World's oceans hit record high temperature as El Niño grows

The world's oceans have reached their highest daily temperature on record, with global sea surface temperatures hitting 21.1°C (70°F) on 22 August, according to the European Union's Copernicus Climate Change Service. This narrowly surpasses the previous record of 21.09°C set in March 2024, and is particularly striking because ocean temperatures typically peak in March and April, not August Source: AP News, BBC, Euronews.

Why it matters

Warmer oceans have wide-reaching consequences. They can supercharge extreme weather, raise sea levels, and harm marine life Source: BBC. Warmer water holds less oxygen and becomes more acidic, threatening fisheries and aquaculture Source: AP News. Marine heatwaves have more than tripled in frequency since the early 1990s, and warmer seas can weaken the ocean's ability to absorb CO2 Source: Euronews.

The role of El Niño

The record comes as a strong El Niño develops in the tropical Pacific, adding heat to an ocean already warmed by decades of human-driven climate change. El Niño is expected to strengthen, potentially reaching levels not seen for decades Source: Euronews. However, scientists caution against viewing El Niño as the sole explanation. As Dr. Samantha Burgess of Copernicus puts it, "El Niño is adding heat to the system, but it is doing so on top of decades of human-driven warming" Source: BBC, Euronews.

What's next

Scientists are watching to see whether this record is a short-lived spike or part of a persistent period of extreme ocean warmth. With El Niño expected to peak between November and January, ocean temperatures may rise further Source: AP News. The record is "another clear signal of an ocean under growing stress," says Burgess Source: BBC.