The Carbon Isotopic Composition of Atmospheric Methane and its Constraint on the Global Methane Budget

Abstract

This chapter develops the context of how the carbon isotopic composition of atmospheric methane can be used to estimate source and sink fluxes. First, it describes the theory behind using atmospheric measurements to constrain surface sources and sinks and then applies this specifically to isotopic ratios in the atmosphere. It then reviews the history of atmospheric δ13C measurements. In the next section it uses these measurements to estimate sources and sinks and examines the sensitivity of the estimates to uncertainties in the present model's parameters. The chapter ends with a brief discussion of how other isotopic species like 14CH4 and CH3D might add to the information contained within the δ13C data.