Indirect Global Radiative Effects from Anthropogenic Emissions of Trace-Gases
Oliver Wild
Frontier Research System for Global Change (FRSGC)
Anthropogenic emissions of short-lived, chemically reactive gases, such as NOx and CO, are known to influence climate by altering the chemistry of the global troposphere and thereby the abundance of the greenhouse gases O3, CH4 and the HFCs. This study uses the characteristics of the natural modes of the tropospheric chemical system to decompose the greenhouse effect of NOx and CO emissions into (i) short-lived modes involving predominantly tropospheric O3 and (ii) the long-lived mode involving a global coupled CH4-CO-O3 perturbation. Combining these two classes of greenhouse perturbations - large, short-lived, regional O3 increases and smaller, long-lived, global decreases in CH4 and O3 - we find that most types of anthropogenic NOx emissions lead to a negative radiative forcing and an overall cooling of the earth.
This abstract is taken from the paper I submitted to Geophysical Research Letters at the end of October; I'll fax you a copy of the paper on Monday morning. In my presentation for the symposium I will expand the topic a little to provide some more background, but this should give you and/or interpreters/translators some useful information to work with.
I'd anticipate covering the following topics:
(1) The role/importance of atmospheric chemistry in global change
- Basic summary of impacts of atmospheric constituents on warming/cooling
(2) The significant impact that mankind has on atmospheric composition
- Anthropogenic contributions to atmospheric O3, NOx, etc
- This will be brief, based on work submitted to JGR in October
(3) Indirect warming/cooling effects of trace gases of anthropogenic origin
- Introduction to indirect radiative effects (how radiatively-inactive species like NOx, CO and NMHCs may contribute to global warming)
- Why these may be important (they're still largely ignored by IPCC)
- This is based on the paper submitted to GRL
