Effects of climatic change on the Thornthwaite moisture index

Water Resources Bulletin
By: , and 



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 United States. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO2 conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO2 conditions. Results indicate that temperature and precipitation changes under doubled-CO2 conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. 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.
Publication type Article
Publication Subtype Journal Article
Title Effects of climatic change on the Thornthwaite moisture index
Series title Water Resources Bulletin
DOI 10.1111/j.1752-1688.1990.tb01400.x
Volume 26
Issue 4
Year Published 1990
Language English
Publisher American Water Resources Association
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Water Resources Bulletin
First page 633
Last page 643
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