Even modest rises in temperature agreed in an international plan to reduce climate disasters, ice caps could melt enough this century to make their losses "irreversible," experts warned Monday.
The 2015 Paris Accord restricts countries to temperature increases "well below" two degrees Celsius (3.6 degrees Fahrenheit) above the pre-industrial level and to less than 1.5C if at all possible.
That margin of getting 1.5-2C hotter in 2100 is the best-case scenario of scientists based on our consumption of natural resources and the burning of fossil fuels, and requires radical, global changes in lifestyle to achieve.
By way of comparison: the normal approach of people – if we continue to emit greenhouse gases at the current rate – the geothermal heat will rise by as much as 4C.
Scientists have known for decades that the ice caps of Greenland and Antarctica are getting smaller, but it was assumed that they would survive a temperature rise of 1.5-2C relatively intact.
According to a new analysis published in the journal Nature Climate Change, even modest global warming could cause irreversible damage to polar ice, which could contribute to catastrophic sea level rise.
"We are saying that 1.5-2C is approaching the limit for which more dramatic effects of the ice caps can be expected," said Frank Pattyn, head of the department of geosciences, Free University of Brussels and lead research author.
His team analyzed data on annual temperature increases, ice sheet coverage and known melting levels and found that both the ice sheets in Greenland and Antarctica would reach a "turning point" of around 2C.
"The existence of a tipping moment implies that ice sheet changes are potentially irreversible, and returning to a pre-industrial climate can not stabilize the ice cap once the tipping point has been exceeded," Pattyn said.
Also read: Five things to know about Greenland
– & # 39; Tipping point this century & # 39; –
The ice in Greenland and Antarctica contains enough frozen water to raise the global sea level a few meters.
The Greenland ice sheet alone has contributed 0.7 millimeter of global sea level rise since the mid-1990s.
And the poles heat faster than elsewhere on earth, with Greenland only 5C warmer in winter and 2C in summer since then.
Although scientists predict that it would take hundreds of years for them to melt, even with huge global temperature rises, Monday's study raises concerns about the only realistic plan of humanity to prevent runaway global warming.
Many models of the 1.5-2C scenario ensure that the threshold is exceeded in the short term, potentially increasing the planet by several degrees before carbon deposition and other technologies are used to bring the temperature back up to 2100.
However, the study warned against this approach, but said that a feedback loop caused by higher temperatures would lead to "self-sustained melting of the entire ice sheet" even if those increases were later compensated.
For Greenland, the team said with 95 percent certainty that large ice caps would take place at 1.8C of warming.
"Tilt points are known for both Greenland and Antarctica for levels of warming that could be reached before the end of this century," Pattyn said.