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In January, 2025, a highly-destructive wildfire in Pacific Palisades, California damaged thousands of houses and buildings. Credit: Robyn Beck/AFP via Getty

The past 11 years have been the hottest on record, with 2025 being the second or third hottest year since observations began, according to a report released today by the World Meteorological Organization (WMO).

The State of the Global Climate 2025 report , which tracks major climate indicators, found atmospheric carbon dioxide and ocean heat reached record levels in 2025. Global surface temperatures were slightly lower in 2025 than the previous year — the hottest on record — but “continue a run of exceptionally high temperatures”, the report states. Sea-ice levels in the Antarctic and the Arctic were among the lowest since 1979.

The speed at which temperatures are rising, the ocean is heating up and glacial ice mass is melting is concerning, says Mandy Freund, a climate scientist at the University of Melbourne, Australia.

“We seem to be entering this new era where temperatures will be significantly higher than what they were ten years ago,” says climate scientist Sarah Perkins-Kirkpatrick, from the Australian National University in Canberra. The past three years have seen a step change in temperature that could only be a result of climate change, she adds.

Energy imbalance

For the first time, the report includes a measure of the accumulation of heat on Earth and in the atmosphere. The indicator, called the Earth’s energy imbalance (EEI), has been used by climate scientists for at least a decade, and is the difference between incoming energy from the Sun and the amount radiated back into space and allows scientists to monitor the rate of global warming. A positive EEI value means that the total amount of heat stored on Earth is increasing.

In 2025, EEI reached its highest level since observations started in 1960, the report states. The increased concentration of greenhouse gases in the atmosphere trap heat, reducing the amount that is radiated back into space.

Thomas Mortlock, a climate analyst at UNSW, Sydney, says that the inclusion of EEI in the WMO report is significant. Typically, it’s the rise in surface temperatures that makes headlines, but the atmosphere absorbs just 1% of the planet’s excess heat so using it to gauge the severity of global warming is “quite misleading,” he says. More than “91% of all of the excess heat that has been received by the Earth since the 1970s has been absorbed in the oceans”, he adds.

The planet’s energy imbalance is a much better descriptor to understand the true impact of global warming, he says.

Freund adds that EEI is also a clearer measure of the long-term changes than comparing average temperatures, which can fluctuate year to year due to events with short-term impacts such as volcanic eruptions or La Niña events.

Record greenhouse gases

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doi: https://doi.org/10.1038/d41586-026-00946-6

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The world just lived through the 11 hottest years on record — what now?