The Greenland ice sheet is close to a melting point of no return

While we assume that Greenland is melting under the pressure of rising global temperatures in recent decades, understanding and studying the causes and processes of this melting is essential to prepare for impacts on coastal regions around the world. The climatologist Dennis Höning of the Potsdam Institute for Climate Impact Research and his team have identified in a new study colon of no return (tipping points) that determine the fate of the Arctic ice cap. THE tipping points they are thresholds at which the behavior of a system undergoes an irreversible change. In this case, we are talking about the permanent loss of large portions of the Greenland ice sheet.

According to the study, published in the journal Geophysical Research Letters of the AGU, the melting of the southern part of the Danish island will undoubtedly occur when humanity releases 1,000 gigatons (1 gigatonne = 1 billion tons) of carbon into the atmosphere.

The second point, more alarming than the previous one, anticipates that the input of 2,500 gigatons of carbon will lead to the almost total loss of the ice cap. To give you an idea of ​​how quickly this could happen: since the 1960s we have emitted something like 100 parts per million of CO₂which corresponds to about 800 gigatons of carbon dioxide.

“The first tipping point is not far from today’s climatic conditions, so we risk crossing it”Höning said. “Once we start sliding, we’ll fall off this cliff and be unable to climb back up.”

A complex interplay of factors, including air and water temperatures, ocean currents, the Arctic atmosphere, precipitation and many others, influence where and how much ice loss occurs each year. There difficulty in predicting how these factors interactcombined with the long time required to study such a massive ice sheet, has made it difficult in the past to accurately predict how the ice sheet might respond to various climate scenarios and, therefore, to different levels of CO emissions₂.

For the analysis the scientists used a model which covered thespan of 20,000 years and in which emissions ranged from 0 to 4,000 gigatons. One of the team’s most important findings is that as the ice sheet melts, its surface will be exposed to hotter temperatures found at lower elevations, creating a cycle of feedback which further speeds up the melting process. Höning explains that if a brief 2 degree Celsius increase in temperature wouldn’t trigger this feedback loop, maintaining high global air temperatures for hundreds of years or more could.

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Once the ice sheet crosses the tipping point, the merger becomes inevitable. This implies that even a reduction of atmospheric carbon dioxide to pre-industrial levels would not be sufficient to significantly regrow the ice sheet and, therefore, reduce sea levels. “We cannot continue carbon emissions at the same pace for much longer without risking tipping points,” Höning warned. “Most of the ice sheet melting won’t happen in the next decade, but it won’t be long before we’re no longer able to counter it.” We’re on our last legs.