Global ocean temperatures have reached record-breaking highs in 2025, according to a major scientific report published in Advances in Atmospheric Sciences. Data from more than 50 climate scientists show that the ocean’s heat content—particularly in the upper 2,000 m—hit its highest level since modern measurements began, marking the ninth consecutive year of record ocean warming.
Oceans absorb roughly 90 % of the excess heat from greenhouse gas emissions, making them vital indicators of global warming. In 2025, they stored an additional about 23 zettajoules of heat compared to 2024—equivalent to decades of global energy use.
This pervasive warming drives more intense storms, stronger rainfall, higher sea levels through thermal expansion, and widespread coral bleaching and ecosystem disruption. The Southern Ocean, tropical Atlantic and Pacific, and North Atlantic stand out as some of the fastest-warming regions.
Scientists warn that continued greenhouse gas emissions will likely push ocean heat content to new highs, with long-lasting impacts on weather patterns, marine life, and coastal communities worldwide.
