Re: The Scariest Climate Change Graph Just Got Scarier
Posted by anascrecca on 3/25/2013, 11:56 am
Jim,
As a geologist, I feel compelled to address your post. Global temperatures and ice volumes over the past 450,000 years are shown here (from various sources):




As you can see, temperatures have fluctuated, almost cyclically, resulting in the advance and retreat of the glaciers (and also the corresponding fall [during glacial periods] and rise [during interglacial periods] of relative sea level) during the various late Pleistocene ice ages. Most scientists attribute these thermal fluctuations to astronomical effects related to small changes in the earth's orbit and orbital precession (wobbling about the axis), and not necessarily asteroid/comet impacts. One can look up Milankovitch cycles for further info on this. Certainly, major asteroid impact events (the Chicxulub in Yucatan, and there was a sizable one in Chesapeake Bay in the Eocene epoch) created their own level of havoc, but I have seen nowhere in the literature that they were responsible for the Pleistocene ice ages. As a note, some scientists postulate that we may be on the cusp of (and perhaps even overdue for) another ice age. That notion would be likely to open up a brand new 55-gallon drum of worms!
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The Scariest Climate Change Graph Just Got Scarier - Target, 3/23/2013, 12:03 pm
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