Plugging in the numbers, we get: What is the total amount of CO2 emitted? We want the answer to be in Gigatons — that’s a billion tons, and in the metric system, one ton is 1000 kg (1e6 g or 106 g), which means that 1Gt = 1015 g (1e15 g). So, the result is 31.8 Gt of CO2, which is very close to recent estimates for global emissions. It is more common to see the emissions expressed as Gt of just C, not CO2, and we can easily convert the above by multiplying it by the atomic weight of carbon divided by the molecular weight of CO2, as follows: And remember that this is the annual rate of emission. Let’s quickly review what went into this calculation. We started with the annual global energy consumption at the present, which we can think of as being the product of the global population times the per capita energy consumption. Then we calculated the amount of CO2 emitted per MJ of energy, based on different fractions of coal, oil, gas, and non-fossil energy sources this is the emissions rate. — Multiplying the emissions rate times the total energy consumed then gives us the global emissions of either CO2 or just C. We now see what is required to create an emissions scenario: A projection of global population A projection of the per capita energy demand A projection of the fractions of our energy provided by different sources Emissions rates for the various energy sources In this list, the three are variables the 4th is just a matter of chemistry. — So, the first three constitute the three principal controls on carbon emissions. Here is a diagram of a simple model that will allow us to set up emissions scenarios for the future:
Plugging in the numbers, we get: What is the total amount of CO2 emitted? We want the answer to be in Gigatons — that’s a billion tons, and in the metric system, one ton is 1000 kg (1e6 g or 106 g), which means that 1Gt = 1015 g (1e15 g). So, the result is 31.8 Gt of CO2, which is very close to recent estimates for global emissions. It is more common to see the emissions expressed as Gt of just C, not CO2, and we can easily convert the above by multiplying it by the atomic weight of carbon divided by the molecular weight of CO2, as follows: And remember that this is the annual rate of emission. Let’s quickly review what went into this calculation. We started with the annual global energy consumption at the present, which we can think of as being the product of the global population times the per capita energy consumption. Then we calculated the amount of CO2 emitted per MJ of energy, based on different fractions of coal, oil, gas, and non-fossil energy sources — this is the emissions rate. Multiplying the emissions rate times the total energy consumed then gives us the global emissions of either CO2 or just C. We now see what is required to create an emissions scenario: A projection of global population A projection of the per capita energy demand A projection of the fractions of our energy provided by different sources Emissions rates for the various energy sources In this list, the three are variables — the 4th is just a matter of chemistry. So, the first three constitute the three principal controls on carbon emissions. Here is a diagram of a simple model that will allow us to set up emissions scenarios for the future:
Earth104Mod8_SA_ws.docx