The Carbon Dioxide Molecule and its interaction with Radiant Heat

[Bilko]

Hi, this is my first post concerning a subject that I would like more information on and feedback on my opinions.

 

In the arguments between the deniers and those promoting AGW there is much claimed and counter-claimed regarding variations in local temperatures, melting ice caps etc.

 

These arguments or debates are between professional scientists and no conclusion is ever reached between them. Only new sets of data for either claim or counter claim. It just goes on and on.

The lynch pin of the anthropogenic global warming controversy concerns the structure of the CO2 molecule (or indeed other 'greenhouse gases') and its atomic interaction with radiant heat.

 

Now if anthropogenic global warming is to be refuted and considering the amounts of anthropogenic CO2 generated over the last 200 years plus that likely to be generated in the future then the lynch pin of the scientific argument for anthropogenic global warming must surely be questioned?

 

i.e does CO2 actually absorb radiant heat? and if it does then does absorb significant amounts of radiant heat? i.e. significant enough to raise temperatures high enough to cause catastrophe. How many units of radiant heat are absorbed by a quantity of CO2? Has this been confirmed by laboratory experiment and if so why are its results not been brought to general attention of the general public. Surely this would kill off any claims by the deniers?.

 

On the other hand why don't any of the deniers actually attempt to refute the claim that the carbondioxide molecule absorbs radiant heat?

 

The CO2 molecule must either absorb radiant heat or doesn't and if it does, does it absorb suffient amounts of radiant heat to be of concern?

 

If there are any controversies regarding AGW then it is a conspiracy to keep the debate or controversy ongoing. Thus enabling scientists and publishers to make money of literature etc

 

One final point, surely there must be something wrong with the GW controversy when dubious characters such as Al Gore and David Icke represent opposing sides of the debate.

[cypress]

Hi, this is my first post concerning a subject that I would like more information on and feedback on my opinions.

 

snip ...

 

The lynch pin of the anthropogenic global warming controversy concerns the structure of the CO2 molecule (or indeed other 'greenhouse gases') and its atomic interaction with radiant heat.

 

Now if anthropogenic global warming is to be refuted and considering the amounts of anthropogenic CO2 generated over the last 200 years plus that likely to be generated in the future then the lynch pin of the scientific argument for anthropogenic global warming must surely be questioned?

 

Perhaps your questions are due to the fact that the controversy regarding AGW revolve around the several complex climatic influences as opposed to the simple physical property of one minor component of our atmosphere.

 

Though some might have you believe that the radiative property of CO2 is the linchpin of the controversy, but it is not. I don't know of any serious argument against the idea that CO2 absorbs certain frequencies of infrared radiation. However you are correct that one must address the key issue which is the degree of impact to climate that does occur with any change in CO2 concentration.

 

i.e does CO2 actually absorb radiant heat? and if it does then does absorb significant amounts of radiant heat? i.e. significant enough to raise temperatures high enough to cause catastrophe. How many units of radiant heat are absorbed by a quantity of CO2? Has this been confirmed by laboratory experiment and if so why are its results not been brought to general attention of the general public. Surely this would kill off any claims by the deniers?.

 

CO2 does absorb a limited range of infrared frequencies. It is quite proficient at absorbing and then reradiating the frequencies in proportion to the ratio of the cube of the absolute temperature so that in the atmosphere a percentage of the outgoing radiation is captured and warms the atmosphere above the temperature it would otherwise be if all other factors were independent. No serious skeptic would argue differently.

 

Is it significant enough, acting alone, not including any follow on effects to raise the temperature by more that one degree centigrade if CO2 concentration were raised from the apparent recent historical mean of 280 ppm to just over 700 ppm? No. Skeptics and most informed proponents alike agree on this point also.

 

The simple absorption characteristics of CO2 in air mixtures is known. The impact it has in the dynamic atmospheric column is not understood and has not been confirmed by experimentation or observation, though order of magnitude impacts have been estimated and observed.

 

The results are widely distributed, it does not kill off the argument because it is not a significant enough quantity to cause an issue without postulating follow on effects.

 

On the other hand why don't any of the deniers actually attempt to refute the claim that the carbondioxide molecule absorbs radiant heat?

