After a year in which wildfires razed Los Angeles, a freak cyclone battered Southeast Asia and drought forced Iran to plan a move of its capital city, new data shows 2025 was the third warmest on record.

Findings from EU's Copernicus Climate Change Service program also reveal 2025 to be the third in a row to average above 1.5 degrees Celsius (2.7 degrees Fahrenheit). Mauro Facchini, who oversees Earth observation for the European Commission, described it as a "milestone none of us wished to reach."

Scientists have long warned about the dangers of passing this temperature threshold set out in the 2015 Paris climate accord. They stress warming above that level will mean more days of extreme heat, as well as increased deadly flooding and devastating storms.

Carlo Buontempo, director of Copernicus's climate change service, said the world is on track to cross the threshold in the longer term. 

"The choice we now have is how to best manage the inevitable overshoot and its consequences on societies and natural systems," he said in a press release. 

Scientists agree on the need to simultaneously cut greenhouse gas emissions by transitioning to clean energy, while adapting to live on a warming planet. 

At last year's United Nations climate summit, countries pledged $120 billion (€102 billion) for vulnerable nations to fund adaptation projects like sea walls, early-warning systems, and drought-resistant crops. Climate finance promises have not always amounted to action.

El Nino contributed to the three-year trend

Greenhouse gases, which absorb and trap heat in the atmosphere, remain the leading cause of hotter global temperatures. Released when we burn oil, coal and gas to power our cars or heat and cool our homes, they are connected to an increase in extreme weather events that are claiming lives around the world. 

The problem is made worse by the destruction of natural carbon sinks like forests that would otherwise absorb CO2.

"Atmospheric data from 2025 paints a clear picture: human activity remains the dominant driver of the exceptional temperatures we are observing," said Laurence Rouil, director of Copernicus's atmosphere monitoring service, adding that "greenhouse gases have steadily increased over the last 10 years."

But in 2023 and 2024, this picture was exacerbated by a particularly powerful el Nino — a climate pattern that occurs every few years and pushes ocean heat into the atmosphere. 

The consequences were visible across the globe. Copernicus found that sea ice at both the North and South Poles hit a record low in 2025. In addition, the Antarctic had its warmest annual temperature on record and half of the world's land area experienced more dangerously hot days than usual.

"The atmosphere is sending us a message, and we must listen," Rouil said.

Edited by: Tamsin Walker