Megadroughts are rare events that can have devastating effects upon a region and its civilization.
Definition
Features of a Megadrought
simple
a drought lasting for multiple decades or even centuries
official
11 year running mean of regional area-averaged precipitation anomalies less than 0 for at least 20 consecutive years
A drought lasting for several years (for example, the Dust Bowl of the 1930s) but not meeting the criteria of a megadrought may be described as prolonged or severe but not as a megadrought. A severe drought lasting less than 10 years may be referred to as subdecadal.
Definition
Features of Subdecadal or Decadal Drought
simple
a drought last for 5 to 19 years
official
11 year running mean of regional area-averaged precipitation anomalies less than 0 for at least 5 consecutive years
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