Population and Wealth, More than Climate, Drive Soaring Costs of U.S. Flood Damage

October 23, 2000


Provided by: NCAR/UCAR/NSF
Summary authors & editors: NCAR/UCAR/NSF; Martin Ruzek

Severe, widespread flooding in the Midwest during the summer of 1993 resulted in $21 billion in damages.

Societal changes, much more than increased precipitation, spurred a steep rise in flood-damage costs in the United States over much of the past century, according to a new study published October 15 in the Journal of Climate. U.S. annual flood losses, adjusted for inflation, rose from $1 billion in the 1940s to $5 billion in the 1990s. "Climate plays an important but by no means determining role in the growth of damaging floods in the United States in recent decades," write the authors, Roger Pielke Jr. and Mary Downton, both of the National Center for Atmospheric Research. Pielke, Downton, and colleagues found that population growth alone accounts for 43% of the rise in flood damages from 1932 to 1997, with a much smaller effect from increased precipitation. "Most of the other 57% increase is due to burgeoning national wealth," says Pielke.

Globally, between 1970 and 1995 floods killed more than 318,000 people and left more than 81 million homeless. During 1991-95 flood related damage totaled more than $200 billion worldwide, representing close to 40% of all economic damage attributed to natural disasters in that period.

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