Record Heat Sunk into World's Seas in 2025
A record-breaking 23 zettajoules of heat was absorbed by the world’s seas in 2025, nearly 40 times the total energy used by humanity that year, according to the tenth Copernicus Marine Service Ocean State Report. This heat, along with increasing ocean acidification and sea level rise, is driving profound changes in the planet's seas. The Mediterranean and Black Seas experienced record-breaking marine heatwaves in 2024, with temperatures exceeding 4.6°C above average and lasting over 30 days. Global mean sea level rose at a rate of 4.2 mm/year between 2012 and 2025, and the oceans became approximately 17% more acidic between 1985 and 2025.5 sourcesSee all sources