If you think the extinction that killed the dinosaurs 65 million years ago was disastrous then think about this.
John Roth deciphered the black streak in the cream-colored marble walls of Oregon Caves. He states the graphite line is graphic evidence of massive global warming at the end of the Permian period caused by enormous amount of carbon dioxide introduced into the atmosphere mostly from methane from the oceans. So much was the carbon dioxide build-up that it was enough to consume all the oxygen present killing almost all land animals on the planet 247 million years ago. And with a potential to kill off most oxygen-breathing species it is unlikely that any living thing survived. They also estimated that temperatures ranged in the low 100s year-round for thousands of years.
To make things worse scientists are not able to discover what triggered the episode.
Source: MSNBC (via: AP)