Global warming has accelerated significantly since around 2015, with the planet heating at nearly twice the rate recorded over the preceding four decades, according to a study published in Geophysical Research Letters. The researchers found that the rate of warming had risen to approximately 0.35°C per decade over the past 10 years, compared with about 0.2°C per decade between 1970 and 2015.
The study, by Grant Foster and Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, found that the acceleration was statistically significant at more than 98 per cent confidence after accounting for the effects of natural climate fluctuations. The findings were based on five major global temperature datasets maintained by NASA, the US National Oceanic and Atmospheric Administration, the UK Met Office and the University of East Anglia, Berkeley Earth, and the European Centre for Medium-Range Weather Forecasts.
The researchers adjusted temperature records to account for three natural influences: El Niño events, volcanic activity and variations in solar radiation. These factors can temporarily raise or lower global temperatures, making it harder to identify changes in the underlying warming trend.
The adjusted records showed that the acceleration had begun around 2013 or 2014, with the warming rate increasing substantially thereafter. The researchers said the evidence remained consistent across all five datasets and two different statistical methods.
The study also found that 2023 and 2024 remained the two hottest years in the instrumental record even after adjustments for natural influences. Both years had recorded exceptionally high temperatures, with El Niño and heightened solar activity contributing to the observed warmth.
"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," Professor Rahmstorf said.
The researchers cautioned that the study was designed to establish whether global warming had accelerated, rather than identify the precise physical causes behind the change. They noted that the observed trend was consistent with climate model projections.
The findings have implications for the Paris Agreement, under which countries committed to limiting the rise in global average temperatures to well below 2°C above pre-industrial levels, while pursuing efforts to restrict it to 1.5°C.
However, crossing 1.5°C in an individual year does not constitute a formal breach of the Paris target, which concerns long-term warming. Global temperatures exceeded that level relative to pre-industrial averages in 2024, but the agreement's threshold is assessed over a sustained period.
The study's findings come amid continuing scientific discussion over the pace of global warming. In a report published in March, climate publication Carbon Brief noted that the researchers' adjusted datasets showed warming rates of between 0.34°C and 0.42°C per decade, depending on the dataset used.
Some scientists have urged caution in interpreting the acceleration. Professor Piers Forster of the University of Leeds told Carbon Brief that describing the trend as accelerating could imply that the rate would continue to increase. He said he was more comfortable describing it as "unprecedented rates of warming".
Dr Zeke Hausfather, a climate scientist and Carbon Brief contributor, also questioned the precision of the adjusted warming estimate, noting that removing the influence of El Niño from surface temperature records involves methodological uncertainty. He identified reductions in cooling sulphur dioxide emissions as a possible contributor to the recent increase in warming.
A separate study published in Nature Communications in September 2026 examined regional patterns in surface warming. It found evidence of accelerated warming in several parts of the world since 1970, particularly across mid-latitudes in the Northern Hemisphere, while also documenting differences in the timing of these changes across regions.
The authors of the Geophysical Research Letters study said the speed at which the planet continues to warm will depend on how quickly global carbon dioxide emissions from fossil fuels are reduced.