The study touches on an event that has become a touchstone in the political debates over global warming's effect on the US.
It follows a report on weather extremes produced by the United Nations-sponsored Intergovernmental Panel on Climate Change. The report noted that on average, droughts in central North America "have become less frequent, less intense, or shorter." But the report also noted that over the course of this century, global warming's influence is likely to intensify droughts in the region.
At its height, the 2012 drought covered not only the six states where the dry-out was most intense – Colorado, Wyoming, Kansas, Nebraska, Iowa, and Missouri. More than 75 percent of the continental US was bathed in yellow, orange, and russets on drought maps denoting conditions ranging from abnormally dry to exceptional drought.