Climate Change Is the Main Driver Behind Europe's Hot Seas, Study Finds

Climate change is the main driver of rising ocean temperatures around Europe, directly adding roughly 2 degrees Celsius of warming to the Mediterranean Sea this summer, according to a study released Wednesday by the World Weather Attribution (WWA) group. "From the Atlantic waters off Ireland to the Mediterranean Sea, Europe's seas are experiencing an alarming surge in temperatures," said co-author Thomas Frolicher, an environmental physicist at the University of Bern. "Our research shows clearly that this is being driven by climate change, in particular by the continued burning of fossil fuels."

Combining observational data with climate model simulations, the WWA team estimated climate change added about 2 degrees C of warming in the Mediterranean and 1.3 to 1.4 degrees C in Western European seas. This year, 90% of the Bay of Biscay and Iberian coast region and 80% of the Western Mediterranean experienced marine heat waves; without the roughly 1.4 degrees C of human-caused warming to date, only about 40% of those areas would have been affected, the group estimated. Some Mediterranean areas recorded sea surface temperatures more than 6 degrees C above normal during the hottest two weeks of summer, and the world's oceans hit record-high temperatures for a second straight month in July, per the EU's Copernicus Climate Change Service.

The WWA reported "evidence of severe ecological impacts," including species shifting northward to cooler waters, disrupting food chains, coastal fisheries and aquaculture, and said warmer sea surface temperatures are also raising humidity, and heat risk, in coastal areas on land. Marine ecologist John Bruno said it was surprising "how little warming it actually takes to tip organisms past that threshold to kill them... it's only about 1 degree C on coral reefs, for example."

Study co-author Claire Bergin of Maynooth University in Ireland noted that "warmer waters for swimming may sound appealing to beachgoers in cooler countries like mine," but added that "the impacts on marine life beneath the surface are more serious."