“Just how bad has California’s drought been? Modern measurements already showed it’s been drier than the 1930s dustbowl, worse than the historic droughts of the 1970s and 1980s. That's not all. New research going back further than the Viking conquests in Europe still can't find a drought as bad as this one.
To go back that far, scientists consulted one of the longest records available: tree rings. Tighter rings mean drier years, and by working with California’s exceptionally old trees, researchers from University of Minnesota and Woods Hole Oceanographic Institute were able to reconstruct a chronology of drought in southern and central California. They identified 37 droughts that lasted three years or more, going back to the year 800.
None were as extreme as the conditions we’re seeing now.”
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