Effects of temperature and precipitation trends on U.S. drought

The contiguous United States has experienced both warming temperatures and a general increase in precipitation during the period 1950–2006. During that time drought has been a recurring phenomenon with a number of large droughts occurring, starting with the major drought in the 1950s in the Central United States and culminating with the persistent drought in the western portion of the country that started in the late 1990s. Here we examine the influence of the multi‐decadal warming trend on drought coverage and the possibility that the general increase in regional and contiguous U.S. precipitation since about 1980 has masked the tendency for increasing drought driven largely by increasing temperature. Results indicate that without the increase in precipitation, severe to extreme drought would have affected as much as 50% more of the U.S. during some months in the most recent drought period.