A comment by S. Fred Singer

In an email, S. Fred Singer wrote:

I believe a fair statement is that the GH [greenhouse] effect of CO2 etc must exist (after all, CO2 is a GH gas and is increasing) but we cannot detect it in the record of temp patterns.

So we must conclude that its contribution to climate change is swamped by natural changes.

Why do models suggest a much larger effect? Because they all incorporate a positive feedback from WV [water vapor], which in actuality is more likely to be negative. Empirical evidence is beginning to support this explanation.

Some background information about Singer is here and here.

From that first link, which is dated July 18, 2000:

We hold a skeptical view on the climate science that forms the basis of the National Assessment because we see no evidence to back its findings; climate model exercises are NOT evidence. Vice President Al Gore keeps referring to scientific skeptics as a "tiny minority outside the mainstream." This position is hard to maintain when more than 17,000 scientists have signed the Oregon Petition against the Kyoto Protocol because they see "no compelling evidence that humans are causing discernible climate change."
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I hold a degree in engineering from Ohio State and a Ph.D. in physics from Princeton University. For more than 40 years I have researched and published in atmospheric and space physics. I received a Special Commendation from President Eisenhower for the early design of satellites. In 1962, I established the U.S. Weather Satellite Service, served as its first director, and received a Gold Medal award from the Department of Commerce for this contribution.