scientists make a major discovery about the role of CO2

Carbon dioxide (CO₂) has been one of, if not the primary, regulators of Earth’s climate for hundreds of millions of years, according to a new study in Nature geoscience. 370 million years ago, our Planet experienced its most intense ice age. During the Paleozoic, much of the land was covered in ice and sea levels fell by more than 100 meters. This ice age lasted about 100 million years. Climate transition periods have always raised questions among scientists, with many varied theories.

Low CO2 leads to significant cooling

The researchers were interested in what caused the onset of this ice age, but also in what led to its exit: they studied the fossilized shells of ancient seashells, known as brachiopodesbrachiopodes. Their shells contain isotopesisotopes of boreborean element allowing control of many environmental parameters. The analysis allowed the researchers to know how much CO₂ was present in theatmosphereatmosphere when these animals lived, millions of years ago.

The researchers’ conclusions are clear: more than solar cycles or any other natural factor, it is carbon dioxide which played a central role. During the Paleozoic, the CO content₂ in the atmosphere was quite low: 330 ppmppmand it even went down to 200 ppm (compared to 412 ppm today). It is therefore this small quantity of CO₂combined with a soleilsoleil less powerful than today, which led to this extreme ice age: in the same way as a high level of CO₂as is currently the case, leads to warming.

However, it should be noted that not all climate variations have exactly the same causes. Some were largely influenced by volcanic eruptionsvolcanic eruptionsbut generally speaking, researchers think that CO₂ played the main role in the climatic evolution of the Earth.