Will Happer

Will Happer is another, highly-respected physicist out of Princeton who compares the anti-CO2 crowd to the prohibitionists prior to the passage of the 18th Amendment. While he does acknowledge long-term warming, he thinks the influence of CO2 is vastly overstated, and that the benefits of a modest reduction in it will be negligible.

In testimony to Congress, he used the following analogy what he means:

The earth's climate really is strongly affected by the greenhouse effect, although the physics is not the same as that which makes real, glassed-in greenhouses work. Without greenhouse warming, the earth would be much too cold to sustain its current abundance of life. However, at least 90% of greenhouse warming is due to water vapor and clouds. Carbon dioxide is a bit player. There is little argument in the scientific community that a direct effect of doubling the CO2 concentration will be a small increase of the earth's temperature -- on the order of one degree. Additional increments of CO2 will cause relatively less direct warming because we already have so much CO2 in the atmosphere that it has blocked most of the infrared radiation that it can. It is like putting an additional ski hat on your head when you already have a nice warm one below it, but your are only wearing a windbreaker. To really get warmer, you need to add a warmer jacket. The IPCC thinks that this extra jacket is water vapor and clouds.