Global warming is not caused by CO2

[Andrew Mason]

http://www.gi.alaska.edu/ScienceForum/ASF8/817.html is how a greenhouse really works:

A greenhouse can use many different techniques for regulating and/or storing heat. These do not illustrate the greenhouse principle. The principle is simple: let shortwave radiant energy in and trap the longwave radiation on its way out.

There is a popular misconception that the greenhouse effect is misnamed, suggesting that the trapping of heat by CO2 in the atmosphere is fundamentally different than the use of glass in a greenhouse. The principle is the same, although the mechanism is different. In a greenhouse the glass reflects the IR radiation back into the greenhouse ie. the IR radiation is not absorbed and reradiated by the glass. With CO2 the IR radiation emitted by the surface of the Earth is absorbed by the CO2, so the temperature of the CO2 increases. The CO2 then emits IR radiation - half of it back toward the earth.

AM

 

[Bystander]

http://www.wmconnolley.org.uk/sci/wood_rw.1909.html

from post #29 this thread, R. McL.

 

[vanesch]

It is well understood that the "greenhouse effect" is a misnoma. An actual greenhouse works by physically preventing air from convecting heat outside of its glass housing. The "greenhouse" effect in the atmosphere is completely different, it works by gas particles absorbing energy in specific bands of the the electro-magnetic spectrum and re-emitting this energy, some of which goes back towards the earth.

Convection is the most efficient form of heat transfer, of course it accounts for a great deal of the Earth's dissipated energy. So much so that I don't think that small changes in CO2 will drive a significant increase in this dissipative mechanism. In fact, I don't really see why it would necessarily act as a convection enhancer in the first place, perhaps it even has the reverse effect? Given that CO2 covers bands of the electro-magnetic spectrum not covered by water vapour or methane, I reckon it's probably more important as a greenhouse gas, because if it weren't there the energy would be free to escape.

As for the discussion surrounding the scientific method, I think we have to look at this science less as a pure mathematical science, such as the type of science that Feynman was doing, and more as a kind of "geophysical hazards" type science. This is mixed with political, financial and of course sociological considerations which detract from the pure science - I don't mean that in an "excuses for poor science" kind of way - it's just how this science is. For example, take the study of volcanology, if the scientist who studies the volcano thinks it's going to erupt, she does her best to check the science but she cannot be 100% certain that it will go; it's still her job to let people know she thinks it's going to go, perhaps she will give them a degree of certainty and allow the authorities to handle the PR. Of course I'm not saying that Feynman was wrong, he was most certainly right in my opinion, and it is a shame that climate science (and Earth sciences in general) isn't closer to the rigourous science conducted by the likes of Feynman, but the complexity of the macroscopic scale forbids it. Incidentally, I'm not so sure that the anthropogenic CO2 emissions = global warming hypothesis is presented as being "proven", I seem to remember a "90% certain" from the IPCC.

To quote a famous glaciology paper, Mann 1978, when the fear of global warming first started to emerge:

Schneider sums up the dilemma facing mankind: despite the crudities and inadequacies of present techniques for modelling the climatic effects of increasing atmospheric CO2 content and the resultant doubts about the magnitude of the warming that would actually occur, we cannot afford to let the atmosphere carry out the experiment before taking action because if the results confirm the prognosis, and we should know one way or another by the end of the century, it will be too late to remedy the situation on account of the long residence time of CO2 in the atmosphere (Keeling and Bacastow estimate that, if all accessible fules were burnt, restoration of pre-industrial levels of CO2 would take at least 10,000 yr).

S

I fully agree with what you write, and I always pointed out that AGW is 1) a genuine possibility, that, given the data, is certainly plausible and 2) that given the potential damage (although that can also be disputed, but ok...) of AGW, even if there were only a 30% chance of it actually happening in dramatic proportions, we should try to mitigate it. So, given the current state of affairs, I think that there is no discussion that we should at least plan how to get our CO2 emissions down, just in case. But that's the social and political part.

However, science is science and it is not because the means to gather proof are harder, that truth is easier to find and hence that one has to be less rigorous. And what disturbs me profoundly in the *scientific* discussion of AGW, is that open but sceptic inquiry is now frowned upon - while it should be the prevailing attitude. When you look at the IPCC and all the supportive bodies around it, it seems that if you even dare to question certain hypotheses of the AGW theory, you are stamped as a heretic, a climate sceptic, etc... with the underlying insinuation that you are or a crackpot, or that you have some or other vested interest in denying AGW, or that you have yourself leading by your emotions and are in a psychological state of denial.

