Broken World

A recent paper in Science describes how the Earth became a hellish desert for over five million years as a result of the Permian Extinction. The trigger is still unclear, and suggested causes range from asteroid impacts to runaway greenhouse effect due to volcanic eruptions. In the tropics, sea temperatures were 40C (104F), and land temperatures were over 50C (122F).

Most of the discussion of the paper appears to be the implications for the current era of global warming. What I find interesting is the fact that it puts severe constraints on the development of life-as-we-know-it.

The tropics were barren hells for five million years. That’s an eternity in evolutionary time. There was life at the poles (or we wouldn’t be here) but it was not able to modify itself enough to recolonize the tropics. What tropical life there was, was shrubs and ferns, and there were no tropical fish, not even guppies.

This puts an upper limit on the allowed temperatures for life on earth-like planets, and gives us a better criterion for setting the inner limit of the ‘Goldilocks zone’ around a star. Yes, it’s possible that life-as-we-don’t-know-it might develop, based on asbestos or something, or that, given half a billion years, rather than just five million, life on earth could adapt, but it helps us better understand just what our limits are.

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2 Responses to “Broken World”

  1. Kurt Kremer Says:

    That’s why I’ve invested in hydrothermal real estate futures. (http://www.newscientist.com/article/dn14208-the-most-extreme-lifeforms-in-the-universe.html)

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