Two researchers collected new tree-ring samples from blue oak trees in central and southern California to see how the state’s three-year drought compares to weather in the past. “We were genuinely surprised at the result,” said associate professsor Daniel Griffin of the University of Minnesota. The ongoing drought is the worst in 1,200 years, said Griffin and Kevin Anchukaitis of Woods Hole Oceanographic Institute in a WHOI release. They compared their data from the blue oak tree, found in some of California’s driest areas, with other estimates of drought severity developed by other researchers. They say the current stretch of low precipitation is not uncommon for California but the high temperatures are.
There is evidence of multi-year “megadroughts” in the past but they probably were punctuated by occasional wet years, say Griffin and Anchukaitis. “The current short-term drought appears to be worse than any previous span of consecutive years of drought without reprieve,” says the Woods Hole release.