The marine heatwave of June 2023 in northern European seas was “unprecedented but not unexpected”, according to new research.
A study by the University of Exeter, the British Met Office and the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) warns that rapid climate change means there is now about a 10% chance of a marine heatwave of this scale occurring annually.
Temperatures in the shallow seas around the UK (including the North Sea) and Ireland (the Celtic Sea) reached 2.9°C above the June average for 16 days in 2023.
Phytoplankton blooms were “significantly disrupted”, and the full impact on marine species still has to be assessed.
“Our findings show that marine heatwaves are a problem now – not just a risk from future climate change,” Dr Jamie Atkins, who led the study during his PhD at Exeter, and is now at Utrecht University, said.
“The unprecedented nature of the June 2023 event put European marine heatwaves firmly in the public consciousness,” he said.
“However, our study shows that – in today’s climate – such events should not be unexpected.”
Co-author Prof Adam Scaife, of the University of Exeter and Head of Long Range Forecasting at the Met Office, said it was “ another example of how steady climate warming is leading to an exponential increase in the occurrence of extreme events.”
The study used a large number of climate model simulations to assess the likelihood of heatwaves at the June 2023 level or above.
It focused on two locations:
In the Celtic Sea – off the south coast of Ireland – the annual chance of such a heatwave rose from 3.8% in 1993 to 13.8% now.
In the central North Sea, the chance rose from 0.7% in 1993 to 9.8% now.
The team say more research is now needed to investigate the impacts of marine heatwaves in European North-West shelf seas.
Dr Atkins’ work was funded by the Natural Environment Research Council (NERC)
The paper, published in the journal Communications Earth & Environment, is entitled: “Recent European marine heatwaves are unprecedented but not unexpected.”
