New data indicates that the world’s average ocean surface temperatures have reached the highest levels ever recorded. Figures from the European Copernicus climate change service show that sea temperatures outside polar regions reached 21.1C (70F) on Saturday. This figure surpasses the previous record of 21.09C, which was set during three separate days in March 2024.
The record comes as the El Niño weather phenomenon, which involves unusually warm waters rising to the surface of the Pacific Ocean, continues to develop. Scientists from Copernicus and the National Oceanography Centre noted that while El Niño adds heat to the environment, it is occurring alongside long-term warming trends linked to human-driven greenhouse gas emissions. The oceans typically absorb more than 90% of the excess heat generated by these emissions, primarily from fossil fuel combustion.
The timing of this temperature peak is considered unusual by researchers because global sea temperatures generally reach their highest point in March or April, coinciding with the end of summer in the southern hemisphere. According to Dr. Jeremy Grist of the National Oceanography Centre, breaking records in August is an early indicator of the current El Niño's strength. Regional heatwaves have also been reported, including in the western English Channel, where temperatures reached 7C above normal in July.
For individuals, these changes may be noticed through more extreme weather events and heatwaves on land, as warmer seas reduce the cooling effect of sea breezes in coastal areas. Marine ecosystems, such as coral reefs, face devastation from intense heat, which can lead to the loss of biodiversity and affect the livelihoods of those dependent on healthy fisheries. The current data shows a global average of 21.1C (70F), a figure that represents the energy state of 70% of the Earth's surface and influences global weather patterns.
The knock-on effects include the potential for even higher temperatures in the coming months. Because El Niño is not expected to peak until around December, scientists anticipate that these records could be surpassed again in early 2027. The Met Office has indicated the current El Niño could be the strongest in centuries. The immediate next steps for researchers involve monitoring the Pacific as the phenomenon strengthens toward its year-end peak, with subsequent global temperature assessments expected in March and April 2027.