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Thank God for CO2

Doug L. Hoffman — The Resilient Earth — April 7, 2013

It has been vilified in the press and maligned in school classrooms by the ignorant. Opposing it has become a cause célèbre in Hollywood an a litmus test for liberal politicians. Labeled man’s chosen weapon for ravaging nature and laying waste to the environment this poor, largely misunderstood gas is in fact essential to our existence. Without carbon dioxide, CO2, we would not be here and Earth would be a frozen lifeless chunk of rock. Forget that life would never have developed on a planet without greenhouse warming, a recent scientific study say the daemon gas has rescued the planet from the deep freeze at least twice during the Neoproterozoic era, roughly 750 to 635 million years ago.

These days it is fashionable to agonize over the extent of polar ice packs, but those who do are naive if they think they know what “normal” levels of ocean ice are. Geological evidence suggests that marine ice extended to the Equator at least twice in the run up to the blossoming of complex life on Earth. That our planet was nearly or completely frozen from pole to pole is called the Snowball Earth hypothesis by climate scientists. In “Dynamics of a Snowball Earth ocean,” Yosef Ashkenazy and colleagues relate the possibility that ocean circulation and mixing processes would have set the melting and freezing rates that determine ice thickness, which in turn would have influenced the survival of photosynthetic life.

Their report, appearing in the journal Nature, does not explain why a Snowball Earth climate occurred but rather how life managed to survive such a freeze over. Note that the marine ice they are talking about is not the wimpy pack ice we see covering the Arctic ocean and surrounding Antarctica today. On Snowball Earth the oceans are covered by 200 meter thick floating glaciers. Here is a paragraph from the paper giving the authors’ motivation:

The flow of thick ice over a Snowball Earth ocean (“sea glaciers”, characterized by dynamics very different from that of thinner sea ice), has received significant attention over the past few years. Similarly, the role and dynamics of atmospheric circulation and heat transport, CO2 concentration, cloud feedbacks, and continental configuration have been studied, as has the role of dust over the Snowball Earth’s ice cover. In contrast, despite its importance, the ocean circulation during Snowball Earth events has received little attention. The few studies that used full-ocean General Circulation Models concentrated mostly on the ocean’s role in Snowball Earth initiation and aftermath. No studies accounted for the combined effects of thick ice cover and flow, and driving by geothermal heating.  Continue reading, here…..

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