[N_Fiddledog]

Zipperfish Zipperfish:

I understand that a serious blow was dealt to this theory a year or two ago,

Nope. Didn't happen. There's been critiques. They've been batted away like little insects with the power of the actual science. The theory is still strong. Never been stronger actually. Critique is a good thing though. It shows where to get stronger. Even the sloppy critiques that have been offered up so far.

$1:

I'll admit to a fairly simplistic view of the matter: the concentration of carbon dioxide in the atmosphere is increasing, we are pumping several billion tons of CO2 into the atmosphere every year, and carbon dioxide is a gas that absorbs and emits in the infrared spectrum (a greenhouse gas). Not too surprising then you might see a measurable change in global average temperatures, especially since the temperature rise does not correlate well wiht solar irraidance (easily the largest factor in our temp).

You're right that is simplistic. I'll try to help you along. I'm just going to try to do it by memory though, so double-check what I hope are the facts. I may be off a percent or two here, or there.

Of the earth's atmosphere only 1% is made up of greenhouse gases.
Of that 1% ninety five percent is water. That's the most prevalent greenhouse gas - water. The 5% remaining of what makes up greenhouse gases are gases of which CO2 is one of a few. C02 makes up 3% of the 1% of the gases designated as greenhouse gases.

The totality of CO2 in the atmosphere makes up 380 parts per million. In other words for every 100,000 molecules of anything in the atmosphere 38 are CO2. Of those 38 molecules three percent are what man puts into the atmosphere artificially. So human caused CO2 by my admittedly bad math makes up about what? about 1 molecule in every 100,000 in the earth's atmosphere right? This is what Al Gore tells us is going to melt the Antarctic.

That is one bad little mama-jama molecule, CO2 is. I don't understand why it doesn't just fry the skin off our bones like those dudes in Raiders of the Lost Arc every time we pop open a pepsi (those bubbles are CO2, ya know? so beware).

Well actually not even the wonderkind over at RealClimate are going to try to sell you on the idea CO2 could offer up that kind of heat all by it's lonesome. Instead they create another theory to make the CO2 forced warming one sound possible. They postulate positive feedbacks on teensy little CO2 that somehow heats up the moisture in the air, and water being the more prevalent gas of greenhouse gases offers up its own heat to the equation.

"Feedbacks" work like this. If you bounce a ball the second bounce will not be as high as the first. This is because negative feedbacks (I'm guessing gravity, natural laws of inertia, push through the atmosphere, and such) act on the bounce giving it less power. Most stuff that happens in the natural world is negative feedback. If positive feedbacks worked on the ball the way Jim and Gavin tell you the second bounce of our little CO2 molecule ball would not only be higher, it would rocket the ball over the nearest skyscraper. That would be positive feedback.

OK, I admit, I could be wrong about some of that. I'm just Joe Lay-Guy. So double-check, and please point out the flaws in that little explanation. I want to tell it right the next time.

BTW this is off-topic a little but want to see where RealClimate gets its funding? I just discovered it, and I'm anxious to share.

RealClimate.org's Leftist Funding

[sasquatch2]

$1:

RealClimate.org's Leftist Funding

Not that long ago, the 80's, the breadcrumbs lead right back to the Kremlin.

[N_Fiddledog]

sasquatch2 sasquatch2:

$1:

RealClimate.org's Leftist Funding

Not that long ago, the 80's, the breadcrumbs lead right back to the Kremlin.

C'mon now Sasq, even for me that's a little much, and I'm on your side, but hey, if you've got support that can paint GISS/RealClimate red, it would be an entertaining read if nothing else. Love to see it.

They do say you can make a slippery connection to the European side of the warming movement, and the old communist regime though. Is that what you're talking about?

[Zipperfish]

$1:

You're right that is simplistic. I'll try to help you along. I'm just going to try to do it by memory though, so double-check what I hope are the facts. I may be off a percent or two here, or there.

Of the earth's atmosphere only 1% is made up of greenhouse gases.
Of that 1% ninety five percent is water. That's the most prevalent greenhouse gas - water. The 5% remaining of what makes up greenhouse gases are gases of which CO2 is one of a few. C02 makes up 3% of the 1% of the gases designated as greenhouse gases.

The totality of CO2 in the atmosphere makes up 380 parts per million. In other words for every 100,000 molecules of anything in the atmosphere 38 are CO2. Of those 38 molecules three percent are what man puts into the atmosphere artificially. So human caused CO2 by my admittedly bad math makes up about what? about 1 molecule in every 100,000 in the earth's atmosphere right? This is what Al Gore tells us is going to melt the Antarctic.

That is one bad little mama-jama molecule, CO2 is. I don't understand why it doesn't just fry the skin off our bones like those dudes in Raiders of the Lost Arc every time we pop open a pepsi (those bubbles are CO2, ya know? so beware).

Well, gross hyperbole aside, if you increase the concentration of carbon dioxide, all other things being equal, you would expect an increase in average surface temperature. This is because 100 molecules of CO2 per about a million molecules in the atmosphere that weren't in the atmosphere a hundred years now reflect/re-emit or otherwise transfer about 50% of their absorbed photons back towards the earth. One thing the skeptics rarely address is, if CO2 has increased by about 30%, why this wouldn't effect the heat balance. An energy budget analysis indicates it should have some kind of measureable effect. Carbon dioxide, though only measured in ppm, is a significant contributor to teh greenhouse effect according to various energy budgets (anywhere from 9 to 26%), so by increasing it 30% one would expect a measureable change. To my way of thinking anyway.


