Over 20 degrees! Heat records are multiplying in Antarctica and new studies alert us to the risks posed by global warming.
These temperatures could have potentially devastating consequences for the tens of millions of inhabitants of mega-cities such as New York, Shanghai or Bombay.
On February 9, it was over 20.75 degrees on Seymour Island (also called Marambio) at the end of the West Antarctic Peninsula facing the southern tip of South America.
We have never seen such a high temperature in Antarctica.
Carlos Schaefer, Brazilian researcher
Two days earlier, on February 7, not far from there, on the Argentinian base Esperanza, the mercury had already reached 18.3 degrees, a historic high according to the National Meteorological Service.
“Shocking records, but unfortunately not surprising, because Antarctica is warming with the rest of our planet,” said Frida Bengtsson, specialist in the marine environment at Greenpeace.
The past decade has been a record heat, and ended in 2019 which was the second warmest ever recorded on the planet (after 2016). And the 2020s start on the same trend with the hottest January ever recorded, according to reports from European and American services.
However, two new studies sound the alarm again this week on the dangers of destabilization of the southern ice cap, while according to climate experts of the UN (IPCC), the sea level has already increased by 15 cm in the 20th century. Consequence: by the mid-2050s, more than a billion people will live in coastal areas particularly vulnerable to floods or extreme weather events amplified by the rise in sea level and climate change.
A study published Friday in the journal Earth System Dynamics, synthesizing 16 new models carried out by researchers from 27 international institutes and coordinated by the Potsdam Institute for Climate Impact Research (PIK), predicts that the only melting in Antarctica could lead to an increase global ocean level up to 58 centimeters by the end of the century if the overall rate of greenhouse gas emissions remains unchanged.
Even in a scenario (improbable given current trends according to a number of experts) of lower emissions in line with the objective of the Paris Agreement of 2015, i.e. global warming of less than 2 degrees compared to the pre-industrial era, the only “Antarctic factor” would raise the sea level from 4 to 37 centimeters.
The effects of the melting of other glacial zones (Greenland cap, mountain glaciers) and the expansion of seawater caused by its warming would obviously add to these projections, the study points out.
In addition, a second study, directed by Australian researchers and published Wednesday in the American journal PNAS, draws a worrying parallel with the last interglacial period of the Earth, 116 000 to 129 000 years ago.
Relying in particular on traces of volcanic ash, the researchers calculated that the ice in the western part of Antarctica (resting directly on the sea floor and therefore more vulnerable to warming) had then melted very early in the cycle warming.
“The melting was probably caused by ocean warming of less than 2 degrees, which has major implications for our future,” says Chris Turney of the University of New South-Wales, lead author of the study: “In an increasing warmer world, we could lose most of the western Antarctic pack ice.
The consequences, already known, are abruptly summarized by Anders Levermann, principal author of the study coordinated by the PIK.
What is certain is that failure to stop burning coal, oil and gas will increase the risk for coastal cities, from New York to Bombay, Hamburg or Shanghai.
Anders Levermann
