Global Oceans Hit Record 20.98 °C June Average on Eve of 2026 El Niño

The last time a strong El Niño emerged—2015-16—global sea temperatures spiked, triggering mass coral bleaching on the Great Barrier Reef and pushing 2016 land temperatures to a then-record; the current readings already match or exceed that warm-up while the El Niño is only forming. This event underscores a century-long trend: ocean heat content has climbed almost uninterruptedly since systematic measurements began after the International Geophysical Year in 1957-58, accumulating roughly 400 ZJ of additional energy. The Copernicus figures, though reliant on blended satellite-buoy models that only reach back to 1979, align with independent NOAA and Argo float data, suggesting the signal is not a European artefact. If the trajectory continues, the ocean will cross thermal thresholds that reorganise circulation patterns—much as the 8,200-year-ago meltwater pulse altered the Atlantic—but on a human rather than geological timescale, redefining weather, fisheries and coastal habitability for the coming century.