Satellite images show that Antarctica’s ice sheet is collapsing faster than previously thought

“Antarctica is collapsing at its edges,” Green said in NASA’s announcement of the results. “And as the ice shelves dwindle and weaken, the massive glaciers on the continent tend to accelerate and increase the rate of global sea level rise.”

The consequences could be dire. He said Antarctica has 88% of the sea-level potential of all the world’s ice.

Ice shelves, permanent floating sheets of frozen fresh water attached to the land, take thousands of years to form and act like struts preventing glaciers that would have easily slipped into the ocean, causing the seas to rise.

When ice shelves are stable, the natural, long-term cycle of birth and regrowth keeps their size fairly constant.

But in recent decades, warming oceans have weakened the shelves from below, a phenomenon previously documented by satellite altimeters that measure the changing height of ice and showing losses averaging 149 million tons per year from 2002 to 2020, according to NASA.

photos from space

For their analysis, Greene’s team compiled satellite images from visible, infrared, thermal, and radar wavelengths to chart glacial flow and calving since 1997 more accurately than ever before over 30,000 miles (50,000 km) of Antarctica’s coast.

Measured losses from calving calves have exceeded natural ice shelf regeneration so much that researchers have found that Antarctica is unlikely to return to pre-2000 levels of glaciers by the end of this century.

The acceleration of ice birth, such as ice thinning, was most pronounced in West Antarctica, an area hit hardest by warming ocean currents. Even in East Antarctica, a region whose ice shelves have long been considered less vulnerable, Green said, “we’re seeing more losses than gains.”

One of the East Antarctic birth events that surprised the world, Green said, was the collapse and disintegration of the massive Konger-Glenzer ice shelf in March, perhaps a sign of greater weakness to come.

Eric Wolf, Royal Society Research Professor at the University of Cambridge, points to the study’s analysis of how the East Antarctic ice sheet behaved during warm periods in the past and models for what might happen in the future.

“The good news is that if we maintain the two degrees of global warming promised by the Paris Agreement, sea level rise due to the East Antarctic ice sheet should be modest,” Wolf wrote in a commentary on the JPL study.

He said failure to reduce greenhouse gas emissions would risk contributing “several meters of sea level rise over the next few centuries”.