Abstract
Earth system is composed of several reservoirs (boxes) such as atmosphere, hydrosphere, biosphere, geosphere and humans. Mass and energy circulations are occurring between these reservoirs. In long-term period, the steady state conditions are attained. However, in a short-term period, geologic events (e. g., volcanic activity) and humans activity (e. g., anthropogenic CO2 emission to atmosphere) largely influence the amount and concentration of elements in reservoirs. For example, atmospheric CO2 concentration has been increasing during the last 250 years due to the anthropogenic CO2 emission. Global geochemical cycle simulations based on multi box model (linear and pseudononlinear model) are useful to clarify the changes in atmospheric CO2 concentration and climate (e. g., atmospheric temperature) during the past and in the future. In this paper, the results of previous model calculations on those CO2 and temperature changes during the past (e. g., 108 years, 6.0×106 years, and 120 years) are given. The unsolved problems on the calculations (the uncertainty of parameters, assumptions on the calculations etc.) are cited.
