The world's oceans are at their hottest June on record, with average temperatures approaching 21°C. This represents a 1.4°C increase since pre-industrial times. The heat added in 2025 equalled 12 Hiroshima bombs per second.
A strong El Niño is developing in the Pacific, with subsurface temperatures 6°C above average. This will likely make 2027 even hotter than 2026 as ocean heat is released. Mediterranean waters are up to 6°C warmer than average.
Marine ecosystems face unprecedented threats from warming, with coral reefs particularly vulnerable. While forecasting abilities have improved, funding cuts threaten climate monitoring networks. The time for urgent climate action is now