About 300 million years ago, the formation of immense amounts 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.
- Glaciations
When CO2 concentration in the atmosphere sank drastically and the Earth cooled, the plant entered a glaciation that almost brushed against what scientists call a "snowball state."
This took place at a time when trees in the extensive forests died during a time called Carboniferous and Permian, and the remains of plants 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 quite 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.
In order to carry out the study, a large set of computer simulations were carried out. While estimates based on ancient soils and fossil leaves show that they fluctuated widely and eventually sank into about 100 parts of CO2 per million parts of all gases in the atmosphere and possibly even lower, model simulations 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 the impact of meteorites have led to five massive extinctions of terrestrial life, during which up to 90% of all species disappeared.