Greenland, West Antarctic ice caps melting at half the speed previously estimated

By News Staff
September 6th 2010 01:00 AM The Greenland and West Antarctic ice caps are melting at half the speed previously predicted, shows a team from the Jet Propulsion Laboratory, Delft University of Technology (TU Delft, The Netherlands) and SRON Netherlands Institute for Space Research in Nature Geoscience. The melting of the ice caps has been charted since 2002 using the measurements produced by the two GRACE satellites. From space they detect small changes in the Earth’s gravitational field and these changes are related to the exact distribution of mass on Earth, including ice and water. When ice melts and lands in the sea, this therefore has an effect on the gravitational field. Based on this principle, previous estimates for the Greenland ice cap calculated that the ice was melting at a rate of 230 gigatons per year (i.e. 230,000 billion kg), which would result in an average rise in global sea levels of around 0.75 mm a year.   For West Antarctica, the estimate was 132 gigatons per year. However, it now turns out that these results were not properly corrected for glacial isostatic adjustment, the phenomenon that the Earth’s crust rebounds as a result of the melting of the massive ice caps from the last major Ice Age around 20,000 years ago. These movements of the Earth’s crust have to be incorporated in the calculations, since these vertical movements change the Earth’s mass distribution and therefore also have an influence on the gravitational field. Researchers from the Jet Propulsion Laboratory in Pasadena (US), TU Delft and SRON Netherlands Institute for Space Research have now succeeded in carrying out that correction far more accurately. …

Greenland, West Antarctic Ice Caps Melting At Half The Speed Previously Predicted