 This paper examines the climatic factors behind one of the worst droughts ever recorded in northeastern Brazil. It found that the drought began in the mid-to-late 1990s, with the extreme droughts of 1993 and 1998, followed by a series of dry years interrupted by relatively wet years in 2007, 2008, 2009 and 2011. These conditions were exacerbated by low rainfall in subsequent years, resulting in a serious water shortage that had devastating effects on the local economy and society. This article was authored by Jose Amarango, Lincoln M. Alves, Regina C.S. Alvala, and others.