Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity

AbstractThe 2011–16 California drought illustrates that drought-prone areas do not always experience relief once a favorable phase of El Nino–Southern Oscillation(ENSO) returns. In the twenty-first century, such an expectation is unrealistic in regions where global warminginduces an increase in terrestrial ariditylarger than the changes in ariditydriven by ENSO variability. This premise is also flawed in areas where precipitation supply cannot offset the global warming–induced increase in evaporative demand. Here, atmosphere-only experiments are analyzed to identify land regions where aridityis currently sensitive to ENSO and where projected future changes in mean aridityexceed the range caused by ENSO variability. Insights into the drivers of these changes in aridityare obtained using simulations with the incremental addition of three different factors to the current climate: ocean warming, vegetation response to elevated CO2 levels, and intensified CO2 radiative forcing. The effect of ocean warmi...