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Natural Hazards

, Volume 29, Issue 2, pp 139–154 | Cite as

Rainfall Variability and Changes in Southern Africa during the 20th Century in the Global Warming Context

  • N. Fauchereau
  • S. Trzaska
  • M. Rouault
  • Y. Richard
Article

Abstract

Rainfall variability and changes in Southern Africa over the 20th century areexamined and their potential links to the global warming discussed. After a shortreview of the main conclusions of various experiments with Global AtmosphericModels (GCM) forced by increased concentrations of greenhouse gases for SouthernAfrica, a study of various datasets documents the observed changes in rainfall featuresat both daily and seasonal time steps through the last century. Investigations of dailyrainfall parameters are so far limited to South Africa. They show that some regionshave experienced a shift toward more extreme rainfall events in recent decades.Investigations of cumulative rainfall anomalies over the summer season do notshow any trend to drier or moister conditions during the century. However, closeexamination reveals that rainfall variability in Southern Africa has experiencedsignificant modifications, especially in the recent decades. Interannual variabilityhas increased since the late 1960s. In particular, droughts became more intense andwidespread. More significantly, teleconnection patterns associated with SouthernAfrican rainfall variability changed from regional before the 70s to near global after,and an increased statistical association to the El Niño – Southern Oscillation (ENSO) phenomenon is observed. Numerical experiments with a French GCM indicate that these changes in teleconnections could be related to long-term variations in the Sea-Surface-Temperature background, which are part of the observed global warming signal.

Southern Africa rainfall variability global warming rainfall variability teleconnections ENSO general circulation models 

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Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • N. Fauchereau
    • 1
  • S. Trzaska
    • 1
  • M. Rouault
    • 2
  • Y. Richard
    • 1
  1. 1.Centre de Recherches de Climatologie, UMR 5080CNRS/Universitaé de Bourgogne, Faculté des Sciences GabrielDijonFrance
  2. 2.Oceanography Dept.University of Cape TownSouth Africa

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