Antarctic ice loss has tripled: study

The frozen continent could redraw the earth’s coastlines if global warming continues unchecked

Antarctica has lost a staggering three trillion tonnes of ice since 1992, according to a landmark study published on Wednesday that suggests the frozen continent could redraw the earth’s coastlines if global warming continues unchecked.

Two-fifths of that ice loss occurred in the last five years, a three-fold increase in the pace at which Antarctica is shedding its kilometres-thick casing, a consortium of 84 scientists reported in the journal Nature .

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

Complete picture

“We now have an unequivocal picture of what’s happening in Antarctica,” said co-lead author Eric Rignot, a scientist at NASA’s Jet propulsion Laboratory. “We view these results as another ringing alarm for action to slow the warming of our planet.”

Up to now, scientists have struggled in determining whether Antarctica has accumulated more mass through snowfall than it loses in meltwater run-off and ice flows into the ocean. But more than two decades of satellite data — the new findings draw from 24 separate space-based surveys — have finally yielded a more complete picture.

Covering twice the area of the continental U.S., Antarctica is blanketed by enough ice pack to lift global oceans by nearly 60 metres (210 feet).

More than 90% of that frozen water sits atop East Antarctica, which has remained mostly stable even as climate change has driven up earth’s average surface temperature by a full degree Celsius.

West Antarctica, however, has proven far more vulnerable to global warming. Already floating, ice shelves breaking off into icebergs do not add to sea level. But massive glaciers on West Antarctica slowly gliding seaward hold enough water to push oceans up by 3.5 metres (11 feet).

Two of these glaciers — Pine Island and Thwaites — have accelerated and are today seen as unstable. Together, they act as corks holding back ice mass further inland from falling into the ocean.

Nearly all of the mass shed over the last quarter century has come from West Antarctica, the study found.

Oceans are currently rising by 3.4 millimetres (0.13 inches) per year. Since 1993, the global ocean watermark has gone up by 84.8 mm (3.3 inches).

In another study published in the journal Nature Communications , scientists pointed out that loss of coral reefs due to spikes in water temperature could double the damage from coastal flooding, and triple the destruction caused by storm surges.

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