The oceans, which store most of the excess heat caused by our greenhouse gas emissions, will still have absorbed a colossal amount of energy in 2023, equivalent to that needed to boil “billions of Olympic swimming pools”. », According to a reference study on Thursday.
By feedback, part of the immense energy contained in the seas contributed to warming the atmosphere and making 2023 the hottest year in history, with its procession of climatic disasters, recalls this summary published in the review Advances in Atmospheric Sciences by 19 researchers, notably from American, Chinese and Italian universities.
The oceans, which cover 70% of the planet’s surface, are a major regulator of the Earth’s climate since they absorb around 90% of the excess heat caused by human activity.
In return, “a warmer ocean leads to a warmer and more humid atmosphere, with more unpredictable weather,” underlines the journal press release.
In 2023, the total heat contained in the oceans between the surface and 2000 meters depth reached a new record, with the addition of around 9 or 15 zettajoules compared to 2022, according to the respective estimates of the Atmospheric Agency and American Oceanic Institute (NOAA) and the Chinese Institute of Atmospheric Physics (IAP) revealed by the study.
A zettajoule corresponds to a joule, the unit of measurement of energy, with 21 zeros behind it.
“Every year, the entire world uses about half a zettajoule of energy to power our economies. In other words, 15 zettajoules is enough energy to boil 2.3 billion Olympic-sized swimming pools,” the press release summarizes.
The energy contained in the oceans is a crucial indicator for observers of global warming, because it is notably less affected by natural climate variability than ocean surface temperatures.
The latter have continued to break seasonal records since April, under the long-term effect of this excess heat accumulated at depth, but also of the return in 2023 of a strong episode of the natural climatic phenomenon. El Niñoexpected to peak in early 2024 in the Pacific Ocean.
This warming of the seas leads to an increase in the salinity of the water and the stratification (the separation of water into different layers) of the oceans, which alters the exchange of heat, carbon and oxygen between the oceans and the atmosphere.
In turn, these phenomena can modify the currents, on which the weather depends, but also reduce oxygen in the water and threaten marine life as well as reduce the absorption capacity of our greenhouse gas emissions in the seas. .