Ice loss to add 0.4 degrees Celsius to global temperatures: study


Ice loss from the West Antarctic and Greenland ice sheets is accelerating and is already surpassing what scientists until recently believed to be the worst melting scenarios.

The loss of billions of tons of ice from Earth’s frozen spaces risks raising global temperatures by another 0.4 degrees Celsius, according to research on Tuesday that highlights the danger of a “vicious circle” of warming.

Arctic summer sea ice levels have dropped by more than 10% every decade since the late 1970s, and mountain glaciers have shed around 250 billion tons of ice annually over the past century.

Read also | Record melting: Greenland lost 586 billion tons of ice in 2019

Ice loss from the West Antarctic and Greenland ice sheets is accelerating and is already surpassing what scientists until recently believed to be the worst melting scenarios.

Decades of studies have sought to quantify how melting Earth’s ice will contribute to sea level rise: Antarctica and Greenland alone contain enough ice water to raise oceans by about 60 meters.

But little research has attempted to predict how ice loss will add to the already 1.0 ° C of global warming emissions from fossil fuels since the start of the industrial age.

Scientists from the Potsdam German Institute for Climate Impact Research (PIK) used a climate model that includes components on the atmospheric, ocean, sea, and land ice data to predict temperature change due to ice loss in a variety of emission scenarios.

Read also | The study raises the alarm for Arctic ice

They found that with current atmospheric CO2 levels – around 400 parts per million – melting Arctic sea ice, mountain glaciers and polar ice caps would raise temperatures by 0.4 ° C.

In addition to 1.5 ° C of warming, our current levels of emissions have made it almost inevitable and the safest limit to global warming under the Paris climate agreement.

The main factor of temperature increase due to ice loss would be due to a process known as albedo feedback, in which the heat-reflecting bright ice is replaced by darker absorbing seawater and / or soil.

“If global ice masses shrink, this changes how much sunlight hitting the Earth’s surface is reflected back into space,” said lead author Nico Wunderling.

Read also | “Artificial snow” could save the affected Antarctic ice sheet, the study says

He likened the albedo effect to wearing white or black clothes in the summer.

“If you wear dark clothes, you warm up more easily,” observed Mr. Wunderling.

This is one of Earth’s so-called climate “feedback loops”, where rising temperatures lead to further loss of ice, which in turn raises temperatures further.

Point of no return

Other ways that temperatures would rise further as the ice retreated include increasing water vapor in the atmosphere, increasing greenhouse effects, the study authors said published in Nature Communications.

Looking exclusively at Arctic sea ice – which unlike the polar ice caps could be totally absent during the summer months within decades – they found that its melting would contribute 0.2 ° C to global temperatures alone.

Read also | Arctic ice melt is disrupting major ocean currents, could alter climate in Western Europe: study

The largest ice masses in Greenland and West Antarctica, by comparison, are huge and will likely take centuries to completely melt even if emissions continue to grow unabated.

But the authors highlighted the risk that those huge bodies of frozen water could soon reach a point of no return as temperatures get higher and higher.

Given the unknowns surrounding the ice cap’s tipping points, Mr. Wunderling said AFP it would be better to act in a “risk averse” way and try to reduce emissions as soon as possible.

Read also | Data: lowest Arctic sea ice extent in July since 1979; in Antarctica, it exceeded the average level in September.

“As global warming continues, it becomes more and more likely that tipping points will be passed, not only in the ice sheets, but in other parts of the climate system as well,” he said.

“If the Paris Agreement is respected, we can avoid many of the strongest and potentially irreversible impacts on the Earth’s ice masses, the global climate and humanity.”


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