Satellite images show Antarctic sea ice is collapsing faster than previously thought

Antarctic coastal glaciers are shedding ice sheets faster than nature can replenish them, doubling previous estimates of damage from the world’s largest ice sheet in the past 25 years, satellite analysis found on Wednesday.

The study, the first of its kind conducted by researchers at NASA’s Jet Propulsion Laboratory (JPL) near Los Angeles and published in the journal Nature, raises new concerns about how rapidly climate change is weakening Antarctica’s floating ice and accelerating global sea level rise. The main conclusion of the study was that the net loss of Antarctic ice due to coastal ice “breaking up” at sea is almost as much as the net amount of ice that scientists already know is lost due to thinning caused by melting. Ice shelves are bottomed out by the warming of the ocean.

Together, thinning and bending have reduced the mass of Antarctic ice shelves by 12 billion tons since 1997, double previous estimates, the analysis concluded. The study’s lead author, JPL scientist Chad Green, said the net loss of the continent’s ice sheet over the past quarter century alone was about 37,000 square kilometers (14,300 square miles), roughly the size of Switzerland.

“Antarctica is falling apart,” Greene said in a NASA announcement about the discovery. “And as the ice shelves shrink and weaken, the continent’s massive glaciers accelerate and increase the rate of global sea-level rise. The consequences can be huge. He said 88% of the sea-level potential of all the world’s ice is in Antarctica.

Ice shelves, permanent floating sheets of frozen fresh water attached to land, take thousands of years to act as buttresses holding back glaciers that would otherwise slide easily into the sea, causing sea level rise. While ice shelves are stable, natural long-term cycles of bending and regrowth keep their size fairly constant.

However, in recent decades, ocean warming has weakened the shelves from below, a phenomenon previously documented by satellite altimeters that measure the evolution of ice extent and show an average loss of 149 million tons per year between 2002 and 2020. to NASA Photos from the location

For their analysis, Green’s team synthesized visible, thermal and infrared wavelength satellite images and radar from 1997 to more precisely map ice flow and calving 30,000 miles (50,000 km) off the Antarctic coastline. Measured calving losses have so far outpaced natural ice shelf replenishment that researchers find unlikely that Antarctica could return to pre-2000 glaciation levels by the end of this century.

Accelerated glacier breakup, like ice thinning, has been most pronounced in West Antarctica, an area hit hardest by warming ocean currents. But even in East Antarctica, an area whose sea ice has long been considered less vulnerable, “we’re seeing more losses than gains,” Greene said. Green said one event in the East Antarctic turn that surprised the world was the collapse and breakup of the massive Conger-Glenger Ice Shelf in March, possibly a sign of further weakening ahead.

Eric Wolff, Royal Society Research Professor at the University of Cambridge, presented his analysis of the behavior of the East Antarctic Ice Sheet during past warm periods and patterns of what might happen in the future. . “The good news is that if we keep to the 2 degrees of global warming promised by the Paris Agreement, sea level rise from the East Antarctic Ice Sheet is expected to moderate,” Wolff wrote in a statement. Commentary on the JPL study

However, if greenhouse gas emissions are not reduced, they risk contributing to “several meters of sea level rise over the next century”.

(This story has not been edited by the Devdiscourse team and is generated automatically from a syndicated feed.)

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