Earth has suffered several extintion events, it is said that now days we are going through the 6th. The probably worst was the permian extintion, less spectacular than the dinosaur's, but for me more worrying. It's the story of a brutal climate change provoked by natural CO2 and Methane emissions (and more factors). Almost 95% of life on oceans and 70% of life on earth were wiped out. We have to take account of what forces are we dealing.