We have had, according to their saying, official members of the IPCC here on this board requesting that discussions be closed simply because they were putting in doubt aspects of the AGW hypothesis, and that this should be treated as crackpot stuff, as if it were creationism or something of the kind. I find this, given the current state of knowledge, a very very worrisome attitude on the scientific level. It is the thing I try to point out (and I might come over as an AGW denier because of that, which I'm not).

Again, there's enough stuff on the table to say that it is not completely crazy to think of AGW, and given its potential dangers in its most extreme forms, that by itself is sufficient to warrant careful policies. Even a 10% chance of AGW (which means that there is 90% chance that AGW is not true) should make us err on the side of caution. Nobody would accept, say, a 10% chance that we would ignite the atmosphere in the coming century or 10% chance of some other global disaster. So the very absence of total proof that there is no AGW is sufficient to warrant careful policies.

But that has *nothing* to do with the question whether it makes sense or not to investigate in the difficulties that the AGW theory still faces. The very fact that taking on this position now makes you a heretic, or a non-scientist, or a spokesman of this or that presumed lobby, is, to me, as a scientist, profoundly shocking.

Also the 90% certainty displayed by the IPCC is itself just a statistical estimate of a distribution of responses to radiative forcings which is based upon certain hypotheses which are then given 100% a priori certainty. I think it is a very optimistic estimate of the actual state of knowledge.

 

[Andre]

We have had, according to their saying, official members of the IPCC here on this board requesting that discussions be closed simply because they were putting in doubt aspects of the AGW hypothesis, and that this should be treated as crackpot stuff, as if it were creationism or something of the kind.

I should not react to the less apparent due diligence of that IPCC groupthink but this is insane. If you can't win the discussion, remove the opponent. Why wasn't this alleged IPCC member invited to refute the rebuttals and demonstrate the robustness of the climate change notion?

Problem is that all evidence has evaporated; the ice cores; the hockeystick and the actual records.

In the beginning there were the ice cores showing a remarkable correlation between "temperature" and carbon dioxide. Given the greenhouse effect hypothesis this appeared to be a rather convincing substantiation, which certainly warranted climate caution.

But later research showed a substantial lag of CO2, following temperatures and the alternate guess of explaining it away as positive feedback, has never been substantiated. Instead, the characteristic behavior of positive feedback is missing. It actually shows that CO2 did nothing observable, essentially falsifying the estimated greenhouse effect of CO2.

Then came the hockey stick, Mann et al ironing out the wrinkles of the Medieval Warming Period and the Little Ice age in the last millennium; showing an overwhelming convincing nobrainer correlation between temperatures and CO2 both rising dramatically in the last millenium.

But then it was demonstrated that the hockey stick was mainly based on an incorrect algoritm, causing all Monte Carlo simulations to produce hockeysticks. Later reconstructions of the last millennium do show the Medieval Warm Period and the Little Ice Age again, demonstrating the predominance of natural variability independent of CO2. Mind that he discussion, whether or not the Medieval Warm Period was warmer than today, is irrelevant and plays no role in asserting the “warming power” of CO2.

An then the actual records; indeed the temperatures and CO2 were rising simultaneously in the last quarter of the last century, again suggesting causality. However the warming trend diminished around the beginning of this century, while the CO2 continued to rise, again demonstrating that natural variability outperforms CO2.

Notice also that melting glaciers, a warmer Arctic and rising sea levels, merely proof changing conditions, but not what caused those changes. Furthermore, notice also that climate model runs, based on the unproven hypothesis merely constitute circular reasoning. That’s no evidence either.

So what is the evidence left that supports substantial warming due to rising levels of CO2? I can’t think of any. Instead we have competing hypotheses (Chilingar et al 2008, Miscolczi 2007) explaining why the basic idea’s of the greenhouse hypothesis may be incorrect.

But it doesn’t matter since we have to curb emissions anyway to transit to sustainable energy, right? Wrong. It matters because science is turned into ideology or dogma here to enforce policy. That will backfire hard eventually when proven incorrect in the future. Perhaps we should let the governments be run by engineers, who can’t afford basing their designs on unproven dogmas.

 

[wolram]

The worrying thing to me is, that scientists can not derive an experiment to prove or dis prove AGW, the laboratory is Earth and is tangible, or is it that this problem IS so testable?

 

[Andrew Mason]

However, science is science and it is not because the means to gather proof are harder, that truth is easier to find and hence that one has to be less rigorous. And what disturbs me profoundly in the *scientific* discussion of AGW, is that open but sceptic inquiry is now frowned upon - while it should be the prevailing attitude. When you look at the IPCC and all the supportive bodies around it, it seems that if you even dare to question certain hypotheses of the AGW theory, you are stamped as a heretic, a climate sceptic, etc... with the underlying insinuation that you are or a crackpot, or that you have some or other vested interest in denying AGW, or that you have yourself leading by your emotions and are in a psychological state of denial.

