The 2012 US drought wasn't caused by global warming. Rather, it was a freak of nature, according to a new federal science study.
Last year's drought was the worst the nation has seen in more than 70 years. Scientists believe that the lack of moisture usually pushed up from the Gulf of Mexico was the main reason for the Midwest drought.
The report was released on Thursday and was compiled by dozens of scientists from five different federal agencies. The scientists looked into why weather reports showed no signs of the impending drought.
Lead author Martin Hoerling, a research meteorologist at the National Oceanic and Atmospheric Administration, explained, "This is one of those events that comes along once every couple hundreds of years. Climate change was not a significant part, if any, of the event."
While the drought spread through two-thirds of the Lower 48 states, researchers focused their study on six states -- Wyoming, Kansas, Nebraska, Colorado, Missouri, and Iowa. For these six states, the drought was the worst seen since records began in 1895.
Hoerling added that the jet stream that draw moisture from the Gulf was stuck much farther north in Canada. Using computer simulations, Hoerling attempted to replicate the drought with man-made global warming conditions. When he couldn't, he concluded that the massive 2012 drought was not caused by humans.
Hoerling used similar methods to link increasing droughts in the Mediterranean Sea region to climate change. But not all scientists agreed that the drought wasn't caused by global warming.
Climate analysis chief at the National Center for Atmospheric Research Kevin Trenberth stated that the report didn't include a factor -- a lack of snowfall in the Rockies the previous winter. The lack of snowfall could have affected the overall moisture in the air. Trenberth added that the study didn't look at how global warming affected the high pressure system that moved the jet stream north last summer.
Trenberth concluded, "This was natural variability exacerbated by global warming. That is true of all such events from the Russian heat wave of 2010, to the drought and heat waves in Australia."
Do you think last year's drought in the US was caused by climate change? Or was it a freak of nature that happens once every two hundred years?
[Image via NOAA]