'Extreme' marine heatwave expected for parts of UK
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- Met Office forecasts an 'extreme' marine heatwave later this week off eastern and southern England, with sea temperatures 4-5C above average and the strongest readings in the English Channel and southern North Sea
- The heatwave was fuelled by 'heat domes' — high-pressure systems parked over Europe in late May and late June that transferred record air temperatures into the shallow seas, on top of long-term ocean warming from climate change
- Dr Ségolène Berthou of the Met Office warned extreme marine heatwaves have been relatively rare for the UK but are now 'much more likely' and projected to become 'average' conditions by mid-to-late century without emissions cuts
- Prof Matt Frost of Plymouth Marine Laboratory said warm-water arrivals like octopus are 'exciting to see' but could displace native species and hit populations of crabs, lobster, scallops, and other shellfish they prey on
- Cool-adapted species such as cod are moving further north while warm-water species including octopus have risen around south-west England, a shift scientists link to warming seas compounded by changes in fishing practices
- Important habitats such as seagrasses and kelp forests are suited to cooler waters and can experience 'mass mortality events' under prolonged heat, with knock-on effects for species that depend on them, according to the National Oceanography Centre in Southampton
Why it matters: UK seas have warmed steadily since the 1980s, and scientists cited in this report say extreme marine heatwaves are now 'much more likely' — triggering mass die-offs of seagrass and kelp that anchor habitats for cod, crabs, scallops, and other commercially and ecologically vital species.
