Refer to the diagram of the carbon cycle on the last page of this handout to answer the following questions. Stocks, in gigatons are shown in parentheses with white text; Flow rates (shown in yellow and red text without parentheses) are in gigatons per year. The yellow figures show natural flows; the red figures are flow attributed to the effects of human activity?

1. (a)Determine thenaturalinflows of carbon to the atmosphere and thenaturaloutflows of carbon from the atmosphere.
2. (b)Is the stock of carbon in atmosphere in dynamic equilibrium in its natural state? What if the effects of human activity are included?
3. (c)What is the residence time of carbon in the atmosphere (use the natural state - ignoring the effects of human activity)?