The biggest temperature increases were recorded in the Middle East, West Asia, northeast Russia, and north Canada.
This year, the world experienced its second-warmest month of May since records began, the European Union’s Copernicus Climate Change Service (C3S) has said in a monthly bulletin.
Global surface temperatures last month averaged 1.4 degrees Celsius (2.5 degrees Fahrenheit) higher than in the 1850-1900 pre-industrial period, when humans began burning fossil fuels on an industrial scale, C3S said.
The latest data comes amid mixed momentum on climate action globally, with China and the EU reducing emissions as the Trump administration and technology companies increase their use of fossil fuels.
“Temperatures were most above average over western Antarctica, a large area of the Middle East and western Asia, northeastern Russia, and northern Canada,” the C3S bulletin added.
At 1.4C above pre-industrial levels, May was also the first month globally not to go over 1.5C (2.7F) in warming in 22 months.
“May 2025 breaks an unprecedentedly long sequence of months over 1.5C above pre-industrial,” said Carlo Buontempo, director of C3S.
“Whilst this may offer a brief respite for the planet, we do expect the 1.5C threshold to be exceeded again in the near future due to the continued warming of the climate system,” Buontempo said.
The increased temperatures were particularly felt in Pakistan’s Jacobabad city in Sindh province, where residents grappled with extreme temperatures in the high 40s, which sometimes reached 50C (122 F).
The soaring temperatures followed another heatwave last June that killed more than 560 people in southern Pakistan.
“While a heatwave that is around 20C might not sound like an extreme event from the experience of most people around the world, it is a really big deal for this part of the world,” Friederike Otto, associate professor in climate science at Imperial College London, told reporters.
“It affects the whole world massively,” Otto added. “Without climate change, this would have been impossible.”
In a separate report released on Wednesday, the World Weather Attribution (WWA) research collaboration said Greenland’s ice sheet melted 17 times faster than the past average during a May heatwave that also hit Iceland.
Mixed momentum on climate action
The latest data comes amid mixed progress on climate change action.
United States President Donald Trump has promised to “drill, baby, drill” during his presidency, even as his country faces increasingly severe weather events, like the fires that tore through California’s capital, Los Angeles, late last year. Emissions from technology companies are also surging, as expanding use of artificial intelligence (AI) and data centres drives up global electricity demand, according to a recent report from the United Nations International Telecommunication Union (ITU).
New analysis by the climate reporting site Carbon Brief found that China’s emissions may have peaked, as the country increased electricity supplies from new wind, solar, and nuclear capacity and reduced its reliance on coal and other fossil fuels.
“China’s emissions were down 1.6 percent year-on-year in the first quarter of 2025 and by 1 percent in the latest 12 months,” Carbon Brief reported last month.
“If this pattern is sustained, then it would herald a peak and sustained decline in China’s power-sector emissions,” it added.
The EU also announced last week that its 27 member states are well on track to meet their goal of a 55 percent reduction in greenhouse gas emissions by 2030.
“Emissions are down 37 percent since 1990, while the economy has grown nearly 70 percent — proving climate action and growth go hand in hand,” said Wopke Hoekstra, the EU’s commissioner for climate, net zero and clean growth.
In the Caribbean, leaders met recently to plan ways to restore the region’s mangrove forests, which help prevent climate change and protect from rising sea levels and intensifying storms.