Global Warming Has Accelerated Since 2015, Study Finds

A new analysis from the Potsdam Institute for Climate Impact Research (PIK) concludes that the pace of global warming has increased since the mid-2010s. The researchers reached that result after adjusting temperature records for short-term natural influences, making the underlying human-driven warming trend easier to see.

What the temperature records show

Across the past decade, the datasets analyzed in the study indicate warming of about 0.35°C per decade. That is notably faster than the average rate of less than 0.2°C per decade recorded from 1970 to 2015.

The study describes the past decade as the fastest-warming period since modern global temperature measurements began in 1880. Its authors found signs that the acceleration began to emerge around 2013 or 2014 and became statistically significant around 2015.

How researchers isolated the warming trend

Year-to-year temperatures do not rise in a smooth line. El Niño, volcanic eruptions and changes in solar activity can temporarily push global temperatures up or down, obscuring the longer-term trend.

To reduce that short-term “noise,” the team examined five widely used temperature records: NASA, NOAA, HadCRUT, Berkeley Earth and ERA5. The researchers adjusted the observations for natural influences, then tested the resulting trend with two statistical approaches: quadratic trend analysis and fractional linear modeling.

According to lead author Stefan Rahmstorf, the adjusted records show an acceleration since 2015 with more than 98% statistical confidence. The finding appeared across all five datasets and did not depend on which of the two analytical methods was used.

What the study does—and does not—establish

The analysis was designed to determine whether the warming rate has changed over time. It did not attempt to identify the precise cause of the acceleration. The authors note, however, that climate models have anticipated a faster warming trend and that the result is consistent with the established understanding of climate change.

Adjusting for El Niño and the recent period of strong solar activity slightly lowers the relative prominence of the record-hot years 2023 and 2024 in the analysis. Even after that adjustment, they remain the two hottest years in the modern instrumental record described by the study.

Why the 1.5°C threshold matters

Rahmstorf said that if the warming rate observed over the past decade continues, the global average temperature could pass the Paris Agreement’s 1.5°C threshold before 2030. This is a projection based on the recent rate, not a claim that every future year will follow the same path.

The future rate of warming will depend heavily on how quickly carbon dioxide emissions from fossil fuels decline. Natural variability can still affect individual years, but it does not remove the long-term warming signal identified across the datasets.