How Humans are Driving the Sixth Mass Extinction
By Jeremy Hance | The Guardian | October 20, 2015
Periodically, in the vast spans of time that have preceded us, our planet’s living beings have been purged by planetary catastrophes so extreme they make your typical Ice Age look like the geological equivalent of a stroll in the park. Scientists count just five mass extinctions in an unimaginably long expanse of 450 million years, but they warn we may well be entering a sixth.