For tourists and residents of Florida who want to cool off in the ocean, the experience of the past week has probably been a disappointment. Earlier this week, the surface temperature of the ocean water reached 38.4 degrees in South Florida, which is a potential record.
“There is no difference between the moisture in the air and swimming in the sea,” says Florida resident Chelsea Ward.
The sea does not cool
When it’s hot, the body responds by sweating, which cools the body down. Taking a cooling dip in the sea is also effective as body heat is transferred to the water. But as ocean temperatures rise, the effect diminishes, according to emergency physician Michael Mullins of Barnes-Jewish Hospital in Saint Louis, Missouri. Hot water returns heat to the body.
“It feels like swimming in soup,” says Mullins.
Strong sun and no wind were behind the exceptionally high temperatures in South Florida.
— I have never experienced a temperature higher than 37 degrees in my 21 years in Key West, says researcher Andy Devanas at the US National Weather Service NWS in Key West.
Warm in the Atlantic and Mediterranean
The question is how representative the high temperatures in South Florida are. The water at the measurement site is shallow and cloudy, and overgrown with seaweed. But what is certain is that the temperature in the sea water along the coast has been a few degrees above normal during July. And in the western Atlantic, near Newfoundland off the coast of Canada, ocean water was 5 degrees warmer than normal in July.
Recently, new record levels were also reported in the Mediterranean off the Spanish south coast. According to the Spanish Meteorological Institute (Aemet), the average temperature in mid-July was 24.6 degrees, which is 2.2 degrees higher than the average for the season.
It is not only humans who suffer when the temperature of the sea water rises. Coral reefs, which are important for biodiversity and to prevent erosion, can be damaged when temperatures rise above 30 degrees.