According to a new paper published in the journal Nature, thanks to a host of self-reinforcing, destabilising mechanisms, the slow melting of the Antarctic ice sheet will cause the sea level to rise by about 2.5 metres even if Paris climate goals are met and temperatures start to fall after reaching 2°C over pre-industrial levels.
“The more we learn about Antarctica, the direr the predictions become,” said co-author on the paper Anders Levermann from the Potsdam Institute for Climate Impact Research. “We get enormous sea level rise even if we keep to the Paris agreement and catastrophic amounts if we don’t.”
According to Jonathan Bamber from the University of Bristol, who was not involved in the research, the study provides compelling evidence for the potentially devastating consequences of even moderate climate warming, which could lead to the removal of entire nations from the world map.
One of the key reasons why the ice sheet is unlikely to re-grow is hysteresis – an effect whereby the value of a physical property lags behind the effect which modulates it. As the ice melts, its surface drops and sits in warmer air, requiring lower temperatures to reform than to remain stable.
The study indicates that the ice sheet will “not regrow to its modern extent until temperatures are at least one degree Celsius lower than pre-industrial levels” – a feat that would be incredibly difficult to achieve at this point.
Given that the Antarctic ice sheet contains about half of the Earth’s fresh water, substantial global warming would lead to massive sea level rise, and that’s not even including the rise caused by melting ice in the Arctic Ocean and Greenland.
“Our results show that if the Paris Agreement is not met, Antarctica’s long-term sea-level contribution will dramatically increase and exceed that of all other sources,” conclude the researchers.