There is a big difference between questioning a theory and taking a position that the theory is wrong. The first is good science. The second is not, unless you can a) provide conclusive evidence against it and b) provide an alternative theory that explains all the evidence.

AM

 

[Andre]

There is a big difference between questioning a theory and taking a position that the theory is wrong. The first is good science. The second is not,

What happened to the scientific method? It's not the subjective position one takes, it's the objective evidence that counts. If you can't falsify a hypothesis, the chance is that there is some truth in it

unless you can a) provide conclusive evidence against it and b) provide an alternative theory that explains all the evidence.

No, conclusive evidence is enough. It doesn't matter if the defendant has a motive and has no alibi and is the owner of the murder weapon. If the DNA of the offender doesn't match, he is innocent. Period. The barrister/counselor doesn't have to proof who else did it.

nevertheless, my previous post shows both elements

 

[vanesch]

The worrying thing to me is, that scientists can not derive an experiment to prove or dis prove AGW, the laboratory is Earth and is tangible, or is it that this problem IS so testable?

Sure, we're doing it right now. We're pumping a lot of CO2 up there. One day, we will have lowered our CO2 output dramatically, or because we all collectively decided so (for good or bad reasons), or because there are no cheap fossil fuels left. That can be 30 years in the future, or 200 years in the future. It is then sufficient to look at the climate records over still some more decades, and the issue will be settled for good. So between 50 and 200 or 300 years, we will know for sure and there will be no more discussion

The drawback is that it is a long experiment...

 

[Andrew Mason]

No, conclusive evidence is enough.

Conclusive evidence is enough to falsify a theory. But that does not necessarily mean that the conclusion is wrong, just the theory supporting the conclusion. To take a position that the conclusion that human activity is warming the Earth is wrong, a scientist has to provide conclusive evidence that the AGW theory is wrong and offer an explanation that is consistent with all the evidence that leads to a different conclusion.

It doesn't matter if the defendant has a motive and has no alibi and is the owner of the murder weapon. If the DNA of the offender doesn't match, he is innocent. Period. The barrister/counselor doesn't have to proof who else did it.

DNA is not always conclusive. It depends on the circumstances. The case of Dr. John Schneeburger is a case in point. The eyewitness (the victim of a rape) said he did it. A DNA sample extracted from his arm did not match the DNA of the perpetrator left at the crime scene. A second DNA test on blood from the Dr. matched the first sample. There was another "theory" that fit all the evidence and the complainant was vindicated and Schneeburger was convicted.

Usually, though, if DNA does not match, the non-match is conclusive evidence exhonerating the accused and proving another theory and resulting in another conclusion ie that the perpetrator was a person whose identity is not known.

AM

 

[Andre]

Conclusive evidence is enough to falsify a theory. But that does not necessarily mean that the conclusion is wrong, just the theory supporting the conclusion. To take a position that the conclusion that human activity is warming the Earth is wrong, a scientist has to provide conclusive evidence that the AGW theory is wrong and offer an explanation that is consistent with all the evidence that leads to a different conclusion.

Wouldn't be the first step, testing the AGW hypothesis with real life data. Sure that has been done and there was evidence that supported it but, repeating myself, now ALL evidence is evaporated, verschwunden. We only see natural variability, there is nothing left that needs to be explained other than natural variability can't explain.

 

[DEMcMillan]

Before moving to other topics, this thread touched on CO₂ level effects on human physiology with little recognition of the ability of closed environments to raise CO₂ levels when large numbers of humans or animals raise CO₂ by their breathing.

Consider a thousand people attending a function in a room of 1000 m² are and 10 m height. As they enter the volume of CO₂ is about 3,500 liters. They each exhale 1 liter each 6 minutes. After 2 hours the level becomes 23,500 liters. No-one notices because each of us is already experiencing a much higher CO₂ inhalational level due to “dead space” exchange effects in which the 5% CO₂ air that we exhale is mixed with incoming air. Now think about the levels achieved on a submarine and the need to be concerned but not dismayed. The CO₂ levels we need to consider are well below toxic levels in all cases.

On the other hand, now land on Venus or Mars with an over 95% CO₂ atmosphere. Respiration now introduces a nineteenfold rise in a gas that dissolves quickly in water and dissociates into hydronium (H₃O⁺ = H⁺) and bicarbonate (HCO₃^-) ions to create an instant acidosis as well as taking away oxygen needed for cerebral activity. The drop in pH becomes as important as the lack of oxygen in killing us.

