Shallow waters off south Florida topped 37.8°C for several hours this week, experts said on Tuesday, potentially setting a world record with temperatures more commonly associated with hot tubs.
A peak temperature of 38.38ºC was recorded at 6pm, but it remained above 37.77ºC for about four hours.
The readings were taken from a single buoy in Manatee Bay, about 60km south-west of Miami, at a depth of 1.5 metres, AFP reported, citing official dat.
Jeff Masters, a meteorologist and former government scientist, tweeted that while there was no official world record for sea surface temperature, a 2020 scientific paper found that the previous high might have been 37.61ºC in Kuwait Bay.
But Mr Masters said that since the new measurement was taken near land, “contamination of the measurement by land effects and organic matter in the water might … invalidate the record”.
“Unless there is photographic proof that debris was not present, it would be difficult to [verify] the record as valid,” he said.
The sauna-like conditions might be enjoyable for some, but sustained extreme heat is devastating for coral reef ecosystems and the species that depend on them.
The non-profit Coral Reef Foundation said one reef in south Florida that it had been working to restore had been devastated.
“CRF teams visited Sombrero Reef, a restoration site we've been working at for over a decade," the organisation's programme manager, Phanor Montoya-Maya, said in a statement.
"What we found was unimaginable – 100 per cent coral mortality."
About 25 per cent of all marine species are found in, on, or around coral reefs, rivalling the biodiversity of tropical rainforests, according to the US National Oceanic and Atmospheric Administration.
Around the world, the Mediterranean Sea reached its highest temperature on record this Monday during an exceptional heatwave, Spanish researchers told AFP on Tuesday.
“We attained a record … in the daily median sea surface temperature of the Mediterranean: 28.71ºC,” Spain's Institute of Marine Sciences said.
The previous record was on August 23, 2003, with a median value of 28.25ºC.
July 2023 is on track to be the hottest absolute month on record, as well as the hottest in possibly thousands of years, according to Nasa climatologist Gavin Schmidt.
“We are seeing unprecedented changes all over the world,” Mr Schmidt said last week, with records being broken on land and in the sea, and the effects mostly attributable to human-caused climate change.
