Jan 31, 2002

Increasing risk of great floods in a changing climate

P. C. D. Milly, R. T. Wetherald, K. A. Dunne & T. L. Delworth
  • States the detection of anthropogenically forced changes in flooding is difficult because of the substantial natural variability; the dependence of streamflow trends on flow regime, further complicates the issue
  • Investigates the changes in risk of great floods—that is, floods with discharges exceeding 100-year levels from basins larger than 200,000 km2—using both streamflow measurements and numerical simulations of the anthropogenic climate change associated with greenhouse gases and direct radiative effects of sulphate aerosols
  • Finds that the frequency of great floods increased substantially during the twentieth century
  • States the emergence of a statistically significant positive trend in risk of great floods is consistent with results from the climate model, and the model suggests that the trend will continue