Not sure what we mean by the Sixth Mass Extinction? What were the other five? Is there really a sixth one going on? Will we all disappear like the dinosaurs? Is this real science or just a Sixth Mass Anxiety Attack?
For a simple explanation, check out the Sixth Mass Extinction blog by Hannah Boyne. It offers a easy-to-read explanation of each of the five previous known extinction events:
The Devonian – actually two events, starting 374 million years ago, when about 75 percent of all animal species became extinct.
The Permian – About 250 million years ago. The greatest known extinction event, wiping out 96 percent of all marine species and 70 percent of all terrestrial vertebrates.
The Triassic – About 200 million years ago. Not as devastating as the Permian. Among other animals, some of the early dinosaurs were wiped out, but the extinction also left openings for the dinosaurs overall to begin their ascent.
The Cretaceous – This was the well-known and most recent extinction that brought an end to the “age of the dinosaurs.” (Not a complete end, since many of them evolved into today’s birds.) Just as the Triassic extinction gave the dinosaurs their big break, the Cretaceous extinction gave the mammals their break.
The author compares rates of extinction today to those previous events and also to the “background rate” – i.e. the general rate of extinction that’s to be expected as all species evolve. She references well-known authors and scientific papers, and refutes the claims of skeptics by citing their articles and answering their main claims.
She concludes that “the Earth is experiencing an extremely elevated level of species loss, primarily due to the impact of humans.”
The blog also includes a poster presentation that covers all the basic information in one big graphic.