2025 is set to be in the top three hottest years on record, scientists warn

This year will also likely round out the first three-year period in which the average global temperature exceeded 1.5C

This year is set to be the world's second or third-warmest on record, potentially surpassed only by 2024's record-breaking heat, the European Union said on Tuesday.

The data is the latest from the Copernicus Climate Change Service (C3S) following last month's Cop30 climate summit, where governments failed to agree to substantial new measures to reduce greenhouse gas emissions.

The lack of meaningful climate action at the UN summit reflected strained geopolitics as the US rolls back its efforts, and some countries seek to weaken CO2-cutting measures.

This year will also likely round out the first three-year period in which the average global temperature exceeded 1.5 degrees Celsius (2.7 degrees Fahrenheit) above the 1850-1900 pre-industrial period, when humans began burning fossil fuels on an industrial scale, C3S said in a monthly bulletin.

"These milestones are not abstract; they reflect the accelerating pace of climate change," said Samantha Burgess, strategic lead for climate at C3S.

Ocean temperatures also remained at record highs through much of 2025, a trend scientists say is helping to fuel more intense storms and heavier rainfall.

Extreme weather continued to hit regions around the globe this year. South and southeast Asia are experiencing the deadliest climate disaster of 2025, with over 1,800 deaths across Indonesia, Sri Lanka, Malaysia and Thailand.

Typhoon Kalmaegi killed more than 200 people in the Philippines last month. Spain suffered its worst wildfires for three decades because of weather conditions that scientists confirmed were made more likely by climate change.

Last year was the planet's hottest on record.

Damaged homes beside Mananga Bridge in Talisay, Cebu Province, central Philippines, after Typhoon Kalmaegi devastated the province and claimed lives (AP)

While natural weather patterns mean temperatures fluctuate year to year, scientists have documented a clear warming trend in global temperatures over time, and confirmed that the main cause of this warming is greenhouse gas emissions from burning fossil fuels.

Last week the World Meteorological Organisation (WMO) also warned that 2023, 2024 and 2025 represent the warmest three-year period ever recorded.

The last 10 years have been the 10 warmest years since records began, the WMO said earlier this year.

The global threshold of 1.5C is the limit of warming which countries vowed under the 2015 Paris climate agreement to try to prevent, to avoid the worst consequences of warming.

The world has not yet technically breached that target, which refers to an average global temperature of 1.5C over decades. But the UN said this year that the 1.5C goal can no longer realistically be met and urged governments to cut CO2 emissions faster, to limit overshooting the target.

Scientists stress that exceeding 1.5C on a multi-year basis would expose millions more people to dangerous heat, crop failures and extreme rainfall.

C3S's records go back to 1940, and are cross-checked with global temperature records going back to 1850.