Global surface temperatures have been climbing at about 0.35°C per decade over the past ten years, nearly double the average pace of just under 0.2°C per decade between 1970 and 2015. The estimate comes from Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and the statistician Grant Foster, who report the acceleration is statistically significant at better than 98 percent confidence.
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The exact figure shifts a little with the dataset. The direction does not.
Five temperature records and a 0.35°C-a-decade slope
Foster and Rahmstorf analyzed five global datasets, from NASA, NOAA, HadCRUT, Berkeley Earth and ERA5, in a paper titled “Global Warming Has Accelerated Significantly” in Geophysical Research Letters (volume 53, issue 5), according to the ScienceDaily write-up of the institute’s release. The paper carries the DOI 10.1029/2025GL118804. Warming over the last decade runs at roughly 0.35°C per decade depending on the record, which makes it the fastest of any decade since instrumental measurements began in 1880, the institute said in its announcement of the study dated March 6, 2026.
Using five records, each compiled by a different group with its own methods for ocean data, station changes and gaps, means no single agency’s processing choices drive the result. NASA, NOAA, HadCRUT, Berkeley Earth and ERA5 each show the break in slope, according to the institute, and the authors report early signs of it in 2013 or 2014 in all five. Rahmstorf, who led the analysis at the Potsdam institute, described the adjusted data as showing an acceleration since 2015 with a statistical certainty of over 98 percent.
The authors place the start of the acceleration around 2015, with early signs in 2013 or 2014 across all five datasets. ScienceDaily carried the release again on October 29, which is why the finding is circulating now rather than in the spring.
Removing El Niño and the solar maximum from 2023 and 2024
The method adjusts the raw temperatures for known natural influences before testing for a change in slope. After correcting for El Niño and the solar maximum, 2023 and 2024 come out somewhat cooler than the original observations, yet both remain the two warmest years on the instrumental record, per the EurekAlert release. Foster said the team can now demonstrate a strong and statistically significant acceleration of global warming since around 2015. Rahmstorf, the lead author, put the statistical certainty at over 98 percent for the adjusted data.
The earlier question was whether recent record years reflected a lasting change in trend. A strong El Niño in 2023 and a peak in solar activity could each pass for acceleration in raw data, which is why the adjustment matters: with those influences removed, the paper reports that the underlying slope still bends upward.
The arithmetic behind the 0.35°C figure is simple. A pace of 0.35°C per decade set against just under 0.2°C per decade means recent warming is running roughly 75 percent faster than the 1970 to 2015 average, and every ten years now adds a little more than a third of a degree to the global mean. The researchers framed that against the 1.5°C above preindustrial levels that governments adopted as the Paris Agreement’s aspirational ceiling, a line the planet is approaching faster at the new rate than at the old one.
ScienceDaily has tracked this line of work through the year, including an August 1 item on a sharp acceleration of global warming and a March 9 item on the sudden acceleration found in the Potsdam analysis. The October 29 release repackages the March paper for a new audience, which is why readers meeting the number for the first time should treat it as seven months old rather than as a new measurement.
Foster and Rahmstorf describe their result as the first time a statistically significant acceleration has been detected once natural influences are removed. That framing matters for readers comparing it with earlier claims: the claim is about the shape of the temperature curve since the instrumental record began in 1880, and the curve in the last decade sits above every earlier decade on it.
The 1.5°C limit and the question of causes
Rahmstorf said that if the present rate continues, it would lead to a long-term exceedance of the Paris Agreement’s 1.5°C limit before 2030. He added that how this unfolds ultimately depends on how rapidly global CO2 emissions from fossil fuels are cut to zero. The institute’s publication record for the paper lists the study, and the Leibniz Association summarized the same result in a news item on the fastest warming pace since 1880.
The study measures the acceleration statistically and does not examine its causes. What it supplies is a firmer baseline: a 0.35°C per decade slope across five independent temperature records, which later attribution work will have to explain. The authors’ rate rests on the last ten years of data, so a cooler stretch or another strong El Niño in coming years would move the endpoint of that estimate.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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