Oceans absorb 30% of carbon dioxide emissions and 93% of excess heat attributable to global warming.
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The oceans suffer the turnly climate change. They recorded a heat record in 2021 for the third consecutive year. And this, despite the presence of the Niña phenomenon – a thermal anomaly of the surface water of the equatorial Pacific, which decreases the overall temperature of the planet. The last six years are, moreover, the hottest ever recorded for the seas of the world, warn 23 American, Chinese and Italian scientists in a study published Tuesday, January 11 in the magazine Advances in Atmospheric Sciences
According to their calculations, last year, the oceans, up to a depth of 2,000 meters, absorbed 14 zettales more than in 2020, or 14 000 billion billions of joules, which equates to 145 The global electricity production in 2020. In the long term, warming more strongly affects the Atlantic and Southern Oceans, but the North Pacific has experienced a “spectacular” increase in heat since 1990 and the Mediterranean recorded a record of Temperature last year.
“The thermal content of the oceans [the heat accumulated by the waters] constantly increases, on a global scale, and it is a primary indicator of human-induced climate change,” says the One of the authors of the article, Kevin Trenberth, researcher at the Colorado National Center for Atmospheric Research (USA).
“Without the oceans, we would suffer more”
Climate change is linked to a surplus of greenhouse gases, whose concentration in the atmosphere increases due to human activities, in particular the combustion of fossil fuel (coal, oil and gas). This leads to a surplus of energy that warms the atmosphere and especially the oceans: they absorb 93% of this excess energy and store it on very long time scales.
If the average temperature on the surface of the globe has not broken record in 2021 – the year should rank as the e warmer – because of the influence of La Niña, the oceans, they continued to reach extremes. “They are much less affected by phenomena such as the Niña,” explains the American climateologist Michael E. Mann, director of the Earth System Science Center of the State University of Pennsylvania.
“Until we reached null net emissions, their warming will continue and we will continue to break the thermal content records of the oceans, such as this year,” he warns. “This is only when we have been able to stabilize the concentration in CO 2 in the atmosphere that the amount of energy that will enter the oceans will decrease year after year, until becoming Now “, complete Benoît Meyssignac, researcher (National Center for Space Studies) at the Laboratory of Geophysics and Space Oceanography in Toulouse, who did not participate in the study. “Fortunately, the planet has as many oceans: they limit warming on the continents. Without them, we would suffer even more,” adds the scientist.
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