Melting ice sheets largest contributor to sea level rise

March 10th, 2011 - 1:38 pm ICT by IANS  

Washington, March 10 (IANS) Melting Greenland and Antarctic ice sheets are overtaking ice loss from mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.

The nearly 20-year study reveals that in 2006, Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average.

That’s enough to raise global sea level by an average of 1.3 mm a year. Ice sheets are defined as being larger than 50,000 sq km, and only exist in Greenland and Antarctica while ice caps are areas smaller than 50,000 sq km, the journal Geophysical Research Letters reports.

“If the present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate Change in 2007,” said lead author Eric Rignot, of NASA’s Jet Propulsion Lab, California, according to a NASA statement.

The pace at which polar ice sheets are losing mass was found to be accelerating rapidly. Each year over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than they did the year before.

Conversely, the 2006 study of mountain glaciers and ice caps estimated their loss at 402 gigatonnes a year on average, with a year-over-year acceleration rate three times smaller than that of the ice sheets.

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