As a person with a physics degree from MIT, I am often surprised at how one can be challenged by a seemingly well-known theory with a new phrasing of a question. This happened for me with Cockburn's claim that there is no atmospheric greenhouse effect at all.
I read the relevant portion of the article he referenced, "Falsification of the Atmospheric CO2 Greenhouse Effects Within the Frame of Physics," by Gerhard Gerlich and Ralf D. Tscheuschner. They point out that it is only fairly low-frequency radio waves that are reflected (actually refracted) by the atmosphere. As a young shortwave radio enthusiast, I am aware of this. So how is it that infrared radiation could be reflected or refracted to create a greenhouse effect?
I was puzzled for many minutes, feeling quite foolish. Had the whole world of science been wrong about this? What was being missed?
Then I remembered: it is not the same effect on infrared radiation that happens for radio waves. For infrared radiation and light, it is all about particular molecules in the atmosphere absorbing different wavelengths very selectively. Gerlich and Tscheuschner seem to have missed this completely.
Here is how the greenhouse effect works. The atmosphere is mostly transparent to visible light. The visible light from the sun hits the Earth and heats up the ground. Some of this heat heads back up toward the sky as infrared light.
But certain molecules in the atmosphere are not transparent to infrared. In particular, water and CO2. They do not allow all of the infrared to escape to space. Yes, some energy does escape to space. But some stays in the atmosphere, heating it up.
It is this heating that makes the Earth warmer than it would be if there were no such absorption of infrared. It is like a blanket over the Earth for infrared.
If Cockburn does not believe there is an atmospheric greenhouse effect at all, it is no wonder he does not believe that the effect is being altered. It would be helpful if he read up on how the effect is real.
This one graph is a good start. Understand that visible light is down around one micron and infrared is everything else on the right of the graph. See the absorption dips due to CO2.