LONDON: Human-caused climate change was the main factor behind record-breaking sea temperatures across Europe this summer, with scientists warning that prolonged marine heat could severely disrupt ecosystems, fisheries and coastal communities.
The Mediterranean experienced its hottest July on record, with the average sea surface temperature reaching 27°C (81°F) last month. An offshore buoy near Mallorca subsequently recorded temperatures of 33°C in early August, highlighting the exceptional intensity of the marine heat.
A new analysis by the World Weather Attribution (WWA) on Wednesday found that human-induced climate change had increased temperatures in the Mediterranean by about 2°C, while warming in the seas around western Europe had risen by approximately 1.4°C.
Scientists said some of the most extreme sea temperatures recorded this year would have been virtually impossible without the warming caused by human activity.
“This has the potential to completely reshape ecosystems that coastal communities rely on for food and income, and drive damaging extreme weather on land too,” said Claire Bergin, a climate scientist at Ireland’s Maynooth University and a co-author of the analysis.
The study examined extreme marine temperatures in several European regions, including the eastern and western Mediterranean, the Iberian coast and the Bay of Biscay.
It concluded that the peak temperatures recorded in these areas would have been extremely unlikely in a climate unaffected by human-caused global warming.
In the Celtic Sea, off the coasts of Britain and Ireland, the most extreme temperatures recorded this year would have occurred only about once every 100 years in a world without human-induced climate change, according to the analysis.
Scientists warned that unusually warm seas could have consequences extending well beyond marine environments. Higher sea temperatures increase atmospheric moisture and can contribute to warmer nights in coastal areas. They can also provide additional energy for intense storms later in the year.
Global warming has already pushed average temperatures to around 1.4°C above pre-industrial levels, according to the World Meteorological Organisation. Scientists say this higher baseline allows atmospheric systems responsible for heatwaves to produce more extreme temperatures.
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Marine ecosystems are particularly vulnerable to prolonged periods of extreme heat. Sudden increases in sea temperatures can trigger mass die-offs of marine species, including corals, while disrupting food supplies for seabirds, marine mammals and other animals.
Such changes can cascade through entire food webs, potentially affecting fisheries and communities whose livelihoods depend on healthy seas.
John Bruno, a marine ecologist at the University of North Carolina, said some marine species were already moving towards cooler northern waters in response to rising temperatures. However, he warned that many species may not be able to adapt quickly enough.
“We are rapidly approaching the absolute biological limits of adaptation for many species,” Bruno said.
The WWA analysis found that marine heatwave conditions had affected about 90% of the Bay of Biscay and 80% of the western Mediterranean this year. Without the additional warming caused by climate change, scientists estimated that the affected areas would have been closer to 40%.
The findings add to growing evidence that climate change is transforming not only temperatures on land but also the world’s oceans, increasing pressure on marine ecosystems and the communities that depend on them.
Scientists said the continuing rise in greenhouse gas emissions, driven largely by the burning of fossil fuels, means extreme marine heat events are likely to become increasingly frequent and severe unless global warming is significantly reduced.
