San Francisco Frontiers - Climate change main driver of European ocean warming: study

"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, Switzerland.

"Our research shows clearly that this is being driven by climate change, in particular by the continued burning of fossil fuels," he added.

Scientists from the World Weather Attribution (WWA) group estimated that climate change added about 2C of warming to the Mediterranean, and over 1.3-1.4C to Western European seas.

They arrived at the figures by combining observational data and climate model simulations.

The WWA said there was "evidence of severe ecological impacts", with species "shifting northwards to cooler waters, disrupting food chains, coastal fisheries and aquaculture".

"Impacts can spill into land too, with higher sea surface temperatures driving up humidity for coastal areas increasing the risks of extreme heat," it said in a statement.

Marine ecologist John Bruno told reporters that it was surprising "how little warming it actually takes to tip organisms past that threshold to kill them".

"It's only about 1C on coral reefs, for example."

He added that some organisms benefit from heatwaves because of a preference for warmer temperatures or the disappearance of their natural enemies.

There is a "kind of reshuffling, reorganisation of communities. So we have what we call winners and losers", he said.

According to the European Union's global warming monitor, the Copernicus Climate Change Service, the world's oceans hit record-high temperatures for a second straight month in July.

The WWA said that some Mediterranean areas had recorded sea surface temperatures more than 6C hotter than normal over the hottest two weeks of the month.

The group added that climate change has driven marine heatwaves to spread across a larger part of European regions.

This year 90 percent of the Bay of Biscay and Iberian coast region and 80 percent of the Western Mediterranean have experienced marine heatwaves, it said.

Without the current 1.4C of human-caused warming, only around 40 percent of those areas would have been affected, it predicted.

Claire Bergin, study co-author and researcher at Maynooth University in Ireland, noted that "warmer waters for swimming may sound appealing to beachgoers in cooler countries like mine".

However, "the impacts on marine life beneath the surface are more serious".

H.King--SFF