Methane fluxes from artificial wetlands: A global appraisal

Methane emissions make an important contribution to the enhanced greenhouse effect, emissions from rice growing being one of its major anthropogenic sources. The estimation of global fluxes of methane from rice and from coarse fiber production depends on extrapolating observed data across countries and agroclimatic zones: the estimates are therefore imprecise. We present a revised estimate of global emissions of 96 Tg CH₄/yr, given 1991 rice areas, and 1991 production data for those tropical coarse fibers that also produce methane under anaerobic conditions. This is higher than many previous studies, which systematically underestimated the fluxes from tropical countries. As the world's population increases, the demand for rice will rise. This demand can only be satisfied through greater rice production, either by bringing new areas into rice growing or by using the present area more intensively. Strategies based on improved water management and fertilizer use will allow increased rice production and yields and reduce the methane flux per unit or rice production.