The world's oceans hit their hottest ever recorded temperatures in July, partly fuelled by developing El Niño conditions in the Pacific, according to the EU's climate monitoring service.
The average sea surface temperature (SST) outside the world's polar regions – between 60 degrees north and 60 degrees south – was 20.96C in July, beating the previous July high of 20.89C, set in 2023.
El Niño is a natural weather pattern in the Pacific, but when combined with human-driven global warming can cause temperature spikes and more extreme weather.
Last month was the joint second-warmest July globally on record, with temperatures 1.47C above the estimated pre-industrial average, according to the Copernicus Climate Change Service.
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Sea temperatures remained exceptionally high across much of the tropical Pacific, where El Niño conditions are developing and forecast to strengthen in the coming months.
Around Europe, sea surface temperatures in July reached record highs along the Atlantic coast and in the western Mediterranean, contributing to widespread strong and severe marine heatwaves.
Meanwhile, western Europe experienced its hottest June and July on record, with prolonged hot and dry conditions fuelling extreme wildfires across the region.
The UK is braced for its fifth heatwave of the year this week, as persistent dry weather puts further pressure on water supplies and could see more areas declared in drought.
Oceans are a vital regulator of the climate, absorbing most of the excess heat generated by greenhouse gas emissions and producing half of Earth's oxygen.
Warmer waters absorb less carbon dioxide, leaving more of the planet-warming gas in the atmosphere.
Higher ocean temperatures can also adversely affect marine ecosystems, as species move in search of cooler waters, disrupting food chains.
Western Europe is experiencing an exceptional run of extreme heat – with record-breaking temperatures in June and July, and some areas facing their third or fourth heat wave since May.
The average temperature across western Europe for June and July was 21.62C – 2.79C above average and the highest for the two-month period.