El Niño Drives Ocean Surface Temperature to Historic High

The world's oceans recorded their highest average surface temperature in June 2026, approaching a critical threshold of 21 degrees Celsius. This figure surpasses the previous records observed in June 2023 and 2024, signaling an alarming and persistent warming trend.

Data from the European Copernicus Marine Service reveals that the average global ocean temperature has steadily climbed throughout the first six months of 2026. The year-to-date average stands at 20.94 degrees Celsius, marking the second-highest average ever recorded for this period. Marine heatwaves have been a significant factor, expanding relentlessly and affecting approximately 82 percent of the global ocean.

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Marine heatwaves have been steadily spreading throughout the entire period, ultimately affecting about 82 percent of the global ocean.

Simon Stiell, lead oceanographer at Copernicus Marine, highlighted that areas like the Mediterranean Sea, the central North Atlantic, and the equatorial Pacific Ocean have experienced particularly intense heat, setting regional records. He described the global ocean as being under sustained thermal stress, a condition exacerbated by the current El Niño event.

The Australian Bureau of Meteorology confirmed the onset of El Niño in mid-June, a climate pattern characterized by abnormal warming in the central and eastern Pacific Ocean, typically lasting nine to twelve months. This phenomenon is widely considered the main driver behind the record-breaking ocean temperatures observed this year.

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The global ocean is under sustained thermal stress.