The role of methane in global warming: where might mitigation strategies be focused?

Anthropogenic sources of methane emissions are thought to be nearly twice as high as emissions from natural sources. As the second most important anthropogenic greenhouse gas after carbon dioxide, methane ought to be addressed by policy makers when they consider reductions of national greenhouse-gas inventories. This article first comprehensively reviews source and sink estimates of methane by natural and anthropogenic sectors (wetlands, wet-paddy rice farming, livestock farming, biomass burning, landfills, coal mining, and venting of natural gas or natural-gas pipeline leaks), then proceeds to suggest where different mitigation strategies might be applied. The final section considers how the scenario of a warmer planet may affect the methane biogeochemical cycle. (C) 1999 Elsevier Science Ltd. All rights reserved.