The world’s oceans, which absorb most of the heat caused by climate change, set new heat records last year, according to a study published Wednesday.
“The oceans continue to warm globally,” explain the authors of this international report, published in the journal Advances in Atmospheric Sciences.
“The inexorable rise in ocean temperatures is the inevitable result of an energy imbalance on Earth, mainly associated with a growing concentration of greenhouse gases,” explain the 24 authors of the report, from American, Chinese and Italian universities.
The oceans absorb more than 90% of the excess heat caused by greenhouse gases generated by human activity.
“The global warming trend is so regular and robust that records are being broken every year,” warn these experts from 16 research centers.
The total heat contained in the oceans between the surface and a depth of 2,000 meters increased last year by 10 zettajoules, that is, 1 joule (basic measure of heat) followed by 22 zeros.
That figure is equivalent to roughly 100 times the electricity production worldwide in 2022.
The warming of ocean waters leads to an increase in their salinity and their stratification (the separation into different layers).
This means that the acidity of the waters increases, and at the same time, that they do not mix so easily.
Both phenomena can alter the exchange of heat, carbon and oxygen between the oceans and the atmosphere, which in turn has consequences for marine life and water cycles.
“Global warming continues and manifests itself in record levels of heat in the oceans, as well as extreme levels in terms of salinity,” said Lijing Cheng, lead author of the study.
“This last point confirms that the salty areas are increasingly so,” he added.
an ecological nightmare
“The oceans absorb almost all the heat caused by humanity’s CO2 emissions,” recalled Michael Mann, a professor at the University of Pennsylvania or co-author of the study.
“That warming will continue until we achieve carbon neutrality, so we will continue to break records,” he predicted.
“Knowing the oceans better is the basis of actions to combat climate change,” he added.
The warming phenomenon began to be detected in the late 1950s.
As the water warms, the level of oxygen drops, which is “a nightmare not only for aquatic life and ecosystems, but also for humans and our terrestrial ecosystems,” the researchers said.
A study by the European Copernicus climate change program revealed on Tuesday that the last eight years were the warmest to date.
During the period 2015-2022, each year registered at least an increase in its average temperature of more than one degree Celsius compared to the pre-industrial average.
And another report, published by the insurer Munich Re, indicated that natural catastrophes caused damages valued at 270,000 million dollars in 2022, an amount despite everything less than 2021.
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