Challenges in isotope measurement of atmospheric methane for better understanding of the global methane budget

Abstract

Many studies addressed the global cycle of methane, an important greenhouse gas. Yet variations of atmospheric methane concentration over the last 40 years have not been well explained. Synthesis analysis, which combines both bottom-up and top-down methodologies, is the current activity of the international research community. Measurements of isotope ratios of atmospheric methane have been made for the last decades. However, the research background has changed dramatically due to advances such as increasing number of data aided by progress of measurement techniques, more detailed survey of isotope signatures of various methane sources, and the aforementioned synthesis analyses. This presentation will cover the current understanding of the global methane budget and challenges in isotope measurement.