Overview
- Copernicus Marine recorded global sea surface temperature of 20.98°C for June, the highest June on record, and classified the first half of 2026 as the second-warmest first half in the data series.
- The tropical Pacific registered an unusually warm first half average of 26.91°C, a level that signals strengthening Pacific warming that experts say could intensify later this year.
- Since the start of 2026 marine heatwaves have covered roughly 82% of the ocean surface and nearly 98% of the Mediterranean, where June averaged 24.34°C and parts of the northwest were about 5.2°C above normal.
- Scientists report mass die-offs and stress in corals, gorgonians, sea urchins and mollusks, and say warmer seas add energy to the atmosphere that raises the odds of heavier storms and extreme rainfall.
- Researchers stress that the change reflects both long-term greenhouse-gas heating—oceans absorb about 90% of excess heat—and natural Pacific variability, with clear risks for fisheries, coastal communities and sea-level rise from thermal expansion.