A comparison of large scale changes in surface humidity over land in observations and CMIP3 general circulation models

Observed changes in the HadCRUH global land surface specific humidity and CRUTEM3 surface temperature from 1973 to 1999 are compared to CMIP3 archive climate model simulations with 20th Century forcings. Observed humidity increases are proportionately largest in the Northern Hemisphere, especially in winter. At the largest spatio-temporal scales moistening is close to the Clausius–Clapeyron scaling of the saturated specific humidity (∼7% K − 1)....