Coal formation almost turned Earth into a snowball: Study
While burning coal is linked to global warming, coal formation about 300 million years ago brought Earth close to a snowball-like state, a Germany-based study reported. During the period, several carbon-absorbing trees got buried leading to coal formation while drastically dropping atmospheric CO2 levels to 100 ppm. A global glaciation event would have occurred at 40 ppm CO2, said researchers.