Global sea surface temperatures reached an unprecedented 21.1°C on Aug. 22, surpassing the previous record of 21.09°C set in March 2024, according to new data. The spike is unusual because ocean temperatures typically peak in March and April, not August. Scientists attribute the anomaly to a combination of climate change and a developing strong El Niño, with studies suggesting oceans may not have been this warm for as much as 125,000 years.
Waters around the Iberian Peninsula are heating 67% faster than the global average, rising at 0.25°C per decade, according to Greenpeace. The Mediterranean exceeded 33°C for the first time, while the Cantabrian Sea broke 28°C for the first time since 1990. Twelve monitoring buoys recorded historic heat records this summer.
Marine heat waves worldwide have more than tripled since the early 1990s, threatening marine ecosystems and contributing to higher sea levels.