World's oceans hit record 21°C average surface temperature in June 2026

The EU's Copernicus Earth-observation programme recorded a record average ocean surface temperature of 21°C in June 2026 — the highest ever measured. The extreme heat is already taking a toll on marine biodiversity after years of scientific warnings. The onset of a potentially powerful El Niño weather pattern could push ocean and atmospheric temperatures even higher through 2026 and into 2027.