In climate change, dire signs of a die-off
By Carl Zimmer | New York Times | Updated: 2011-04-17 07:48
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The number of species facing extinction may be underestimated. Deprived of seal, a polar bear raided a goose nest. Jouke Prop |
Over the past 540 million years, Earth has seen five great mass extinctions. In each of those catastrophes, an estimated 75 percent or more of all species disappeared in a few million years or less.
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