The rate of global warming has accelerated at a higher rate since 2015 than in any decade since records began in 1880, according to a new study that strips away the background noise of natural fluctuations. However, not everyone agrees with the paper’s findings.
In the study, published Friday (March 6) in the journal Geophysical Research Lettersscientists used statistical evidence to demonstrate accelerated warming over the past decade, which they say is the first time scientists have identified the “statistically significant acceleration of global warming” since 2015.
“The warming trend almost doubled after 2014,” co-author of the study Stefan Rahmstorfhead of Earth System Analysis at the Potsdam Institute for Climate Impact Research in Germany, told LiveScience in an email. “The acceleration of the global warming rate means that we will cross the 1.5 °C (2.7 degrees Fahrenheit) limit earlier,” he said, adding that they were surprised by the drastic increase.
Between 1970 and 2015 the average rate of warming was attached of just under 0.2 degrees Celsius (0.36 F) per decade. But over the past 10 years, the researchers found that the estimated rate of warming was 0.35 C (0.63 F) per decade. There has also been a consistent upward trend in the global average surface temperature, according to the study.
Scientists generally attest that the extent and rate of warming over the past 150 years has exceeded the extent and rate of change experienced in the past 24,000 yearswhich includes the end of the last ice age.
But it’s hard to tease out how much of this accelerated warming is human-made greenhouse gas emissions and how much can be attributed to natural influences on the climate, such as e.g El Nino. Rahmstorf and his co-author Grant Fostera retired climate analyst, wanted to remove these natural fluctuations to better understand the warming trend.
– The key was to reduce the “noise” in the data, i.e. to remove the effect of natural variation, in order to get a better signal-to-noise ratio, Rahmstorf said and explained that this gives the signal increased visibility.
Rahmstorf and Grant used five established global temperature datasets, including those from NASA; National Oceanic and Atmospheric Administration; and Berkeley Earth. Then they removed the three environmental factors driving the warming — the El Niño-Southern Oscillation cycle, volcanic eruptions and solar variations — and tested the data sets for acceleration in warming since 1970.
The findings showed an acceleration of global warming, they said. Finally, they estimated warming rates by developing a model that looked at changes every decade since 1895.
The results showed a “statistically significant acceleration of global warming since about the year 2015,” they wrote in the study. In one statementRahmstorf said the confidence was 98% and was consistent across datasets and analysis methods.
If the current rate of warming continues, he added, this paper and previous research have shown we will pass 1.5 C (2.7 F) of warming by 2030.
Disagreement on the field
But not all researchers are convinced by Rahmstorf and Grant’s findings. Their methods for removing these variables from the analysis are imperfect and may leave residual effects, Zeke Hausfara researcher at Berkeley Earth told LiveScience. He argued in a paper published last year that man-made or human activities are increasing the Earth’s surface temperature. This has further been linked to faster sea level rise and changes in land precipitation.
“It is widely agreed that there has been a detectable acceleration in warming in recent years,” he said. “But it remains unclear how much of the additional warming in the last decade in particular is a forced response (or) an unforced variation.”
Robert Lunda statistician at the University of California, Santa Cruz, also agrees that there is solid evidence that the Earth is warming, but was less sure whether we are experiencing an accelerated rate of warming. Lund, who applies the laws of probability to climate change models, were among the authors of 2024 paper who argued that a recent increase in the rate of global warming was not yet detectable. Despite the warm years of 2023 and 2024, he told LiveScience, we must urge caution while claiming that the Earth is suddenly warming. “There is no statistical evidence for that,” he said.
Lund found problems with various aspects of the analysis, for example including factors such as El Niño. He said that one also had to account for the uncertainties caused by them, since models can not yet catch the intricate atmosphere-ocean interactions. However, the authors did not do this, he noted.
While Lund and Hausfather are cautious about the warming trend, they agree that we are getting close to exceeding the thresholds established in The Paris Agreementwhich aims to keep the rate of global warming to 2 C above pre-industrial levels and continue efforts to limit the increase to 1.5 C above pre-industrial levels.
Earth seems to be already on track for this, as a recent one Report on emissions gap found that the planet will pass the 1.5 C threshold within the next decade. This could double the proportion of people exposed to extreme heat, Live Science reported last November.
For Rahmstorf, this study also serves as a warning. “We need to be much faster in replacing fossil fuels like coal, oil and gas and leaving them behind,” he said.
