Climate change and energy policy - The impacts and implications of aerosols

Anthropogenic increases in aerosol concentrations are believed to significantly affect climate, notably by exerting a negative radiative forcing which counteracts, to some extent, the positive radiative forcing of greenhouse gases (GHGs). The potential effects of aerosols and their short atmospheric lifetimes raise issues which are critical to climate policy This paper isolates the implications of aerosols by treating aerosol emissions as a policy variable separate from GHG emissions, but Linked through energy policy, Using a simple climate model, results show that with no GHG abatement, changes in aerosol emissions can significantly affect net radiative forcing, but that the positive forcing of GHGs continues to dominate, Aerosols are also shown to reduce the difference in net radiative forcing between abatement and 'business-as-usual' policies, while the ability to reduce this effect through aerosol emissions from energy policy is limited, However, the conclusion that aerosols are beneficial to climate because they counteract greenhouse warming is then questioned; scenarios with high aerosol and GHG emissions are expected to yield both greater uncertainty in mean temperature and a greater likelihood of changes in other climate parameters. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.