Interviewer: So Michael, why did you write the last four articles (1,2,3,4) on the transmission of infrared radiation through the atmosphere: that stuff is already well known?
Me: I know, but I was irritated by a friend of a friend who wrote an “exposé” of why carbon dioxide can’t cause global warming.
Interviewer: Curious. Were they an expert in Climate Science? Or had they made a study of radiative transfer through the atmosphere?
Me: Neither. I think they were an electrical engineer.
Interviewer: An electrical engineer? Why did they think that their assessment outweighed the view of the large number of experts who had studied this intensively over the last century or so?
Me: I think it is an example of the Dunning-Kruger effect in which people who don’t know about a subject fail to appreciate how little they know. We are all affected by it at times.
Interviewer: OK, So you wrote all this just to set them straight?
Me: Yes, and hopefully to help others who are curious about radiative transfer. It is complicated.
Interviewer: And how do you feel about it now?
Me: Numb and Tired. But OK. I like one or two of the graphs I have created, and I enjoyed learning how to make animated GIFs. I have also learned quite a bit about MODTRAN.
Interviewer: But…
Me: But the articles took literally weeks to prepare and I still don’t feel satisfied with them. However now, if I see anyone else write stuff like this:
The bottom line is that once Carbon Dioxide reaches a concentration that makes the atmosphere completely opaque in the band where it resonates, further increases in the concentration cannot result in any additional blocking
I will know exactly where to send them. And so will you.
Protons for Breakfast 
January 3, 2017 at 9:37 am |
[…] sense of science « 3. Light transmission through the atmosphere 5.What was all that about? […]
January 3, 2017 at 11:56 am |
Could the Dunning-Kruger effect be a significant cause of anxiety in the competent, and the more competent the person the more anxious they get because of their under-perception of their own competence?
January 3, 2017 at 12:00 pm |
Good point. Perhaps it is a direct corollary: the Hui-de Podesta effect?
January 3, 2017 at 12:53 pm |
Seriously, it’s a great series of posts, almost like spending evenings in the NPL lecture theatre, just without the demos. Scott Adams (Dilbert) has an interesting series of comments on this stuff, from his viewpoint as a hypnotist / cartoonist who correctly predicted the Trump win on the basis of Trump’s persuasiveness. He says there’s a problem when scientists use facts and predictive models to persuade people:
“Climate scientists might be right that CO2 will cause catastrophic warming. And fear is a great persuader. But this particular fear is a bit abstract. It isn’t like a nuclear bomb that can kill us all instantly. Climate worries are in the unpredictable future and won’t affect everyone the same way. Persuasion-wise, the climate scientists only have facts and prediction models to make their case. And what are the weakest forms of persuasion known to humankind?
Facts and prediction models.
And how are climate scientists trying to solve this problem? Mostly by providing more facts and more prediction models. And by demonizing the critics. The net effect of all that is to systematically reduce their own credibility over time, even if they are right about everything.
I think you see the problem.”
Part of Scott’s Modus Operandi is to be the most annoying devil’s advocate that he can be. But the general point he raises is still valid. We as scientists are used to trying to admit we are wrong when we’re wrong, and also to use evidence to form our views. Scott points out that non-scientists don’t work this way. This doesn’t matter if you’re trying to measure the accuracy of your thermometer- it doesn’t have immediate effect on the public, but it does matter very much when you’re trying to persuade a planet to act on the facts that you present. I have no advice on this- as a scientist I don’t know how to think like a non-scientist.
http://blog.dilbert.com/
March 9, 2017 at 10:51 pm |
I appreciate your blog technique of asking oneself questions However, I was always taught to suspect my sanity when I started answering them myself. 🙂
December 24, 2023 at 3:31 pm |
Thanks for these articles. One question that is bothering me: As I understand it, the reradiation of the sun’s energy from the earth is itself primarily in the infrared band. If that radiation upward has a natural bandwidth then the fact that the bandwidth of the blocked band in the atmosphere grows with the concentration of CO2 would become irrelevant once the blocked band in the atmosphere becomes wide relative to the natural bandwidth of the reradiation from the earth. What am I missing?
December 24, 2023 at 4:15 pm |
Larry, Good Afternoon,
And well done for reading the articles: they are a tough read! I don’t think you are missing anything. But here are a couple of thoughts to place this in context.
In the last 1 million years or so, Earth’s climate has been delicately poised. Tiny changes in the length of summer near the snowline have been sufficient to drive Earth into and out-of ice ages. The transitions into and out-of ice ages proceed quite differently, but they are caused by a cascade of self-reinforcing events.
So, for example, slightly longer summers near the snowline (where snow remains on the ground all year) melt the snow and push the snowline polewards. This decreases albedo which causes warming and release of methane and CO2 from warmed land and seas which reinforces the warming trend.
Similarly, slightly shorter summers near the snowline let the snow lie over summer and push snowline towards the Equator. This extra snow increases albedo which causes cooling and reduces atmospheric CO2, which reinforces the cooling trend.
These two processes are delicately balanced and there does not appear to be a stable point. But over this million year period, CO2 concentrations have only varied in a narrow band – between about 180 ppm and 300 ppm.
Currently we are in new territory, where the initial driving force for the climate change is CO2 itself, rather than CO2 acting as part of a feedback system.
And part of this feedback process is the way atmospheric transmission varies with CO2 concentration. If were to allow CO2 concentrations to rise so high that the Earth warmed so much that we were shifted out of our local stable climate minimum, then all bets would off. I don’t think anyone really knows what would happen as ice melted, methane was released, and a cascade of uncontrolled processes followed.
If we are lucky, then we will not have pushed ourselves out of the feedback minimum in which we have lived for the last million years or so. In such an extreme case – the case you are describing where blocking of infrared radiation reached extreme values – there would be so many new things happening, the change in bandwidth would probably be just one of many significant processes.
Does that make sense?
In any case: best wishes!
M
December 24, 2023 at 4:56 pm
Michael, thanks for your speedy response. I am inferring that the width of the spectrum of the reradiation from the earth up to the atmosphere is currently much wider than the width of the spectrum being blocked in the atmosphere. That would mean that further increases in CO2 density would in fact substantively increase the amount of light from the earth being blocked in the atmosphere. What are these bandwidths currently? Of course that could depend on whether the reradiation was from land, sea, or ice, I would suppose.
December 24, 2023 at 5:03 pm
Larry, the usual approximation is to treat the Earth as a blackbody emitter with a temperature of 15 °C i.e. 273 + 15 = 288 K.
You can see what this looks like using a calculator such as this one.
It’s obviously much broader than the CO2 blocking bands. To block the entire spectrum would require Venusian levels of CO2.
All the best
M