The world’s oceans absorbed an unprecedented amount of heat in 2025, as per a recent international study. The analysis, published in Advances in Atmospheric Sciences, revealed that the ocean’s heat content surged last year, reaching 23 Zetta Joules of energy. This amount is equivalent to 37 years of global energy consumption at the 2023 level, according to the Xinhua news agency.
The study involved over 50 scientists from 31 research institutions globally. By pooling data from various international centers and research groups, the researchers found that the heat content in the upper 2,000 meters of the ocean hit a record high in 2025, indicating a consistent upward trend.
Ocean warming in 2025 was not uniform, with approximately 16% of the world’s ocean area experiencing record-high heat levels. An additional 33% ranked among the top three warmest years in their historical records. Regions like the tropical and South Atlantic, the North Pacific, and the Southern Ocean witnessed the fastest warming.
Despite setting a new record for heat stored in the deep ocean, global average sea-surface temperatures in 2025 followed a slightly different pattern. The year marked the third warmest on record, with sea-surface temperatures remaining around 0.5 degrees Celsius above the recent baseline and slightly below the peaks observed in 2023 and 2024.
Elevated surface temperatures in 2025 had tangible effects, leading to increased evaporation and heavier rainfall. These conditions intensified extreme weather events, such as severe flooding in Southeast Asia and Mexico, as well as drought in the Middle East, according to the researchers.
The study cautioned that ongoing ocean heating has significant repercussions, including contributing to sea-level rise through thermal expansion, exacerbating marine heatwaves, and enhancing extreme weather phenomena by adding more heat and moisture to the atmosphere. Scientists stressed that as long as the Earth continues to accumulate heat, ocean heat records will continue to be broken.
