From time to time, I engage with science deniers on the Web, typically in Comment sections, and primarily regarding aspects of climate science or physics. Some think this to be a waste of time, but, as I enjoy debating (have since high school), and I’m not a scientist who might have something to lose doing this (I’m an engineer and statistician), and I feel it important that it be made plain that not only the arguments some of these people make can be readily countered, they are also bupkis. I do not expect to convince the people in question, but I see the engagement as a kind of online performance art for anyone who might stray across it in their Web travels.
In the case I am writing about today, there was an exchange in the comments section of a post by Solar City, initiated by one, apparently well known character of this kind, going by the handle SuperCorrector1. Now, I do not know that this is actually a real person. It has been thought and rumored that various climate denying organizations have bots which visit Comment sections of energy- or climate-related social media, and, being rule-based, are smart enough to appear to engage various posters with denialist ranges and standard online disruptive techniques. So, for instance, they’ll make a falsifiable assertion about something, and, then, when they are finally challenged to produce an argument that supports their assertion they, typically, engage in an ad hominem attack against someone who responds. Some of these are quite crude. Alternatively, if the bot is smarter or, possibly, if there is a person behind the handle, they’ll grab something which appears relevant from a stock set of claims such as those at WattsUpWithThat or elsewhere, and put it out. Alternatively, and sometimes things from WattsUpWithThat fall into this category, they severely cherry pick data, or articles. I have seen deniers write things and attribute them to famous scientists. (I chased one down to the original scientist who was quite surprised.) If the reader wants to know more about this, John Cook, the operator of Skeptical Science (and not John D Cook, the statisitican and author of one of my favorite blogs, which used to be called Endeavor) runs a course, “Making sense of climate science denial“, which I recommend.
In any case, I’m not sure how the SuperCorrector1 encounter began, but there was an assertion about carbon dioxide and its role in climate disruption through radiative forcing. The science denier claimed CO2 had nothing to do with it, that it was a trace gas, and it had no thermal capacity. Along the way, SuperCorrector1 claimed it was a scientist, although never backed it up, and could not answer the simplest of questions, for instance, having to do with the difference between diatomic and triatomic gaseous molecules, such as the difference between the radiative effects of Nitrogen versus Carbon Dioxide, and why the molecular shape was important. The denier continued to assert that the only aspect which mattered was the relatively small amounts of CO2 in atmosphere, that it was good for plants, and refused to respond on topic when pressed with, well, Oxygen is good for mammals but if atmospheric is sufficiently rich in O2 it is toxic, or the 7 ppmv toxicity of hydrogen cyanide at standard temperature and pressure (“STP”).
In the end, failing to engage in the discussion, SuperCorrector1 claimed I was “making things up”. I asked why couldn’t he be quantitative about his assertions and asked if a reference would serve. I provided one in the form of a quote regarding exactly how potent CO2 is in this regard from the nice textbook by Grant Petty titled A First Course in Atmospheric Radiation (2nd edition, 2006). That’s below:
Despite the diluteness of CO2 in air (about 370 parts per million by volume), the strongest part of the Q branch (Fig. 9.13b) absorbs all but 5% of radiation over just a 1-meter path in air at 1000 mb pressure!
Figure 9.13(b) from the textbook is reproduced below. The exclamation mark is not mine but, really, Petty’s. I’ve provided another figure documenting the same below, from a different source. These are experimentally derived.
The significance of this is that Earth’s natural thermal emission spectrum, given by the chart below, aligns well with this super strong absorption line of CO2. And that’s pretty much the entire story, after a few basic physical principles like blackbody radiation are thrown in, and the realization that this absorption is so strong, what’s involved is a warming of the atmosphere, mostly at low altitudes, cooling of the upper atmosphere, and, therefore, a reduced amount of blackbody emissions to space, which is the only way a planet can cool in the absence of atmosphere. Consequently, radiative forcing and climate disruption, due to excess CO2.
This is also why this blog has a subtitle of 667 per cm.