Increasing Northern Hemisphere Water Deficit

Abstract:

Monthly precipitation (P) and potential evapotranspiration (PET) values obtained from the CRUTS3.10 data set are used to examine changes in water deficit (i.e. positive values of PET minus P) for the Northern Hemisphere (NH). Analyses indicate that annual, cool season (October through March), and warm season (April through September) NH deficit have increased during the 1901 through 2009 period, with the greatest increases during the warm season after about 1990. The largest increases in deficit have occurred for most of the already arid regions of the Northern Hemisphere. The increases in deficit may be a warning that the world is becoming more arid, particularly during warm season months.