Roger Pielke Sr 
Friday, Feb 20, 2009
There is a lawsuit to the U.S. Supreme Court on the issue of the regulation of carbon dioxide by the Environmental Protection Agency (EPA). This subject is also introduced on Prometheus today (see ).
A main focus of this lawsuit is whether EPA has the requirement to regulate CO2. This is a political issue and beyond the expertise of the Climate Science weblog.
I summarize below the conclusions from these weblogs of Climate Science on the scientific question as to whether CO2 is a pollutant:
A. From the Climate Science weblog of August 9, 2005 
“The question is: How does atmospheric carbon dioxide fit into this definition? Carbon dioxide does occur naturally, of course, and is essential to life on Earth, as it is an essential chemical component in the photosynthesis process of plants. This is in contrast with other trace gases in the lower atmosphere such carbon monoxide, ozone, and sulfur dioxide which are have direct health and environmental effects on humans and vegetation. Indeed, when combustion is optimized, less carbon monoxide and more carbon dioxide are produced. There are no positive effects that I am aware of at any level of these pollutants in the lower atmosphere.
Thus, it is more informative to define anthropogenic inputs of carbon dioxide as a climate forcing, as was done in the 2005 National Research Council Report. This provides the recognition that carbon dioxide does not have direct health effects as implied by the news article that carbon dioxide “fouls? the air, but it does significantly affect our climate.
Of course, carbon monoxide, ozone and sulfur dioxide are also climate forcings. When these other atmospheric constituents are referred to in news articles and elsewhere, we would benefit by a distinction between an “air pollutant? and a “climate forcing? depending on the context. ”
Full article here