What is "megadrought"

n. (context climatology English) A drought lasting for decades or centuries.

A megadrought (or mega-drought) is a prolonged drought lasting two decades or longer. Past megadroughts have been associated with persistent multiyear La Niña conditions (cooler than normal water temperatures in the tropical eastern Pacific Ocean).

The term megadrought is generally used to describe the length of a drought, and not its acute intensity. In scientific literature the term is used to describe decades-long droughts or multi-decadal droughts. Multiyear droughts of less than a decade, such as the Dust Bowl drought of the 1930s, are generally not described as megadroughts even though they are of a long duration. In popular literature multiyear or even single year droughts are occasionally described as megadroughts based upon their severity, the economic damage they inflict or other criteria, but this is the exception and not the rule.