While we are in the health-carbon area we seem to be missing a major point in the recent dialogue about carbon and its potential negative effects on “World” climate. The rising use of “fossil fuels” in the last half century has had one unambiguous effect on the World. It has released very low ¹⁴C carbon into the atmosphere, lowering the elevation that was produced by atmospheric testing from the end of World War II to 1969. The rise and fall are of the same magnitude, returning us to pre-WWII ¹⁴C levels. This confirms the allegation of the magnitude of the addition. It also means that ¹⁴C levels would be 30% higher without fossil fuel use.

What is the ¹⁴C doing to our health? We have 18% carbon bodies. For a 70 kg adult, this converts to 6.3x10²⁶ carbon atoms. One in a trillion (10^-12) is ¹⁴C, giving us 6.3x10^{14 14}C atoms in our bodies. ¹⁴C half life is 5,730 years, giving us a rate of disintegration of 6x10⁸ per day or 7,000 per second. Each event emits an electron from the nucleus whose average energy is 156 keV. A molecular bond can be broken by 2 eV of energy. A feature of this disintegration is that the atomic number of the product goes up 1. It is once again nitrogen, altering the chemistry of its molecule. In DNA, this means a chain disruption that needs repair. DNA chain repair takes time and an unrepaired change mediated by the altered state can lead to a chromosomal crossover linkage. Such crossovers are responsible for malignant diseases and other proliferation problems. No-one has been able to quantify the C to N effect. General features of exposure to radiation are used to estimate the problem’s magnitude. What ever its magnitude, this problem is 30% less than it would have been without fossil fuel use.

 

[vanesch]

While we are in the health-carbon area we seem to be missing a major point in the recent dialogue about carbon and its potential negative effects on “World” climate. The rising use of “fossil fuels” in the last half century has had one unambiguous effect on the World. It has released very low ¹⁴C carbon into the atmosphere, lowering the elevation that was produced by atmospheric testing from the end of World War II to 1969. The rise and fall are of the same magnitude, returning us to pre-WWII ¹⁴C levels. This confirms the allegation of the magnitude of the addition. It also means that ¹⁴C levels would be 30% higher without fossil fuel use.

What is the ¹⁴C doing to our health? We have 18% carbon bodies. For a 70 kg adult, this converts to 6.3x10²⁶ carbon atoms. One in a trillion (10^-12) is ¹⁴C, giving us 6.3x10^{14 14}C atoms in our bodies. ¹⁴C half life is 5,730 years, giving us a rate of disintegration of 6x10⁸ per day or 7,000 per second. Each event emits an electron from the nucleus whose average energy is 156 keV. A molecular bond can be broken by 2 eV of energy. A feature of this disintegration is that the atomic number of the product goes up 1. It is once again nitrogen, altering the chemistry of its molecule. In DNA, this means a chain disruption that needs repair. DNA chain repair takes time and an unrepaired change mediated by the altered state can lead to a chromosomal crossover linkage. Such crossovers are responsible for malignant diseases and other proliferation problems. No-one has been able to quantify the C to N effect. General features of exposure to radiation are used to estimate the problem’s magnitude. What ever its magnitude, this problem is 30% less than it would have been without fossil fuel use.

Ok, this is going to get off topic, but this is dramatic for 2 reasons, the first one being that if there are people 5000 years of so from now are going to get all of their history wrong because of that erroneous C-14 scale, and second, because if it happens to be true that there is hormesis, then we are doing away with all that good radiation that would have stimulated our cell repair mechanisms

No, seriously, I don't think that the slight lowering of the radiation dose due to C-14 compensates all the toxic stuff we inhale because of coal powered plants...

 

[billiards]

Wouldn't be the first step, testing the AGW hypothesis with real life data. Sure that has been done and there was evidence that supported it but, repeating myself, now ALL evidence is evaporated, verschwunden. We only see natural variability, there is nothing left that needs to be explained other than natural variability can't explain.

That's a bold statement.

Although it raises a fair point:

Looking at these temperatures, and comparing to the life-over-time chart below, it would seem that Humans have evolved on a planet with bipolar glaciation, a fairly unusual state of affairs in Earth History. How will the humans react to change? My guess is they'll get scared and try to kill each other, who knows, maybe they will become extinct?


http://lachlanhunter.deadsetfreestuff.com/geological_time.jpg

 

[Andre]

... the first one being that if there are people 5000 years of so from now are going to get all of their history wrong because of that erroneous C-14 scale, ...

