About 300 million years ago, the formation of immense quantities of coal led to planet Earth near global glaciation, turning it into an icy ball. A new study, published in Proceedings of the National Academy of Sciences details the process.
When CO2 concentration in the atmosphere sank drastically and Earth cooled, the plant entered a glaciation that almost brushed what scientists call a "snowball state" .
This took place at a time when trees in extensive forests died during a time called Carboniferous and Permian, and plant remains eventually formed most of the coal that is now used as a fossil fuel.
According to the author of the study, Georg Feulner of the Potsdam Institute for Climate Impact Research in Germany:
It is rather ironic that the formation of coal, which today is an important factor for the dangerous global warming, once almost led to global glaciation. The amount of CO2 stored in the Earth's coal reserves was large enough to unbalance our climate. When released by burning coal, CO2 is destabilizing the earth system again.
A large set of computer simulations were carried out to carry out the study. While estimates based on ancient soils and fossil leaves show that they fluctuated widely and eventually sank in about 100 parts of CO2 per million parts of all gases in the atmosphere and possibly even lower, simulations of model now reveal that global glaciation occurs below 40 parts per million .
We should definitely keep CO2 levels in the atmosphere below 450 parts per million to keep our climate stable and, ideally, much lower than that. Raising the amount of greenhouse gases beyond that limit means taking us out of space.
Both temperature changes and meteorite impacts have resulted in five massive extinctions of terrestrial life, during which up to 90% of all species disappeared.