Snowball Earth (BBC Horizon Documentary)


BBCHORlZON

Published on Jan 11, 2013

Snowball Earth describes a theory that for millions of years the Earth was entirely smothered in ice, stretching from the poles to the tropics. This freezing happened over 650 million years ago in the Pre-Cambrian, though it’s now thought that there may have been more than one of these global glaciations. They varied in duration and extent but during a full-on snowball event, life could only cling on in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis.

Global Climate Change http://courses.dce.harvard.edu/~envre130
Environmental Justice http://courses.dce.harvard.edu/~envre145
Environment Ethics http://courses.dce.harvard.edu/~envre120

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