Even the modest rise in temperature agreed under the 2015 Paris Agreement could result in irreversible ice sheet loss, a new study by a group of scientists at the Free University of Brussels has warned.
In December 2015, leaders of 196 countries met in Paris and signed an agreement to keep the global temperature rise below 2° above pre-industrial levels, and if possible below 1.5°. To achieve this goal, nations pledged to cut their greenhouse gas emissions over the coming years. The United States agreed to reduce its climate pollution by 26-28 per cent from 2005 levels, and the EU revealed a plan to cut emissions by 40 per cent by 2030 on 1990 levels.
Scientists have known for decades that ice sheets of Antarctica and Greenland are shrinking continuously, but they believe these sheets can survive a temperature rise of 1.5-2° relatively well.
Earlier this year, a study warned that Antarctic ice is melting at faster than ever, with the rate increasing threefold in the last five years. Before 2012, the Antarctic region was losing ice at a rate of 76 billion tonnes per year, causing a sea-level rise of 0.2 mm per year. However, since 2012, the ice loss rate has increased sharply, at 219 billion tonnes per year, contributing 0.6 mm per year in sea-level rise.
Now the study, published in the journal Nature Climate Change, warns that even modest rise in temperatures agreed under Paris agreement could cause irreversible loss to the polar ice, resulting in devastating sea level rises.
Researchers analysed the data on ice sheet coverage, annual rise in temperature, and known melt levels and concluded that ice sheets in Greenland as well as Antarctic would reach a "tipping point" at around 2°.
"The existence of a tipping point implies that ice-sheet changes are potentially irreversible - returning to a pre-industrial climate may not stabilise the ice sheet once the tipping point has been crossed," said Frank Pattyn, head of the department of geosciences at the Free University of Brussels and lead study author, told AFP.
In Greenland, the major ice sheets would melt with a temperature rise of 1.8°, the study claims.
Many climate models suggest that 1.5-2° scenario would cause the planet to heat several degrees higher in the short term, but by 2100, the temperature would come down to an acceptable range through carbon capture and use of other technologies.
The new study is against this approach, however, and warns that high temperatures would set off a feedback loop that would cause "self-sustained melting of the entire ice sheet" even if temperatures decrease later.
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