THE INFLUENCE ON CLIMATE FORCING OF MINERAL AEROSOLS FROM DISTURBED SOILS

AEROSOLS influence the global radiation budget(1), and so changes in t he atmospheric aerosol load due to either natural causes or human acti vity will contribute to climate change(2). A large fraction of the mas s of tropospheric aerosol is wind-blown mineral dust, and its contribu tion to radiative forcing can be locally significant(3,22). Model calc ulations indicate that 50 +/- 20% of the total atmospheric dust mass o riginates from disturbed soils(4) (those affected by cultivation, defo restation, erosion, and frequent shifts in vegetation due to droughts and rains),Here, using a radiative transfer model embedded in a genera l circulation model, we find that dust from disturbed soils causes a d ecrease of the net surface radiation forcing of about 1 W m(-2), accom panied by increased atmospheric heating that may be a significant forc ing of atmospheric dynamics. These findings suggest that mineral dust from disturbed soils needs to be included among the climate forcing fa ctors that are influenced by human activities.