The global average sea surface temperature hit a new record high of 21.1 degrees Celsius on August 22, 2026, surpassing the previous record of 21.09 degrees set in March 2024 [1, 2, 3, 4]. The record-breaking temperature was measured by the Copernicus Climate Change Service using data from buoys, ships, satellites, and integrated estimates taken 10 meters below the ocean surface [1, 3, 4].
Experts attribute the record partly to the intensifying El Nino event, which is adding extra heat on top of decades of human-driven ocean warming. Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts (ECMWF), said, "El Nino is adding heat to the system, but it is doing so on top of decades of human-driven warming" [1]. Burgess also described the record as "another clear signal of an ocean under growing stress" [2].
The timing of the record is unusual as ocean surface temperatures normally peak in March or April after the Southern Hemisphere summer, not in August [1, 2, 3, 4]. The current El Nino event is expected to reach its peak between November 2026 and January 2027, with some forecasts suggesting it could be the strongest in decades or even centuries [2, 3, 4]. Jeremy Grist, senior researcher at the National Oceanography Centre, noted, "We have already broken records, which is an early indicator of the strengthening El Nino. All else equal, we might expect ocean temperatures to break records again around March or April 2027" [3].
Rising ocean temperatures pose multiple risks including sea level rise, marine heatwaves, damage to coral reefs and seagrass habitats, and more extreme weather events such as intensified storms and heatwaves on land [1, 2, 3, 4]. Warmer oceans also reduce their capacity to absorb carbon dioxide, weakening a vital natural carbon sink [1, 2].
Besides the Pacific El Nino zone, several other regions including the western Mediterranean Sea, British and European surrounding seas, and the western English Channel are experiencing abnormally warm waters and marine heatwaves [1, 3, 4]. Tim Smyth, head of science at Plymouth Marine Laboratory, reported that the marine heatwave in the western English Channel has persisted for more than three years and reached temperatures about 7 degrees Celsius above normal this July, a situation he described as "unprecedented" [3, 4].
Human greenhouse gas emissions, mostly from burning fossil fuels, have caused over 90% of the excess heat now absorbed by the oceans [3, 4]. The ocean surface temperature trends continue to be monitored closely by climate services worldwide.
The El Nino event is forecast to peak between November 2026 and January 2027, with potential for further ocean temperature records to be set in early 2027 depending on its development [2, 3, 4].
