Its only source of heat is solar radiation. Calculate the effective temperature of Mars. Cycling of CO 2 with the terrestrial biosphere Consider the following global cycle of carbon between the atmosphere, the terrestrial vegetation, and the soil. Calculate the lifetime of carbon in the terrestrial vegetation reservoir against transfer to the litter and soil. Tree leaves eventually fall to produce litter.
Acid rain causes a decrease of microbial activity in the litter and in the soil.
We assume that CaCO 3 on the ocean floor was in equilibrium with oceanic CO 3 2- in preindustrial times. Ocean uptake of fossil fuel CO 2 has since disrupted this equilibrium by decreasing CO 3 2- levels. Dissolution of CaCO 3 is a slow process, taking place on a time scale of several thousand years. By that time we will most likely have exhausted all our fossil fuel reserves. 3 2- has finally been reachieved.