The Arctic Ocean is warming up much faster than predicted by climate models used by United Nations experts, accelerating the melting of the sea ice, warn two Swedish studies published on Tuesday.
Relatively warm currents deep in the Arctic are actually warmer and closer to the surface than experts previously thought, coming into direct contact with sea ice and accelerating its melting in winter, according to these studies. the University of Gothenburg, published by the Journal of Climate.
Bad news
“
This is not really good news
,” commented Céline Heuzé, a climatologist from this university and director of one of the studies.
The researchers compared their observations to calculations of 14 models taken into account by the IPCC, the group of experts in charge of the main UN climate reports.
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The role of deep water flowing under the Arctic from the Atlantic is underestimated by these models, they conclude.
"
We are sure that what is happening in the Arctic in real life does not happen as in the models
," said Céline Heuzé to AFP.
“
The predictions that are shared by the IPCC are a little too optimistic.
It's going to be even worse and faster than expected
."
The discrepancy between these conclusions and the forecasts is due to the lack of expeditions and on-site observations, explains the researcher.
"
It's not easy to go to the Arctic, so when there is an expedition, everyone wants to collect a lot of different data and priority is not necessarily given to deep waters
", continues the scientist.
"Arctic Amplification"
The surface of the sea ice has already been reduced by an average of 9% in winter and 48% in summer since the first satellite photographs in 1979, when its thickness decreased by 66%, recalls one of the studies.
A deficiency aggravated by the lack of access to Russian data, even more so with the cancellation of shipments to Russia since the invasion of Ukraine.
Already last year, a study had revealed that the Arctic atmosphere had warmed up four times faster than elsewhere over the past forty years, i.e. double compared to the models used by the IPCC.
Unlike the atmosphere, which only warms the surface of the Arctic in spring and summer, the warming of the ocean causes the sea ice to melt all year round, especially in winter.
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The disappearance of sea ice accelerates warming due to a phenomenon called "
Arctic amplification
".
This occurs when sea ice, which naturally reflects the sun's heat, melts and turns back into dark seawater which absorbs more solar radiation and heats up.