Thinning Antarctic ice shelf finally crumbles after heatwave

Satellite images show the 1,200 square-kilometre Conger Ice Shelf collapsed completely on or around March 15.

Ice shelves, permanent floating sheets of ice attached to land, take thousands of years to form and act like levees holding back snow and ice that would otherwise flow into the ocean, causing seas to rise.

The March heat wave, with temperatures reaching 70 degrees Fahrenheit (40 degrees Celsius) above normal in parts of East Antarctica, was tied to the atmospheric river phenomenon, said Peter Neff, a glaciologist at the University of Minnesota.

This process creates columns hundreds of miles long that carry water vapour from the tropics, creating an effect Neff described as "a fire hose of moisture."

"The (Antarctic) climate is incredibly variable but this was off-scale," Neff said. "This was at least twice as extreme of a warming event as we would have expected."

Temperatures in the region normally sit around -60 degrees Fahrenheit (-51 degrees Celsius) at this time of year, but they were around 10 degrees (-12 Celsius) earlier this month.

Surrounded by vast oceans and buffered by winds that tend to protect it from large warm-air intrusions, the frozen continent is responding more slowly to climate change than the Arctic, which is warming at three times the rate of the rest of the world.

In the last century, East Antarctica barely warmed at all, but some regions have been affected and the continent lost an average of 149 billion tonnes of ice per year from 2002 to 2020, according to NASA. The loss of the Conger Ice Shelf is the latest example of changes afoot.