Global warming has accelerated since around 2015, and researchers at the Potsdam Institute for Climate Impact Research say they now have the first statistically significant evidence to show it. Stefan Rahmstorf said the adjusted data indicate an acceleration of global warming since 2015 with more than 98 percent statistical certainty, after natural temperature swings were stripped out of the record.
The finding matters because it puts a sharper number on something scientists have been watching for years: the long-term warming trend is not only continuing, it is moving faster than it did in earlier decades. Over the past decade, temperatures have risen at an estimated pace of about 0.35 degrees Celsius per decade, compared with just under 0.2 degrees per decade from 1970 to 2015, and that recent pace is higher than in any previous decade since instrumental records began in 1880.
Researchers reached that result by examining five global temperature data sets from NASA, NOAA, HadCRUT, Berkeley Earth and ERA5. They used a quadratic trend analysis and a piecewise linear model to test whether warming had changed since the 1970s, then adjusted for known natural influences that can temporarily mask or exaggerate the trend. Grant Foster said the point of that filtering is to reduce the noise so the underlying long-term signal becomes clearer.
The reason the shift can be seen as beginning in 2015 even though it started to show up in 2013 or 2014 is the way the signal emerges in the statistics. In all five records, the acceleration first became visible a little earlier, but the broader break from the older pace only became clear around 2015. That is the line the researchers draw because it is where the change in rate becomes persistent rather than just a short-lived swing.
That distinction matters because natural variations can still push individual years up or down without changing the long-term direction. The team adjusted for El Niño and the solar maximum, and the extreme warmth of 2023 and 2024 was reduced slightly in the analysis. Even so, those two years remained the warmest since instrumental records began, a reminder that the faster trend is showing up on top of record-breaking heat, not instead of it.
The study, published in Geophysical Research Letters, does not explain exactly which physical processes are driving the acceleration. It does, however, leave little doubt about the statistical pattern itself: across all five records, the same overall shift appeared, and the warming rate since around 2015 is now clear enough for the researchers to say it is no longer a question of whether the planet has entered a faster phase, but how quickly that phase may intensify from here.
