Video: What's happening to the middle class?

I want to offer you a different lens through which to better understand the climatological and environmental crises that we—indeed all of humanity—are facing. I would like you to view these crises through the long lens of our planet’s geologic and evolutionary history.

From the beginning of our planet’s formation, some 4.6 billion years ago, to the present there have been five major extinction events which destroyed anywhere from70% (during the Devonian Period) to 95% (at the end of the Permian Period) of all living things on earth. These extinctions were natural events: caused by some combination of rapid and dramatic changes in climate, combined with significant changes in the composition of environments on land or in the ocean brought on by plate tectonics, volcanic activity, climate change (including the super cooling or super heating of earth), decreases in oxygen levels in the deep ocean, changes in atmospheric chemistry (acid rain), changes in oceanic chemistry and circulation, and in at least one instance, a cosmological event—the massive asteroid strike inChicxulub, near what is now the Yucatan peninsula.