A new analysis in Geophysical Research Letters shows Earth warming at ~0.36°C per decade since 2014—about double the prior rate of 0.18°C per decade—with 98% confidence after accounting for natural factors. Led by Stefan Rahmstorf, the study warns the Paris Agreement's 1.5°C limit could be breached by 2028, amid debates over short-term trends and data uncertainties.
Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and colleagues examined five global temperature datasets, isolating effects of El Niño, volcanic eruptions, solar cycles, and other natural variability. They found warming accelerated from roughly 0.18°C per decade before 2013-14 to 0.36°C per decade since, with 98% statistical confidence attributing it to human activities rather than fluctuations. The study echoes prior warnings, including a recent report by James Hansen, who testified on climate risks to US Congress in 1988.
This speedup follows record-hot years like 2023 and 2024 and is linked to a 2020 reduction in sulfur dioxide emissions from shipping, which previously masked warming via aerosols. Further pollution cuts could sustain the trend, though Rahmstorf suggested it might ease soon. Projections indicate the 1.5°C threshold above pre-industrial levels—aimed for in the 2015 Paris Agreement to avert severe risks—could be exceeded by 2028, or already based on some 20-year averages.
Rahmstorf warned: “Every tenth of a degree matters... also the risk of crossing tipping points,” citing threats like collapse of the Atlantic Meridional Overturning Circulation (AMOC), which could cause Southern Hemisphere droughts, US East Coast sea level rise, and more. He added that even temporary 'overshoot' above 1.5°C risks irreversible changes, such as 24 feet of sea level rise from Greenland Ice Sheet melt, and criticized the US government for inaction: “it is actually quite tragic that the U.S. government has decided to put their head in the sand.” Heightened risks target coral reefs, west Antarctica, the Amazon, and more, as noted by the IPCC.
Critics urge caution. Zeke Hausfather of Berkeley Earth called evidence strong but noted potential overestimation from imperfect removal of natural factors. Sofia Menemenlis of Princeton highlighted uncertainties in satellite sea surface temperatures and the short decade-scale trend. Daniel Schrag of Harvard questioned El Niño corrections and unaccounted oscillations like the Pacific Decadal Oscillation, saying: “This whole phenomenon is terrifying. It doesn’t need to be exaggerated, and when you exaggerate, you lose credibility.”