 

Because if they did, they would properly be labeled a fool.

 

The CO2 molecule must either absorb radiant heat or doesn't and if it does, does it absorb suffient amounts of radiant heat to be of concern?

 

It does but this reality is a completely different question than what change in absorption occurs with a change in concentration from 280 ppm to the 400 ppm we are now approaching or the 560 - 700 ppm some estimate we could reach by the end of this century. An even more focused question is what impact would that change have on global surface temperature. This question is proving to be very difficult to answer.

 

If there are any controversies regarding AGW then it is a conspiracy to keep the debate or controversy ongoing. Thus enabling scientists and publishers to make money of literature etc

 

One final point, surely there must be something wrong with the GW controversy when dubious characters such as Al Gore and David Icke represent opposing sides of the debate.

 

There will always be some on both sides looking to profit from controversy. I am not sure that a conspiracy is involved.

[swansont]

These arguments or debates are between professional scientists and no conclusion is ever reached between them.

 

Actually, not so much. AGW critics are by and large not experts in the field.

 

 

Now if anthropogenic global warming is to be refuted and considering the amounts of anthropogenic CO2 generated over the last 200 years plus that likely to be generated in the future then the lynch pin of the scientific argument for anthropogenic global warming must surely be questioned?

 

i.e does CO2 actually absorb radiant heat? and if it does then does absorb significant amounts of radiant heat? i.e. significant enough to raise temperatures high enough to cause catastrophe. How many units of radiant heat are absorbed by a quantity of CO2? Has this been confirmed by laboratory experiment and if so why are its results not been brought to general attention of the general public. Surely this would kill off any claims by the deniers?.

 

CO2 absorbs radiant energy because it has absorption peaks in the IR (near 4 and 15 microns, the latter being very important), which is where blackbody radiation is emitted from something with the temperature of the earth. But the sunlight coming in has a different wavelength range, where absorption is not as strong. So energy gets in, and some of it gets "trapped" on the way out, and can be re-radiated toward the earth.

 

 

 

On the other hand why don't any of the deniers actually attempt to refute the claim that the carbondioxide molecule absorbs radiant heat?

 

They do. They are wrong.

 

 

If there are any controversies regarding AGW then it is a conspiracy to keep the debate or controversy ongoing. Thus enabling scientists and publishers to make money of literature etc

 

If GW was false, the scientists would study something else and publish those results (which is not an income source — it costs money out of your grant to publish). The number of people employed in atmospheric sciences is a small fraction of all scientists. The rest of us do OK without any controversy.

[John Cuthber]

Most of the "arguments" between the believers and the non believers seem to be about minor points.

I don't know how well this BBC site will work outside the UK, but it shows some noted skeptics pretty much agreeing with those who say we cause global warming.

 

http://news.bbc.co.uk/panorama/hi/front_page/newsid_8758000/8758352.stm

[JohnB]

Hi Bilko. As one of the resident sceptics, here is my take.

 

Firstly I have to agree with both swansont and cypress. Anybody who denies the increased forcing due to radiant physics is a fool and wrong. Increase the CO2 and the temperature will go up. IIRC about 1.1 degree for a doubling of CO2. This fact of basic physics is not in dispute at all as far as I can tell.

 

Secondly, the world has warmed over the last 100+ years. This fact is also not in dispute. Not only physics, but actual historical records show this to be true. (For example, there aren't "Ice Fairs" on the Thames River as there were in the 1860/1870s. The river no longer freezes in winter.)

 

Now it starts to get hairier. We get into Attribution and Feedbacks and the confidence levels associated with them.

 

Attribution is the process of working out how much of the warming (or cooling) in the 20th Century is due to which forcing. CO2 is a positive forcing and drives the temps up, many aerosol pollutants block light and are negative forcings, cloud patterns can change from natural causes and therefore be a positive or negative forcing depending on their height. You can add in the Sun, land use changes, Milancovich Cycles, major current reversals and pretty much everything that can effect the climate.

 

The idea is to work out how strong each of these forcings are at given points in time. During the 20th Century we had 2 warming and 1 cooling phase. 1910-1940 warmed, 1940-1970 cooled and 1970-2000 warmed. So attribution is used to determine what the forcings were in each of these periods to produce the observed temperature changes.

