The sea surface has just experienced the hottest month of May ever, the European service Copernicus said on Wednesday, after a record month of April.
“Sea surface temperatures have already reached record highs and our data show that the average temperature of all ice-free seas in May 2023 was higher than any other May,” said Samantha Burgess, deputy director of the Copernicus European Climate Change Service (C3S). ).
The latter is based on computer analyzes generated from billions of measurements from satellites, but also from ships, airplanes or weather stations around the world.
Some of the data used by Copernicus goes back to 1950, but most to 1979.
The average temperature at the surface of the oceans (still outside of the ice-covered areas) in May was “about 19.7°C, or 0.26°C above the 1991-2020 average,” a Copernicus spokesman told AFP.
Like a sponge, the ocean has absorbed about 90% of the increase in heat caused by human activity.
Its warming is causing “unprecedented cascading effects,” the UN points out, such as melting ice, rising sea levels, ocean heat waves and ocean acidification. The ability to absorb CO2 is also declining, while the ocean now absorbs 25% of all carbon emissions.
Globally, May was the second warmest on record.
“May 2023 was the second warmest in the world as we see the El Niño signal continuing to rise in the equatorial Pacific,” added Samantha Burgess.
El Niño is a natural weather phenomenon generally associated with rising temperatures, increasing drought in some parts of the world, and heavy rainfall in others.
It last occurred in 2018-2019, triggering a particularly long La Niña episode of nearly three years, with adverse effects, most notably a drop in temperature.
In early May, the World Meteorological Organization (WMO) estimated that there was a 60% chance that El Niño would develop by the end of July and an 80% chance by the end of September.
According to data released in early May by the American observatory NOAA, the sea surface (outside the polar waters) broke its annual temperature record in April.