Jan Lieser had just started going through the dozens of satellite images he looks at every day when he realised something was missing. As a glaciologist at the University of Tasmania’s Institute for Marine and Antarctic Studies, he knew the shape of every ice shelf sticking out from the coast of East Antarctica. And on 17 March 2022, there was a gap where most of the Conger glacier’s ice shelf had broken off into an iceberg the size of Vienna and drifted away.
Lieser was stunned. He had been keeping an eye on Conger since the last few pieces of the neighbouring Glenzer ice shelf had broken up 10 days before, but he had not expected to see it disintegrate so quickly. “All of a sudden the rest of the land-fast ice collapsed, and the ice shelf moved northward and turned 90 degrees sideways. Two features we had been monitoring for years weren’t there anymore,” he says. “In my 15 years of looking at it, I have not expected to see that in East Antarctica.”
Glaciers flow toward the ocean, and an ice shelf is the part that floats on the water, rubbing up against islands, underwater ridges or other glaciers. Ice shelves are often called Antarctica’s “safety band”. When they break up, the glaciers behind them can start flowing faster into the sea, contributing to sea level rise. The Conger glacier is relatively small and slow, but the swift demise of its safety band nonetheless had scientists worried. This was the first ice shelf on record to collapse in East Antarctica, the vast frozen dome separated from the more travelled West Antarctica by the tortuous sandstone ridges of the Transantarctic Mountains. While the melting West Antarctic ice sheet may have already reached a tipping point, scientists had long thought that its eastern counterpart, the coldest place on Earth, was resistant to global warming. In 2012 the East Antarctic ice sheet had even been found to be gaining mass overall.
But new research is revealing chinks in East Antarctica’s icy armour. [Continue reading…]