Credit: © Jens Buurgaard Nielsen

Melting ice sheets and glaciers in Greenland contribute to sea level rise and freshening in the North Atlantic Ocean. A new study shows that glacial decline is affecting the Earth's crust as well.

When the large continental ice sheets melted at the end of the last Ice Age, the underlying crust rebounded, much like the surface of a mattress when a weight is removed. Using data from a network of Global Positioning Satellite stations, Shfaqat Khan from the Technical University of Denmark and colleagues1 found that smaller-scale glacial decline also causes detectable uplift in Greenland. The team found that the crust underlying an area near Kulusuk on the southeast coast had risen about 35 mm between 2001 and 2006. They attribute ~60% of the uplift to glacial volume loss from two outlet glaciers located north of Kulusuk. Ice-sheet thinning along the southeast coast accounts for the remaining rebound.

The most rapid increase occurred after spring 2004, concurrent with an acceleration of glacial melting in southern Greenland. The rebound observed at the Kulusuk site suggests that the total rate of ice volume loss along the southeastern coast must be greater than 160 km3 per year — a substantial fraction of Greenland's overall contribution to sea level rise.