Irvine, Calif. - Loss of ice in Antarctica has caused global sea levels to rise by 7.6 millimeters since 1992, with 40 percent of the increase happening in just the past five years, according to a team of 84 scientists, including discipline-leading experts from the University of California, Irvine.
Their assessment of conditions in Antarctica is based on combined data from 24 satellite surveys and updates 2012 findings. Results from the project - known as the Ice Sheet Mass Balance Inter-Comparison Exercise - were published today in Nature.
They show that prior to 2012, Antarctica lost ice at a steady rate of 76 billion tons annually - a 0.2 mm-per-year contribution to sea level rise. But since then, there has been a sharp, threefold increase. Between 2012 and 2017, the continent lost 219 billion tons of ice annually - a 0.6 mm-per-year sea level contribution.
"Gravity measurements from the GRACE [Gravity Recovery & Climate Experiment] mission help us track the loss of ice mass in the polar regions and impacts on sea level at points around the planet," said co-author Isabella Velicogna, UCI professor of Earth system science. "The data from GRACE's twin satellites show us not only that a problem exists, but that it is growing in severity with each passing year."
GRACE is a joint mission of NASA and the German Aerospace Center.
Antarctica stores enough frozen water to raise global sea levels by 58 meters, and knowing how much ice it's losing is key to understanding the effects of climate change today and in the future.
The threefold jump in ice loss from the continent as a whole is a combination of increased melting in West Antarctica and the Antarctic Peninsula, with a small signal from the ice sheet in East Antarctica.
West Antarctica experienced the largest change, with ice losses growing from 53 billion tons per year in the 1990s to 159 billion tons annually since 2012. Most of this came from the huge Pine Island and Thwaites glaciers, which are retreating rapidly due to melting by warm ocean waters.
At the northern tip of the continent, ice shelf collapse at the Antarctic Peninsula has driven a 25 billion-ton increase in ice loss since the early 2000s. The East Antarctica ice sheet is thought to have remained relatively stable over the past 25 years.
"With the number of scientific studies focusing on this region, the technological tools we have at our disposal and data sets spanning several decades, we have an unequivocal picture of what's happening in Antarctica," said co-author Eric Rignot, Donald Bren Professor and chair of Earth system science at UCI. "We are confident in our understanding of ice mass change in Antarctica and its impact on sea levels. We view these results as another ringing alarm for action to slow the warming of our planet."
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Rignot, who led the ice mass budget studies for the assessment, and Velicogna, who directed gravity measurement, also serve as research scientists at NASA's Jet Propulsion Laboratory. The project was supported by NASA and the European Space Agency.
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Journal
Nature