Global Warming Didn't Cause Massive U.S. Drought: Dry Spell was a 'Freak of Nature' (Video)

Last year's drought in the United States was the worst on record. Farmers watched as their crops shriveled while thousands of cattle and other livestock were slaughtered due to rises in the price of feed. While some have speculated that global warming was the cause of this massive drought, though, it turns out that it wasn't. Instead, the dry spell was a freak of nature--a perfect storm of conditions that left the Great Plains high and dry.

The 2012 Central Great Plains drought developed suddenly, according to the government report. It wasn't just a progression or continuation of the prior year's drought. Instead, it developed discretely over the Central U.S. It left cracked ground and shriveled plants in its wake, progressing from abnormally dry to exceptional drought conditions during June 2012. In fact, it's estimated that losses from this drought were $12 billion.

The last drought of this magnitude occurred in 1934 and 1936, during the height of the Dust Bowl. The event at the time was compounded by poor farming practices, which left the topsoil vulnerable to being blown away by dry winds. This left the land destitute as many farmers travelled to cities to find work, only to be turned away. The event inspired great works such as "The Grapes of Wrath," which tells the harrowing tale of a farming family in one of the worst situations imaginable.

So what exactly caused this drought if not global warming? It turns out that it was mostly due to natural variations in weather. Moist air from the Gulf of Mexico failed to stream northward in late spring since cyclone and frontal activity were shunted unusually northward. This, in turn, prevented rain from falling on the Great Plains due to a lack of moisture in the air.

"This is one of those events that comes along once every couple hundreds of years," said lead author Martin Hoerling, in an interview with the Associated Press. "Climate change was not a significant part, if any, of the event."

Unfortunately, it's likely that these droughts will continue in the future. There's been an increase of La Niñas, which play a huge part in whether or not droughts occur. The system, which is part of natural cycles, cools the Central Pacific Ocean and influences weather systems.

Want to see the drought in action? Check out how it progressed across the U.S. below, originally appearing here.