Effects of Aerosols on Climate

(Both natural and anthropogenic aerosols affect climate.)

1.  Radiation absorption:  heats the layer in which the aerosols occur.

2.  Reflection and scattering of incoming sunlight:  cools the underlying surface.

3.  Absorption and reemission of infrared radiation:  warms the surface at night.

4.  Precipitation enhancement:  aerosols act as condensation nuclei.

5.  Aerosol deposition on ice fields and snow:  decreases albedo, accelerates
     melting.

The net effect of aerosols on surface temperatures is a cooling effect.  Both theory and observations support this conclusion.  Sulfate-rich aerosols (both volcanic and anthropogenic) are especially effective in cooling the surface.  This may explain why the more polluted northern hemisphere has exhibited less global warming than the southern hemisphere.