The Earth nearly froze over when today’s coal was first buried
Tuesday October 10, 2017. 04:50 PM , from Ars Technica
Enlarge (credit: Harvard University)
Our burning of fossil fuels is, to an extent, a reversal of a process that happened millions of years ago. At one point, all this carbon was in the air. Over millions of years, life extracted it from the air before dying and getting buried. Geology took over from there, gradually converting the formerly living material into things like coal and oil. Since this process was relatively slow, it presumably didn't result in radical changes to the climate.
But a new study suggests that it came really, really close. Lots of the fossil fuels we currently use derive from the Carboniferous, a 60-million-year-long period where forests flourished across much of the Earth. While not sudden, activity during this time period did pull a lot of carbon out of the atmosphere, and so a researcher decided to look at some of the consequences. The results suggest that the Earth skirted the edge of a global freeze, forming glaciers in the mountains of the tropics.
The Devonian is the period that predated the Carboniferous, and it's notable for the first appearance of both forests and tetrapods, the four-limbed vertebrates that include us. But forests really started getting going in the Carboniferous, leaving behind massive deposits of coal. At this time, the Earth also underwent an extinction event that saw the collapse of forests and the appearance of widespread glaciers.
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