1. Suppose world carbon emissions are expressed by the following: Carbon emissions = (energy/person) × (carbon/energy) × (population) The initial carbon emission rate is 5 × 10 9 tonne C/yr and there are 700 × 10 9 tonnes of carbon in the atmosphere now. a. If the per capita energy demand grows by 1.5% every year, fossil fuel emissions of carbon per unit of energy grow by 1% every year, and world population grows at 1.5% per year, how long would it take to emit a total amount of carbon equal to the amount now contained in the atmosphere? b. If half of the carbon that people emit stays in the atmosphere (while the other half gets used up in other parts of the biosphere), how long would it take for fossil fuel combustion to double the atmospheric carbon concentration? 2. Consider the following disaggregation of carbon emissions: Carbon emissions (kg C/yr) = Population × Energy kJ/yr ( ) Person × Carbon kgC ( ) Energy kJ ( ) Using the following estimates for the United States and assuming that growth rates remain
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