Rate of Antarctica's ice melting has tripled since 2012, study finds


The latest figures show East Antarctica is losing relatively little ice a year - about 31 tons (28 metric tons) - since 2012.

They also highlight the existential threat facing low-lying coastal cities and communities home to hundreds of millions of people.

Prior to 2012, Antarctica lost 67 billion tonnes (74 billion tons) per year, contributing to a 0.2-millimeter rise in sea levels.

The largest change by far is recorded in an area dominated by marine-terminating glaciers known as West Antarctica.

Between 60 and 90 percent of the world's fresh water is located in Antarctica - the size of Mexico and the United States combined - and if that were to all melt, sea levels would shoot up by nearly 61 metres, which would prove catastrophic for billions of people around the world.

An additional increase in ice losses came from the smaller glaciers of the Antarctic Peninsula, which are also melting rapidly but contain less sea level rise potential.

The global research team analyzed 24 satellite-based estimates of Antarctic ice sheet mass to calculate these rates.

Altogether, across the continent, 34,000 square kilometers (13,000 square miles) of the ice shelf has been lost since the 1950s.

During the same period, the loss of ice for the Antarctic Peninsula went up from seven billion tonnes annually to 33 billion tonnes annually. However, ice retreat today is about more than 20 times that rate - more than 3,200 feet (1 kilometer) per year.

This unthinkable vision can be avoided, but the researchers say the world's climate efforts in the next 10 years will be crucial to securing the mitigated benefits of a low emissions destiny - which would see Antarctica's ice shelves remain intact, only contributing about half a metre to sea level rise by 2070.

Changes in global sea level, from 1992 to 2017, due to contributions from the Antarctic ice sheet.

The research was done by taking data from satellites that have been flying over the Antarctic region for 25 years. "The future of Antarctica is tied to that of the rest of the planet and human society", said Steve Rintoul, of the Centre for Southern Hemisphere Oceans Research in Hobart, Tasmania, and one of the research team. This roughly suggests that Antarctica glacial melting is now adding about 0.5 millimeters per year to sea level rise. The increases are on the order of a few millimetres per year, but scientists need to account for them to ensure their other measures of ice loss are accurate.

"Satellites have given us an unbelievable, continent-wide picture of how Antarctica is changing", said Dr. Pippa Whitehouse, a member of the IMBIE team from Durham University, according to a University of Leeds press release.

Even though Antarctica is covered in ice year-round, its ice sheets retreat and advance in annual cycles, a pattern that has persisted for thousands of years.

Ice mass loss is clearly speeding up, driven largely by what's going on in West Antarctica.

Sea levels will rise and all coastal countries could be seriously threatened by flooding if nothing is done to stop the massive melt of sea ice in Antarctica, according to nine award-winning scientists who have spent decades studying the icy continent and the waters around it.

"The next piece of the puzzle is to understand the processes driving this change", Durham University's Pippa Whitehouse said.

The changes will not be steady, in any case, said Knut Christianson, an Antarctic researcher at the University of Washington in Seattle, by email. However, he says that now the data is tracking a higher scenario, which could mean almost 6 inches of additional sea level rise in the next century.