It's exactly that atmospheric 14C variation that has played an essential role in the myth forming. In the early days of ice core layer counting and the discovery of the large isotope excursions (d18O) it was assumed that these resembled temperatures, which is not unlogical. So seeking confirmation of that, the ice core records were compared with many other geologic records which were carbon dated. However, little one was aware of the high variability of the delta14C in atmospheric CO2, which led to mismatching. For instance some glacial readvance was carbon dated 12,000 years BP and the start of the alleged hyper cold Younger Dryas was counted to about 12,900 - 12,700 years ago. It seemed a perfect match and one could move ahead with such a nice evidence.

Now the problem is that 12,000 14C years calibrates with INTCAL04 to about 13,830 calendar years which is in the middle of the alleged warm Bolling Allerod interval.

Of course one never looks back to see if the process was still valid with modern information available, because that would seriously challenge this interpretation:
edit:

see for instance:
http://www.aip.org/history/climate/cycles.htm
http://www.aip.org/history/climate/rapid.htm

 

[DEMcMillan]

Vanesch wrote

No, seriously, I don't think that the slight lowering of the radiation dose due to C-14 compensates all the toxic stuff we inhale because of coal powered plants...

You seem to equate nitrogen oxide and sulfur dioxide effects with radiation exposure. Do you have any evidence to support your position. I live in an area where all electricity is generated from coal. No-one here knows of such a relationship. If you are right we need to abandon solar and wind power because, being periodic, they will need to be supported by coal. Nuclear is not suited to periodic use. Periodic Sierra hydroelectric use is prominent in California in summer but is at capacity. I have lived before where wind power was used and was annoyed by the devices’ appearance without knowing yet of the bird deaths.

30% is more than a little. People in the radiation-cancer field usually make the relationship linear. The DNA repairase process may produce some positive feedback, increasing disease more than linearly.

I lived for 14 years in the Southern California air basin where inversions mediated by the Pacific were a regular feature. Aldehydes and opacity were the main source of difficulty. Collection of gasoline vapor to avoid its entry into the air has reduced opacity. Conversion of diesel trucks to natural gas is useful there but cab conversions are all for show. Future supplies of natural gas are threatened by a number of NIMBY movements. An attempt there to have ships use only low gravity bunker oil while in the area is being met with resistance that will raise shipping costs.

 

[Andrew Mason]

Wouldn't be the first step, testing the AGW hypothesis with real life data. Sure that has been done and there was evidence that supported it but, repeating myself, now ALL evidence is evaporated, verschwunden. We only see natural variability, there is nothing left that needs to be explained other than natural variability can't explain.

So I guess you can explain Venus' surface temperature without reference to CO2 content of its atmosphere.!?

AM

 

[vanesch]

Vanesch wrote
You seem to equate nitrogen oxide and sulfur dioxide effects with radiation exposure. Do you have any evidence to support your position. I live in an area where all electricity is generated from coal.

I don't have any evidence because there is no evidence at all that low levels of radiation exposure have any health effect at all - one only takes on *by convention* the LNT model in radiation protection, because it is the severest model that makes sense. From that model one can calculate the expected number of victims due to a radiation exposure. It is 5.6% of chance to die prematurely per Sievert of equivalent dose. I think, off the top of my head, that the dose you are talking about must be around 100 microsievert per year or so (C-14 is a fraction of the natural body self-irradiation, next to cosmic and telluric irradiation which amounts to a few hundred microsieverts a year).

The average world exposure is 2.4 mSv / year, of which about 0.4 mSv comes from medical diagnosis exposure (world average) and 1.2 mSv / year medical diagnosis exposure in the West (dentists and the like). Most of the natural background radiation varies, from about 1 mSv to 10 mSv per year, but there are some places where this gets in the 100 mSv / year, without observable effects which can clearly be distinguished from other variability.
So I don't think we should get nervous because of 0.1 mSv or so...

That said, a serious fraction of particulate and chemical air pollution is due to coal fired plants, and that pollution is known to lead to a significant number of death per year. Coal brings in the environment large amounts of mercury, of radium, of uranium, etc...

No-one here knows of such a relationship. If you are right we need to abandon solar and wind power because, being periodic, they will need to be supported by coal. Nuclear is not suited to periodic use.

That's a misunderstanding. See https://www.physicsforums.com/showpost.php?p=1949854&postcount=235 and related posts.

Nuclear is flexible, more so than coal. The only sources which are more flexible are hydro and gas. But nuclear can follow load for more than 99% of the time.

30% is more than a little. People in the radiation-cancer field usually make the relationship linear. The DNA repairase process may produce some positive feedback, increasing disease more than linearly.

Actually, the DNA repair mechanism is more the theoretical basis for models where the effect of a small dose variation is smaller than given by an overall linear relationship, and maybe even a threshold or even hormesis.

