A robust null hypothesis for the potential causes of megadrought in western North America

Toby Ault, Cornell University, Department of Earth and Atmospheric Science, Ithaca, NY, United States, Scott St George, Univ of MN-Dept of Geography, Minneapolis, MN, United States, Jason E Smerdon, Lamont-Doherty Earth Observatory, Palisades, United States, Sloan Coats, University of Colorado-Boulder, New York, NY, United States, Justin S Mankin, Columbia University of New York, Lamont-Doherty Earth Observatory, Palisades, NY, United States, Carlos Carrillo Cruz, Cornell University, Earth and Atmospheric Research, Ithaca, NY, United States, Benjamin Cook, Lamont -Doherty Earth Observatory, Palisades, NY, United States and Samantha Stevenson, National Center for Atmospheric Research, Boulder, CO, United States