THE first survey of gravity changes caused by the Antarctic ice sheet has confirmed that it is shrinking at an alarming rate.
The result comes from the Gravity Recovery and Climate Experiment (GRACE), a pair of NASA/German satellites. The twin satellites fly in formation, 220 kilometres apart, and measure small changes in Earth’s gravity caused by shifts in the distribution of its mass.
Isabella Velicogna and John Wahr from the University of Colorado in Boulder analysed GRACE observations and found that between April 2002 and August 2005 the Antarctic ice sheet shrank by 150 cubic kilometres annually.
Most of the…
