Old Molecules, New Climate: Metasequoia’s Secrets

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The Arnold Arboretum of Harvard University

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Around forty-five million years ago, the Arctic was ice free, scarcely the expanse of lichen-encrusted rock and glaciers that we see there today. Fossil records reveal that an extensive forest flourished throughout the early Cenozoic, when the canopy was predominated by Metasequoia and other deciduous conifers. The single remaining species of this genus, M. glyptostroboides, is known as the dawn redwood and is now restricted to a small population in south-central China, around forty-two hundred miles (sixty-eight hundred kilometers) south of this historic distribution. When botanists first learned about the living population more than seventy years ago, no one could have imagined that those plants would provide crucial clues for understanding more than one hundred million years of historic climate change—not to mention changes to come. Yet the rare discovery of fossils containing exquisitely preserved organic tissues and biomolecules, coupled with new molecular research techniques, has revealed just that.