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Warming warning: West Antarctic ice loss rate tripled in 25 years, study shows

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This chart shows the contribution to global sea levels due to changes in the mass balance of the Antarctic ice sheet between 1992 and 2017. (IMBIE / Planetary Visions Graphic)

An analysis of satellite data collected since 1992 suggests that ocean-driven melting has led to a tripling in the rate of ice loss from West Antarctica, from 53 billion to 159 billion metric tons per year.

The study was conducted by a group of researchers as part of the Ice Sheet Mass Balance Inter-comparison Exercise, or IMBIE, and published today in the journal Nature.

Estimated annual ice loss from the Antarctic Peninsula rose from 7 billion to 33 billion metric tons over the same 25-year period, due to ice shelf collapse.

East Antarctica’s ice sheet, however, is gaining mass at an average rate of 5 billion metric tons per year. The main factor behind that gain appears to be fluctuations in snowfall, researchers said.

The analysis suggests that 3 trillion tons’ worth of Antarctic ice losses have increased global sea levels by 7.6 mm (0.3 inches) since 1992, and that the increase is accelerating.

“The continent is causing sea levels to rise faster today than at any time in the past 25 years,” one of the study’s lead authors, Andrew Shepherd of the University of Leeds, said in a news release. “This has to be a concern for the governments we trust to protect our coastal cities and communities.”

Benjamin Smith, senior principal investigator at the University of Washington Applied Physics Laboratory, said climate scientists are getting a better handle on crucial questions relating to the impact of Antarctic melting, thanks to more advanced satellites.

“We’re at a really exciting time in Antarctic glaciology, in that we have a lot of mature technologies for measuring ice-sheet changes that were not available when I started in the field in the early 2000s,” Smith said.

Satellites contributing to the project include CryoSat, Sentinel-1 and the U.S.-German GRACE satellites. Future data from spacecraft such as ICESat-2, GRACE-FO and NISAR should provide an even more detailed picture of global ice loss and sea level rise.

“The next piece of the puzzle is to understand the processes driving this change,” Durham University’s Pippa Whitehouse said. “To do this, we need to keep watching the ice sheet closely, but we also need to look back in time and try to understand how the ice sheet responded to past climate change.”

Shepherd, Smith and Whitehouse are among 80 IMBIE team members listed as authors of the Nature paper, “Mass Balance of the Antarctic Ice Sheet From 1992 to 2017.” This week’s issue of Nature features several other reports on Antarctica and its future.

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