The West Antarctic Ice Sheet is melting. Scientists led by research leader Benjamin Davison from the University of Leeds have now discovered how strong: According to their study, which was published in the journal "Nature Communications", more than three trillion tons of ice have fallen from the glaciers in the so-called Amundsen Sea over the past 25 years. Region in West Antarctica lost.

The researchers' study is based on computer simulations. According to this, a total of 3331 billion tons of ice melted between 1996 and 2021. This in turn has caused the global sea level to rise by nine millimeters. According to the study, a deviation of plus/minus 420 billion tons is possible.

To get an idea of ​​the amount of ice that melted, the researchers offer a comparison: With this amount, you could cover the entire British capital, London, with a two-kilometer layer of ice, or the whole of Germany with a ten-meter layer of ice. Torsten Albrecht from the Potsdam Institute for Climate Impact Research (PIK) explained to tagesschau.de that although this amount is only a fraction of the total ice mass in Antarctica, PIK sees one of several tipping points in the climate system here. Once they are in a critical state, minor influences could have a major impact on the entire Earth's climate - a self-reinforcing effect.

Even if the rise in sea level of a little less than one percent seems small at first glance, the scientists point out the short period in which it was observed. For comparison, they state that global sea levels have risen by almost 20 centimeters since the start of the industrial revolution.

The main reasons for the ice melt in the Antarctic are, on the one hand, the increased sea temperature and changed currents. These led to the loss of shelf ice and a faster flow rate of the glaciers. The result is that more ice breaks off the glaciers and drifts into the sea.

The researchers were struck by the extent to which precipitation had an impact on glacier melt. Although it is normal for glaciers to lose ice, it would normally be compensated for as snowfall on the ice mass. But especially in years when there was little snowfall - especially between 2009 and 2013, the loss of ice mass was particularly high. Years like 2019 and 2020, in which an above-average amount of snow fell, could not compensate for this loss.

"The 20 glaciers in West Antarctica have lost a great deal of ice over the past quarter century, and there is no evidence that this process will reverse anytime soon," Davison said. It is not yet clear what impact this would have. But one thing is certain: if all the ice in West Antarctica melted, the global sea level would rise by about one meter.

Sources: Study, tagesschau.de