[Ed. – Other information published lately indicates that similar processes release significant methane into the atmosphere as well. Maybe the cattle can rest easier now.]
The concentration of carbon dioxide (CO2) in the atmosphere determines whether the Earth is in greenhouse or ice age state. Before humans began to have an impact on the amount of CO2 in the air, it depended solely on the interplay of geological and biological processes, the global carbon cycle. A recent study, headed by the GFZ German Research Centre for Geosciences in Potsdam, shows that the break-up of continents – also known as rifting – contributed significantly to higher CO2 concentrations in the atmosphere.
The carbon distribution on Earth is highly unbalanced: In fact only one-hundred-thousandth of the carbon dioxide on our planet is found in the atmosphere, biosphere and the oceans with the remaining 99.999% bound in the deep Earth. However, this enormous carbon store at depth is not isolated from the atmosphere. There is a constant exchange between the underground and the surface over millions of years: Tectonic plates that sink into the deep mantle take large amounts of carbon with them. At the same time it was believed that deep carbon is released due to volcanism at mid-oceanic ridges in the form of CO2.