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    The North And South Poles Need Not Be Icy

    Variousmag
    Monday, July 8, 2019 Last Updated 2019-10-23T18:04:05Z
    Perhaps because of that Moon-forming whack, Earth’s axis is tilted enough so that most sunlight falls on the equator.

    Yet this doesn’t mean that the poles are always icy. Just 34 million years or so ago—a blink of the eye in geologic terms—Antarctica’s average temperature was 14 degrees Celsius (57 °F).

    The nearby seas were a balmy 22 degrees Celsius (72 °F).Throughout most of its history, Earth hasn’t had the big polar ice caps that it sports today.

    The amount of incoming sunlight doesn’t matter. What matters is the level of carbon dioxide and the resultant global warming.

    Scientists aren’t sure exactly why the poles went into the freezer 20 million years or so ago. Some say it happened after India and Asia collided as part of the plate tectonics dance.

    This collision raised Tibet and the Himalaya Mountains. Since weathering happens faster on steep ground, more bits of continental rock washed into the oceans, increasing the carbon-holding capacity of the seas.

    Carbon fell out of the atmosphere, and the greenhouse effect soon switched over to global cooling.Not all researchers are onboard with this idea.

    They say there isn’t enough evidence to definitely prove one theory over another, though they do agree it had to do with CO2. Perhaps, they suggest, it was due to changes in vegetation.
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