Overview

• The June 2023 event pushed shallow seas around the UK to 2.9°C above the June average for 16 days, labeled unprecedented but not unexpected.
• Using large ensembles of climate models, the study estimates about a 10% chance each year of a heatwave matching June 2023 levels in the region.
• Annual risk has surged since 1993, rising from 3.8% to 13.8% in the Celtic Sea and from 0.7% to 9.8% in the central North Sea.
• Scientists report significant disruption to phytoplankton blooms and warn that full ecosystem and human‑health impacts remain under investigation.
• Warmer coastal waters also supplied heat and moisture that contributed to record land temperatures and heavier rainfall over the British Isles.