Methane has been a major contributor to the enhanced greenhouse effect during the 1980s, second only to carbon dioxide. Because of uncertainties about the sources and sinks of methane, policy discussions focus on more manageable substances like carbon dioxide and CFCs. In this paper it is argued that international response with respect to methane does not have to wait until the uncertainties are resolved or carbon dioxide controls have been negotiated.
Methane has a short lifetime relative to most other greenhouse gases. Model calculations with the Integrated Model to Assess the Greenhouse Effect (IMAGE) indicate that a 10% reduction of current methane emissions combined with a stabilization of carbon monoxide emissions by 2025 would probably stabilize atmospheric methane concentrations at present-day levels. A stricter carbon monoxide reduction by 50% would even permit the emissions of methane to increase by about 6% to stabilize atmospheric concentrations.
Controls of CFCs, HCFCs and nitrogen oxides have an adverse effect on methane concentrations, making necessary additional reductions of methane emissions. But even if these controls materialized a considerable slowing down of the present rate of increase around the turn of the century would be possible. Through improved management techniques such controls are considered to be a realistic option in the not too distant future. This offers a unique opportunity to show globally that effective control of greenhouse gases is indeed possible. If temperature feedbacks on methane emissions from natural wetlands, rice paddies and methane hydrates do materialize, the reductions would have to be larger, but not as large as the reductions required to stabilize the atmospheric concentrations of longer-lived greenhouse gases.
A protocol on methane as part of a global climate convention should focus on technology transfer and increased research opportunities especially in developing countries.