There’s a Heatwave In the Sea and Scientists Are Worried – Slashdot

An anonymous reader quotes a report from the BBC: The month of June and the first few days of July were hotter than any in recorded history, according to the World Meteorological Organization (WMO). Residents in the south of the US and southern Europe have been enduring sweltering temperatures, bringing excessive heat warnings, wildfires and plummeting air quality. However, records are not just being broken on land — but in the water. Global ocean sea surface temperatures were higher than any previous June on record, according to a report by the Copernicus Climate Change Service, with satellite readings in the North Atlantic in particular “off the charts.” Last month also set a record at the US National Oceanic and Atmospheric Administration (NOAA) for the biggest difference between expected and actual sea surface temperatures. Water temperatures around Florida, in particular, have been particularly warm. Scientists have also been tracking a large ongoing marine heatwave off the west coast of the US and Canada since it formed in May.

While the heatwave has since lessened in the north-east Atlantic, according to non-profit science organization Mercator Ocean International, another in the western Mediterranean now appears to be intensifying, particularly around the Strait of Gibraltar. This week, sea surface temperatures along the coasts of Southern Spain and North Africa were 2-4C (3.6-7.2F) higher than they would normally be at this time of year, with some spots 5C (9F) above the long-term average. Extreme marine temperatures have also recently been observed around Ireland, the UK and in the Baltic Sea, as well as areas near New Zealand and Australia. More recently, scientists suspect a possible heatwave south of Greenland in the Labrador Sea. “We are having these huge marine heatwaves in different areas of the ocean unexpectedly evolve very early in the year, very strong and over large areas,” says Karina von Schuckmann, an oceanographer at Mercator Ocean.

Carlo Buontempo, director of the European Union’s Copernicus Climate Change Service, says scientists expect big temperature variations in the Pacific Ocean associated with the El Nino weather pattern, a phase of planet-warming weather which is just beginning, although NOAA is monitoring a large heatwave in the Gulf of Alaska that has been sitting offshore since late 2022. But what we’re currently seeing in the North Atlantic is “truly unprecedented”, says Buontempo. Scientists are still trying to unravel its full causes. […] More broadly, experts say the persistence of recent marine heatwaves is a worrying sign about how climate change is unfolding, alongside heatwaves on land, unusual melting of snow cover in the Himalayas and a loss of sea ice. Von Schuckmann notes that, even if humans stopped pumping CO2 into the air tomorrow, the oceans would continue to warm up for many years yet. “I am concerned as a climate scientist that we are further than we thought we are.”