English Abstract 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
report it is argued that international response with respect to methane does
not have to wail 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 indicate that a 20% reduction of methane
emissions combined with a stabilization of carbon monoxide emissions by 2025
would probably stabilize methane concentrations at present-day levels. A
stricter carbon monoxide emissions reduction by 35% would even permit the
emissions of methane to increase with 10-15% to stabilize atmospheric
concentrations. Existing controls of ozone and nitrogen oxides would have
to be strenghtened. A sonsiderable slowing down of the present rate of
increase (0,9%) around the turn of the century would be possible. Through
improved management technqiues 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.
