Breakdown: Why the Western megadrought is ‘the worst in 1,200 years’

Published: Mar. 17, 2022 at 7:20 AM CDT
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MEMPHIS, Tenn. (WMC) - The southwestern United States is in the midst of the worst megadrought in at least 1,200 years, researchers found.

A megadrought is defined as a drought lasting two decades or longer.

The drought that has enveloped southwestern North America for the past 22 years is the region’s driest since at least the year 800, according to a new UCLA-led study.

The region’s high temperatures and low precipitation levels from summer 2020 through summer 2021, the current drought has exceeded the severity of a late-1500s megadrought that previously had been identified as the driest such drought in the 1,200 years that the scientists studied.

Map released: February 17, 2022
Data valid: February 15, 2022
Map released: February 17, 2022 Data valid: February 15, 2022(

UCLA geographer Park Williams, the study’s lead author, said with dry conditions likely to persist, it would take multiple wet years to remediate their effects.

“It’s extremely unlikely that this drought can be ended in one wet year,” he said.

Existing climate models have shown that the current drought would have been dry even without climate change, but not to the same extent.

Warmer temperatures are increasing evaporation, which dries out soil and vegetation.

In fact, human-caused climate change is responsible for about 42% the dry soils since 2000, the paper found.

“Without climate change, the past 22 years would have probably still been the driest period in 300 years, but it wouldn’t be holding a candle to the megadroughts of the 1500s, 1200s or 1100s,” Williams said.

Regulators have continued to implement water conservation measures in response to water shortages caused by the drought.

Williams said initiatives like this will help in the short term, but water conservation efforts that extend beyond times of drought will be needed to help ensure people have the water they need as climate change continues to intensify drought conditions.

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