The last great swing took place as the ice age was ending, and it was a doozy. Temperatures in Greenland shot up by 15°F in a decade, or perhaps even faster. Then things settled into a new and very different regime. For the next ten thousand years, temperatures in Greenland (and the rest of the world) remained more or less constant, decade after decade, century after century. All of civilization falls within this period of relative tranquility, and so this sort of calm is what we take to be the norm. It’s an understandable mistake, but still a mistake. Over the last hundred and ten thousand
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