Overview
- The EU Copernicus services announced on Wednesday that June 2026 saw the highest average global sea surface temperatures on record, about 21.0°C according to the Copernicus Marine Service and 20.86°C in a separate Copernicus dataset.
- The June peak caps six months of unusually warm oceans in 2026, a period that featured widespread marine heatwaves affecting roughly 82% of the global ocean during the first half of the year.
- Regional June records were reported, including the Mediterranean at about 24.3°C and the tropical Pacific at about 27.26°C, with hotspots in the central North Atlantic and off Peru and California.
- Copernicus and other scientists warn that a likely El Niño developing this year, combined with background greenhouse-gas warming, makes further temperature records and amplified weather extremes more probable through late 2026.
- Warmer oceans store most excess heat from emissions, so higher sea temperatures cause sea-level rise by thermal expansion, add moisture that fuels stronger storms and heavy rain, and drive coral bleaching and marine die-offs — risks that could translate into more floods, droughts and coastal impacts for people.