The world's oceans recorded their hottest ever July, with sea surface temperatures partly driven by developing El Niño conditions in the Pacific, according to the EU's Copernicus Climate Change Service. This matters because oceans regulate the global climate by absorbing most excess heat from greenhouse gas emissions, and warmer waters absorb less carbon dioxide, leaving more of it in the atmosphere, while also disrupting marine ecosystems as species migrate to cooler waters.

The average sea surface temperature outside polar regions reached 20.96C in July, surpassing the previous July record of 20.89C set in 2023, making it the joint second-warmest July globally on record at 1.47C above pre-industrial levels. Western Europe also had its hottest June and July on record, averaging 21.62C, fuelling severe wildfires, drought and record-low river levels on the Seine, Rhine and Danube, with the UK bracing for its fifth heatwave of the year amid growing water supply pressures.