Recent Variations in Surface Atmospheric Humidity


Water vapor is the most significant of the gases responsible for the natural greenhouse warming of the atmosphere. Comprehensive observations and analyses of the hydrological cycle are crucial for the improved understanding, modeling and prediction of climate. An analysis of observations by DOE-sponsored researcher Phil Jones points to evidence of a reduction in relative humidity over land areas in the tropics over the past ten years. It is noted that land surface is warming faster than the oceans resulting in differential evaporation rates and decreased land surface relative humidity. These results, based on the observational record, appear to be at variance with a prevailing modeling view summarized in the IPCC’s Fourth Assessment Report.


Simmons, A. J., K. M. Willett, P. D. Jones, P. W. Thorne, and D. Dee. 2009. “Low-Frequency Variations in Surface Atmospheric Humidity, Temperature, and Precipitation: Inferences from Reanalyses and Monthly Gridded Observational Datasets,” Journal of Geophysical Research 115, D01110. DOI: 10.1029/2009JD012442.