The atmosphere contains about 700. billion metric tons of carbon in the form of carbon dioxide. In the carbon cycle, about 200. billion metric tons of carbon (as carbon dioxide) enters the atmosphere each year. Assuming that 200. billion metric tons of carbon also leaves the atmosphere annually, how many years does the average carbon atom spend in the atmosphere in each cycle?

Question

Quizplus · Accepted Answer

If 200. billion metric tons of carbon enters and leaves the atmosphere annually, then the total amount of carbon in the atmosphere remains constant at 700. billion metric tons. Therefore, the average carbon atom spends 1 cycle of carbon entering and leaving the atmosphere, which takes 2 years, in the atmosphere. So, the average carbon atom spends 2/7 = 0.29 years in the atmosphere before being removed by the carbon cycle.

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