Weather and climate extremes have been varying and changing on many different time scales. In recent decades, heat waves have generally become more frequent across the United States, while cold waves have been decreasing. While this is in keeping with expectations in a warming climate, it turns out that decadal variations in the number of U.S. heat and cold waves do not correlate well with the observed U.S. warming during the last century. Annual peak flow data reveal that river flooding trends on the century scale do not show uniform changes across the country. While flood magnitudes in the Southwest have been decreasing, flood magnitudes in the Northeast and north-central United States have been increasing. Confounding the analysis of trends in river flooding is multiyear and even multidecadal variability likely caused by both large-scale atmospheric circulation changes and basin-scale “memory” in the form of soil moisture. Droughts also have long-term trends as well as multiyear and decadal variability. Instrumental data indicate that the Dust Bowl of the 1930s and the drought in the 1950s were the most significant twentieth-century droughts in the United States, while tree ring data indicate that the megadroughts over the twelfth century exceeded anything in the twentieth century in both spatial extent and duration. The state of knowledge of the factors that cause heat waves, cold waves, floods, and drought to change is fairly good with heat waves being the best understood.
Monitoring and Understanding Changes in Heat Waves, Cold Waves, Floods, and Droughts in the United States: State of Knowledge
Authors:
Thomas C. Peterson and Richard R. Heim AffiliationsNOAA/National Climatic Data Center, Asheville, North Carolina Robert Hirsch Affiliations
U.S. Geological Survey, Reston, Virginia Dale P. Kaiser Affiliations
Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, DOE, Oak Ridge, Tennessee Harold Brooks Affiliations
National Severe Storms Laboratory, NOAA, Norman, Oklahoma Noah S. Diffenbaugh Affiliations
Stanford University, Stanford, California Randall M. Dole Affiliations
NOAA/Earth System Research Laboratory, Boulder, Colorado Jason P. Giovannettone Affiliations
Institute for Water Resources, U.S. Army Corp of Engineers, Alexandria, Virginia Kristen Guirguis Affiliations
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, and University Corporation for Atmospheric Research, Boulder, Colorado Thomas R. Karl Affiliations
NOAA/National Climatic Data Center, Asheville, North Carolina Richard W. Katz Affiliations
National Center for Atmospheric Research, Boulder, Colorado Kenneth Kunkel Affiliations
Cooperative Institute for Climate and Satellites, Asheville, North Carolina Dennis Lettenmaier Affiliations
University of Washington, Seattle, Washington Gregory J. McCabe Affiliations
USGS, Lawrence, Kansas Christopher J. Paciorek Affiliations
Department of Statistics, University of California, Berkeley, Berkeley, California Karen R. Ryberg Affiliations
U.S. Geological Survey, Bismarck, North Dakota Siegfried Schubert Affiliations
NASA Goddard Space Flight Center, Greenbelt, Maryland Viviane B. S. Silva Affiliations
Climate Services Division, NOAA/NWS/OCWWS, Silver Spring, Maryland Brooke C. Stewart Affiliations
STG, Asheville, North Carolina Aldo V. Vecchia Affiliations
U.S. Geological Survey, Bismarck, North Dakota Gabriele Villarini Affiliations
IIHR–Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa Russell S. Vose Affiliations
NOAA/National Climatic Data Center, Asheville, North Carolina John Walsh Affiliations
University of Alaska Fairbanks, Fairbanks, Alaska Michael Wehner Affiliations
Lawrence Berkeley National Laboratory, Berkeley, California David Wolock Affiliations
USGS, Lawrence, Kansas Klaus Wolter Affiliations
NOAA/Earth System Research Laboratory, Boulder, Colorado Connie A. Woodhouse Affiliations
University of Arizona, Tucson, Arizona Donald Wuebbles Affiliations
University of Illinois at Urbana–Champaign, Urbana, Illinois
Final Form: 30 November 2012
Published Online: 1 June 2013
June 2013
