World's oceans set new heat record in 2025: Study

Beijing, Jan 9 The world's oceans absorbed more heat in 2025 than in any other year since modern record-keeping began, a new international study revealed on Friday.

Published in the journal Advances in Atmospheric Sciences, the analysis shows that the ocean's heat increased last year, amounting to a staggering 23 Zetta Joules of energy -- equivalent to 37 years of global energy consumption at the 2023 level, Xinhua news agency reported.

The findings stem from a major collaboration involving over 50 scientists from 31 research institutions worldwide.

The researchers, including those from the Institute of Atmospheric Physics, Chinese Academy of Sciences, China, highlighted that ocean warming is not uniform. In 2025, about 16 per cent of the world's ocean area saw record-high heat, while an additional 33 per cent ranked among the top three warmest years in their historical records. The fastest warming occurred in regions including the tropical and South Atlantic, the North Pacific, and the Southern Ocean.

While heat stored in the deep ocean set a new record, surface temperatures exhibited a slightly different pattern. The global average sea-surface temperature in 2025 was the third warmest on record, remaining about 0.5 degrees Celsius above the recent baseline and slightly below the peaks observed in 2023 and 2024.

Nevertheless, these elevated surface temperatures have significant real-world impacts, driving increased evaporation and heavier rainfall. They played a key role in intensifying extreme weather events in 2025, such as severe flooding in Southeast Asia and Mexico and drought in the Middle East, the researchers said.

The study warned that continued ocean heating carries profound consequences. It directly contributes to sea-level rise through thermal expansion, exacerbates and prolongs marine heatwaves, and adds more heat and moisture to the atmosphere, which can strengthen storms and other extreme weather phenomena.

Scientists emphasised that as long as the planet continues to accumulate heat, ocean heat records will keep being broken.

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