Rate of Antarctic ice melt triples since 2012
June 14, 2018
The rate of ice loss in Antarctica has tripled since 2012, causing global sea levels to rise at their fastest rate in 25 years, a new study published by an international team of experts said Wednesday
Over the last quarter century, about 3 trillion tons of Antarctic ice melt made ocean levels rise by 7.6 millimeters (0.3 inches), according to the study published in the journal Nature. About two-fifths of that rise, or 3 millimeters, has occurred since 2012.
The study of Antarctic ice mass changes by scientists working for NASA and the European Space Agency is the most comprehensive to date. It combined 24 satellite surveys and involved 80 scientists from 42 international organizations.
If all of Antarctica's ice were to melt, global sea levels would rise by 58 meters (190 feet).
The study found that from 1992 to 2011, Antarctica lost about 83.8 billion tons (76 billion metric tons) of ice per year, causing an annual sea level rise of 0.2 millimeters. Between 2012 and 2017, ice loss per year tripled to 241.4 billion tons, amounting to a 0.6 millimeters sea level rise per year.
"Under natural conditions we don't expect the ice sheet to lose ice at all," said lead author Andrew Shepherd of the University of Leeds in England. "There are no other plausible signals to be driving this other than climate change."
About 70 percent of melting occurred in West Antarctica, where ocean-induced melting resulted in 58.4 billion tons of ice loss per year in the 1990s and 175.3 billion tons a year since 2012.
Part of West Antarctica "is in a state of collapse," said co-author Ian Joughin of the University of Washington.
Meanwhile, ice-shelf collapse in the Antarctic Peninsula led to the northern tip of the continent losing 27.6 billion tons of ice per year since the early 2000s.
East Antarctica has remained relatively stable during the past 25 years. East Antarctica largely sits on land mass and is not subject to the same forces that are driving the melting process in West Antarctica and the Antarctic Peninsula.
Scientists said much of the retreating ice shelf is caused by ocean-induced melting, when warmer water causes melting from the edges and below ice sheets.
Lead author Rob Massom, of the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Center, said reduced sea ice coverage has also exposed ice shelves to ocean swells.
"Sea ice acts as a protective buffer to ice shelves, by dampening destructive ocean swells before they reach the ice shelf edge," said Massom.
"But where there is loss of sea ice, storm-generated ocean swells can easily reach the exposed ice shelf, causing the first few kilometers of its outer margin to flex," he said, adding this exacerbates pre-existing fractures on the ice shelves and their collapse.