Well actually not even the wonderkind over at RealClimate are going to try to sell you on the idea CO2 could offer up that kind of heat all by it's lonesome. Instead they create another theory to make the CO2 forced warming one sound possible. They postulate positive feedbacks on teensy little CO2 that somehow heats up the moisture in the air, and water being the more prevalent gas of greenhouse gases offers up its own heat to the equation.

$1:

"Feedbacks" work like this. If you bounce a ball the second bounce will not be as high as the first. This is because negative feedbacks (I'm guessing gravity, natural laws of inertia, push through the atmosphere, and such) act on the bounce giving it less power. Most stuff that happens in the natural world is negative feedback. If positive feedbacks worked on the ball the way Jim and Gavin tell you the second bounce of our little CO2 molecule ball would not only be higher, it would rocket the ball over the nearest skyscraper. That would be positive feedback.

Gravity acting on a ball isn't feedback. The force of gravity is not related to any variable associated with the ball. Aerodynamic drag would be negative feedback since the drag increases with the velocity of the ball. The output (ball velocity) feeds back to the input (drag force).

And, yes, I imagine that RealClimate gets funding from leftists, just as I imagine the Amercian Enterprise Institute is funded by those on the political right. It's certainly difficult to separate the science from the politics, or from the personalities involved. That's why I think the truth or fiction of AGW will only become evident over some time. Probably 2020 or 2025.

[N_Fiddledog]

But basically you get my point right? Proportionately the amount of CO2 in the atmosphere is so small it's difficult to get a picture in our heads of just how proportionately tiny it is. From pre-industrial days to today that teeny bit has increased by a third you tell me, and therefore the world has to get warmer. Is that the theory?

But in the geologic past the world has been 4,000 parts per million higher and we went into an ice age. This particular era we're in today is considered cold and CO2 impoverished compared to other epochs. Vertebrate life thrived when CO2 levels were 5 times higher.

http://ff.org/centers/csspp/library/co2 ... ioxide.htm

I think maybe you still don't get how unlikely it is the kind of warming you're suggesting can come from what you seem to see as little CO2 sun molecules in your brain. It's possible I'm not describing it right. Try this then.

$1:

What have we learned so far? We know the entire atmosphere isn't composed of pure CO2, and the current concentration in the atmosphere is only about 380 parts per million and it's what we call a "trace gas". But we've been talking about a flat target, and in reality our problem is 3-dimensional. We need to now imagine a really really big room with one-inch marbles floating instead of bottle caps. Closest to us, the CO2 marbles are spaced 723 feet apart. Farther back in the room, the density has thinned to 1446 feet apart, and at the far end (the edge of space) the marbles have thinned to zero.

Next, let's load up a B-B gun with 100 B-Bs, 8 of which are silver and 92 of which are black. The 8 silver B-Bs are the only ones capable of heating up the CO2 molecules if they happen to hit one. Then we start shooting at our 3-dimensional target, hoping to hit one of the few red marbles with one of the few silver B-Bs. This whole picture we have drawn illustrates something called the "capture cross-section", or likelihood that a CO2 molecule will absorb a particle of "heat" radiating from the earth.

Some of the sharper physics students out there are probably asking themselves, "Hey what about scattering?" If your physics professor ever gave you the question, "Why is the sky blue?", then you're familiar with Raleigh scattering theory and you've probably already done the math and learned that in the temperature ranges we're dealing with here, the scattering is so small as to be negligible.

Now, to finish this problem, we need to estimate a "capture cross section" - the probability that a particular CO2 molecule mixed in with everything else in the air will ever encounter one of the highly specific IR photons in the absorption spectrum. We'll assume the mixing is homogeneous, and set the geometry for capture based on the known percentage of CO2 in the air, which is 380 PPM. So based on this highly simplified picture, how much heat can our trace amounts of CO2 actually absorb? The math is simple: 8% ( or .08 ) x 380 PPM ( .000380 ) = .0000304, or about thirty millionths of the radiated heat.

Bear in mind, that's the maximum permissible absorption by all of the CO2 presently in our atmosphere. Man's percentage contribution is currently at only about 3% of that. Now, let's see what we can blame humans for, what the "man-made" contribution ( 3% of the total ) is. Again, multiply .0000304 x .03 = .000000912 . Let's round that up to the nearest single number and just say, Man-made CO2 doesn't appear physically capable of absorbing much more than one-millionth of the radiated heat (IR) passing upward through the atmosphere...

In short, the laws of physics don't seem to allow CO2 it's currently assumed place as a significant "greenhouse gas" based on present concentrations.

Dr. Roy W. Spencer has one of the best comments we've read on this subject:
Al Gore likes to say that mankind puts 70 million tons of carbon dioxide into the atmosphere every day. What he probably doesn't know is that mother nature puts 24,000 times that amount of our main greenhouse gas -- water vapor -- into the atmosphere every day, and removes about the same amount every day. While this does not 'prove' that global warming is not manmade, it shows that weather systems have by far the greatest control over the Earth's greenhouse effect, which is dominated by water vapor and clouds.

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