‘Historic’ ocean heatwave strikes seas near Devon, Cornwall, and Ireland | Aquatic Species

The sea off the coast of the UK and Ireland is witnessing an unprecedented marine heatwave, with temperatures rising by as much as 4°C above average for the spring in certain areas. This rapid increase is particularly concerning for marine biologists, as the intensity and nature of the water temperature rise off the coasts of Devon, Cornwall, and the west coast of Ireland are unheard of. Dr Manuela Truebano, a marine scientist at the University of Plymouth, highlights the unusual timing of the event, saying that such high temperatures this early in the year are alarming. The usual springtime water temperatures would be around 11°C-12°C, but current temperatures have reached 15°C-16°C. The fear is that if these temperatures continue into the summer, there could be mass die-offs of fish and other marine life. Marine biologists are also concerned about the broader implications of this heatwave, including changes in plankton reproduction patterns, which could lead to decreased fish numbers later in the year. The Met Office has confirmed that the heatwave has persisted for over two months, attributing the increase in heat to several factors including prolonged high-pressure systems and weak winds. Data shows that marine heatwaves are becoming more frequent, with a 2019 study revealing a 50% increase in heatwave days from 1925-54 to 2016. Dr Jonathan Tinker, a marine climate scientist at the Met Office, predicts that such events are likely to become more frequent and intense, offering a glimpse into the future of changing ocean conditions and weather patterns.

Source: https://www.theguardian.com/environment/2025/may/22/marine-heatwave-sea-temperatures-devon-cornwall-ireland