The ice sheets covering both ends of Earth are losing mass at an accelerating pace, and are on a faster-than-projected path to surpass other sources of rising sea levels, according to a new study.
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"The magnitude of the acceleration suggests that ice sheets will be the dominant contributors to sea level rise in forthcoming decades," the team of researchers concluded after surveying 18 years of satellite and modeling data from Antarctica and Greenland.
"That ice sheets will dominate future sea level rise is not surprising — they hold a lot more ice mass than mountain glaciers," lead author Eric Rignot, of NASA's Jet Propulsion Laboratory, said in a statement.
"What is surprising is this increased contribution by the ice sheets is already happening," he added. "If 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."
The IPCC's estimate is actually a range — between seven inches and two feet by 2100, with little attributed to ice sheets because the science was less certain when the report was written.
Rignot's team noted that, if current trends hold, the ice sheet melt will raise sea levels by nearly six inches by 2050. Total sea level rise could top 12 inches once melting glaciers and thermal expansion are factored in, they noted.Story: 'Squishy' ice shifts climate models, study says
The researchers used two different techniques to study data between 1992 and 2009, and both concluded significantly faster ice loss.
Greenland's ice sheet lost mass faster than it did in each previous year — by an average of 21.9 gigatonnes a year. (A gigatonne is one billion metric tons, or more than 2.2 trillion pounds.)
In Antarctica, the year-over-year speed up averaged 14.5 gigatonnes.
Other researchers on the team were from the National Center for Atmospheric Research in Boulder, Colo., and Utrecht University in the Netherlands.
The study will be published later this month in the peer-reviewed Geophysical Research Letters, a journal of the American Geophysical Union.
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