How the U.S. Megadrought Will Affect 2022 and Beyond

Nancy J. Delong

This posting appeared in the January/February 2022 issue of Learn magazine as “All-Time Dry.” Turn into a subscriber for unrestricted access to our archive.

Just halfway by means of the summer months of 2021, a startling history was set: By one evaluate, almost 100 p.c of the Western U.S. was in drought. In 122 yrs of observation, never ever had that much land been that dry west of the Continental Divide.

Absence of precipitation was a issue. But even a lot more significant had been superior temperatures. In June by itself, 202 all-time history highs had been set in the West. For the Southwest, these extremes amplified a 20-yr megadrought that is been drying out the location and, most notably, the Colorado River Basin.

In the effort and hard work to satisfy soaring h2o requires in the basin, the two most significant reservoirs in the U.S. — lakes Mead and Powell along the Colorado River — both shriveled to historic lows this summer months. “It’s a ticking time bomb,” states Brad Udall, a h2o and climate exploration scientist at Colorado Condition College.

The drying up, or aridification, of the Southwest has been taking a toll on the snowmelt-dependent Colorado River for many yrs. As a consequence, its natural flows have diminished by virtually 20 p.c given that 2000. Meanwhile, demand for its h2o — the lifeblood of an economic climate exceeding $one.four trillion — has only improved, with around 40 million people counting on it today.

(Credit score: Tim Roberts Pictures/Shutterstock)

On Aug. 16, the U.S. Bureau of Reclamation issued the to start with-ever lack declaration for Lake Mead. This will trigger considerable cuts in 2022 to h2o deliveries, particularly to agricultural consumers, in Arizona, Nevada and Mexico. Arizona will just take the major reduce, totaling about a fifth of its Colorado River supply. Inhabitants in towns like Phoenix, the swiftest expanding in the U.S., will be spared. But farmers who irrigate crops with h2o from the Central Arizona Undertaking canal will see their supplies diminished by about thirty p.c. 

Larger cuts that would hit towns, not just farmers, may possibly be coming. “With expanding populations and continued advancement in the metro regions of Las Vegas, Phoenix, and L.A., it’s extremely about how h2o source problems will effect these urban regions in the not-so-distant potential,” states David Simeral, a climate scientist with the Desert Investigation Institute.

Scientists caution that, for the Southwest in specific, including parts of the Colorado River Basin, the prolonged warmth could sign a new, a lot more-arid norm further than short term droughts.

A 2020 examine printed in Science showed that the period between 2000 and 2018 was the driest given that the late 1500s. And, notably, about forty six p.c of the severity of this present-day megadrought could be attributed to human-brought on climate adjust. “This seems to be just the commencing of a a lot more intense trend towards megadrought as world wide warming carries on,” the examine authors cautioned. 

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