UK Waters Hit by 'Extreme' Marine Heatwave as Global Temps Peak
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- Met Office confirmed UK waters are enduring an "extreme" marine heatwave — the third and most intense of 2025 — with sea temperatures on average 2C above normal and some locations reaching "severe" conditions 4-5C warmer than usual.
- Dr Ségolène Berthou of the Met Office linked the rapid development to last month's heat dome over Europe, noting "the ocean didn't have enough time to cool down between the two land heatwaves."
- Copernicus Climate Change Service and Copernicus Marine Service confirmed global sea surface temperatures have surpassed previous records for this time of year, previously set in 2023 and 2024.
- UN Secretary-General António Guterres called the arrival of El Niño conditions "an urgent climate warning," demanding an end to fossil fuel addiction and a rapid shift to renewables.
- Prof John Pinnegar of the Centre for Environment, Fisheries and Aquaculture Science warned the extreme conditions can trigger "mass-mortality events" for some marine species while encouraging new arrivals in UK waters.
- The marine heatwave coincides with the UK's third land heatwave of summer, with temperatures on track to exceed 30C for up to 10 consecutive days, and Berthou said there is "no sign of an end to it."
- Brixham market in south-west England sold a record 100 tonnes of octopus in a single day last month, illustrating how shifting species distributions are already reshaping the UK fishing industry.
Why it matters: UK fishermen and marine ecosystems face immediate disruption: Pinnegar of Cefas warns mass-mortality events are possible for some species, while Brixham's record 100-tonne octopus catch in a single day shows species redistribution is already reshaping the commercial fishing industry. With the Met Office saying there is "no sign of an end" to waters running 4-5C above normal, the crisis is no longer forecast but ongoing.
