World leaders promised in 2015 to try to limit the long-term temperature rise to 1.5C, which is seen as crucial to help avoid the most damaging impacts.
This first year-long breach doesn’t break that landmark “Paris agreement”, but it does bring the world closer to doing so in the long-term.
Urgent action to cut carbon emissions can still slow warming, scientists say.
“To go over [1.5C of warming] on an annual average is significant,” says Prof Liz Bentley, chief executive of the Royal Meteorological Society.
“It’s another step in the wrong direction. But we know what we’ve got to do.”
A landmark UN report in 2018 said that the risks from climate change – such as intense heatwaves, rising sea-levels and loss of wildlife – were much higher at 2C of warming than at 1.5C.
But temperatures have kept rising at a concerning pace, data from the EU’s Copernicus Climate Change Service from the past year shows, illustrated in the graph below.
The period from February 2023 to January 2024 reached 1.52C of warming.
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This year-long breach is no major surprise. January was the eighth record warm month in a row.
In fact, one science group, Berkeley Earth, says that the calendar year 2023 was more than 1.5C above pre-industrial levels. Other science bodies, such as Nasa, put the past 12 months slightly below 1.5C of warming.
These small differences are mainly due to the way global temperatures are estimated for the late 1800s, when measurements were more sparse.
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