Multidecadal “megadroughts” were a notable feature of the climate of the American Southwest over the Common Era, but we know relatively little about the occurrence of such droughts in southwestern South America where a decadal-scale drought is currently impacting much of Chile. Nathan Steiger, an adjunct research scientist in the PaleoDynamics Lab, has published a paper using the Paleo Hydrodynamics Data Assimilation (PHYDA) product to both characterize megadroughts in southwestern South America and determine the degree to which they occurred at the same time as those in the American Southwest. He and coauthors report strong evidence that megadroughts in the two regions did occur synchronously in the past as a consequence of unusually frequent La Niña events in the tropical Pacific. This assessment of coupled megadroughts in North and South America provides a comprehensive theory for the causes of coupled megadroughts, particularly during the Medieval era. The work also provides the first detailed accounting of megadroughts in southwestern South America.
The PHYDA was developed by Nathan as a postdoctoral scientist in the PaleoDynamics Lab and is available here. His paper on coupled megadroughts can be found here.