"It's humbling, and a bit worrying, to admit that no year has confounded climate scientists' predictive capabilities more than 2023 has." Coming from Gavin Schmidt, this admission carries a lot of weight. The director of NASA's Goddard Institute for Space Studies, one of the world's leading laboratories for the study of global warming, wrote it in an article published in the scientific journal Nature on March 19. Though he is more accustomed to logical demonstrations and implacable explanations, this time he instead raised several questions about this "huge heat anomaly," which turned out to be the hottest year on record.
How did surface temperatures, which reached up to 1.45°C above pre-industrial levels, manage to break previous records each month by up to 0.2°C; and even by half a degree from September 2023 onwards? On a planery scale, that is a huge scale. The anomaly has "come out of the blue" and reveals "an unprecedented knowledge gap perhaps for the first time since about 40 years ago, when satellite data began offering modellers an unparalleled, real-time view of Earth's climate system," writes the climatologist.
If this temperature anomaly does not stabilize by August, the world will find itself in "uncharted territory," he says. "It could imply that a warming planet is already fundamentally altering how the climate system operates, much sooner than scientists had anticipated," writes Schmidt.
An out-of-control climate? A surge in warming? Schmidt didn't dare use these frightening phrases. Yet his article has raised the specter of an acceleration of the climate crisis beyond what models have predicted. This is a debate that has divided the scientific community.
"The year 2023 has surprised and worried us a lot," acknowledged Zeke Hausfather, a climatologist at the Berkeley Earth research institute. Not a day went by in 2023 without a record being broken, be it air temperatures unseen for possibly 100,000 years; sea levels that rose four times as much as in 2022; glaciers that receded at an accelerated rate; or, above all, exceptional ocean temperatures, exceeding previous levels by margins previously thought impossible.
Scientists have been unable to fully explain the feverish surge in temperatures. There is, of course, the underlying trend of human-induced climate change, which, by 2022, had already raised the Earth's temperature by 1.26°C since the pre-industrial era. From 2022 to 2023, greenhouse gas concentrations in the atmosphere have continued to rise, driven by the combustion of fossil fuels (coal, oil, gas) and by deforestation, "but the extra load since 2022 can account for further warming of only about 0.02 °C," writes Schmidt in Nature.
You have 75.12% of this article left to read. The rest is for subscribers only.