Key facts
- A marine heatwave is forecast to reach 'extreme' levels around parts of the UK this week.
- Sea temperatures could be 4-5C above average in affected areas.
- The event is attributed to recent 'heat domes' and ongoing climate change.
- Marine life, including seagrasses and shellfish, faces significant stress and potential die-offs.
- Warm-water species, such as octopus, are increasing in UK waters, impacting native species and fisheries.
- Scientists warn that such events are likely to become more frequent without greenhouse gas emission reductions.
A marine heatwave is expected to reach 'extreme' levels around parts of the UK later this week, according to the Met Office, raising concerns for marine life and fishing communities. Sea temperatures could reach 4-5C above average in places, particularly off the coasts of eastern and southern England.
The event is fuelled by recent 'heat domes' that brought record-breaking air temperatures, compounded by long-term ocean warming due to climate change. Important marine habitats such as seagrasses and kelp forests, which are suited to cooler waters, can experience high levels of heat stress, leading to reduced growth or mass mortality events. This could have knock-on effects for species that rely on these habitats.
Dr. Zoe Jacobs of the National Oceanography Centre noted that current temperatures are already typical for the height of summer, warning of serious impacts on ecological systems if the event persists. Researchers have observed longer-term shifts, with cool-adapted species like cod moving north and warm-water species such as octopus increasing around south-west England.
Prof. Matt Frost of the Plymouth Marine Laboratory highlighted the negative consequences of these shifts, including declines in cod populations and the potential displacement of native species by newcomers. The increase in octopus numbers, while potentially offering a new market for fishermen, can negatively impact populations of crabs, lobster, scallops, and other shellfish.
The southern North Sea and English Channel are shallow, allowing them to heat up quickly. While temporary heatwaves have occurred before, scientists fear this event could be particularly intense and long-lasting. These intense events are becoming more likely as they occur in an already warmer ocean, driven by human-caused climate change. Dr. Ségolène Berthou of the Met Office warned that marine heatwave conditions are projected to become average by mid-to-late century if greenhouse gas emissions are not reduced.