About 300 million years ago, the formation of immense amounts of coal drove the planet Earth near the global glaciation, turning it into an icy ball. A new study, published in Proceedings of the National Academy of Sciences, details the process.
When the concentration of CO2 in the atmosphere sank drastically and the Earth cooled, the plant entered a glaciation that almost touched what scientists call a "snowball state".
This took place at the time that the trees in the vast forests died for a time called Carboniferous and the Permian, and the remains of the plants eventually formed most of the coal that is used today as fossil fuel.
As the study author explains, Georg Feulner, from the Potsdam Institute for Climate Impact Research, in Germany:
It is quite ironic that the formation of coal today is an important factor for dangerous global warming, once almost leading 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.
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 at some point sank in 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 changes in temperature and the impact of meteorites have caused five mass extinctions of terrestrial life, during which up to 90% of all species disappeared.