The Globalized Great Lakes

If you want to know what the climate was like in Great Lakes country just before this latest period of global warming, you might have to climb the Rockies. In 1990, the bones of a giant pika, a diminutive member of the rabbit family, were discovered in a cave in the Niagara Escarpment, and were later carbon-dated to 9,780 years before the present, when the climate around the glaciated Great Lakes region was decidedly colder than it is now and the escarpment itself probably poked up above a plain of solid ice. As the climate continued to warm, American pikas migrated west, and are now found only on tree-line talus slopes of the Rocky Mountains, where it still gets cold enough to entertain glaciers. Giant pikas, a slightly less diminutive subspecies, went extinct altogether, part of what John L. Riley, who helped excavate their bones in Ontario, calls “the long list of species that perished soon after the last glacier receded” in The Once and...