Antarctic ice loss has tripled in a decade. If that continues, we are in serious trouble

Antarctica’s ice sheet is melting at 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’d 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, Irvine, and one of the many authors from institutions in 14 separate countries. The lead author was Andrew Shepherd of the University of Leeds in the U.K.

“The detailed record shows an acceleration, starting around 2002,” said Beata Csatho, one of the study authors and a glaciologist at the State University of New York at Buffalo, 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!!”

For the total period from 1992 through the present, the ice sheet has lost nearly 3 trillion tons of ice, equating to just under 8 millimeters of sea level rise. Forty percent of that loss has occurred in just the last 5 years, again underscoring the increase in losses recently.

Looking closer, the rapid, recent changes are almost entirely driven by the West Antarctic ice sheet, which scientists have long viewed as an Achilles’ heel. It is known to be losing ice rapidly because it is being melted from below by warm ocean waters, a process that is rendering its largest glaciers unstable.

West Antarctica lost 159 billion tons of ice a year from 2012 through 2017, compared with just 65 billion tons from 2002 through 2007.

The growth is largely attributable to just two huge glaciers – Pine Island and Thwaites. The latter is increasingly being viewed as posing a potential planetary emergency, because of its enormous size and its role as a gateway that could allow the ocean to someday …read more

Source:: Nationalpost

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