"This is right in line with what people were thinking of in the 1900s as a worst-case scenario. But today I think we need to be even preparing for conditions in the future that are far worse than this." The Southwest is in the middle of the megadrought: Here's how it got thereThe Southwest is the driest it's been since the late 1500s. "Climate change is literally baking the water supply and forests of the Southwest, and it could get a whole lot worse if we don't halt climate change soon." The intense dry spell that has parched the western U.S. the past 22 years is the region's worst "megadrought" since at least the year 800, a new study says.Megadroughts, which are defined as intense droughts that last for decades or longer, once plagued western North America.