Global ocean warming sets a new record in 2025

A latest report released on Jan 9 by the Institute of Atmospheric Physics, Chinese Academy of Sciences indicated global ocean warming set a new record in 2025.

The report, whose cover features a "dragon palace" in peril with bleaching corals and sick "shrimp soldiers" and "crab generals", reveals that record-high ocean heat content in the upper 2,000 meters in 2025, the largest jump on record from 2024 to 2025 (+23 zettajoules) since 2017. Also, the year of 2025 was ranked among the top five warmest years in about 71 percent of the ocean surface area. Global annual mean sea-surface temperature in 2025 remained about 0.5 C above the 1981-2010 average baseline. The report will continue to monitor ocean temperatures and publish research findings through November 2026.

This is the ninth consecutive year that Cheng Lijing's team at the Institute of Atmospheric Physics, Chinese Academy of Sciences, has released its ocean temperature report and also the ninth time it was published in Advances in Atmospheric Sciences. Starting with just two people, Cheng's team is now a global collaboration involving 55 scientists from 31 institutions worldwide.

Ocean warming isn't just a coastal issue: the ocean absorbs over 90 percent of excess heat, reshaping the weather and raising the risk of extremes. And because the ocean is simply too vast, international cooperation isn't optional — it's the only way to see the full picture.

See more information, please click https://doi.org/10.1007/s00376-026-5876-0

Intern Lian Yige contributed to this story.