3. Life and non-life on Earth form a combined system (Gaia Theory) Carbon, nitrogen, phosphorus, calcium are in constant circulation between the earth’s major environmental compartments Earth’s compartments remain in balance as long as the rate of flow of matter and energy in and out of the compartments is unchanged. Changes in the environmental compartments will occur if the circulation (in and out flow) of the substances is perturbed. Atmospheric CO 2 has been increasing because the rate of input is larger than the rate of output from the atmosphere.

4. Major Biogeochemical Processes Visualized by Aerosols Dust storms Volcanoes Anthropogenic pollution Fires