SOURCE: The Guardian

DATE: July 9, 2019

SNIP: Antarctica faces a tipping point where glacial melting will accelerate and become irreversible even if global heating eases, research suggests.

A Nasa-funded study found instability in the Thwaites glacier meant there would probably come a point when it was impossible to stop it flowing into the sea and triggering a 50cm sea level rise. Other Antarctic glaciers were likely to be similarly unstable.

Recent research found the rate of ice loss from five Antarctic glaciers had doubled in six years and was five times faster than in the 1990s. Ice loss is spreading from the coast into the continent’s interior, with a reduction of more than 100 metres in thickness at some sites.

The Thwaites glacier, part of the West Antarctic ice sheet, is believed to pose the greatest risk for rapid future sea level rise. Research recently published in the Proceedings of the National Academy of Sciences journal found it was likely to succumb to instability linked to the retreat of its grounding line on the seabed that would lead to it shedding ice faster than previously expected.

Alex Robel, an assistant professor at the US Georgia Institute of Technology and the study’s leader, said if instability was triggered, the ice sheet could be lost in the space of 150 years, even if temperatures stopped rising. “It will keep going by itself and that’s the worry,” he said.

Modelling simulations suggested extensive ice loss would start in 600 years but the researchers said it could occur sooner depending on the pace of global heating and nature of the instability.