AJACCIO: An “exceptional” marine heatwave is gripping the western Mediterranean with surface temperatures up to five degrees Celsius (41 degrees Fahrenheit) hotter than average, according to experts.

Although the record-breaking heatwave that baked northern Europe and Britain this month has subsided, the experts said the persistently hotter-than-normal temperatures in the Mediterranean posed a threat to the entire marine ecosystem.

“This huge marine heatwave began in May in the Ligurian sea” between Corsica and Italy, said Karina von Schuckmann, an oceanographer at the non-profit research group Mercator Ocean International. It then spread to the Gulf of Taranto in the Ionian Sea, she said.

By July, the heatwave had engulfed the Balearic Islands, Sardinia, and the Tyrrhenian Sea.

“The surface temperature anomaly map shows higher than normal values, in the order of +4 to +5C from the east of the Balearic Islands to the east of Corsica,” Mercator said in a statement.

While humans might find the warmer water temperatures pleasant in the tourist hotspots of the western Mediterranean, the group warned that “ocean warming impacts the entire ecosystem.” “It is important to be aware of the possible consequences for local fauna and flora, as well as the occurrence of extreme weather events that could result in natural disasters,” it said. Von Schuckmann said that unusually warm temperatures could cause irreversible migration for some species and “mass die-offs” for others.

She noted knock-on effects for industries such as tourism and fishing which rely on favourable water conditions. According to the UN’s climate science body, marine heatwaves have already doubled in frequency globally since 1980.

Published in Dawn, July 29th, 2022