Oceans in Asia smash heat records — what it means for extreme weather

During cyclone Ditwah Sri Lanka received 10% of its yearly rainfall in a single day. Credit: © Cyrielle Beaubois/Getty The amount of heat stored in oceans in Asia reached the highest level on record last year, according to the World Meteorological Organization. Ocean heat has risen sharply in the region since the 1990s, destabilizing ocean currents and marine life and driving up sea levels. The annual State of the Climate in Asia report, released today, found that in 2025, ocean heat content — the amount of heat stored down to a depth of 700 metres — was around 700 million joules per square metre higher than the 1991–2020 average. Almost all of Asia’s oceans, including the Indian Ocean, Western Pacific, parts of Arctic Ocean and the inland Caspian Sea, experienced periods of extreme heat last year, called a marine heatwave. This is alarming because so much of the region experienced heatwaves at the same time, says Jodie Rummer, a marine biologist at James Cook University in Townsville, Australia. Sea levels also hit record highs, caused by the combination of ocean warming and melting glaciers, ice caps and ice sheets. Across coastal areas of the northern Indian Ocean, between the Philippines and Japan, sea levels rose faster than the global average. …