Bibliographical noteFunding Information:
We thank Jan Esper, Kevin Anchukaitis, and Grant Harley for their thoughtful comments on this manuscript. B.L.C acknowledges funding from the U.S. National Science Foundation (grant # 1803995 , ‘Spatiotemporal variability in Western United States snowpack during the Common Era’) and U.S. Geological Survey (grant # G16AC00266 , ‘Water resource relevant hydroclimatic reconstructions for Western North America’). S.S.G. acknowledges funding from the U.S. National Science Foundation (grant # 1602512 , ‘Quantifying the risk of widespread megadrought in North America’) and support from the Alexander von Humboldt Foundation (fellowship, ‘Decadal to multidecadal variability in the Earth’s climate viewed through the lens of ancient trees’).