Albedo effect

[glc]

Is CO2 an important gas in the atmosphere? Well it obviously is in its role of supporting life on the planet. Whether it is as a gas that provides a significant bulk of the current additional 30 degree warmth to the planet I am not convinced.

Why don't you read this.

www.warwickhughes.com/papers/barrett_ee05.pdf

In particular take note of the section IR Sectroscopy of Greenhouse Gases on page 3.

You might also want to take a look at this

www.barrettbellamyclimate.com/page16.htm

You say N2 and O2 are as significant as CO2 in terms of absorption/emission. Now tell me in which region of the spectrum N2 and O2 are absorbing. Does it overlap with CO2 or H2O bands or do they absorb in their own distinct band.

[glc]

Also as I noted in my reply to GLC we don't even know if CO2 is an important greenhouse gas in the quantities it exists in our atmosphere.

Yes we do. I don't know why you keep repeating this. Look at the emissions spectrum plots. CO2 is clearly absorbing IR energy in the 580-750 cm^-1 region and emitting at a higher altitudes.

[icefisher]

Jun 7, 2009 18:48:31 GMT glc said:

Is CO2 an important gas in the atmosphere? Well it obviously is in its role of supporting life on the planet. Whether it is as a gas that provides a significant bulk of the current additional 30 degree warmth to the planet I am not convinced.

Why don't you read this.

www.warwickhughes.com/papers/barrett_ee05.pdf

In particular take note of the section IR Sectroscopy of Greenhouse Gases on page 3.

You might also want to take a look at this

www.barrettbellamyclimate.com/page16.htm

You say N2 and O2 are as significant as CO2 in terms of absorption/emission. Now tell me in which region of the spectrum N2 and O2 are absorbing. Does it overlap with CO2 or H2O bands or do they absorb in their own distinct band.

These articles GLC describe a theory. Are there any tests of sufficient resolution to prove the theory? It kind of reminds me of the calculations used to detect outer planets in the universe. As the science got better they found more stuff out there.

You are making a claim that the theory is the end all, be all, but where is the evidence?

[glc]

These articles GLC describe a theory.

The article I referenced describes well established scientific fact. The author, Jack Barrett, has published some 70 odd papers related to chemistry and spectroscopy of small molecules. He's also written a number of text books on the subject.

You are making a claim that the theory is the end all, be all, but where is the evidence?

This is the evidence. The Barrett article discusses the properties which determine which gas molecules absorb IR radiation. I repeat this is well established science. If you deny this you are denying basic chemistry and physics.

[socold]

Jun 7, 2009 17:42:59 GMT nautonnier said:

"Feedbacks are proportional to forcing. If you have no forcing, the feedback aint gonna be doing anything. The forcing for say doubling co2 or increasing solar output 2% is independent of feedbacks and therefore the climate's response."


This is totally untrue. The climate is a chaotic system - feedbacks need not be proportional in anyway at all and they definitely will not be simple they may be part of a chain of system responses to the input or to the system reaction to the input..

You say a key word here - input. Yes exactly we need to know the input and that's why the concept of radiative forcing was formed. Changes in solar output, greenhouse gas level, volcanic eruptions etc - all of these things change the radiative balance of Earth. So the change to the radiative balance, or the radiative forcing is the input. The behavior of the climate system to this input determines it's response to this input, which will be to return the Earth to radiative balance.

If the Earth starts absorbing 1wm-2 more energy than it emits then that's our forcing. The question then is how the climate responds to that and that question depends on feedbacks. Perhaps each 1wm-2 inbalance leads to 0.2C warming. Or perhaps it causes 0.7C. The difference in response depends on the feedbacks.

It is calculated that doubling co2 in the atmosphere would cause a radiative forcing of 3.7wm-2 inbalance, or in other words doubling co2 in the atmosphere would cause the Earth to be emitting 3.7wm-2 less into space. How the climate responds to this, including what feedbacks do, is another question entirely.

"No negative feedbacks would simply dampen the climate response to any unit of forcing, not negate it."