 

It's not enough just to note the temperatures going up and down, we are trying to understand all the variables that make it go up and down. A system doesn't change for no reason, there must be either an internal or external forcing that makes it change.

 

Feedbacks are processes that depend on previous forcings. They can also be considered forcings in their own right and again come in positive (they will accelerate the trend) and negative (they will decrease the trend) types. One thing to remember here is that positive and negative refers to trends, not temperatures. In a time of warming a positive feedback will make things warmer but in a cooling phase a positive feedback will make things colder.

 

The biggest feedback is water vapour, which is also the most powerful of the GHGs. As the world warms, more water vapour is put into the air and this increases the warming. A positive feedback. However, it also forms more clouds, which can be either a positive or negative feedback as I said before.

 

It's the balance of the values that are used in attribution and feedbacks that we use in our Climate Models. Most of these seem to centre around the 2.4 to 3.2 degrees rise for a doubling of CO2. (With a range about 1.2 to 8 degrees rise)

 

So put simply, we know (from physics) that doubling the CO2 will result in around a 1.1 degree rise in temperature. Everything above or below that value is based on interpretation of the attribution and feedbacks in the system. It is this area and the confidence expressed in the conclusions that are in dispute.

 

One more thing to keep in mind. Polar bears, growing seasons and melting ice are indicitive of only one thing, the world is warming. They are not in any way evidence that the actions of mankind had anything to do with the warming. All of the effects would happen whether man was responsible or not. Anybody who says otherwise is being dishonest. However, and just to make things a bit more confusing, melting Polar Ice is actually a feedback in the climate system due to albedo changes.

 

By the same token, beware of those on my side who talk about "scams" or the like. These people would classify as the "extremist" end of the spectrum and are generally incapable of rational discussion.

 

Your best bet is some of the more "moderate" blogs and keep reading about the science. (I've been reading all sorts for years and am still a beginner.)

 

And always remember that what you read in the newspaper or see reported on TV or the newsnet is not always what the scientists involved actually said.

[Bilko]

Perhaps your questions are due to the fact that the controversy regarding AGW revolve around the several complex climatic influences as opposed to the simple physical property of one minor component of our atmosphere.

 

Though some might have you believe that the radiative property of CO2 is the linchpin of the controversy, but it is not.

 

Well if anthropogenic global warming is caused by greenhouse gases such as CO₂ and if CO₂ is the most common GHG, then without anthropogenic emissions of CO₂ or other GHGs then there would be no controversy.

 

 

CO2 does absorb a limited range of infrared frequencies. It is quite proficient at absorbing and then reradiating the frequencies in proportion to the ratio of the cube of the absolute temperature

 

So why are the the frequencies not reradiated out into space, in proportion to the ratio of the cube of the absolute temperature?

 

 

so that in the atmosphere a percentage of the outgoing radiation is captured and warms the atmosphere above the temperature it would otherwise be if all other factors were independent. No serious skeptic would argue differently.

 

Makes me wonder why they are indeed sceptics at all.

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Hi Bilko. As one of the resident sceptics, here is my take.

 

Firstly I have to agree with both swansont and cypress. Anybody who denies the increased forcing due to radiant physics is a fool and wrong. Increase the CO2 and the temperature will go up. IIRC about 1.1 degree for a doubling of CO2. This fact of basic physics is not in dispute at all as far as I can tell.

 

Secondly, the world has warmed over the last 100+ years. This fact is also not in dispute. Not only physics, but actual historical records show this to be true. (For example, there aren't "Ice Fairs" on the Thames River as there were in the 1860/1870s. The river no longer freezes in winter.)

 

Now it starts to get hairier. We get into Attribution and Feedbacks and the confidence levels associated with them.

 

Attribution is the process of working out how much of the warming (or cooling) in the 20th Century is due to which forcing. CO2 is a positive forcing and drives the temps up, many aerosol pollutants block light and are negative forcings, cloud patterns can change from natural causes and therefore be a positive or negative forcing depending on their height. You can add in the Sun, land use changes, Milancovich Cycles, major current reversals and pretty much everything that can effect the climate.

