Paris, France.- The melting of the polar ice caps of Greenland and Antarctica, in addition to increasing the level of the oceans, could multiply extreme weather events and destabilize the climate in some regions in the coming decades, according to a study published in Nature.
The billions of tons of melt water, particularly from Greenland, could weaken the ocean currents that currently carry cold water to the south by plunging it to the bottom of the Atlantic and pushing the tropical waters to the north, more close to the ocean. surface.
Known under the acronym AMOC (meridian return circulation of the Atlantic), this oceanic mechanism plays a crucial role in the climate system and helps maintain some warmth in the northern hemisphere.
"According to our models, the melting of the ice will cause significant disruption in ocean currents and will change the levels of warming of the Earth," explains lead author Nicholas Golledge of the Antarctic Research Center at Victoria University in Wellington in New Zealand. in the study published Wednesday.
Many previous studies have focused on the melting rate of polar ice caps under the effect of climate change, as well as on its "inflection point", ie from which temperature increase its disappearance will be unavoidable.
But less on the way in which its waters could influence the climate itself.
"The changes we see in our large-scale simulations favor a more chaotic climate, with more extreme weather events, more frequent and intense canicides," says Natalya Gomez, of McGill University in Canada.
– +15 cm in 2100? –
According to the researchers, by the middle of the century, "the water that melts from the polar caps of Greenland will significantly disturb the AMOC", which already shows signs of slowing down.
It's a much shorter time than expected, "said Helene Seroussi of the California Institute of Technology, who was not involved in the study.
Among the probable consequences of this weakening is the increase in air temperature in the High Arctic, in eastern Canada and in Central America, as well as its decline in the area of u200b u200bthe world. Western Europe.
The caps of the Antarctic and Greenland, which can reach a thickness of 3 km, contain more than two thirds of the fresh water on the planet, enough to cause an increase in the ocean of 58 and 7 meters respectively, if completely time.
In another study published Wednesday in Nature, some of these same scientists reveal the new projections on the contribution of the melting of the Antarctic to the rise in sea level in 2100, a topic much debated in the scientific community.
A controversial report in 2016 suggested that the continent's ice cliffs could crumble and cause a one meter rise in the oceans by the end of the century, forcing displaced tens of millions of people around the world.
"We have reviewed the data and concluded that this is not the case," said lead author Tamsin Edwards of the King's College in London.
According to her, the two new studies predict that Antarctica will contribute "more probably" to an increase of 15 cm up to 2100, with a maximum of about 40 cm.
The UN Intergovernmental Panel on Climate Change will publish a long-awaited report on the rise in ocean levels in September. AFP