The melting West Antarctica could contribute to sea level rises of up to 7m over the next few centuries.
Credit: SNWA
PERTH: Scientists at the British Antarctic Survey in Cambridge made the discovery using satellites to plot changes in the Earth's gravity from 2002 to 2005.
The results, published in the US journal, Science, confirm concerns raised by other science groups that the melting of big parts of West Antarctica could contribute to sea level rises of up to 7m over the next few centuries.
The East Antarctica sheet appears to be stable, with recent studies suggesting an increase in thickness at rate of 1.8cm a year. The latest data was collected by twin satellites, known as Grace, which orbit the Earth measuring changes in the gravity field over Antarctica. The loss of ice detected by the Grace satellites is equal to an annual increase in global average sea level of 0.4mm.
While the satellites can monitor the entire ice sheet, they cannot pinpoint where the changes are taking place. Another downside is they cannot distinguish between ice and rock, which is corrected for by estimating the rise (towards the surface) of the rock surface of Antarctica.
Uncertainties in the models mean the annual loss of ice can be as low as 72 cubic kilometres or as high as 232 cubic kilometres.
The identical satellites, launched in 2002 as part of the NASA and German Aerospace Centre Gravity Recovery and Climate Experiment, will continue to monitor the ice continent until the Grace mission ends about 2009, which will better refine the rate of loss of ice. BAS researchers also plan to put global positioning systems on rocky outcrops to measure their rise directly.