 

The idea is to work out how strong each of these forcings are at given points in time. During the 20th Century we had 2 warming and 1 cooling phase. 1910-1940 warmed, 1940-1970 cooled and 1970-2000 warmed. So attribution is used to determine what the forcings were in each of these periods to produce the observed temperature changes.

 

It's not enough just to note the temperatures going up and down, we are trying to understand all the variables that make it go up and down. A system doesn't change for no reason, there must be either an internal or external forcing that makes it change.

 

Feedbacks are processes that depend on previous forcings. They can also be considered forcings in their own right and again come in positive (they will accelerate the trend) and negative (they will decrease the trend) types. One thing to remember here is that positive and negative refers to trends, not temperatures. In a time of warming a positive feedback will make things warmer but in a cooling phase a positive feedback will make things colder.

 

The biggest feedback is water vapour, which is also the most powerful of the GHGs. As the world warms, more water vapour is put into the air and this increases the warming. A positive feedback. However, it also forms more clouds, which can be either a positive or negative feedback as I said before.

 

It's the balance of the values that are used in attribution and feedbacks that we use in our Climate Models. Most of these seem to centre around the 2.4 to 3.2 degrees rise for a doubling of CO2. (With a range about 1.2 to 8 degrees rise)

 

So put simply, we know (from physics) that doubling the CO2 will result in around a 1.1 degree rise in temperature. Everything above or below that value is based on interpretation of the attribution and feedbacks in the system. It is this area and the confidence expressed in the conclusions that are in dispute.

 

One more thing to keep in mind. Polar bears, growing seasons and melting ice are indicitive of only one thing, the world is warming. They are not in any way evidence that the actions of mankind had anything to do with the warming. All of the effects would happen whether man was responsible or not. Anybody who says otherwise is being dishonest. However, and just to make things a bit more confusing, melting Polar Ice is actually a feedback in the climate system due to albedo changes.

 

By the same token, beware of those on my side who talk about "scams" or the like. These people would classify as the "extremist" end of the spectrum and are generally incapable of rational discussion.

 

Your best bet is some of the more "moderate" blogs and keep reading about the science. (I've been reading all sorts for years and am still a beginner.)

 

And always remember that what you read in the newspaper or see reported on TV or the newsnet is not always what the scientists involved actually said.

 

So are you as a spectic more or less saying that yes anthropogeniuc emissions of CO₂ can cause GW, but not enough to justify being alarmed about?

[swansont]

So why are the the frequencies not reradiated out into space, in proportion to the ratio of the cube of the absolute temperature?

 

Radiation goes basically in a random direction. Some goes out to space, and some goes back to earth, which means less goes into space than of there was no absorption taking place.

 

 

(Radiated power actually varies as T^4, but that's something that has propagated from an earlier post)

[cypress]

Well if anthropogenic global warming is caused by greenhouse gases such as CO₂ and if CO₂ is the most common GHG, then without anthropogenic emissions of CO₂ or other GHGs then there would be no controversy.

 

While it is clear that CO₂ is a greenhouse gas, It is not clear that global warming (i.e. an increase in the average surface temperature relative to a longer term mean) has as a root cause greenhouse gases.

 

 

So why are the the frequencies not reradiated out into space, in proportion to the ratio of the cube of the absolute temperature?

 

They are (though as swansont corrected it is the fourth power of temperature difference). The key is that since the energy flux of re-radiation is a function of temperature differences, if the temperature of the atmosphere were constant and equal to the surface temperature, then there would be no variable impact, but since the temperature profile is not constant, one must adjust for convective and conductive heat loss from CO₂ to other molecules and differentiate over the temperature profile. This is not an easy thing to model over the air column. However reasonable estimates appear to fall into the range of 0.3 - 1.1 degrees for a doubling in CO₂ from 280 to 560 ppm and up to 1.4 for 700 ppm. If this were accurate and the only effect, then AGW would be a non-issue.

 

Makes me wonder why they are indeed sceptics at all.

 

I suspect that you still don't quite understand the issue.

 

So are you as a spectic more or less saying that yes anthropogeniuc emissions of CO₂ can cause GW, but not enough to justify being alarmed about?

