Author: Laurel Hamers / Source: Science News

Antarctica is losing ice at an increasingly rapid pace. In just the last five years, the frozen continent has shed ice nearly three times faster on average than it did over the previous 20 years.
An international team of scientists has combined data from two dozen satellite surveys in the most comprehensive assessment of Antarctica’s ice sheet mass yet. The conclusion: The frozen continent lost an estimated 2,720 billion metric tons of ice from 1992 to 2017, and most of that loss occurred in recent years, particularly in West Antarctica. Before 2012, the continent shed ice at a rate of 76 billion tons each year on average, but from 2012 to 2017, the rate increased to 219 billion tons annually.
Combined, all that water raised the global sea level by an average of 7.6 millimeters, the researchers report in the June 14 Nature. About two-fifths of that rise occurred in the last five years, an increase in severity that is helping scientists understand how the ice sheet is responding to climate change.
“When we place that against the [Intergovernmental Panel on Climate Change’s] sea level projections, prior to this Antarctica was tracking the low end of sea-level-rise projections,” says study coauthor Andrew Shepherd, an earth scientist at the University of Leeds in England. “Now it’s tracking the upper end.”
Antarctica currently contains enough frozen water to raise the oceans by 58 meters. Melting ice from the continent is a major driver of the sea level rise that’s threatening coastal communities and ecosystems around the world with flooding as the climate changes (SN: 12/27/14, p. 29). A good estimate of Antarctica’s ice loss will help climate scientists better predict future sea level rise, Shepherd says, as the planet continues to warm.
Melting ice in Antarctica has been fueling global sea level rise for a while, but the rate at which it’s occurring has sped up in the last five years. The majority of the ice loss is happening in West Antarctica.

But in a place as big as Antarctica, it’s not easy to gauge the…
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