Study warns of moderate risk of warming by "irreversible" ice loss

Even modest temperature increases agreed as part of an international plan to limit the climate disaster could allow the icecaps to melt enough for their loss to be "irreversible," experts warned on Monday.

The 2015 Paris Agreement limits countries to temperature rises "well below" two degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels and to less than 1.5 C if possible.

This approximate warming scenario of 1.5-2 ° C by 2100 is the best possible scenario for scientists, based on our consumption of natural resources and the burning of fossil fuels. This will require radically change the way of life of each.

For comparison, the usual human approach – if we continue to emit greenhouse gases at the current rate – will see the heat of the Earth reach up to 4 ° C.

Scientists have known for decades that the ice sheets of Greenland and Antarctica are narrowing, but it was assumed that they would survive a temperature rise of 1.5 to 2 ° C relatively untouched.

However, according to a new analysis published in the journal Nature Climate Change, even moderate global warming could cause irreversible damage to the polar ice, contributing to a catastrophic rise in sea level.

"We are saying that 1.5-2C is close to the limit for which more dramatic effects can be expected from the pack ice," Frank Pattyn, head of the university's geoscience department, told AFP. free of Brussels and author of the study.

His team analyzed data on the annual temperature rise, ice cap coverage and known melting levels, and found that the ice sheets of Greenland and Antarctic would reach a "tipping point" to 2 ° C.

"The existence of a tipping point implies that changes in the icecap are potentially irreversible -" the return to a preindustrial climate might not stabilize the icecap once the tipping point has passed ", said Pattyn.

– & # 39; tipping point this century & # 39; –

The ice in Greenland and Antarctica contains enough frozen water to raise the sea level by several meters.

The Greenland ice sheet alone has contributed 0.7 millimeters of sea level rise each year since the mid-1990s.

And the poles are warming faster than anywhere else on Earth, with Greenland alone having warmed 5 ° C in winter and 2 ° C in summer since then.

Although scientists predict that it would take hundreds of years to melt, even with huge increases in global temperature, Monday's study is a source of inspiration. concern for the only realistic plan of humanity aimed at avoiding global warming.

Many models in the 1.5-2C scenario are able to cross the threshold in the short term, which could potentially warm the planet by several degrees, before using carbon capture and other technologies to bring back temperatures to 2100.

The study warned, however, against this approach, saying that a feedback loop triggered by higher temperatures "would lead to an autonomous melting of the icecap", even if these increases were later compensated.

For Greenland, the team said with 95% certainty that the major ice sheet decline would occur at 1.8 ° C warming.

"For Greenland and Antarctica, there are tipping points known for the warming levels that could be achieved by the end of the century," Pattyn said.

Ice in Greenland and Antarctica contains enough frozen water to raise sea levels by several meters