World ocean breaks temperature record amid intensifying El Niño
The average surface temperature of the world's oceans outside the polar regions rose to a record 21.1C on August 22. This is the highest daily value in the Copernicus Climate Change Service dataset, which covers the period from 1979 for operational climate monitoring.
The new maximum exceeded the previous record of 21.09C, set in March 2024. The peculiarity of the current record is not only the value itself but also the time of year: usually the average ocean temperature reaches its maximum in March and April after the summer in the Southern Hemisphere.
The previous August maximum was 20.98C in 2023. In 2026, ocean temperatures either set records for the respective season or remained near them for many months. In July, the average sea surface temperature between 60 south and 60 north latitude was 20.96C - this was also the highest July value on record from Copernicus.
Copernicus links the new record to a combination of long-term anthropogenic warming and the rapid intensification of El Niño in the tropical Pacific. El Niño itself periodically raises global temperatures, but this time it is developing against the backdrop of an ocean that has already warmed significantly over previous decades.
The World Meteorological Organization expects El Niño to continue strengthening during August-October. According to forecasts from global climate centers, the temperature anomaly in the key region of the tropical Pacific could average about 2.9C for the season. The peak of the current episode is expected later in the autumn.
Why further ocean warming is dangerous
Rising ocean temperatures have consequences not only for the climate but also for the economies of coastal regions. Warmer water expands, contributing to sea level rise, and marine heatwaves damage coral reefs, seagrass beds and other ecosystems on which fisheries and aquaculture depend.
According to Copernicus, the number of days with marine heatwaves globally has increased more than threefold since the early 1990s. This places increasing pressure on marine ecosystems and communities whose economies depend on the ocean.
A warmer ocean also transfers more heat and moisture to the atmosphere, which can intensify heavy rainfall and individual storm systems. In addition, as the temperature rises, water absorbs carbon dioxide less effectively, weakening one of the main natural systems that limit the accumulation of CO in the atmosphere.
At the same time, Copernicus emphasizes that a single daily record should be assessed in a broader climate context. ECMWF experts continue to monitor the situation to determine whether the exceedance of the previous maximum will be short-lived or whether high ocean temperatures will persist.
Based on materials from: Copernicus Climate Change Service, World Meteorological Organization
