Hello doctor, the planet is no longer breathing. The examinations are clear: according to measurements from the Mauna Loa research center, which is a world reference, the concentration of CO2 in the atmosphere reaches 426 parts per million, a record broken on a human scale. “We have never reached such a figure for 14 million years,” notes Nathalie Huret, professor of atmospheric physio-chemistry at the University of Clermont Auvergne and the CNRS.
To better understand this figure, and what it implies, 20 minutes contacted Cathy Clerbaux, research director at CNRS specializing in monitoring atmospheric composition. “If you take a cube of air, it’s going to be 99.9% nitrogen, oxygen and a little argon. But it’s the 0.1% that plays a very important role in the climate,” explains Cathy Clerbaux. In addition to carbon dioxide, water vapor, neon, helium and even ozone are found in this 0.1%.
No impact on health
“Imagining that the cube contains a million molecules, we then find 426 molecules of CO2 there today,” she illustrates. Enough to make the air “unbreathable” and have an impact on health, when we sometimes mention ppm in pollution alerts? No, says the expert. “We saw it during Covid with CO2 sensors in closed classrooms. At the end of the day, you can have 1,000 ppm at the end of the day, and at worst you will have a little headache, but it is not poison,” she reassures.
“We must not confuse air quality and greenhouse gases”, explains Nathalie Huret, “to say that the air is unbreathable is an abuse of language”. CO2 does not directly attack our respiratory tract, the air we exhale being much more saturated with carbon dioxide, but “it accumulates in the atmosphere”, where it can remain for almost a century. “Without these greenhouse gases, it would be -18°C on Earth,” explains Cathy Clerbaux, “but we are adding too much! »
The ocean is saturated
In normal times, however, we can rely on two “allies” to regulate the presence of CO2 in the air: the ocean and vegetation, which each absorb “around 25% of emissions”, says Nathalie Huret. But “with the increase in the acidity of the oceans, we observe that they digest CO2 a little less than before,” notes Cathy Clerbaux. In short, carbon sink number one is saturated.
However, 426 ppm is not much, you might say. Except that when the Mauna Loa laboratory began its measurements, in 1958, “the average was between 280 and 300 ppm”. Such developments have already existed, but “they took place over thousands and thousands of years, here we are on a time scale of 100 years”, points out Nathalie Huret. Just enough so that the CO2 produced at the beginning of the 20th century begins to evaporate. Since then, human emissions have exploded, and all this CO2 will remain in the atmosphere for several more decades, worsening global warming.
Too fast to adapt?
“Emissions continue to increase but more slowly,” breathes Cathy Clerbaux. “We may reach a peak in emissions, but the concentration will continue to increase,” she warns. And the thermometer with it, even if the scorching year of 2023 is also linked to the El Nino phenomenon, a cyclical factor aggravating droughts and bad weather in Brazil. “The problem is the speed at which the concentration of CO2 increases,” she says.
This is going “even faster than expected”, alarms Nathalie Huret. “Even if we limit our emissions, we will exceed the 1.5°C threshold of the Paris agreement,” she believes. With an average temperature 2 degrees higher than pre-industrial averages, “everything is in the red”. Suffering biodiversity, rising sea levels, long and intense heat waves, locally intense precipitation, droughts, “everything will be disrupted, regardless of location”, because our ecosystems “do not have time to recover. adapt “. “Our climate system will have to find a new balance, and that will have very strong consequences on biodiversity and our survival,” she concludes. If the concentration of CO2 alone is not enough to suffocate us, it is enough to take our breath away.
