Sunday, December 10, 2023

Climate: the Arctic would warm up four times faster than the rest of the globe

The Arctic is warming four times faster than the rest of the globe. This is the alarming conclusion of a study published on August 11 in the scientific journal “Nature”.

The authors of the paper, based in Norway and Finland, analyzed four sets of temperature data collected across the Arctic Circle by satellites since 1979. Conclusion, they say: the Arctic has warmed on average 0.75°C per decade, almost four times faster than the rest of the planet.

“Arctic Amplification”

Scientists already knew that the Arctic was warming more than the rest of the globe. In 2019, the IPCC estimated that the Arctic was warming “more than twice the global average”, under the so-called Arctic amplification effect.

This phenomenon is linked to albedo: any surface absorbs part of the solar energy it receives and reflects another part of this energy back into space. Ice and snow are the materials that reflect the most solar energy. However, when Arctic sea ice and snow melt, it forces the surrounding seawater to absorb more solar radiation. However, seawater has a much lower ability to reflect radiation: it therefore heats up at high speed.

Rethinking weather models

The team of scientists found that most leading climate models projected Arctic warming about a third lower than their own data showed. “I was surprised that our conclusion was much higher than the usual figure,” Antti Lipponen, one of the co-authors, told AFP. The conclusions of this new study therefore raise fears of an underestimation of the climate models that have prevailed until now.

The difference could be explained, according to the researchers, by the obsolescence of previous models. “The next step might be to take a look at these models, see why they don’t predict what we see in observations and what impact that has on future climate projections,” said Antti Lipponen.

The study also highlighted strong disparities depending on the areas of the Arctic observed. Thus, the sector of the Norwegian archipelago of Svalbard and that of Novaya Zembla, in Russia, have warmed up by 1.25°C per decade, or about seven times faster than the rest of the globe.

Acceleration of sea level rise

The warming of the Arctic is already having consequences for the inhabitants of the region and the local fauna. But it will also have a more global effect, warns Antti Lipponen: “As the Arctic warms, its glaciers will melt, which will have a global impact on sea levels. “And to add:” This will affect us all. »

According to the IPCC, the sea level has risen by 20 cm since 1900. However, the rate of this rise has almost tripled since 1990 and, depending on the scenarios, the oceans could still gain 40 to 85 cm by the end of the century. The Greenland Ice Sheet, which recent studies may be approaching the “tipping point” of melting, contains a quantity of icy water capable of raising the level of the Earth’s oceans by up to six meters.


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