 

Yes, I too am a skeptic and this is exactly my thought on the topic. Review of the empirical data indicates recent warming but all but somewhere between 0.0 and 0.4 of it can be accounted for by natural causes observed in operation during historical periods of increased temperatures. This is a far cry from the 1.5 degrees C predicted by the IPCC models. These models are used to derive the estimates the warming alarmists cite. I believe the models are incorrect.

[JohnB]

So are you as a spectic more or less saying that yes anthropogeniuc emissions of CO2 can cause GW, but not enough to justify being alarmed about?

 

Yes and no.

 

In some areas my answer is "I don't know, data insufficient". Being well aware of the uncertainties involved, I'm pretty certain that anybody who thinks they do know is pretty much fooling themselves. Only by minimising the uncertainties in the data and the processes involved can you convince yourself that you are "sure" of your answers. I find myself wary of people who can find certainties in uncertain data.

[Bilko]

While it is clear that CO₂ is a greenhouse gas, It is not clear that global warming (i.e. an increase in the average surface temperature relative to a longer term mean) has as a root cause greenhouse gases.

 

Quite, but I was referring to anthropogenic global warming. So if anthropogeniuc emissions of CO2 do indeed contribute to global warming, then the CO₂ molecule's interaction with radiant heat must be the lynch pin of the AGW argument. What other human activity could cause AGW apart from passing wind maybe?

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Consecutive posts merged

Yes and no.

 

In some areas my answer is "I don't know, data insufficient". Being well aware of the uncertainties involved, I'm pretty certain that anybody who thinks they do know is pretty much fooling themselves. Only by minimising the uncertainties in the data and the processes involved can you convince yourself that you are "sure" of your answers. I find myself wary of people who can find certainties in uncertain data.

 

The way I see it is that since CO₂ does indeed absorb heat, then surely it will contribute to general GW and with the steady increases of emissions, GW will inevitably increase to the point of catrastophe.

Edited July 12, 2010 by Bilko
Consecutive posts merged.

[cypress]

Quite, but I was referring to anthropogenic global warming. So if anthropogeniuc emissions of CO2 do indeed contribute to global warming, then the CO₂ molecule's interaction with radiant heat must be the lynch pin of the AGW argument. What other human activity could cause AGW apart from passing wind maybe?

 

Fair enough, I see your point. I stand corrected. If humans are warming the planet, then CO₂ is likely the primary input.

 

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Consecutive posts merged

 

The way I see it is that since CO₂ does indeed absorb heat, then surely it will contribute to general GW and with the steady increases of emissions, GW will inevitably increase to the point of catrastophe.

 

The theoretical amount of impact CO₂ has on radiant forcing declines exponentially so that after 700 ppm the incremental impact becomes nearly negligible. In order for there to be a catastrophe, the potential for significant impact must exist. Evidence for this potential seems to rest solely on models that appear to be incorrect. I am not worried about a catastrophe.

[JohnB]

What other human activity could cause AGW apart from passing wind maybe?

 

Land use change could be a biggy that has been underrated, for a start.

 

The way I see it is that since CO2 does indeed absorb heat, then surely it will contribute to general GW and with the steady increases of emissions, GW will inevitably increase to the point of catrastophe.

 

Possible, but I don't think probable. The first thing to be remembered is that forcings from the increase in CO2 are logarithmic and not linear. If we assume a climate sensitivity of 3 degrees for a doubling of CO2, what does this mean in the real world? (Ignoring feedbacks)

 

If the concentrations go from the preindustrial 280 ppm to 560 ppm the temps go up 3 degrees. However we have to go to 1120 ppm to get the next 3 degrees and 2240 ppm for the next. So the process slows down greatly over time.

 

Secondly you are assuming an unlimited supply of fossil fuels to drive the CO2 increase and as many will quite happily tell you, we are running out of them so at some point we will stop. (Even if it's because there's nothing left to burn)

 

Thirdly you are assuming no great changes in energy production or societal needs in the next hundred years or so. I quote from a speech given by Michael Crichton back in 2003;

Let’s think back to people in 1900 in, say, New York. If they worried about people in 2000, what would they worry about? Probably: Where would people get enough horses? And what would they do about all the horse****?

 

Horse pollution was bad in 1900, think how much worse it would be a century later, with so many more people riding horses? But of course, within a few years, nobody rode horses except for sport.

