Tropospheric aerosols affect the radiative forcing of the Earth's climate. Utilizing a new state-of-the-art atmospheric general circulation model, an investigation is made of the climate sensitivity due to the presence of tropospheric aerosols. Both the shortwave and longwave properties of the aerosols are considered. The aerosol species considered include natural and anthropogenic sulfate and dust, organic and black carbon, and sea-salt. The inclusion of aerosols results in a better agreement with the globally-averaged clear-sky reflected solar flux observations measured by the Earth Radiation Budget Experiment (ERBE) satellite. We focus primarily on the impact of the aerosols on the land-surface energy and water budgets, and the hydrologic cycle in the troposphere. We also examine the relative roles of natural and anthropogenic sources and assess their significance in the present day climate.