The world’s oceans recorded their warmest June ever observed, according to European Union scientists, who warned that exceptionally high sea surface temperatures are likely to continue as a developing El Niño combines with long-term climate warming.
The Copernicus Marine Service said global sea surface temperatures reached a June record of 21.0 degrees Celsius, surpassing previous highs set during the same month in 2023 and 2024.
Scientists said the first half of 2026 was marked by sustained ocean warmth and widespread marine heatwaves affecting much of the world's seas.
The Copernicus Marine Service said the first six months of 2026 were characterized by persistently elevated sea surface temperatures, with marine heatwaves steadily expanding across the globe.
According to the agency, around 82 percent of the global ocean was affected during the period.
The Mediterranean, the central North Atlantic and the equatorial Pacific were identified as major hotspots, reflecting what scientists described as an ocean under sustained thermal stress.
The agency said record temperatures outside the polar regions exceeded the previous June highs observed in both 2023 and 2024.
Scientists noted that while annual ocean temperature peaks are typically recorded in July and August, current conditions suggest additional records may still be possible later this year.
Researchers said the expected development of a potentially powerful El Niño could further increase temperatures in both the oceans and the atmosphere through 2026 and into next year.
Copernicus Climate Change Service Director Carlo Buontempo said, "With ocean temperatures at these levels and El Niño on the horizon, we are likely to see more temperature records fall in the coming months."
Scientists warned that warmer oceans can influence global weather patterns, increase atmospheric moisture, strengthen tropical cyclones and heavy rainfall, contribute to sea-level rise and place additional stress on coral reef ecosystems through prolonged marine heatwaves.
The findings follow a United Nations scientific assessment released last month that described the world's oceans as being in a deepening crisis as warming and sea-level rise continue to accelerate.
Scientists also noted that oceans absorb about 90 percent of the excess heat generated by greenhouse gas emissions, making them a key indicator of changes in the Earth's climate system.