The world's oceans reached their hottest ever recorded temperatures for July, with the average sea surface temperature outside polar regions climbing to 20.96°C — surpassing the previous record of 20.89°C set in 2023, according to the European Union's Copernicus Climate Change Service. Scientists attribute the spike to a combination of factors: long-term human-driven climate change, the developing El Niño weather pattern in the Pacific, and reduced aerosol particles in the atmosphere following environmental clean-air regulations, which — while beneficial for human health — have removed a layer of reflective shielding that previously slowed the warming of ocean surfaces.
El Niño is a naturally occurring climate cycle centred in the tropical Pacific, in which warmer-than-usual surface waters shift global weather patterns, intensifying droughts, storms and rainfall in different parts of the world. Scientists are forecasting an especially strong El Niño this year, and its effects are already amplifying an underlying warming trend: the world is now roughly 1.4°C warmer on average than it was in the late 19th century. July 2026 was the joint second-warmest July globally on record, sitting 1.47°C above the pre-industrial average. In Europe, record-high sea surface temperatures were recorded along the Atlantic coast and in the western Mediterranean, contributing to widespread marine heatwaves. July was also the third consecutive month of exceptional heat in western Europe, where the average temperature for June and July combined reached 2.79°C above normal.
The consequences extend well beyond uncomfortable summers. Warmer oceans absorb excess atmospheric heat and produce around half of Earth's oxygen, but their capacity to regulate the climate is under strain. As seawater warms it expands, accounting for roughly a third of sea level rise recorded so far. Hotter seas are also driving longer and more intense marine heatwaves that bleach coral reefs and devastate kelp forests and fisheries. Oceanographer Sjoerd Groeskamp of the Royal Netherlands Institute for Sea Research (NIOZ) notes that fish are migrating to cooler waters, disrupting ecosystems and threatening communities dependent on fishing, while coral — unable to relocate — faces mass die-offs. Ocean warming also reduces the mixing of surface and deep waters, lowering oxygen levels and accelerating acidification, which weakens shell-forming species such as oysters and mussels.
The impacts are already reshaping daily life across Europe. England and Wales recorded their driest July since records began 190 years ago, large parts of England and all of Wales have been officially declared in drought, and the UK is bracing for a fifth heatwave of the year. Massive wildfires have burned across western Europe, with authorities describing activity as