Antarctica’s melting reaches tipping point – DW – 06/28/2024

Two scientists have found that Antarctica is heading toward “uncontrolled melting” of its ice sheets, caused by warm ocean water infiltrating between the ice and the land on which it lies, a study published Tuesday (25.06.2024) said. .) journal Nature Geoscience.

Although this has been observed before, the models used by the UN Panel on Climate Change (IPCC) to project the impact of global warming on Antarctica have not yet taken this phenomenon into account, thereby underestimating the ice loss.

Pass the turning point

As ocean temperatures rise due to human-caused global warming, Antarctica’s ice sheets are melting, posing the threat of global sea level rise and endangering coastal communities.

“Increasing ocean temperatures could lead to a critical point beyond which ocean water flows unrestrictedly under the ice sheet through an uncontrolled melting process,” the study notes.

Warm water seeps in and speeds up the melting.

Antarctic ice sheets lie on cliffs and extend beyond the coast, floating on the sea. Previous research has shown that warm seawater seeps into the “base zone” where land and ice meet and is channeled inland from beneath the floating ice.

As water warms, even slightly, seepage accelerates over short distances of 100 meters to tens of kilometers, melting ice along the way, heating it from below, explains study lead author Alexander Bradley.

Sea level rise

The risk of sea level rise occurs when ice melts faster than new ice forms on the continent. Some areas of Antarctica are more vulnerable to this process than others due to the shape of the land, which has valleys and depressions where seawater can accumulate under the ice.

Pine Island Glacier, the biggest contributor to sea level rise on the white continent, is at high risk of melting due to the slope of the terrain, which allows more seawater to flow in, according to the study.

Bradley calls for scientific models to be updated to take this phenomenon into account: “It really just highlights the need for urgent climate action to prevent these tipping points from being crossed,” he concludes.

Yu (AFP, Nature)