@article{9146, abstract = {The factors governing the rate of change in the amount of atmospheric water vapor are analyzed in simulations of climate change. The global-mean amount of water vapor is estimated to increase at a differential rate of 7.3% K − 1 with respect to global-mean surface air temperature in the multi-model mean. Larger rates of change result if the fractional change is evaluated over a finite change in temperature (e.g., 8.2% K − 1 for a 3 K warming), and rates of change of zonal-mean column water vapor range from 6 to 12% K − 1 depending on latitude. Clausius–Clapeyron scaling is directly evaluated using an invariant distribution of monthly-mean relative humidity, giving a rate of 7.4% K − 1 for global-mean water vapor. There are deviations from Clausius–Clapeyron scaling of zonal-mean column water vapor in the tropics and mid-latitudes, but they largely cancel in the global mean. A purely thermodynamic scaling based on a saturated troposphere gives a higher global rate of 7.9% K − 1. Surface specific humidity increases at a rate of 5.7% K − 1, considerably lower than the rate for global-mean water vapor. Surface specific humidity closely follows Clausius–Clapeyron scaling over ocean. But there are widespread decreases in surface relative humidity over land (by more than 1% K − 1 in many regions), and it is argued that decreases of this magnitude could result from the land/ocean contrast in surface warming.}, author = {O’Gorman, P A and Muller, Caroline J}, issn = {1748-9326}, journal = {Environmental Research Letters}, keywords = {Renewable Energy, Sustainability and the Environment, Public Health, Environmental and Occupational Health, General Environmental Science}, number = {2}, publisher = {IOP Publishing}, title = {{How closely do changes in surface and column water vapor follow Clausius–Clapeyron scaling in climate change simulations?}}, doi = {10.1088/1748-9326/5/2/025207}, volume = {5}, year = {2010}, }