But in any case, any non-linear relationship between dose and effect that remains in agreement with effects at higher, measured doses will have a lower effect of a small increase in dose than the linear model. If you don't believe this, do the example with a quadratic model. It is only in the improbable case where the "quick rise" would be exactly on the background level that one would get a worse effect. The reason why this is improbable is that there are very large variations in natural background from place to place.

Now, what you may not know is that the radioactive exposure of people by coal fired plants is several times higher than due to the entire nuclear industry, and with nearby coal fired plants, this can amount up to 200 microsievert per year. That's still a low dose, btw, but of the order of the C-14 effect you were talking about.

EDIT: that said, we are really off-topic here, and any further discussion should be in the nuclear engineering forum...

 

[Andre]

So I guess you can explain Venus' surface temperature without reference to CO2 content of its atmosphere.!?

AM

That's not the question. It's not about challenging the radiative proportions of CO2, it's about understanding how it works. The question is if the condition of Venus would constitute support/proof for the IPCC greenhouse hypothesis or would it support the convection hypothesis of Chilingar et al. Let's see,

The IPCC assumes a global temperature increases of about 3 degrees per doubling CO2, Now if you do the math for Venus doubling the CO2 starting with 1ppmv you'd end up with an order of magnitude of about 20 degrees per doubling. It would require a rather creative explanation to talk that together.

However Chilingar et al propose that the Earth atmosphere is mainly heated by convection The convection transports the heat up so that the chance increases that emitted energy escapes to space rather than being re-absorpted at the Earth surface. How is this for Venus? The strong radiative properties of the CO2 are suppressing convection in the lower atmosphere. Hence energy emitted from the surface has a far larger chance to hit the surface again. Venus is missing the convective air conditioner of Earth.

Hence the Venus numbers don't add up for the IPCC hypothesis but the missing convection in the lower layers do support Chilingar et al.

There is a lot more to say about the origin of the heat of Venus but that's less relevant here.

 

[Andre]

That's a bold statement.

Sorry Jack, I intended to react earlier but I wasn't sure what you intended to suggest.

Anyway, I don't seem to recall that the IPCC had presented the geological alleged greenhouse-icehouse pendulum as evidence for CO2 causing warming. It could be equally true that warming caused higher CO2 levels as the ice cores suggest. Apart from that, there are deviations. The Paleocene greenhouse appears to have had http://lib.bioinfo.pl/pmid:11423657 .

So I stand by my capitals for ALL evidence being evaporated.

 

[mheslep]

...The IPCC assumes a global temperature increases of about 3 degrees per doubling CO2, Now if you do the math for Venus doubling the CO2 starting with 1ppmv you'd end up with an order of magnitude of about 20 degrees per doubling. It would require a rather creative explanation to talk that together...

Most of IPCC's 3 degrees/ 2x CO2 is from feedbacks, mainly water vapor effects, as you often point out, so I don't think one can compare directly to Venus in this way.

 

[billiards]

Sorry Jack, I intended to react earlier but I wasn't sure what you intended to suggest.

Anyway, I don't seem to recall that the IPCC had presented the geological alleged greenhouse-icehouse pendulum as evidence for CO2 causing warming. It could be equally true that warming caused higher CO2 levels as the ice cores suggest. Apart from that, there are deviations. The Paleocene greenhouse appears to have had http://lib.bioinfo.pl/pmid:11423657 .

So I stand by my capitals for ALL evidence being evaporated.

Let me apologize, I originally intended to make a point about your "all evidence evaporated" claim seeming a bit ... extreme. Then I got to thinking about how in terms of geological time we're going through a cold spell, and that any warming we experience will be within natural variability. Yet that doesn't necessarily mean that the cause of the warming is natural!

The point I failed to make in that post was that even though 6+ degrees of warming would seem to be "natural" within the range of temperatures experienced over geological time, we are perhaps encouraging this warming by pumping out CO2.

 

[DEMcMillan]

vanesch has seen no benefit from fossil fuel use in the fall in ¹⁴C body radiation from 10,000 to 7,000 disintegrations/sec since 1969. He uses radiation hormesis to make his argument. I looked for ¹⁴C experiments to document its hormesis and could find none. Are there any? I will use chronic myelogenous leukemia as an example of a disease produced by ¹⁴C. Its post-exposure incidence rose after Hiroshima http://en.wikipedia.org/wiki/Chronic_myelogenous_leukemia and has been falling widely in recent years http://seer.cancer.gov/statfacts/html/cmyl.html . Its hallmark is the Philadelphia chromosome, making it an early unsuccessful target of genetic engineering. The product of the crossover, a tyrosine kinase, has become a target of a successful treatment. Radiation hormesis http://en.wikipedia.org/wiki/Radiation_hormesis is more controversial than chemical hormesis, a newer version of the homeopathy of a century ago. vanesch doesn’t seem to consider it in his treatment of coal products, but it is an easy assertion for me. My southern California experience taught me that aesthetic judgments need to be supported by health burden data. Do you have any significant information about coal use air product toxicity? It is an important consideration.

