World's oceans record hottest June ever as marine heatwaves spread

The world's oceans experienced their hottest June on record, according to European scientists, in the latest sign of accelerating climate change and its growing impact on marine systems.

Global average sea surface temperatures reached 20.98 degrees Celsius in June, beating the previous records set in 2023 and 2024, the EU's Copernicus service said. It capped six months of near-unprecedented ocean warmth, with prolonged marine heatwaves across large parts of the globe.

The Mediterranean broke its own June record at 24.3 degrees Celsius, with marine heatwaves affecting almost the entire basin during the first half of the year. The tropical Pacific also recorded its hottest June, at 27.26 degrees Celsius. In all, marine heatwaves affected around 82 percent of the world's oceans over the period.

Scientists warned that the onset of a potentially strong El Niño weather pattern could push ocean and atmospheric temperatures even higher through the rest of the year and into next, making further records likely.

Warmer oceans have wide-ranging consequences, from bleaching coral reefs and disrupting fisheries to fuelling more intense storms and heatwaves on land. Researchers said the figures pointed to the planet heading into what one described as uncharted territory.