Science: Glaciers Important Factor in Sea Level Rise

The Greenland Ice Sheet is melting at an increasing rate—three times faster than in the preceding five years, according to new research published in the 11 August 2006 issue of the journal Science.

In their study, Jianli Chen and colleagues estimate Antarctica’s mass is disappearing at about 240 cubic kilometers per year. If this finding is confirmed, it adds to the body of evidence of increased global warming in recent years and would indicate that melting polar ice sheets are contributing to global sea level rise. The researchers used the Gravity Recovery and Climate Experiment (GRACE) satellite mission to collect data on this second-largest ice sheet on Earth. The satellite measured gravity variation over Greenland and researchers compared monthly data between April 2002 and November 2005 for this report.

In another climate study published in Science, Andrew Monaghan and an international group of colleagues published a study which found no increase in Antarctic snowfall accumulation over the past five decades. This contradicts several previous observational studies using satellite data showing an increase in net snow accumulation.

Precise accumulation data are important because many scientists are uncertain about the role Antarctic ice sheets play in predicting global sea level. Some experts contend a net snow accumulation could play a role in mitigating the ongoing global sea level rise. The researchers studied 16 regions on the continent. Combining field observational data from ice cores and model simulations, the team showed no statistically significant changes in net snowfall over 50 years. Other researchers using climate models have suggested that Antarctic snowfall should increase as world temperature rises because warm air creates more snow since it can hold more moisture than cold air can.

Evelyn Brown

11 August 2006