A study published on June 28th in the journal Nature Climate Change warns that over the last 30 years, the temperature at the South Pole has risen three times faster than the global average. An unexpected situation that worries scientists. Indeed, the increase in temperatures in Antarctica could accelerate the dreaded rise of the oceans. After this spring's spectacular rise in temperatures in the Antarctic, the temperature of the South Pole has risen three times faster than the global average. ArcticThe warming of the poles is decidedly problematic.
Antarctica is marked by extreme climatic variability, with strong differences between the coasts and the interior of the continent, especially the icy plateau where the geographic South Pole is located. Thus, most of West Antarctica and the Antarctic Peninsula experienced warming and melting of the ice in the second half of the 20th century. At the same time, on the contrary, the South Pole had rather cooled. At least until the 1980s, before this trend was reversed, as shown in thestudy published on Monday in Nature Climate Change magazine.
With +0.61°C per decade, between 1989 and 2018, the temperature recorded on the Amundsen-Scott base at the geographic South Pole has risen more than three times the world average, the researchers say. A result that surprised them. « It was believed that this part of Antarctica - the isolated high plateau - would be safe from warming. We discovered that this was no longer the case... The new book, "The New York Times," one of the authors, Kyle Clem, of Victoria University in Wellington, told AFP.
The "primary mechanism" that led to this rapid warming of the South Pole, where the temperature is permanently well below 0°C (annual average around -49°C), is linked to a warming in the tropical zone of the Western Pacific Ocean. This has led to a drop in atmospheric pressure in the Weddell Sea and pushed warm air towards the South Pole, according to the study.
Even if climate models show that it is "not impossible" that the rate of warming of 0.61°C per decade occurred naturally, it is "very unlikely", insisted Kyle Clem, who pointed out that out of +1.8°C in 30 years at the South Pole, these models attribute +1°C to man-made climate change.
" The real message (...) is that no place is immune to climate change. "said Sharon Stammerjohn and Ted Scambos of the University of Colorado, who are especially concerned about the Antarctic coastline and the ice cap. « The effects of climate change have long been felt there. "and the continent's contribution to global warming and sea-level rise could become "catastrophic," they say.
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Oceans that could rise 25 meters
Indeed, several studies converge to announce a faster-than-expected rise in sea levels. A study conducted by Australian researchers and published in October 2019 in the journal Nature had concluded that there was a risk of sea levels rising by more than 25 metres, on a very rapid time scale, as early as 2030. To arrive at this grim prediction, they compared what is happening today with what was happening about three million years ago, in the Pliocene.
This era is particularly interesting because its climatic configuration is not very far from the one we are currently experiencing. It can therefore be used as a predictive model. During this period, the concentration of CO2 in the atmosphere reached levels comparable to those we are recording today: more than 400 parts per million.
Three million years ago, a period of intense temperature warming began. They reached levels equivalent to an increase of 2°C compared to pre-industrial times. Let us recall that we are currently at almost 1.5°C. According to the IPCC's forecasts, we should reach, or even exceed the 2°C provided for in the Paris Agreement as early as 2030 if we do not drastically reduce our greenhouse gas emissions today.
Rising temperatures have melted the ice, particularly in Antarctica, which has lost a third of its ice surface. This melted ice poured into the oceans, causing them to rise 25 metres.
Australian researchers have concluded that most of the sea-level rise during the Pliocene came from the Antarctic ice caps. During the warm Pliocene, the geography of the Earth's continents and oceans and the size of the polar ice sheets were similar to those of today, with only a small ice sheet over Greenland during the warmest period. The melting of the Greenland ice sheet would have contributed up to five metres to the maximum 25-metre rise in global sea level recorded in the Whanganui Basin.
Twenty-five metres is much more than climate experts predict. According to the recent Intergovernmental Panel on Climate Change (IPCC) Special Report on Oceans and Cryosphere, glaciers and polar ice caps continue to lose mass at an accelerated rate. Until now, the increase has been expected to be in the range of 0.60 to 1.1 metres by 2100. But the new study is formal: we will be in Pliocene conditions as early as 2030, ten years from now!
Researchers are therefore pushing the logic of the results of their experiments to the limit: it is quite possible that Antarctica will melt and lose a third of its surface area, which would potentially cause, according to their hypotheses, a rise in the level of the world's seas of around 20-25 metres.
Such a scenario would reshape shores around the world. Indeed, if such a scenario were to occur, it would dramatically change our geography and result in disasters difficult to conceive.
Especially since the effects of climate change are cumulative, this rise in the oceans would aggravate the impact of storms and other extreme phenomena that climatologists predict due to the increase in temperatures, particularly those of the ocean. Higher sea levels would cause damage farther inland if submerged by submerged waves. The impact of a cyclone like Katrina would be multiplied.
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