 

[Andrew Mason]

That's not the question. It's not about challenging the radiative proportions of CO2, it's about understanding how it works. The question is if the condition of Venus would constitute support/proof for the IPCC greenhouse hypothesis or would it support the convection hypothesis of Chilingar et al. Let's see,

The IPCC assumes a global temperature increases of about 3 degrees per doubling CO2, Now if you do the math for Venus doubling the CO2 starting with 1ppmv you'd end up with an order of magnitude of about 20 degrees per doubling. It would require a rather creative explanation to talk that together.

However Chilingar et al propose that the Earth atmosphere is mainly heated by convection The convection transports the heat up so that the chance increases that emitted energy escapes to space rather than being re-absorpted at the Earth surface. How is this for Venus? The strong radiative properties of the CO2 are suppressing convection in the lower atmosphere. Hence energy emitted from the surface has a far larger chance to hit the surface again. Venus is missing the convective air conditioner of Earth.

Radiation is entirely a function of termperature. A black body at a given temperature emits a radiation distribution according to Planck's law. So it has nothing to do with CO2's radiative properties.

Convection and conduction operate in the atmosphere. The surface heats by absorbing radiation from the sun. The layer of atmosphere in contact with the surface warms by conduction. That layer moves due to change in buoyancy and is replaced by cooler air which, in turn, warms by conduction from the surface. The result is that heat is transferred to the atmosphere.

This has the effect of cooling the surface of the Earth by transfering some of the heat to the atmosphere. But now IR radiation from the atmosphere, in addition to the radiation from the sun, reaches the Earth surface thereby increasing the amount of radiation from (and therefore temperature of) the surface.

My question is how does increasing the CO2 affect the conduction/convection process and introduce more cooling, as Chilingar et al suggest?

AM

 

[Andrew Mason]

That's not the question. It's not about challenging the radiative proportions of CO2, it's about understanding how it works. The question is if the condition of Venus would constitute support/proof for the IPCC greenhouse hypothesis or would it support the convection hypothesis of Chilingar et al.

...

Hence the Venus numbers don't add up for the IPCC hypothesis but the missing convection in the lower layers do support Chilingar et al.

The IPCC says that there is another important mechanism of heat transfer operating in the atmosphere (other than conduction/convection). It says that radiation from the Earth is absorbed by certain gases, particularly CO2 which is opaque to a broad range of infrared radiation. The atmosphere continues to be warmed by conduction and convection but also by this absorption of radiation. It is this additonal heating that raises the temperature beyond what normal conduction/convection contributes. This increases the radiation reaching the surface and therefore the surface temperature.

Chilingar et al do not appear to address this at all.

AM

 

[Andre]

The IPCC says that there is another important mechanism of heat transfer operating in the atmosphere (other than conduction/convection). It says that radiation from the Earth is absorbed by certain gases, particularly CO2 which is opaque to a broad range of infrafred radiation. The atmosphere continues to be warmed by conduction and convection but also by this absorption of radiation. It is this additonal heating that raises the temperature beyond what normal conduction/convection contributes. This increases the radiation reaching the surface and therefore the surface temperature.

Chilingar et al do not appear to address this at all.

AM

That's, right they don't. But the keyword is emission altitude. (sorry short in time right now)Mind that if the incoming radiation is worth a blackbody temperature of -18C then at radiation equilibrium, the outgoing emission must originate from the same temperature range. No?

That's somewhere high in the atmosphere, what happens below there is a mixture of conduction, convection and radiation. More later

 

[Andrew Mason]

That's, right they don't. But the keyword is emission altitude. (sorry short in time right now)Mind that if the incoming radiation is worth a blackbody temperature of -18C then at radiation equilibrium, the outgoing emission must originate from the same temperature range. No?

Not exactly. If outward radiation from any part of the surface or of the atmosphere is not absorbed on its way out, it will leave the earth. If it is aborbed, it will be re-radiated and 50% of it will be radiated back toward the earth. If above certain level the atmosphere did not contain any molecules that could absorb outward radiation and below that level the molecules absorbed ALL the radiation coming from below, the temperature of the atmosphere at that level would be the blackbody temperature of the earth. But the atmosphere is not like that.

Radiation emission orginates from all different levels at all different temperature ranges. Generally, the atmosphere is at thermal and radiation equilibrium at all altitudes.

