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Relative impacts of mitigation, temperature, and precipitation on 21st-century megadrought risk in the American Southwest

Finds that changes in the mean hydroclimate state, rather than its variability, determine megadrought risk in the American Southwest
Estimates of megadrought probabilities based on precipitation alone tend to underestimate risk
States that business-as-usual emissions of greenhouse gases will drive regional warming and drying, regardless of large precipitation uncertainties
Finds that regional temperature increases alone push megadrought risk above 70, 90, or 99% by the end of the century, even if precipitation increases moderately, does not change, or decreases, respectively. Although each possibility is supported by some climate model simulations, the latter is the most common outcome for the American Southwest in Coupled Model Intercomparison 5 generation models
Finds that an aggressive reduction in global greenhouse gas emissions cuts megadrought risks nearly in half

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