…since our species evolved, average temperatures have never been much more than two or three degrees higher than they are right now. [Predictions cited in the article call for increases of 4.9 to 7.7 degrees.]One of the scientists quoted models the effects of global warming on rainfall patterns. The entire continental United States ends up in varying degrees of drought and severe drought as a result of the warming.
...A possible consequence of even a four- or five-degree temperature rise--on the low end of projections for doubled [concentrations of carbon dioxide]--is that the world will enter a completely new climate regime, one with which modern humans have no prior experience.
...It is believed that the last time carbon dioxide levels were in this range was three and a half million years ago, during what is known as the mid-Pliocene warm period, and they likely have not been much above it for tens of millions of years.
Much of the article discusses emerging science in paleoclimatology (the study of the climate of the past) which tells us that civilization after civilization has fallen at least, in part, due to rapid and severe climate change.
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