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How Drought Works


The Wages of Drought
A black blizzard swallows the horizon in 1935.
A black blizzard swallows the horizon in 1935.
PhotoQuest/Getty Images

Like many so-called "disasters," drought is only a disaster if you consider it within the context of human civilization. There's nothing insidious about an annual dry season, and shifts in climate have taken place throughout history, turning forest into grassland into desert. Animal populations migrate, less-hardy vegetation dies out and the ecosystem transforms.

But humans skew all of this through their curious habits of living everywhere, growing crops and using way too much water. Think of all the water you use in a day for drinking, hygiene, waste management, recreation, lawn care, home and auto cleaning. On top of that, we cultivate huge fields of fruits and vegetables that depend on irrigation -- and a great deal depends on those crops.

Just consider federally subsidized corn production in the United States. The resulting produce doesn't just wind up on the dinner table covered in butter; it feeds livestock, enters the fuel tank in the form of ethanol and becomes high-fructose corn syrup. So when drought reduces supply, steady demand causes prices to rise. As corn prices rise, so do the prices of products that depend on corn.

Factor in a global commodities market, and you can quickly see how drought in one food-producing part of the world can have global ramifications. South Korea, Japan, Peru, Guatemala, El Salvador, Colombia and much of East Africa all regularly import U.S. corn.

Furthermore, large-scale industrial farming techniques can actually exacerbate drought conditions. By the 1930s, farmers in the U.S. Midwest had replaced native, drought-resistant prairie grasses with vulnerable wheat. Seriously dry conditions set in, farms failed, tilled topsoil turned to dust and "black blizzards" rolled across the country in what we came to call the dust bowl. By 1934, roughly 35 million acres of farmland perished [source: PBS].

To fully consider the relationship between drought and human civilization, however, you have to consider climate change. The planet's average temperature has risen by 1.4 degrees F (0.78 degrees C) over the past century [source: EPA]. This increase might not sound all that dire at first, but even slow, steady warming boosts the odds of dangerous climate shifts and extreme weather conditions such as flood and drought [source: EPA]. The world has seen an increase in drought length and severity since the 1970s, and we can expect more of the same as Earth's temperatures increase by an estimated 2 to 11.5 degrees F (1.1 to 6.4 degrees C) over the next hundred years [source: EPA].

To a certain extent, the threat of drought is uncertain and unpredictable, yet there are ways to mediate its impact and protect people from its effects.