Virtually every year, we hear stories about droughts in one place or another. It would be interesting to take an informal poll on what people thought was the cause of droughts. Most likely, people would be apt to claim that the cause is mostly global warming or some such. The problem with this is that information has been accumulating for at least the last few years that appears to disprove much of the global warming theory. So what causes drought?
Meaning of 'drought'
This word is often used to mean a lack of precipitation. Though this could lead to drought, it isn't actually drought. The Sahara and Death Valley don't get much rainfall, but they aren't normally referred to as being drought-stricken. The true meaning of the word is the lowering of the aquifer or water table. Since rain and snow generally replenishes the aquifer, a few years of below average precipitation can certainly have the result of lowering the water table. However this neither explains the real cause, nor does it explain why some areas receiving normal amounts of precipitation might be considered as suffering drought conditions.
In the United States alone, there are many areas that are considered to be in drought, almost every year. Some of those places might not surprise anyone, such as in hot and arid areas of Texas and Oklahoma. It might surprise people to learn that Denver, Colorado, surrounded by the snow-capped Rockies, has a drought almost every year. Droughts aren't confined to hot and dry areas.
Common drought areas like Denver and Aspen, Colorado, places in Florida and California, Utah and New Mexico, as well as others, do have something in common: People. This makes sense, when you stop to think about it. If there were no people in Denver, in a particularly hot, dry season, the water table would drop, because that is normal. It most likely wouldn't drop to drought levels, though. If there are a lot of people, however, water is commonly drawn out of the aquifer at an increasing rate as temperatures increase. The result is drought, and it tends to be the most severe during the hottest and driest years.
Thus, while nature can certainly lead to droughts, and has throughout history, in the modern era the most common cause of droughts is mankind. This is why they even occur in places where the water supply is plentiful, such as in the U.S. Pacific Northwest. The interesting part about this is that while there is very little that man can do to change the climate, they can do a great deal to prevent or stop the most common droughts that occur yearly, since man is mostly responsible for them. How? Water conservation is the key, and there is even an incentive for it, as conserving water also tends to lower the water bill.
(Photo by Tim McCabe, USDA Natural Resources Conservation Service, public domain, courtesy of USDA NRCS, USDA NRCS Photo Gallery: NRCSCA91002.tif. The picture is of a lake near San Luis Obispo, California during a drought.)