CO2, Blankets, The Surface of the Earth and Pet Peeves
April 20, 2010Posted by on
This is something that has bugged me repeatedly and is something of a pet peeve: People keep mistaking the the air above the surface of the Earth as the surface of the Earth and sorry folks but CO2 can not cause the surface of the Earth to get warmer. Even some pretty bright people keep making that mistake and they keep overlooking the basics of thermodynamics, I have even gotten into this with people with physics degrees and every time they pull out equations that show the air above the surface will rise but those equations do not show the surface temp to rise.
Now for the context all this. People like to use a blanket as an analogy for the atmosphere to explain how the atmosphere and CO2 works. However I myself do not like that analogy for this reason: the atmosphere is not a blanket. When was the last time you had a 10 mph blanket current or a thunderstorm in it. Both of those atmospheric phenomena cause energy to be transferred from one place to another. Notice I said energy not heat and for a very good reason while hat is a form of energy not all energy in the atmosphere is in the form of heat, and example of this is the phenomena of lightning. However we will use the blanket analogy since it will show that the idea of a blanket can “warm” and object underneath it is false.
First my background, when I started out in the US Navy I was in their Nuclear Power Program and graduated from the Nuke Power School. Now the first thing you need to know about nuclear power, besides how fission works, is that the whole thing is based on thermodynamics and anyone trained in that program has a very firm grasp on that subject.
You will need a few items if you want to actually run the test instead of a thought experiment. Those items are:
- A good sized rock, preferably round but not necessary. You should try to get one about the size of your fist. (Our stand in earth)
- A small blow dryer. (Our artificial sun)
- 2 towels to wrap the rock in (they act as the “blanket” atmosphere with CO2 in it)
- A thermometer that is fast reading. Something that can read temps from a distance (FLIR) would be best.
- A timepiece such as a wrist watch.
That is it for materials required, now onto the experiment.
To start measure the temperature of the room you are in and take note of that. Then heat the rock up with the blow dryer until the rock reads 90° F (well above any temperature controlled room). Let the rock sit for 2 mins and then read the temperature. Take note of that temperature and all the others for comparison at at the end of the experiment. Wait 2 more minutes and read the temperature again and keep repeating until the rock reaches room temperature. This would correspond to what would happen to the earth if it had no atmosphere and after the sun sets, and this is also our control for the next step in the experiment.
Reheat the rock back up to 90°F but this time wrap one of the towels around it then repeat what you did before, reading the temperature every two minutes.
Now here is where we answer the question does back radiation from CO2 “warm” the surface of the earth. After 2 minutes after wrapping that rock up there is only three possible outcomes:
- The temperature went above 90°F thus warming it (this is the position that everyone that says back radiation from CO2 “warms” the surface is saying technically)
- The temperature stayed at 90°F showing neither warming or cooling
- The temperature went below 90° F thus the rock cooled.
Now most of us don’t need to actually run the experiment to know the temperature of the rock went down after 2 mins once it was no longer being warmed by the blow dryer. Now what you will notice is that it takes longer for the rock to reach room temperature. Now the question is what happens if I increase our blanket by adding a second towel. This would correspond to a doubling of CO2 in the atmosphere. If you actually run the experiment and you wrapped that rock in two towels you will discover two things.
- The temperature of the rock still goes down.
- Just because you doubled the thickness of the blanket it doesn’t take twice as long for the rock to reach room temperature.
So in conclusion what you find is that a blanket can not “warm” anything, it can only slow down the rate at which something loses its heat and it works the same for CO2. The reason for that goes back to basic thermodynamics: You can’t raise temperature of something without “work” (For those that don’t know “work” is an actual scientific term) and in this case that means adding energy/heat. The work supplied for all the energy/heat in the experiment came from our artificial sun the blow dryer, and you can not get a higher temperature then what it puts into this. Now the actual surface of the earth is a little more complicated. You see besides the work supplied by the sun, it also gets some from the core of the earth, so it also has two sources of energy to raise the temperature. Another difference is that unlike our simple experiment the Sun unlike the blow dryer is always, 24/7 365, putting energy into the earth’s system. Just because it is night where you are, it is daylight somewhere else and sun is raising temperatures there. Now we all know what happens with hot and cold air, Cold air sinks and hot rises and so it also works in the atmosphere. That is where air currents come into play, you can have an air current pulling heat out of an area where the sun is shining and transporting it to an area where the sun has set. The same principal for Thunderstorms, moving and transporting heat/energy.
However when we get back to the concept that CO2 is acting like a blanket and warming the surface of the earth, we have shown that it is false. CO2 is just slowing down heat loss from the surface of the earth, it is not warming it itself since the energy that CO2 “captured” and turns into heat is nothing more then the energy that the Sun and the earths core have put into the system, thus it can never make the surface warmer then those two heat/energy sources cause.
Keep this in mind the air, even one micron above the dirt, is not and has never been the surface of the earth. It’s just the bottom layer of the so called blanket.