After extreme temperatures in 2023, scientists are divided about accelerating global warming

“It is humbling, but also alarming to realize that no year has defied climate scientists’ predictions as much as 2023.” Coming from Gavin Schmidt, the admission carries a lot of weight. The director of NASA's Goddard Institute for Space Studies, one of the leading laboratories studying global warming, speaks in an unusual way. In a comment published in the magazine natureMarch 19. Those who are more accustomed to logical proofs and continuous explanations this time will have many questions about this year ” puzzle “which turned out to be the hottest ever.

How could surface temperatures, which reached 1.45 degrees Celsius above pre-industrial levels, break previous records by 0.2 degrees Celsius, and even by half a degree Celsius since September 2023, a huge margin on a global scale? They “From where I don't know”revealed a “The lack of knowledge is unprecedented in the last 40 years, when satellites provided a real-time view of the Earth's climate system »“, writes the climate scientist.

If this anomaly does not stabilize by August, the world will find itself in a critical situation “An area not marked on the map”. “This could mean that global warming is already radically changing the way the climate system works, much sooner than scientists expected.”is actually drawn by Gavin Schmidt.

Climate out of control? Rush? Gavin Schmidt does not risk using these painful formulas. But his comment raises the issue that the climate crisis is accelerating beyond what models predict. A debate that is deeply divided within the scientific community.

El Niño, the usual suspect

“The year 2023 surprised us and worried us a lot.”, says Zeke Hausfather, a climate scientist at the Berkeley Earth Institute. Not a day goes by in 2023 without a record being broken, both for air temperatures not seen since. Maybe 100,000 yearsA rise in sea levels four times greater than in 2022, the accelerating retreat of glaciers, or above all, the exceptional heat in the oceans, which exceeds previous rates by margins that were once thought impossible.

A bout of fever that scientists cannot fully explain. There is, of course, the underlying trend of human-induced climate change, which is already warming the Earth. to 1.26 °C since the pre-industrial era. Between 2022 and 2023, greenhouse gas concentrations in the atmosphere will persist, driven by the burning of fossil fuels (coal, oil and gas) and deforestation. But this extra energy can only explain an additional temperature rise of about 0.02 degrees Celsius, says Gavin Schmidt.

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