World’s seas heated by a record 23 zettajoules last year
A new report from the Copernicus ocean state project reveals that the world's oceans absorbed a record 23 zettajoules of heat last year. This thermal injection is contributing to accelerated sea-level rise, increased acidification, and widespread coral bleaching.
Why it matters
The rapid warming of the oceans signals a fundamental shift in the Earth's climate system, threatening marine ecosystems and coastal stability globally.
Bleached coral in Thailand: Between January 2023 and September 2025, 84% of global coral reefs experienced bleaching-level heat stress. Bleached coral in Thailand: Between January 2023 and September 2025, 84% of global coral reefs experienced bleaching-level heat stress. Environment World’s seas heated by a record 23 zettajoules last year The injection of thermal energy, 40 times that used by humanity in total, comes amid an increasing rise in sea levels and continuing acidification
Prefer the Guardian on Google A record-breaking 23 zettajoules of heat was sunk into the world’s seas last year, leaving ocean waters hotter, higher and less hospitable, a report has found.
The explosive addition of thermal energy, which was almost 40 times greater than all the energy humanity used that year, comes amid far-reaching changes to the deep water bodies fundamental to life on Earth.
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