 

And in 2000, France was getting 80% its power from an energy source that was unknown in 1900. Germany, Switzerland, Belgium and Japan were getting more than 30% from this source, unknown in 1900. Remember, people in 1900 didn’t know what an atom was.

 

They didn’t know its structure. They also didn’t know what a radio was, or an airport, or a movie, or a television, or a computer, or a cell phone, or a jet, an antibiotic, a rocket, a satellite, an MRI, ICU, IUD, IBM, IRA, ERA, EEG, EPA, IRS, DOD, PCP, HTML, internet. interferon, instant replay, remote sensing, remote control, speed dialing, gene therapy, gene splicing, genes, spot welding, heat-seeking, bipolar, prozac, leotards, lap dancing, email, tape recorder, CDs, airbags, plastic explosive, plastic, robots, cars, liposuction, transduction, superconduction, dish antennas, step aerobics, smoothies, twelve-step, ultrasound, nylon, rayon, teflon, fiber optics, carpal tunnel, laser surgery, laparoscopy, corneal transplant, kidney transplant, AIDS. None of this would have meant anything to a person in the year 1900. They wouldn’t know what you are talking about.

 

Do you really think the "not much change" assumption to be well founded?

 

Lastly, and I left it until last because of the age, is the historical record.

 

 

As you can see the CO2 levels have been far, far higher than todays without the temps going into runaway warming. If it didn't runaway at 7,000 ppm in the Cambrian it's unlikely to do so today at 400 ppm. However one must be careful when using graphs of such old periods. Note the size of the "Estimate of uncertainty" for the CO2, it could have been 7,000 ppm in the Cambrian, but it could have only been 3,000 too.

 

Also note the lack of uncertainty/error bars for the temperatures. With the maximum temps always around the 22 degree mark, I do wonder if it is "real" or simply an artifact of our detection methods. Did the temps stop at 22 degrees, or does it just look like it? And in either case, why?

 

Another reason to be wary of very long term climate temps is time. Over Geological time periods, the Earth itself changed dramatically. In making any sort of "detailed" comparison I don't believe that you can go back more than 50 million years. While the continents were in roughly the same positions for longer than that, a defining event occurred 50 million years ago, North and South America joined and cut the Atlantic off from the Pacific. This will have resulted in wholesale changes to the ocean currents and climate over the face of the planet. I think that comparing before and after, except in very general terms is a case of apples and oranges.

 

Now, if you meant "catastrophe" in terms of our civilisation having to adapt to major changes, that is another matter. Yes, we will. Even if we became absolutely CO2 neutral, the climate would still change. In the short time that humans have been on the face of the Earth, sea levels have been between 8 metres higher than today and 150 metres lower than today.

 

Unless we can actually find a way to accurately control the planetary climate only one thing is certain in the future. Climate catastrophe will come and there will be nothing we can do about it except adapt. In that respect at least, it doesn't matter if we burn fossil fuels, have all the wind and solar power money can buy, or live in grass huts, the climate will change and we will have to adapt.

 

To think anything else is to live in a fantasy world.

 

Just as a side note, it appears to be becoming more accepted in the Archaeological community that rapid climate change may have had far more impact on ancient societies than previously thought. "Rapid" being 200 years or less. Climate change apparently caused the end of the "Oasis" peoples and caused them to move to the Nile Valley and become the Pharonic Egyptians. It has also been linked (in both strong and weak fashions) to the falls of the Harappans in India, the Hittites, the Assyrians, the Maya in Central America, even the Clovis people in North America, many peoples at many times all over the globe. The ruins of advanced, city building civilisations are strewn around the globe, many were destroyed, but many more seem to have just "died" with the reason a mystery. Perhaps it's not such a mystery after all.

 

CC may even have been a factor in the fall of Rome as at the end of the "Roman Warm Period" Rome and Italy became more and more dependent on grain shipments from Egypt and other warmer lands. Colder times in Europe meant lower harvests and more reliance on imports. It can also have a bearing on why the Germanic and other Northern tribes moved south to attack the Empire. It was cold, they were starving, they had little choice.

 

It may turn out that rapid climate change was one of the major reasons for societies "ending".

Edited July 12, 2010 by JohnB