World’s oceans set June heat record, EU monitor says

Global average sea surface temperatures reached 20.98 C in June, the highest monthly figure on record, according to the European Union’s Copernicus Marine Service. The reading surpassed the previous records set in 2023 and 2024. Average temperatures for the first half of 2026 stood at 20.04 C, slightly below the same period in 2024.

Marine heat waves widespread Marine heat waves covered about 82 percent of the world’s oceans during the first six months of the year. That extent ranks as the second-largest after 2024. The Mediterranean recorded its hottest June at 24.3 C. Marine heat waves affected 98 percent of that basin during the same period.

The tropical Pacific posted its warmest June on record at 27.26 C. The region matched its 2016 record for the January-to-June period.

El Nino outlook Scientists said current conditions could mark the beginning of a new phase that leads to further temperature records. Carlo Buontempo, director of the Copernicus Climate Change Service, stated that ocean temperatures at these levels and an approaching El Nino increase the chance of additional records in coming months.

Simon Van Gennip, lead oceanographer for the Copernicus Marine Service, said the combination of El Nino and continued greenhouse-gas emissions will likely place 2026 among the warmest years recorded. El Nino is defined by unusually warm waters in parts of the Pacific that release heat into the atmosphere and alter global wind, cloud, and weather patterns.

The pattern can raise the risk of floods, droughts, and wildfires in different regions. Oceans absorb roughly 90 percent of the excess heat from greenhouse-gas emissions. Warmer waters increase atmospheric moisture, expand in volume, and create conditions that can bleach coral reefs during prolonged heat events.

The report follows a U.N. scientific assessment issued last month that described the oceans as being in a deepening crisis due to faster warming and rising sea levels.