Melting glaciers can endanger world cities, warn simulations – ČT24 – Czech Television

Simulations by scientists from Potsdam, Germany, confirm that a very slow but relentless process is continuing: if temperatures rise by four degrees Celsius compared to pre-industrial times, sea levels will rise by six and a half meters, writes the Italian daily La Repubblica.

“What we are losing in Antarctica today is lost forever,” said scientists at the Potsdam Institute. Their study shows the effects of rising temperatures on glaciers in Antarctica. “Antarctica contains more than half of the world’s fresh water, which is frozen in a large ice cap up to five kilometers thick,” says study lead author Ricarda Winkelmann of the University of Potsdam.

And as the water in the ocean and the air above it warm due to greenhouse gas emissions, the white cover of the South Pole loses volume and becomes unstable. Due to the vastness of Antarctica, its potential to cause sea level rise is huge: even when warmed by two degrees, the melting of glaciers and the outflow of water into the ocean will cause the level to rise by 2.5 meters. A warming of four degrees will cause the level to rise by six and a half meters, and a warming of six degrees will raise the level by almost 12 meters.

The critical scenario is in humanity’s hands

Long-term changes are irreversible, scientists warn. According to the model, the state from which there is no return is a temperature increase of ten degrees. This is a critical threshold that would correspond to the disappearance of ice in Antarctica. A subsequent rise in sea levels would have catastrophic effects on cities located closer to the coast.

“The Antarctic polar cap is basically our last legacy from a previous period in Earth’s history. It has existed for about 24 million years. Our simulations show that once they dissolve, they never return to their original state, even if the temperatures drop again. Temperatures would have to return to pre-industrial levels to fully recover. This scenario is highly unlikely, “says another author of the study, Anders Levermann.

Conversely, in a more likely scenario, many cities, such as London, Mumbai, New York and Shanghai, would be at risk. “In other words, what we are losing in Antarctica today is lost forever,” Levermann adds.

The reason why this tendency is irreversible is the mechanisms manifested in the behavior of ice sheets in warming conditions. “In West Antarctica, for example, the main factor in ice loss is the warm ocean water, which causes more melting under the sea’s ice platforms, which in turn can destabilize the earth’s ice sheet. This causes glaciers the size of Florida to slide into the sea. Once temperatures exceed a threshold of six degrees Celsius above pre-industrial levels, the vast mountains of ice in the ocean, where the water is warmer, slowly shrink until they finally dissolve, as we can see in Greenland, ”said study co-author Torsten Albrecht.

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