Human Impacts on Surface Humidity Changes


Water vapor is the most important contributor to the natural greenhouse effect. The amount of water vapor in the atmosphere is expected to increase under conditions of greenhouse-gas induced warming, leading to a significant feedback on anthropogenic climate change. The authors of a recent publication in the journal Nature, sponsored in part by BER, identify and explore the causes of changes in surface specific humidity over the late twentieth century using a new observational data set of surface humidity with output from a coupled climate model. They identify a significant global-scale increase in surface specific humidity attributable mainly to human influence. The changes in atmospheric humidity may have important implications in determining the geographical distribution and maximum intensity of precipitation, the potential maximum intensity of tropical cyclones, human heat stress, and surface hydrology.


Willett K.M., N.P. Gillett, P.D. Jones, and P.W. Thorne. 2007. “Attribution of observed surface humidity changes to human influence,” Nature 449, 710.