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Effects of climatic change on the Thornthwaite moisture index

Journal Article · · Water Resources Bulletin; (USA)
; ; ;  [1]
  1. Geological Survey, Trenton, NJ (USA) Denver Federal Center, Lakewood, CO (USA)
The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous US. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO{sub 2} conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO{sub 2} conditions. Results indicate that temperature and precipitation changes under doubled-CO{sub 2} conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the US. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic-change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation.
OSTI ID:
6232375
Journal Information:
Water Resources Bulletin; (USA), Journal Name: Water Resources Bulletin; (USA) Vol. 26:4; ISSN WARBA; ISSN 0043-1370
Country of Publication:
United States
Language:
English