The world’s oceans absorbed record levels of heat in 2025, setting yet another high-water mark for global warming and intensifying climate disasters, scientists say. As the planet’s largest heat sink, the oceans now provide the most unmistakable evidence of the accelerating climate crisis.
More than 90% of the excess heat from human-caused emissions is stored in the oceans, making ocean heat content a far more reliable indicator of long-term warming than air temperature. Almost every year since 2000 has broken the previous record—a trend that will continue until emissions fall to net zero.
This rising ocean heat is fuelling stronger storms, heavier rainfall, and longer marine heatwaves, devastating marine ecosystems and accelerating sea-level rise through thermal expansion. The consequences threaten billions of people worldwide in coastal regions.
Although comprehensive measurements date back only to the mid-20th century, scientists say the oceans are likely hotter than at any point in at least 1,000 years and warming faster than at any time in the last 2,000 years.
“Global warming is ocean warming,” said Prof John Abraham of the University of St Thomas. “If you want to understand how much the Earth has warmed—and how fast it will continue to warm—the answer is in the oceans.”
Published in Advances in Atmospheric Sciences, the analysis draws on independent global datasets measuring heat in the upper 2,000 metres of the ocean, where the vast majority of warming is now being stored—largely unseen, but with profound consequences. Read More
News Credit: The Guardian
Picture Credit: Michael Probst/AP