Fate of products of degradation processes: Consequences for climatic change

The end products of atmospheric degradation are not only CO2 and H2O but al so sulfate and nitrate depending on the chemical composition of the substan ces which are subject to degradation processes. Atmospheric degradation has thus a direct influence an the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diame ter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently le ading to a radiative forcing which is estimated to be about -0.8 watt per m (2) by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and sm aller droplets and these clouds have a higher albedo and are more stable co mpared to clouds with larger droplets. Not only sulfate, but also nitrate a nd polar organic compounds, formed as intermediates in degradation processe s, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m(-2) and an indirect effe ct of as large as -5 watt m(-2). About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large ra diative forcing is obviously non-uniform and depends on local conditions.