Global Oceans Reach Record Heat, Driven by Climate Change and El Nino
World's oceans hit record high temperatures, driven by climate change and El Nino, with more warming expected.
The world's oceans have reached their highest recorded temperatures, according to the European climate service Copernicus. Sea surface temperatures hit 21.1 degrees Celsius over the weekend, narrowly surpassing the previous record set in March 2024. The warming is attributed to a combination of human-induced climate change and a growing El Nino event.
Samantha Burgess, strategic climate lead at Copernicus, said the record ocean temperature is a result of background warming from climate change, which has raised ocean temperatures by about 0.8 degrees Celsius, and an additional boost from El Nino. She described the situation as "another sign of our climate system under strain and the ocean under immense pressure."
The warmer ocean has significant consequences for marine life and coastal communities. Burgess noted that corals and marine organisms become stressed in hot water, leading to fish mortality as warmer oceans carry less oxygen and nutrients. It also alters air circulation and upwelling, potentially increasing harmful algal blooms that affect shellfish.
Warmer oceans also amplify the effects of heatwaves on land. Burgess explained that in Europe this summer, warm ocean temperatures prevented the cooling effect of sea breezes at night, intensifying heatwave conditions. Additionally, warmer oceans become more acidic and can strengthen storms, making them rainier and increasing storm surge risks.
Typically, global sea surface temperatures peak in March or April, but this year's record was set in August. Burgess said the oceans are likely to warm further as the current El Nino, which is already as large as recent ones and still growing, reaches its peak between November and January.
Burgess emphasized the need to reach net zero emissions quickly, noting that the climate will continue to warm as long as fossil fuels are burned. She pointed to the upcoming COP 31 climate talks in Turkey as an opportunity for ambitious mitigation and adaptation actions.