The oceans, which absorb most of the heat caused by global warming, set new heat records last year, according to a study released Wednesday by an international team of scientists.
“The oceans continue to warm globally,” conclude the authors in an article published by the journal Advances in atmospheric sciences. “The inexorable rise in ocean temperatures is the inevitable result of an energy imbalance on Earth, associated first and foremost with a growing concentration of greenhouse gases”, write the 24 researchers, including from American, Chinese and Italian.
The oceans absorb more than 90% of the excess heat caused by greenhouse gases emitted by human activity.
“The global warming trend is so steady and robust that annual records continue to be set every year,” they point out.
They thus established that the total heat contained in the oceans between the surface and 2000 meters in depth reached a new “record” last year, with the addition of around 10 zettajoules in 2022.
Ten zettajoules correspond to one joule, which measures an amount of heat, with 22 zeros behind it. This figure equates to about 100 times the world’s electricity generation last year.
This phenomenon is also accompanied by an increase in salinity and stratification (the separation of water into different layers) of the oceans.
These two phenomena can alter the exchanges of heat, carbon and oxygen between the oceans and the atmosphere, in turn affecting marine life and water cycles.
“Global warming continues and is manifested by record heat in the oceans but also by extremes in terms of salinity,” commented Lijing Cheng, the lead author of the study. “This last point highlights the fact that salty areas are getting saltier and saltier,” he explains.
“The oceans absorb most of the heat caused by humanity’s CO2 emissions,” said Michael Mann, a professor at the University of Pennsylvania and co-author of the study.
“This warming will continue until we reach carbon neutrality and we will thus continue to break records for the heat contained in the oceans”, he predicted.
“Better awareness and knowledge of the oceans form the basis of actions to combat climate change,” says the researcher.