Question
CFC-11 and CFC-12 are very potent greenhouse gases. Suppose the emission of 1 Tg of CFC-11 causes a 1.0 W m-2 instantaneous perturbation in the radiation budget. The emission of the 1 Tg of CFC-12 causes a 1.5 W m-2 radiative forcing.
The 100 year global warming potential for CFC-11 is estimated to be 4750. Global warming potential is a measure of how much energy would be trapped by the emission of one molecule of a given gas over a specified time period, in this case 100 years, relative to CO2. Global warming potential depends on both the atmospheric lifetime of a gas, as well as its ability to absorb infra-red radiation.
Use the information on the lifetimes and relative radiative forcing strengths of CFC-11 and CFC-12, as well as the global warming potential of CFC-11 to estimate the global warming potential of CFC-12. You may assume that the radiative forcing of each species is simply proportional to its concentration.
Hint: Use the model from part (a) to calculate the total energy absorbed by the instantaneous injection of 1 Tg of each CFC into the atmosphere over 100 years. The ratio of these two energies is the ratio of the global warming potentials.
The 100 year global warming potential for CFC-11 is estimated to be 4750. Global warming potential is a measure of how much energy would be trapped by the emission of one molecule of a given gas over a specified time period, in this case 100 years, relative to CO2. Global warming potential depends on both the atmospheric lifetime of a gas, as well as its ability to absorb infra-red radiation.
Use the information on the lifetimes and relative radiative forcing strengths of CFC-11 and CFC-12, as well as the global warming potential of CFC-11 to estimate the global warming potential of CFC-12. You may assume that the radiative forcing of each species is simply proportional to its concentration.
Hint: Use the model from part (a) to calculate the total energy absorbed by the instantaneous injection of 1 Tg of each CFC into the atmosphere over 100 years. The ratio of these two energies is the ratio of the global warming potentials.
Answers
Bane Havoc
Model from Part (a) is
dC/dt = E - (C/tau)
C - concentration of the gas [Tg]
E - emission rate [Tg/yr]
t - time [yr]
tau - represents the lifetime of the gas in the atmosphere, before it is removed, either by chemical reactions or deposition to the surface [yr]
dC/dt = E - (C/tau)
C - concentration of the gas [Tg]
E - emission rate [Tg/yr]
t - time [yr]
tau - represents the lifetime of the gas in the atmosphere, before it is removed, either by chemical reactions or deposition to the surface [yr]