As you may have noticed from the announcement that appeared for the past week or so on my sidebar, the Soho Forum held a debate Monday night on the issue of Global Warming. The official resolution for the debate was Resolved: There is little or no rigorous evidence that rising concentrations of carbon dioxide are causing dangerous global warming and threatening life on the planet. The debaters were Craig Idso for the affirmative, and Jeffrey Bennett for the negative.

For those who haven’t heard of it, the Soho Forum sponsors debates, roughly monthly, on current policy issues. The venue is usually the Subculture Theater, at 45 Bleecker Street in Manhattan. The Forum’s Director is long-time Barron’s senior editor Gene Epstein; and the Chief Operating Officer is my daughter Jane. Other recent Soho Forum debate topics have included things like the Israeli-Palestinian conflict and the causes of the 2008-09 financial crisis.

Holding a debate on the issue of global warming or “climate change” — and particularly one focused on the scientific question of whether empirical evidence supports or refutes the hypothesis of potential dangerous warming — is often difficult. Contrary to what you might think, the problem is not that it is hard to find scientifically-literate advocates for the skeptic position. Actually, there are plenty of those. Rather, the problem generally is that adherents to the alarmist cause refuse to debate anyone who disagrees with their position, often denigrating their adversaries as “climate deniers.” So Gene Epstein deserves credit for locating Mr. Bennett, and Mr. Bennett also deserves credit for being willing to put his position to the test.

On the other hand, the whole endeavor gave some real perspective on the practical limits of the human mind, or at least the large majority of even very intelligent human minds, to grapple with the basics of scientific reasoning and the scientific method. At its most fundamental, the scientific method is just an exercise in rigorous logic. A hypothesis is formulated. Evidence with respect to the hypothesis is accumulated. And then basic logical rules are applied: adverse evidence refutes the hypothesis; in contrast, evidence consistent with the hypothesis can never definitively prove it, but only leaves it to survive for the next challenge. All hypotheses are always open to the next challenge. The best proof that a hypothesis might be correct — or at least, close to correct, or maybe, better than any other alternative yet formulated — is that multiple attempts to refute it have so far failed. That’s the whole game. It’s not all that complicated, but it’s just not how most people think about things.

For more detail on the background of the debaters, go here for Craig Idso, and here for Jeffrey Bennett. Idso has a Ph.D. in Geology from Arizona State University, and is best known for running the Center for the Study of Carbon Dioxide and Global Change and the CO2 Science website. Bennett has a Ph.D. from the University of Colorado in Astrophysical, Planetary, and Atmospheric Sciences, and has written a book titled Global Warming Primer.

In accordance with what I would think is the scientific method, Idso focused his presentation on multiple examples of empirical data that refute the hypothesis that catastrophic global warming could be caused by human CO2 emissions. Significant points included:

• It was warmer earlier in the current interglacial period, particularly during what is called the Holocene Optimum (about 7000 to 3000 BC), than currently, even though the CO2 concentration of the atmosphere was lower.

• Based on data from the Vostok ice cores, the temperature in each of the four previous interglacial periods, stretching back about 1 million years, reached peaks higher than current temperatures, even though the atmospheric CO2 concentration was lower.

• Again based on data from the Vostok ice cores, during past exits from glacial periods, rising atmospheric concentrations of CO2 have followed, rather than preceded, increases in temperature, thus refuting the hypothesis of causation driven by CO2 concentration.

• In more recent years, the best available (unaltered) data from world thermometers indicate that temperatures declined from approximately the 1940s to the 1970s, even though atmospheric CO2 concentrations were rising during those decades.

You will note that each of these points addresses the core focus of the scientific method: Do the best empirical data contradict and therefore invalidate the hypothesis (here, that rising CO2 concentrations cause dangerous global warming)? So how did Bennett respond?

• In accordance with the scientific method, it ought to have been Bennett’s first priority to give a detailed rebuttal to each of the refutations offered by Idso of the hypothesis under debate. However, Bennett offered no detailed rebuttal to any of those points, and really no rebuttal at all other than general statements, repeated several times in somewhat different words each time, akin to “he has cherrypicked the data” or “the evidence he presents isn’t correct.”

• Instead, Bennett led with the usual theme of supposedly increasing severe weather events. Wildfires! Hurricanes! Droughts! Floods! He presented multiple examples of the disasters, but no aggregate statistics demonstrating that such events had actually increased over time. I would call this an appeal to the emotion of the audience, rather than anything deriving from the scientific method.

• And then, Bennett’s key point: There are “over 50,000 peer reviewed studies” addressing the hypothesis under discussion, and “99.9% of them” are “consistent with” the conclusion of dangerous global warming driven by human CO2 emissions. Bennett never discussed the details of any of the 50,000 papers, making the argument basically an appeal to authority, rather than an application of the scientific method.

Bennett repeated the phrases in quotes (“50,000 peer review studies” and “99.9% consistent”) multiple times. Frankly, I thought the “99.9%” was ridiculous. A site called No Tricks Zone makes a cottage industry of collecting and summarizing papers that publish data contradicting the dangerous climate change hypothesis as reflected in climate models, for example most recently here on April 11. There are many hundreds of such papers — far more than the 50 that would be 0.1% of Bennett’s 50,000. But even suppose that that 99.9% figure was right. Under the scientific method, 49,950 papers “consistent” with the hypothesis would be useless to sustain it if 50 papers based on credible evidence refuted it.

In rebuttal, Idso was ready with a collection of charts and graphs on the question of the extreme weather events. Several of the charts he used are the same charts appearing in the Alarmist Claim Rebuttal document of which Idso is a co-author. Charts he presented showed no increase in hurricanes, no increase in tornadoes, no increase in burned area from wildfires, and so forth.

The debate was in Oxford style format, and at both the beginning and end the audience members voted as to their views of the resolution. Before the debate, the audience was 22% for the affirmative, and 29% for the negative. After the debate, it went to 42% for the affirmative and 41% for the negative. Idso was declared the winner, based on moving the needle 20% in his direction, versus Bennett moving the audience only 12% in his direction.

So, do you think that getting an audience to focus on the science of this subject for an hour and a half will quickly convince them all of the insanity of the catastrophic global warming hypothesis? Unfortunately, that’s just not how this works. And this was a relatively libertarian-leaning audience.

In a week or so a full podcast of the debate will appear on the Soho Forum website.