Study detects statistically significant acceleration of global warming since around 2015

Global warming has accelerated significantly since around 2015, according to a peer-reviewed analysis that isolates the long-term trend by removing short-term natural influences on temperature records. The study, led by Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research (PIK) and co-authored by statistician Grant Foster, was published in Geophysical Research Letters (agupubs.onlinelibrary.wiley.com).

After accounting for the effects of El Niño/Southern Oscillation, volcanic eruptions and solar variations, the researchers found that the estimated warming rate over the past ten years has been around 0.35°C per decade, depending on the dataset. This compares with just under 0.2°C per decade on average from 1970 to 2015. The recent rate exceeds that of any previous decade since instrumental records began in 1880, the Potsdam Institute reported (pik-potsdam.de).

“We can now demonstrate a strong and statistically significant acceleration of global warming since around 2015,” Foster said. The adjusted data show the acceleration with a statistical certainty of over 98 percent, consistent across all five major global temperature datasets examined—NASA, NOAA, HadCRUT, Berkeley Earth and ERA5—and independent of the analysis method chosen, according to Rahmstorf (sciencedaily.com).

The team applied a method refining earlier work to estimate and subtract the influence of the three natural factors using independent measurements and lagged correlation analysis. This reduces the “noise” that can mask changes in the underlying warming signal. Two statistical approaches were used to test for a change in rate since the 1970s: quadratic trend analysis and a piecewise linear model with an objectively determined changepoint. Both supported acceleration beginning to become apparent around 2013–2014 and clearer by about 2015 (agupubs.onlinelibrary.wiley.com).

Even after adjustments that reduced the extreme warmth of 2023 and 2024 by removing El Niño and solar maximum effects, those years remained the two warmest on record in the datasets. The study focused on detecting and quantifying the statistical acceleration rather than identifying its causes. The authors noted that an increasing warming rate falls within the range produced by current climate models (pik-potsdam.de).

“If the warming rate of the past 10 years continues, it would lead to a long-term exceedance of the 1.5°C limit of the Paris Agreement before 2030,” Rahmstorf stated. “How quickly the Earth continues to warm ultimately depends on how rapidly we reduce global CO₂ emissions from fossil fuels to zero.” Independent climate scientists commenting on the findings noted broad agreement on detectable recent acceleration while emphasizing that the precise contribution of forced response versus residual variability continues to be examined, and that continued monitoring will be needed to confirm whether the higher rate persists (theguardian.com).

The analysis builds on previous discussions of possible acceleration that had not previously reached conventional statistical significance thresholds when natural variability was fully accounted for. By reducing that variability, the adjusted records reveal a clearer departure from the relatively steady post-1970s trend.