NCPA - National Center for Policy Analysis

No Increase in Floods as Planet Warms

June 22, 2011

Greek researchers with the National Technical University in Athens presented a paper at the European Geosciences Union (EGU) earlier this year and concluded, "Analysis of trends and of aggregated time series on climatic (30-year) scale does not indicate consistent trends worldwide.  Despite common perception, in general, the detected trends are more negative (less intense floods in most recent years) than positive," says the Heartland Institute.

The new study confirms previous peer-reviewed studies finding little or no increase in flooding events as the planet has modestly warmed during the past century. 

  • Scientists at the U.S. Geological Survey reported in a 1999 Geophysical Research Letters study that streamflow as a whole increased in the United States throughout the 20th century, but most of the increase occurred during low-flow and mid-flow events.
  • A U.S. Geological Survey study published in March 2006 in the peer-reviewed Journal of Hydrology similarly found more precipitation but little or no increase in flooding events.
  • A National Oceanic and Atmospheric Administration study published in April 2009 in the Journal of the American Water Resources Association reported streamflow trends are rising during low-flow seasons, but there is no increase during high-flow seasons.

While flood events may not be increasing in frequency or intensity, the propensity of people to build in flood plains ensures flooding will remain a strong concern that will likely result in rising death tolls and property damage, says Heartland.

Source: Kenneth Artz, "No Increase in Floods as Planet Warms," Heartland Institute, June 13, 2011.  D. Bouziotas et al., "Long-Term Properties of Annual Maximum Daily River Discharge Worldwide," European Geosciences Union, 2011.

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