Stabilizing Atmospheric Concentrations: Towards International Methane Control.

摘要

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 the report 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 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 strengthened. A considerable slowing down of the present rate of increase (0.9%) around the turn of the century would be possible.