Today, Congresswoman Michelle Bachmann paid a visit to SCSU. She represents (in one way, at least) Minnesota’s Sixth Congressional District, which includes St. Cloud. Her ridiculous and frankly embarrassing statements made time again in public don’t really merit repeating here. Instead, I want to focus mostly on the claims that Chris Horner made today, presenting his case against cap and trade and the scientific consensus on global warming. He was brought along as a speaker by Congresswoman Bachmann, because she was so impressed with his rhetoric that he displayed in Washington a few weeks ago. Congresswoman Bachmann didn’t have much to say, except for some prepared remarks that were brief.

So, who then is Horner? He is an attorney and fellow at the Competitive Enterprise Institute, a conservative think tank. He’s written a few partisan books, talked a lot, etc. There was also Alfred Pekarek, an SCSU assistant professor in the Earth and Atmospheric Sciences department who studies mostly rocks. But he’s an ardent global warming denier who has happened to write some nonsense for the AAPG. (The AAPG, in 2007, became the last major scientific organization to affirm human’s role in global warming, after falling out of line with the scientists who work with them.) Of course, Dr. Pekarek has published no peer-reviewed scientific papers on the subject, but he was mostly there as a figurehead anyway. Horner did all the talking. So what did Horner have to say?

The topic of the discussion was cap and trade, whereby the government sets a cap for carbon emissions and companies are given allowances for polluting so much. If you fall below this limit, you can trade (sell) your allowances to other companies that don’t meet this limit. The idea is that the free market will take over and corporations will stop polluting the air. Quite frankly, I don’t care for cap and trade, and I think it’s a stupid idea. It doesn’t work and so emissions don’t go down. That automatically eliminates it as any solution. This was part of Horner’s argument too, but mostly he was worried about it being anti-competitive, against the consumer, big interests, etc. That’s all well and fine, I don’t care to debate him on that issue since it doesn’t interest me (I’ve already stated it’s not a solution).

However, in what could be called the second part of his presentation, which was nominally called a question-and-answer session, Horner went on about the perceived lies in the global warming debate, though it isn’t much of a debate anymore. Horner really focused on three main things in his drivel, which, by now, has become old, tired, and thoroughly refuted: The IPCC sham, historical temperature record, and the relationship between solar forcing and temperature.

Horner took issue with the claim that the Intergovernmental Panel on Climate Change (IPCC) is made up of over 2,000 scientists who author their authoritative assessment reports. But the IPCC only claims to have 450 lead authors, not over 2,000, and 800 contributing authors. Furthermore, they release four reports (one of which is a synthesis of the other three). Only one deals with the actual physical basis for global warming, which is the Working Group I report. The IPCC claims this report was made by some 600 authors (lead and contributing) and reviewed by over “620 expert reviewers.” In its annex (PDF) they list all of their authors and their reviewers for that report. Wikipedia will actually make it easier for you, as it has a list of the contributors and their roles. Overwhelmingly these contributors come from the field of climatology or atmospheric sciences. That’s certainly a lot more than the Oregon Petition can say. (Never mind that every major national science academy in the world accepts the IPCC’s conclusions as the consensus on global warming.)

One thing Horner could not stop repeating is that in the historical temperature record, temperatures led CO2 emissions. What this means is that the the Earth saw a temperature increase before there was a CO2 increase (so temperature drove CO2 to go up, not the other way around), which Horner then construed to mean that CO2 could not be possibly be causing the current global warming. Well, of course, Horner is dead wrong. It is true that in the historical temperature record going back 600,000 years, CO2 lags behind temperature increases by about 200 to 1,000 years. This is because temperature increases cause increases in CO2, and this CO2 in turn causes a temperature increase (this is called a positive feedback in the technical literature). And we actually have a pretty good understanding of what caused these temperature to go up, which is something called orbital forcings, meaning small changes in the Earth’s orbit (Milankovitch cycles) change how much sunlight hits the planet, one of the reasons for ice ages and glaciations. This increased the CO2 in the atmosphere (by mechanisms I don’t care to go in detail about here), and after a certain period of time the CO2 took over as the main contributor to the temperature increases. (That is, temperature increased for some 5,000 years, only during 800 or so of which temperature led CO2; CO2 caused the other 4,200 years of warming.) That’s what the ice core record shows. So it’s very clear, still, that CO2 is a greenhouse gas that causes temperature to go up. The climate record shows this. But it’s also elementary physics and chemistry. The radiative properties of CO2 have been known for over 100 years. That there was a lag in the historical record in no way contradicts our understanding of how CO2 affects temperature, and it is this understanding that we use to explain the current global warming. For the sake of brevity, this post by RealClimate explains quite well the relationship between human activity and CO2 increases, and how it’s causing current global warming.

Finally, Horner points to the Sun as the main contributor to global warming. He says the Sun’s output matches quite well with variations in temperature. Again, this is flatly incorrect. A 2006 paper published in Nature by Foukal et al. showed that the Sun’s brightness has not increased over the past 1,000 years and that it has, in fact, contributed very little to the current global warming. When you look at recent solar variation, it doesn’t even come close to fitting the temperature record. The most liberal numbers, by Scafetta and West, suggest the Sun has contributed some 45 to 50 percent of the temperature increase between 1900 and 2000, and only 25 to 30 percent between 1980 and 2000. Likewise, the IPCC has found that the Sun slightly contributed to the increase in temperature between 1750 and 1950, but little after that. So when you take the Sun out of the equation, you simply cannot explain current warming.

Horner did address several other points, but this post is already getting quite long. I’d be glad to address them some other time. Suffice it say Horner is way off base with the scientific community, as are Congresswoman Bachmann and Dr. Pekarek. Instead, they wish to politicize the issue so they can propagandize and use all sort of rhetoric to win over gullible partisans. What we should do is focus on the science, and the peer-reviewed published literature is unequivocal on it stance on anthropogenic global warming.

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