Have we already breached the 1.5°C global warming target?
Although the climate goals set by the Paris Agreement are based on the long-term average temperature, one year of high temperatures might be a sign that the 1.5°C threshold has already been reached
By Madeleine Cuff
10 February 2025
A climate protester’s flag in Düsseldorf, Germany
Ying Tang/NurPhoto/Shutterstock
Last month, researchers confirmed that 2024 was the first year to see global average temperatures rise more than 1.5°C above pre-industrial levels. It was a symbolic moment, given the world’s collective goal, set in 2015 under the Paris Agreement, to keep long-term warming to a 1.5°C threshold. But scientists were quick to stress that this goal is based on a 20-year average temperature, so global efforts to deliver on it are still – technically at least – in play.
Yet experts are increasingly asking whether shorter periods of high temperatures could be a sign that the world has already breached 1.5°C. Can we conclude that this target has bitten the dust?
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Emanuele Bevacqua at the Helmholtz Centre for Environmental Research–UFZ in Germany and his colleagues set out to investigate whether a single warm year above 1.5°C could be a signal that long-term warming will soon reach that level.
Using a combination of real-world observations and climate models, Bevacqua and his team studied warming thresholds already breached between 1981 and 2014. They found that the first single year exceeding 0.6°C, 0.7°C, 0.8°C, 0.9°C and 1°C above the pre-industrial benchmark has consistently fallen within the first 20-year period in which the average temperature reached the same thresholds.
By that measure, the first single year above 1.5°C puts the world within the 20-year period scientists use to define 1.5°C of long-term warming, the team concludes. “It is highly probable that we are already within the 20-year period,” says Bevacqua. “We are most likely within the first 10 years [of the period]”.