Again an extremely simplistic view of a chaotic system. But I suppose you can be forgiven as you don't believe in ANY negative feedbacks. An input into a chaotic system at the 'right time' can move the system from one 'attractor' to another stable state around another attractor. The way the Earth moves from ice-age to inter-glacial seems to be this kind of change.

If the climate is heavily chaotic and unpredictable in it's response to a given forcing then this is a greater reason for us not to provide such a forcing by means of doubling co2 in the atmosphere if we don't know what will happen. What you are describing are tipping points, which oddly enough I do not disagree with. They are indeed a risk.

It's far safer for us if the climate responds proportionally to the forcing so that a 2% solar output increase leads to about twice the warming as a 1% increase. Fortunately it looks like tipping points are few and far between.

"Obviously, but it's the forcing that is being calculated, not it's effect."

But it is the effect of the forcing that AGW proponents are waving in front of politicians to scare them into killing industries and taxing other businesses into bankruptcy. Of COURSE it is the effect that you are calculating - you are the one SoCold that keeps on telling us of an ice free Arctic - that's an effect not a forcing!

We are talking about the radiative forcing - the input. The confidence that a doubling of co2 causes about 3.7wm-2 forcing is very high. But that doesn't tell us how much warming it produces. You need to know the climate sensitivity degreesC/wm-2 to figure that out - and that involves the feedbacks.

There are basically two parts to this:

1) The input - the radiative inbalance caused by something (1% increase in solar activity, doubling of co2, pinatubo, etc).

2) The response - ie the response to the inbalance, how much the temperature of the earth will change to get back into radiative balance. This involve feedbacks.

[icefisher]

Jun 7, 2009 19:54:36 GMT glc said:

These articles GLC describe a theory.

The article I referenced describes well established scientific fact. The author, Jack Barrett, has published some 70 odd papers related to chemistry and spectroscopy of small molecules. He's also written a number of text books on the subject.

I don't care what his credentials are GLC thats not scientific evidence. Darwin also had a theory. He also had a finch.

Where is the "finch" for this theory?

[icefisher]

Jun 7, 2009 20:52:44 GMT socold said:

It is calculated that doubling co2 in the atmosphere would cause a radiative forcing of 3.7wm-2 inbalance,

We are talking about the radiative forcing - the input. The confidence that a doubling of co2 causes about 3.7wm-2 forcing is very high.

You didn't say it is "demonstrated". Instead you said it was "calculated". I think you are describing a theory without empirical evidence to support it.

I don't think you can get to "very high" assurance on any science theory without a shred of evidence to support it.

[glc]

I don't care what his credentials are GLC thats not scientific evidence.

I would have thought that the thousands upon thousands of laboratory experiments that take place daily and consistently show that the IR absorption properties of various gases are exactly as Barrett describes would be enough.

I'm now deeply suspicious of what you're asking as I suspect that, whatever my response, it's not going to be enough to satisfy you. Ok - what the heck - I'll play along

What is it that you are not convinced about?

[glc]

You didn't say it is "demonstrated". Instead you said it was "calculated". I think you are describing a theory without empirical evidence to support it.

You're wrong. There is both the "theoretical" calculations and the observations to support them. The radiative transfer equations (via MODTRAN) are able to produce an emission spectrum for any region on earth (warm, cold, temperate....) which can be validated by satellite observations of those same regions.

You're getting yourself into an ever deeper hole. I'd stop digging if I were you.

[jtom]

Lifted straight from www.warwickhughes.com/papers/barrett_ee05.pdf

"If the concentration of CO2 were to be doubled in the absence of the other GHGs the increase in absorption would be 1.5%. In the presence of the other GHGs the same doubling of concentration achieves an increase in absorption of only 0.5%,
only one third of its effect if it were the only GHG present. Whether this overlap effect is properly built into models of the atmosphere gives rise to some scepticism."

So according to this, two-thirds of the possible CO2 absorption is already being captured by other GHGs, AND THE AUTHOR QUESTIONS WHETHER THE MODELS ADEQUATELY ACCOUNT FOR THE OVERLAP.

