The world\u2019s oceans absorbed colossal amounts of heat in 2025, setting yet another new record and fuelling more extreme weather, scientists have reported.<\/p>\n
More than 90% of the heat trapped by humanity\u2019s carbon pollution is taken up by the oceans. This makes ocean heat one of the starkest indicators of the relentless march of the climate crisis, which will only end when emissions fall to zero. Almost every year since the start of the millennium has set a new ocean heat record.<\/p>\n
This extra heat makes the hurricanes<\/a> and typhoons hitting coastal communities more intense, causes heavier downpours of rain and greater flooding<\/a>, and results in longer marine heatwaves<\/a>, which decimate life<\/a> in the seas. The rising heat is also a major driver of sea level rise via the thermal expansion of seawater, threatening billions of people.<\/p>\n Reliable ocean temperature measurements stretch back to the mid-20th century, but it is likely the oceans are at their hottest for at least 1,000 years and heating faster than at any time in the past 2,000 years<\/a>.<\/p>\n The atmosphere is a smaller store of heat and more affected by natural climate variations such as the El Ni\u00f1o-La Ni\u00f1a cycle. The average surface air temperature in 2025 is expected to approximately tie with 2023 as the second-hottest year since records began in 1850, with 2024 being the hottest. Last year the planet moved into the cooler La Ni\u00f1a phase of the Pacific Ocean cycle.<\/p>\n \u201cEach year the planet is warming \u2013 setting a new record has become a broken record,\u201d said Prof John Abraham at the University of St Thomas in Minnesota, US, and part of the team that produced the new data.<\/p>\n \u201cGlobal warming is ocean warming,\u201d he said. \u201cIf you want to know how much the Earth has warmed or how fast we will warm into the future, the answer is in the oceans.\u201d<\/p>\n