Sobering Lessons from the Past

There is a lengthy and interesting post on ScienceBlogs by GrrlScientist today about The Great Dying:The Great Dying was the largest mass extinction event on earth. It occurred approximately 251 million years ago and marks the boundary between the Permian and Triassic geologic periods, commonly known as the PT boundary.Apparently some new evidence is pointing to a massive buildup of CO2 and a