Wednesday, October 04, 2006
We Have Been Sold a Bill of Goods on Global Warming
The overwhelming constituent of our atmosphere is nitrogen, which does not trap heat. Neither does the second most plentiful atmospheric gas, oxygen. Nitrogen is 78% and oxygen is 21% of the atmosphere. The rest is made up of the trace gases, so called because, if you do the difficult math, nitrogen and oxygen make up 99% of the atmosphere. All the other gases in the atmosphere is just 1% So you see how little of the atmosphere consists of greenhouse gases, which are only part of that 1%.
There are four significant greenhouse gases in our atmosphere and we are glad to have them because it is very cold in space [Doug Sundseth says it's vacuum, neither hot nor cold, and he's probably right]. Some are better at trapping heat than others but they exist in different concentrations so the effect, the heat trapping effect, is a combination of inherent ability and concentration. Water vapor, that is, mists and clouds, has the biggest effect even though it's not that efficient at trapping heat. There's a lot of it in the air.
Water vapor in fact traps 95% of the heat that is trapped by gas in the atmosphere. CO2 is next with 3.618%; nitrous oxide does .950%; methane does .360% and all the other heat trapping gases together do .072%. See what I mean about overwhelming?
And nearly all the water vapor in the air, 99.99% to be precise, is naturally occurring and would be up there even if there were no humans on Earth. Only .01% comes from man. Nothing.
Likewise most CO2 is naturally occurring--all the animals breathing out, all the plants rotting, venting from volcanoes and natural fires, together that makes up 96.775% of the CO2 in the air. Man-made CO2 is only 3.225% of the total. The same, roughly, goes for nitrous oxide, but we humans are producers of just over 18% of the world's methane. But if you add up the contribution to keeping us warm here on Earth to just the man-made greenhouse gases, it comes to a whopping .28%. Next to nothing.
Put it another way, of any 10,000 units of atmospheric heating caused by greenhouse gases, 9,972 are natural and 28 are caused by men. All the dire warning studies leave out the effect of clouds and mists and say we're causing a significant part of the warming (5.53%) but it's a crock.
I'm no longer caring about global warming because it's nothing we did. And there's nothing we need to do to stop it, assuming we could. Our driving our big, selfish SUVs causes but a tiny piece of a tiny piece of a tiny piece of a tiny piece, regressing nearly to nothing. Case closed.
Although the math is convincing, I am not so sure about the science.
Meanwhile, back to yesterday: Leon Trotsky first pplied the term "fellow traveler" to non communists who were inclined toward the views of the Communist Party. He used the Russian word "poputchik." The term "fellow traveler" in this sense came later in the New York publication "Nation" in 1936:
"The new phenomenon is the fellow-traveler. the term has a Russian background and means someone who does not accept al your aims but has enough in common with you to accompany you in a comradely fashion part of the way. In this campaign both Mr. Landon and Mr. Roosevelt have acquired fellow travelers."
"...it is very cold in space."
This is a common statement, but it doesn't really mean much. Temperature is a function of the mean kinetic energy of the molecules in the area. When there are nearly no molecules, as is the case in near vaccuum, the temperature is pretty meaningless.
In fact, the primary thermodynamic feature of "space" is that it is a remarkably good insulator. A spaceship is nearly indistinguishable from a Dewar flask. (The most commonly known tradename of Dewar flasks sold in the US is Thermos.) Hot stuff stays hot and cold stuff stays cold. And if you produce heat, you need to figure out how you are going to to dispose of it. (The International Space Station uses at least a couple of big thermal radiators to dissipate heat, for instance.)
As far as the meat of your post, perhaps it would be worthwhile to take a high-level look at thermodynamic equilibrium. A system is in equilibrium when its inputs and outputs are balanced. If inputs rise or outputs fall, the equilibrium temperature will rise until they are again equal. Conversely, if inputs fall or outputs rise, the equilibrium temperature will fall.
So, to understand how a system equilibrates, we need to take a look at both the input and output sides of the equation.
Heating depends on the amount of energy absorbed, which is a function of the reflectivity of the body (albedo) and the energy flux. You can increase heating by raising the energy flux (solar output) or by reducing the reflectivity.
Reduced reflectivity is a significant part of the reason for urban heat islands (warmer air near cities). Macadam (blacktop) and tar roofs dramatically reduce reflectivity and thus increase heat retention.
From the available evidence, solar output has increased in the last few years. We've observed things that indicate heating of other planets in the solar system, such as reduction of the sizes of the polar caps on Mars.
On the output side, cooling is a function of the temperature of the body and its reflectivity in the frequencies emitted by the body. Radiation of a black body is proportional to the fourth power of the absolute temperature (Kelvin or Rankine scales), so as the temperature rises, radiation rises very rapidly. But it's inversely proportional to reflectivity in the infrared.
Greenhouse gases are nearly transparent in visual frequencies, so they let photons from the sun through pretty easily, but more reflective in infrared frequencies, so the lower-energy heat photons don't escape as easily as they would in the absence of greenhouse gases.
For a practical example of the effect of greenhouse gases, compare the changes between daytime high temperatures and nighttime low temperatures in a wet area like New Orleans (for instance) and a dry area like Phoenix. New Orleans has an 8-9 degree (C) difference between average daytime high and average nighttime low, depending on the time of the year. For Phoenix, the number is 14-17 degrees (C). The atmospheric water vapor reduces cooling. (Note that the two cities are at about the same latitude, and Phoenix is only a bit higher in altitude.)
Roger is absolutely correct that the dominant greenhouse gas is water vapor, but water vapor has an interesting property: As the atmospheric concentration increases, the probability of water droplets forming increases. (Those would be clouds.) Clouds are still pretty good at reflecting IR back to the surface, but they're darn good at reflecting visible light back into space, too. So rather than just playing with the output side of the equation, they also change the input side.
The anthropogenic greenhouse gas warming theories that I've seen rely on CO2 forcing an increase in atmospheric H2O. It's not clear that they account adequately for the reduction in energy inputs attendant upon such an increase.
Upshot: Warming may be caused by an increase on the input side or by a decrease on the output side of the equation. It seems likely that we have an increase on the input side, and it's not clear whether there's a significant decrease on the output side. It's also not clear what, if anything we can or should do about either side of the equation.
Doug, I think your discussion is mostly valid, but I must take issue with the following:
"From the available evidence, solar output has increased in the last few years."
Actually, we have recently been in a solar minimum portion of the 11 year cycle. Also, here's my previous post on the warming of other planets.