A megadrought is a prolonged drought lasting 20 years or longer. It can have very significant impacts on human.
Historically, megadroughts have led to the mass migration of humans away from drought lands, which results in a significant population decline from pre-drought levels.
Famous megadrought events include the African Sahel region, which has suffered multiple megadroughts throughout history, with the most recent lasting from approximately 1400 AD to 1750 AD.
In addition, North America experienced at least four megadroughts during the Medieval Warm Period.
Now researchers from Cornell University, Columbia University, and NASA Goddard Institute for Space Studies find that global warming can increase megadrought risks in the American Southwest. The finding is published in Science Advances.
Researchers found that a megadrought in the American Southwest would impose unprecedented stress on the limited water resources of the area. In addition, it is not enough to estimate megadrought risks just based on precipitation.
Importantly, emissions of greenhouse gases from business will drive regional warming and drying, regardless of large precipitation uncertainties.
Researchers predicted that regional temperature increases alone would push megadrought risk above 70% by the end of the century, even if precipitation increases moderately.
One possible way to reduce the megadrought risks is to cut the global greenhouse gas emissions. This may decrease megadrought risks nearly in half.
In addition, efficient water resources in the drought-stricken American Southwest are likely to help the region thrive during a changing climate.
Citation: Ault TR, et al. (2016). Relative impacts of mitigation, temperature, and precipitation on 21st-century megadrought risk in the American Southwest. Science Advances, 2: e1600873. DOI: 10.1126/sciadv.1600873.
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