Antarctic ice sheet melting 6 times faster than 1980s, say scientists

An atypical study, led by a group of international scientists, including those from NASA’s Jet Propulsion Laboratory (JPL), found that the yearly loss of ice from Antarctica has increased dramatically by an alarming rate of 280 per cent between 2001 and 2017, resulting in rising of sea levels more than half an inch in the last four decades. The research team, which also comprises members of the Utrecht University, Netherlands, discerned that between 1979 and 1990, Antarctica shed an average of 40 gigatons of ice mass annually. From 2009 to 2017, about 252 gigatons per year were lost.

The pace of melting rose at an alarming level over the four-decade period. From 1979 to 2001, it was an average of 48 gigatons annually per decade. The rate jumped 280 per cent to 134 gigatons for 2001 to 2017.

Researchers conducted the longest-ever assessment of remaining Antarctic ice mass for the study, which was first appeared in journal Proceedings of the National Academy of Sciences. The project, which was also geographically comprehensive, examined a total of 18 regions encompassing 176 basins, as well as surrounding islands.

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"As the Antarctic ice sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries," said Eric Rignot, a professor at the University of California, Irvine in the US.

Techniques used to estimate ice sheet balance included a comparison of snowfall accumulation in interior basins with ice discharge by glaciers at their grounding lines, where ice begins to float in the ocean and detach from the bed.

Data were derived from fairly high-resolution aerial photographs taken from a distance of about 350 meters via NASA's Operation IceBridge; satellite radar interferometry from multiple space agencies; and the ongoing Landsat satellite imagery series, begun in the early 1970s.

Rignot said that one of the key findings of the project is the contribution East Antarctica has made to the total ice mass loss picture in recent decades. "The Wilkes Land sector of East Antarctica has, overall, always been an important participant in the mass loss, even as far back as the 1980s, as our research has shown," he added.

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"This region is probably more sensitive to climate change than has traditionally been assumed, and that's important to know because it holds even more ice than West Antarctica and the Antarctic Peninsula together," he added. The sectors losing the most ice mass are adjacent to warm ocean water, researchers said.

"As climate warming and ozone depletion send more ocean heat toward those sectors, they will continue to contribute to sea level rise from Antarctica in decades to come," said Rignot, who's also a senior project scientist at JPL.

(With inputs from agencies)