The Augusta Chronicle recently had a guest column entitled "CO2 emissions must drop" (July 27). In this column, the author states, "The scientific community is virtually unanimous in calling for a crash program to reduce emissions of carbon dioxide and methane, the principal greenhouse gases." Apparently the author is only reading reports from the mainstream media, and not from the many scientific papers and journals.

In 1998 Dr. Arthur Robinson, director of the Oregon Institute for Science and Medicine, sent a petition to the U.S. government not to sign the Kyoto Protocol. This petition was signed by 17,000 scientists and engineers. Since that time 31,000 people in several scientific fields have signed this petition. This petition stated: "There is no convincing scientific evidence that human release of carbon dioxide, methane or other greenhouse gases is causing (or will in the foreseeable future cause) catastrophic heating of the earth's atmosphere and disruption of the earth's climate." This is hardly "virtually unanimous opinion."

On Dec. 13, 2007, 100 scientists (the Bali 100) wrote an open letter to the U.N. secretary general, which stated in part: "In stark contrast to the oft repeated assertion that the science of climate change is settled, significant new peer-reviewed research has cast even more doubt on the hypothesis of dangerous human-caused global warming."

The basis for the current concern on carbon dioxide levels is entirely based on computer models. These models are subject to many boundary conditions of unknown or uncertain effect. Slight tweaking of these variables can result in grossly different results.

The greatest greenhouse gas of all is water vapor, and that is not included in the models. Since 1990 more than $50 billion have been spent on "global warming" and $5 billion are being allocated to global warming studies yearly in the United States. Despite this, there is no actual evidence that carbon dioxide causes runaway global warming. Surely this money could be better spent.

Russell Harmon, Aiken, S.C.