Roy Spencer makes a new try to explain the “greenhouse effect” to the people in More Musings from the Greenhouse by recalling the “blanket theory”:
- If you are lying in bed and are too cold, you can turn up the electric blanket (increase energy gain), or add a regular blanket (decrease the rate of energy loss). If you add even more blankets, you will gradually make the temperature under the blankets higher…but at the same time you make the temperature of the outer blankets colder.
But is this true? Does Roy Spencer describe a correct “blanket theory”?
Will increasing the blanket effect by doubling the CO2 cause warming of the Earth surface and cooling at the top of the atmosphere radiating to outer space?
To seek an answer consider a house being heated inside with a certain given heat source, and consider the effect of increasing the insulation of the walls of the house, that is decreasing the heat transfer coefficient of the wall. Heat balance can be expressed as
where is the inside temperature, the outside temperature of the wall and is the constant heat source.
We see that the outside temperature is determined by the heat source assuming the outside radiates according to Stefan-Boltzmann to a surrounding at 0 K.
We see that the temperature gradient , and thus the inside temperature , increases with better insulation with decreasing . But we do not see the outside temperature decreasing under better insulation. The flowers outside the house will continue to bloom as before, unless is decreased.
The same conclusion is reached in A Skeptic’s Guide to the Greenhouse Effect.
This little exercise illustrates that the “greenhouse effect” is not well described in climate science nor well understood by climate scientists, yet is supposed to require fundamental changes of human conditions.
PS No response from Roy on my comment and questions.
- It seems your objection is to the existence of any IR radiation flowing from cooler bodies to warmer bodies as part of the radiative transfer process. Without studying the issue more, I cannot think of an immediately obvious way to prove you are wrong.
- But the net effect on radiative transfer might be the same whether you use the concept of back radiation or not…in the usual calculation of radiative flux divergence of radiation in an atmospheric layer, there are radiative fluxes being absorbed by the layer from layers on either side, and there is flux being emitted by the layer. The sum of these is the *net* flux divergence, which you claim is in reality the only flux which is occurring. This is my understanding of your position.
- If you want to think of it that way, then I cannot immediately think of an example which proves you are wrong.
- But all we are discussing here are the details of the mechanism by which IR energy flows from a warmer body to a cooler body. It does not change the fact that making the cooler body a little warmer will then reduce the rate of IR emission from the warmer body to the cooler body, which through conservation of energy means it will change the temperature of the warmer body. One does not necessarily need to invoke “back radiation” to achieve that effect.
- Since you admit that the presence of an atmosphere reduces the rate of IR emission from the surface to outer space, then you implicitly admit that something like the “greenhouse effect” does exist, at least in terms of its influence on surface temperature. You are just disputing the details of the mechanism usually used to explain the process. Am I correct?
How could I possibly object to the statement that something like the “greenhouse effect” does exist? Are we talking science or not?
Can I deny that “something like “creation” does exist”? If not, am I then a creationist?