[socold]

Jun 7, 2009 23:45:42 GMT icefisher said:

Jun 7, 2009 20:52:44 GMT socold said:

It is calculated that doubling co2 in the atmosphere would cause a radiative forcing of 3.7wm-2 inbalance,

We are talking about the radiative forcing - the input. The confidence that a doubling of co2 causes about 3.7wm-2 forcing is very high.

You didn't say it is "demonstrated". Instead you said it was "calculated". I think you are describing a theory without empirical evidence to support it.

I don't think you can get to "very high" assurance on any science theory without a shred of evidence to support it.

There is empirical evidence to support it. The calculations of IR transmission in the atmsphere are built upon physics derived from experiments and constrained by observations made in the atmosphere and from space. All empirical evidence.

The amount of additional radiation that would be absorbed if there was was twice as much co2 in the atmosphere is calculatable using modern physics to a degree of accuracy wherin the uncertainty is small. It's about 3.7wm-2 less energy reaching space. How the planet's temperature changes as it adjusts back into equillibrium is another question entirely with a far less certain answer.

[socold]

Jun 8, 2009 0:40:10 GMT jtom said:

Lifted straight from www.warwickhughes.com/papers/barrett_ee05.pdf

"If the concentration of CO2 were to be doubled in the absence of the other GHGs the increase in absorption would be 1.5%. In the presence of the other GHGs the same doubling of concentration achieves an increase in absorption of only 0.5%,
only one third of its effect if it were the only GHG present. Whether this overlap effect is properly built into models of the atmosphere gives rise to some scepticism."

So according to this, two-thirds of the possible CO2 absorption is already being captured by other GHGs, AND THE AUTHOR QUESTIONS WHETHER THE MODELS ADEQUATELY ACCOUNT FOR THE OVERLAP.

The argument seems to be
"I don't know therefore I know it's doubtful"

[icefisher]

Jun 8, 2009 0:45:38 GMT socold said:

Jun 7, 2009 23:45:42 GMT icefisher said:

There is empirical evidence to support it. The calculations of IR transmission in the atmsphere are built upon physics derived from experiments and constrained by observations made in the atmosphere and from space. All empirical evidence.

If I am not mistaken there have been 4 people in this thread asking for a reference to this study Socold. Just stomping your feet and claiming it exists does not prove it does exist.

[glc]

So according to this, two-thirds of the possible CO2 absorption is already being captured by other GHGs, AND THE AUTHOR QUESTIONS WHETHER THE MODELS ADEQUATELY ACCOUNT FOR THE OVERLAP.

Gosh - I hadn't spotted that. This completely demolishes my argument.

Thank you, jtom, I am well aware there is an overlap in the CO2 and WV absorption bands. Even the IPCC and RC are aware of it. It doesn't alter the fact, though, that increasing CO2 will, as shown by well understood radiative transfer equations, impede the flow of outgoing LW radiation from the earth's atmosphere.

Rest assured I choose my sources carefully. Jack Barrett is a leading climate sceptic (though on this blog he'd be considered a rampant warmista) who has argued for many years (since 1992 at least) with prominent figures in the IPCC. JB says pretty much what I'm saying here, i.e. doubling the concentration of CO2 in the atmosphere will raise global temperatures by about a degree.

Icefisher (like a few others) does not accept the well established science put forward by Barrett (and Lindzen and Spencer and Christy ....) and instead appears to have developed his own theory on how various gas molecules interact with IR radiation.

[jimcripwell]

I would like to thank everyone for this, very informative, discussion. The impression I have had for some time is that, with no direct evidence that links the increase of CO2 in the air to warming temperatures, the attempt by the IPCC to end-run this problem, is all smoke and mirrors. People quote 3.7 watts/m2 as if the number was written on tablets of stone. But when we ask for what are, IMHO, absolutely vital references to the science which supposedly backs up such numbers, there are no references. The warmaholics claim that there is science to support their case. I have seen very little science in this discussion. But, again, many thanks for confirming my funny internal feelings.