The rate of global warming has accelerated since 2015, faster than in any decade since records began in 1880, according to a new study that filters out the background “noise” of natural change. But not everyone agrees with the paper’s findings.
In the study, published Friday (March 6) in the journal Geophysical Research Letters, researchers use statistical evidence to prove the acceleration in global warming over the past decade, and say it is the first time scientists have seen a “statistically significant acceleration in global warming” since 2015.
“The warming trend has almost doubled since 2014,” study co-author Stefan Rahmstorff, head of Earth system analysis at Germany’s Potsdam Institute for Climate Impact Research, told Live Science via email. “Accelerating rate of global warming means more than 1.5°C [2.7 degrees Fahrenheit] We lifted restrictions earlier,” he said, adding that they were surprised by the sudden spike.
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Between 1970 and 2015, the average warming rate was fixed at just under 0.2 degrees Celsius (0.36 °F) per decade. However, researchers found that the estimated warming rate over the past decade was 0.35 degrees Celsius (0.63 degrees Fahrenheit) per decade. Research shows that there is also a consistent upward trend in the Earth’s average surface temperature.
Researchers have generally demonstrated that the magnitude and rate of warming over the past 150 years has exceeded the magnitude and rate of change experienced over the past 24,000 years, including the end of the last ice age.
However, it is difficult to determine how much of this accelerated warming is due to anthropogenic greenhouse gas emissions and how much is due to natural climate impacts such as El Niño. Rahmstorff and his co-author, former climate analyst Grant Foster, wanted to remove these natural variations to better understand warming trends.
“The key was to reduce the ‘noise’ in the data, that is, remove the effects of natural variations and obtain a better signal-to-noise ratio,” Rahmstorff said, explaining that this improves the visibility of the signal.
Rahmstorff and Grant used five established global temperature datasets, including one from NASA. National Oceanic and Atmospheric Administration. and Berkeley Earth. They then removed three environmental factors that drive warming (the El Niño Southern Oscillation cycle, volcanic eruptions, and solar variability) and tested the dataset for accelerated warming since 1970.
The findings indicate an acceleration of global warming, the researchers said. Finally, they developed a model that looked at decadal changes since 1895 to estimate the rate of warming.
The results showed “a statistically significant acceleration of global warming starting around 2015,” the researchers wrote in their paper. Rahmstorff said in a statement that the certainty was 98% and consistent across datasets and analysis methods.
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He added that if current rates of warming continue, this paper and previous studies show that warming will exceed 1.5 degrees Celsius (2.7 degrees Fahrenheit) by 2030.
Differences of opinion in the field
But not all researchers are convinced by Rahmstorf and Grant’s findings. Zeke Hausfather, a research scientist at Berkeley Earth, told Live Science that the method of removing these variables from the analysis is imperfect and could leave residual effects. In a paper published last year, he argued that anthropogenic or human activities are increasing the Earth’s surface temperature. This has also been linked to accelerating sea level rise and changes in land precipitation.
“There is widespread agreement that warming has measurably accelerated in recent years,” he said. “However, it remains unclear how much of the additional warming, especially over the past decade, is due to forced responses.” [or] It is a change that is not forced. ”
Robert Rand, a statistician at the University of California, Santa Cruz, agrees that there is strong evidence that the planet is warming, but he is less certain that the rate of warming is accelerating. Lund, who applies the laws of probability to climate change models, is also one of the authors of a 2024 paper arguing that the recent spike in the rate of global warming has gone undetected. Despite the hot years of 2023 and 2024, we need to be careful, he told Live Science, arguing that the Earth is suddenly getting warmer. “There’s no statistical evidence of that,” he said.
Lund found problems with various aspects of the analysis, including the inclusion of factors such as El Niño. He said models still cannot capture the complex interactions between the atmosphere and ocean, so the uncertainties caused by them must also be taken into account. But the authors did not do so, he noted.
While Lund and Hausfather are alarmed by the warming trend, they agree that we are inching closer to exceeding thresholds set by the Paris Agreement, which aims to limit the rate of global warming to 2 degrees Celsius above pre-industrial levels and pursue efforts to limit the rise to 1.5 degrees Celsius above pre-industrial levels.
The Earth appears to be already on that trajectory, as the recent Emissions Gap Report found that the planet will exceed the 1.5°C threshold in the next decade. This could double the proportion of people exposed to extreme heat, Live Science reported last November.
For Rahmstorff, the study also serves as a warning. “We need to replace fossil fuels like coal, oil and gas sooner and leave them behind completely,” he said.
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