According to recent studies, a large portion of the Greenland ice cap is on the verge of a turning point, beyond which rapid melting would be unavoidable even if global warming was stopped.
Greenland's ice has now poured into the ocean in trillions of tons due to rising temperatures triggered by the climate crisis. The melting of its ice cap would result in a 7-meter rise in global sea level.
In a 140-year record of ice-sheet height and melting speeds in the Jakobshavn basin, one of Greenland's five largest and fastest-melting basins, the latest study discovered warning signs of a tipping point. A vicious cycle in which melting cuts the height of the ice cap, exposing it to the colder weather found at lower altitudes, which induces further melting, is the leading suspect for an increase in melting.
Destabilizing Ice Sheets
This ice sheet is destabilizing, according to the report. Uncertainties in the study suggested that it might have already crossed the point of no return or be on the verge of doing so in the coming decades, per the scientists. Even if the tipping point was reached, they said, it didn't mean the whole ice sheet was doomed because a smaller ice sheet might still exist in a stable state.
"We're on the verge of reaching the turning point, and every year the CO2 emissions continue as they have," said Niklas Boers of the Potsdam Institute for Climate Impact Studies in Germany. The latter co-authored the study with Martin Rypdal of the Arctic University of Norway. "It's possible [the boiling point] has been reached, but it's unclear. However, our findings indicate that melting will be significantly increased in the near future, which is concerning."
According to Boers, ice equal to 1-2 meters of sea-level rise was likely already destined to melt, but it would take years and a lifetime to melt the entire ice sheet. "To get back to the initial height of the Greenland ice cap, we will actually have to drive temperatures back below pre-industrial levels," he added.
The new study just looked at one region of Greenland. Still, Boers said there was no explanation why it shouldn't be the same in other areas of the ice sheet: "We may be finding this that is occurring in certain parts of Greenland, but we just don't know for sure because we don't have the high-quality evidence for other parts."
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Point of No Return
The Greenland ice sheet has already reached the point of no return, according to media reports in August 2020, but scientists said this was a misinterpretation of science. Scientists warned in 2019 that the earth has already passed through several temperature tipping points.
Temperature data, ice cores, and modeling were used in a recent analysis published in the Proceedings of the National Academy of Sciences of the United States of America to recreate the ice sheet's elevation and melting rates since 1880. A close analysis of the magnitude and length of shifts over time showed warning signs of an impending breaking point, demonstrating that the ice sheet's potential to regenerate from melting is rapidly dwindling.
The feedback loop caused by falling ice-sheet height appears to be the largest factor, but other feedbacks may play a role in destabilizing it. These include the thinning of coastal glaciers, allowing more ice to slip into the sea, and reduced falls of fresh white snow exposing the darker surface of the ice sheet, which then absorbs more heat from the sun. But warmer temperatures may also result in damper air and more snowfall, counteracting some ice losses.
Dire Need of More Data
Boers said the Greenland ice sheet dynamics were very complex and that using today's incomplete knowledge to estimate a precise date when a tipping point is passed would give a false sense of certainty.
Beyond rising sea levels, large-scale melting of the Greenland ice sheets will have long-term environmental implications. It can stop the Gulf Stream ocean current, with ramifications for the Amazon rainforest and tropical monsoons.
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