An emissions-based view of climate forcing by methane and tropospheric ozone
Article first published online: 18 FEB 2005
Copyright 2005 by the American Geophysical Union.
Geophysical Research Letters
Volume 32, Issue 4, February 2005
How to Cite
2005), An emissions-based view of climate forcing by methane and tropospheric ozone, Geophys. Res. Lett., 32, L04803, doi:10.1029/2004GL021900., , , and (
- Issue published online: 18 FEB 2005
- Article first published online: 18 FEB 2005
- Manuscript Accepted: 24 JAN 2005
- Manuscript Revised: 24 DEC 2004
- Manuscript Received: 2 NOV 2004
 We simulate atmospheric composition changes in response to increased methane and tropospheric ozone precursor emissions from the preindustrial to present-day in a coupled chemistry-aerosol-climate model. The global annual average composition response to all emission changes is within 10% of the sum of the responses to individual emissions types, a more policy-relevant quantity. This small non-linearity between emission types permits attribution of past global mean methane and ozone radiative forcings to specific emissions despite the well-known non-linear response to emissions of a single type. The emissions-based view indicates that methane emissions have contributed a forcing of ∼0.8–0.9 W m−2, nearly double the abundance-based value, while the forcing from other ozone precursors has been quite small (∼−0.1 for NOx, ∼0.2 for CO + VOCs).