Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future : University of Washington paleontologist Peter D. Ward demonstrates in Under a Green Sky that the ancient past is not just of academic concern. Everyone has heard about how an asteroid did in the dinosaurs, and NASA and other agencies now spend large sums of money tracking so-called near Earth objects. Unfortunately, we may not be protecting ourselves against the likeliest cause of our species' demise. Ward's argument, which has been presented to his peers via several papers in Science, is that all but one of the major extinction events in the history of the world have been brought on by climate change - the same global warming that we are experiencing today. Ward explains how those extinctions happened, and then applies those chilling lessons to the modern day: expect drought, superstorms, poison-belching oceans, mass extinction of much life, and sickly green skies.