Number of extreme storms and floods per year in the United States, 1900–2010. NRDC / Data from EM-DAT: the International Disaster Database (see Appendix A)

According to data collected by the International Disaster Database, the frequency of disastrous storms and floods has increased over the past 100 years, particularly in the past three decades.5 Extreme storms reached a peak in the mid-1990s, but floods appear to be occurring at a steadier rate. Given the extreme storms and floods that have occurred recently, 2011 may turn out to be another peak year. Indeed, April 2011 was the wettest on record for the Central climate region, which includes Illinois. March 2011 was the second-wettest March on record for Washington, the fifth-wettest for Oregon, and the ninth-wettest for California.

Thirsty for Answers: Preparing for the Water-related Impacts of Climate Change in American Cities