The world’s oceans absorbed unprecedented amounts of heat in 2025, setting another record and amplifying climate disasters, scientists report. Oceans take up more than 90% of the excess heat from carbon pollution, making them the clearest measure of global warming’s pace and persistence. The added heat fuels stronger hurricanes and typhoons, heavier rainfall and flooding, and longer marine heatwaves that devastate ocean life. It also accelerates sea-level rise through thermal expansion, threatening coastal communities worldwide.
The analysis, published in Advances in Atmospheric Sciences, shows the top 2,000 metres of the oceans now hold heat equivalent to more than 200 times global annual electricity use. Reliable measurements suggest oceans are likely hotter than at any time in at least 1,000 years and warming faster than in the past two millennia. While air temperatures fluctuate with cycles like El Niño and La Niña, ocean heat continues its steady climb. Hotspots in 2025 included the tropical and South Atlantic, the North Pacific, and the Southern Ocean, where winter sea ice near Antarctica has sharply declined. Scientists warn warming, acidification and deoxygenation are making marine ecosystems more fragile. Researchers stress the trend will continue until emissions fall to zero, underscoring that future risks hinge on human choices.
