Implications of Variation in Carbon Sources for the Global Warming Potential of Methane

Abstract

Methane is the most important biogenic greenhouse gas (GHG) next to carbon dioxide (CO2) and water vapours. Since industrialization its concentration in atmosphere has grown by 145 per cent over its pre-industrial concentration (Hogan & Harris, 1994; Khalil & Rasmussen, 1994). Paddy fields are one of the major anthropogenic sources of methane emission (Bachelet & Neue, 1993). Methane emission has attributed considerable attention because of its concordance with paddy cultivation in the tropical countries of South and South East Asia. Initial estimates of methane emission from paddy cultivation were made by IPSEP (1989) and IPCC (1990), however, over the years, earlier estimates of the emission have been scaled down substantially (Dixon et al., 1994). Certain crucial demeanors of methane emission in the context of global warming (GW) have bypassed the current debate, including the recent IPCC (1994–95) assessments. The objective of this chapter is to highlight the importance of the nature and the dynamics of methane in relation to carbon source and their implication to global warming potential (GWP) of methane. It also underscores the need to visualize methane emission from rice paddies, natural wetlands and other biogenic sources from ecological and carbon cycling perspective.