Antarctica’s ice sheet is melting at a rapidly increasing rate, now pouring more than 200 billion tons of ice into the ocean annually and raising sea levels a half-millimeter every year, a team of 80 scientists reported Wednesday.
The melt rate has tripled in the past decade, the study concluded. If the acceleration continues, some of scientists’ worst fears about rising oceans could be realized, leaving low-lying cities and communities with less time to prepare than they had hoped.
The result also reinforces that nations have a short window — perhaps no more than a decade — to cut greenhouse-gas emissions if they hope to avert some of the worst consequences of climate change.
Antarctica, the planet’s largest ice sheet, lost 219 billion tons of ice annually from 2012 through 2017 — approximately triple the 73 billion-ton melt rate of a decade ago, the scientists concluded. From 1992 through 1997, Antarctica lost 49 billion tons of ice annually.
The study is the product of a large group of Antarctic experts who collectively reviewed 24 recent measurements of Antarctic ice loss, reconciling their differences to produce the most definitive figures yet on changes in Antarctica. Their results — known formally as the “Ice Sheet Mass Balance Inter-Comparison Exercise” (IMBIE) — were published Wednesday in the journal Nature.
“We took all the estimates across all the different techniques, and we got this consensus,” said Isabella Velicogna, an Antarctic expert at the University of California at Irvine and one of the many authors from institutions in 14 countries. The lead author was Andrew Shepherd of the University of Leeds in England.
“The detailed record shows an acceleration, starting around 2002,” Beata Csatho, one of the study authors and a glaciologist at the University at Buffalo, said in an email.
Csatho noted that comparing the first and last five-year periods in the record reveals an even steeper acceleration. “Actually, if you compare 1997-2002 to 2012-2017, the increase is even larger, a factor of more than 5!!” she wrote.