1/ With August now over, the ongoing soil-moisture drought in southwestern North America has now, at 23 years old and counting, matched the duration, and probably exceeded the severity, of the “megadrought” that struck the region from 1571–1593. 2/ The current megadrought has not been dry the whole time in terms of regionally averaged summer soil moisture, but the other megadroughts of the past 1200 years weren’t either. Of the last 23 years, 19 were dry, tying a record set by the 1100s and 1200s megadroughts.

1/ New study by Ben Cook (@DustyBowl), Jason Smerdon, and me in @NatureClimate. 2000-21 drought was likely the driest 22 years in >1200 years in SW North America. CMIP6 climate models suggest ~40% of the severity was due to human-caused climate trends. nature.com/articles/s4155… 2/ The cause of drier-than-average soils in the 2000s was low precipitation, but high temperature and vapor-pressure deficit (combined effect of temperature and humidity on atmospheric aridity) made the 2000s drought more severe.