Consider the following questions:
The equilibrium sensitivity of the climate to a doubling of CO_2 ,denoted ΔT_2X is a critical uncertain parameter in the climate change problem.
1a). Briefly explain the procedure by which ΔT_2X is normally calculated.
1b). State and explain briefly three major physical (abiotic) feedback processes that affect the value of the equilibrium sensitivity to CO_2 doubling ΔT_2X.
You should also Briefly explain, in GENERAL TERMS ONLY, why such feedbacks affect the value of ΔT_2X.
1c). For a given increase in CO_2 concentration the predicted temperature increase at a given point in time (2100 say) will not depend solely on the equilibrium climate sensitivity. What additional process or processes are involved and how do they affect the atmospheric temperature.
1d). If the pre industrial atmosphere contained 560 giga-tonnnes of carbon (GtC) then according to the global warming potential value used by the IPCC, what mass of methane would be required to give a radiative forcing equivalent to a doubling of atmospheric CO_2 ; ignoring any complicating feedback? Give your answer to two significant figures.
Note. When answering this question could you please set out calculations clearly explaining what you are doing in each step....I really need to understand how to do this.