE

摘要

We use monthly measurements of time-variable gravityfrom the GRACE (Gravity Recovery and ClimateExperiment) satellite gravity mission to determine the icemass-loss for the Greenland and Antarctic Ice Sheets duringthe period between April 2002 and February 2009. We findthat during this time period the mass loss of the ice sheetsis not a constant, but accelerating with time, i.e., that theGRACE observations are better represented by a quadratictrend than by a linear one, implying that the ice sheetscontribution to sea level becomes larger with time. InGreenland, the mass loss increased from 137 Gt/yr in2002-2003 to 286 Gt/yr in 2007-2009, i.e., an accelerationof —30 ± 11 Gt/yr~2in 2002-2009. In Antarctica the massloss increased from 104 Gt/yrin 2002-2006 to 246 Gt/yrin 2006-2009, i.e., an acceleration.of —26 ± 14 Gt/yr~2in2002-2009. The observed acceleration in ice sheet massloss helps reconcile GRACE ice mass estimates obtainedfor different time periods. Citation: Velicogna, I. (2009), Increasing rates of ice mass loss from the Greenland and Antarcticice sheets revealed by GRACE.