Physicist Gerald Marsh, who kindly advises The National Center on science issues, has a letter in the December 29 Financial Times:
Sir, While it is becoming increasingly fashionable to maintain that carbon dioxide is a pollutant, it was rather shocking to see the Financial Times buy into what can at best be charitably characterised as a form of "political correctness" ("The price of carbon emissions," December 27).
Carbon dioxide is a minor greenhouse gas that occurs naturally in the atmosphere and helps to maintain the earth at a temperature suitable for life - the principal greenhouse gas is water vapour. Carbon dioxide is essential to the growth of all plants. Without it plants could not grow and all animal life would die. In no way is this gas a pollutant. To call it one is misleading.
Calling carbon dioxide a pollutant is a political statement, not a scientific one. Behind the politics is the claim that the small observed global warming trend is due to the burning of fossil fuels rather than being of natural origin.
Despite popular perception, the 2001 report of the Intergovernmental Panel on Climate Change (IPCC) did not show that human activities were responsible for global warming. Its conclusions were based on computer models of the earth's climate. However, the problem is so complex that the art of constructing such models is still in its infancy. The uncertainties are so great that the claim by the IPCC that "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations" is "likely" to be unfounded. We do not yet understand the earth's climate well enough to be able to assess the long-term effect of the carbon dioxide that comes from burning fossil fuels.
The earth has been warming erratically for 10,000 years. That has been good, up to now, because it is what made the non-equatorial latitudes habitable. We can expect that warming trend to continue, no matter what we do about carbon dioxide.
Gerald E. Marsh, Chicago, IL 60615, US