The radiation distribution (the graph of intensity of radiation as a function of frequency) as seen from space will be the Planck curve corresponding to the blackbody temperature of the earth. That never changes (unless the emissivity of the Earth changes, which is a function of the Earth's albedo). What changes is the altitude in the atmosphere where the temperature matches the Earth's blackbody temperature. As the atmosphere warms, the altitude at which the air matches the blackbody temperature of the Earth increases.
AM

 

[Andre]

As the atmosphere warms, the altitude at which the air matches the blackbody temperature of the Earth increases.

Or the cloud cover and density increases, due to the accelleration in the water cycle, reducing the insolation, reducing the temperature, remember Pallé et al (posted earlier).

The albedo variation is digitized from Pallé et al 2006, (fig2) variation in %. The global temperature variation in tenths of degrees in in top graph is from the file http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt issued by the Hadley Met office in the UK

Given that in the Stefan Boltzman law for grey body a variation of 10% in albedo as we see here amounts to about 2.5 degrees in temperature, instead of about 0.5 degrees. Hence, it appears that there is a significant negative feedback somewhere, suppressing a larger variation.
Edit: erratum 1% changed into 10%

 

[Andre]

Please close this conspiracy thread.

Wouldn,t you think that this would require some substantiation. Please go carefully over the thread and find evidence of conspiracy first.

 

[vanesch]

Please close this conspiracy thread.

I don't see a conspiracy here. There is no discussion of how the mean vile powerful Dr. Mad and the rich industrials to his boots and corrupt politicians are manipulating the minds of the innocent. There is a discussion of what scientific evidence there actually is that CO2 is the main cause of global warming, and what other plausible mechanisms could compete with that.

I myself have a few questions concerning the scientific *certainty* some display about the fact that CO2 is the main cause of a dramatic heating. I'm not putting into question its plausibility, but I'm putting into question its scientific certainty - meaning that there is a proof that is such, that any other mechanism would by necessity also violate some laws of physics. If that scientific case would be *beyond the slightest bit of reasonable doubt*, and if no other thinkable mechanism could be proposed challenging it without at the same time, say, challenging energy conservation or the second law of thermodynamics, and if it were a namecalling thread, then yes, this would be a conspiracy thread. But simply asking in a critical way of what exactly is the proof beyond doubt that CO2 is the sole, main origin of dramatic heating is, I would think, legitimate, no ?
Confronting the actual scientific case to a challenging critical question is all we could hope to promote, no ? Only better understanding can result from this.

 

[vanesch]

vanesch has seen no benefit from fossil fuel use in the fall in ¹⁴C body radiation from 10,000 to 7,000 disintegrations/sec since 1969. He uses radiation hormesis to make his argument.

That was a half joke of course, I don't need hormesis. I was just pointing out that if you go for one hypothesis, you can also go for another one, and arrive at a different conclusion.

What is true however, is that there is no indication of any health effect of small doses, and that the linear no threshold model is just that: a model. It has the property of being the severest model for small dose variations, and that's why it is adopted in health physics: one wants to err on the safe side. But again, there are no serious scientific indications that small doses do have effects.

Now, even if the LNT model turns out to be correct, it means that its effect is in the noise. If we can't measure it, it means that the global effects are unimportant, compared to other causes. According to this model, the average natural background radiation should cause about 0.6% of deadly cancers. Compare that to the real incidence of cancer deaths (something between 13-20%), and you see that it is a negligible effect.

BTW, I didn't find any reference to C-14 in the articles you cited.

The dose burden of C-14 as compared to the total natural background radiation, and even to the medical doses we are subject to, is rather small.

Concerning the coal pollution and victims, here's a link,
http://www.sierraclub.org/cleanair/factsheets/power.asp

but I agree that this is not a peer-reviewed thing at all.

There is also http://www.hsph.harvard.edu/news/press-releases/archives/2002-releases/press10172002.html

Something more official from the WHO:
http://www.who.int/entity/quantifying_ehimpacts/countryprofilesebd.xls

(41 000 yearly victims of air pollution in the USA).

However, I would also like to see some more substantiated material concerning this.

 

[Andre]

I don't see a conspiracy here. There is no discussion of how the mean vile powerful Dr. Mad and the rich industrials to his boots and corrupt politicians are manipulating the minds of the innocent.

How subtle. If one wonders whether or not this is happening, perhaps include "enron" in the google searches.

But looking back at the thread. I still don't see any evidence presented that singles out CO2 to cause the recent global warming at the end of the former century and I see no evidence that CO2 was the reason for any temperature fluctuation in the past.

 

[Andrew Mason]

...I'm not putting into question its plausibility, but I'm putting into question its scientific certainty - meaning that there is a proof that is such, that any other mechanism would by necessity also violate some laws of physics. If that scientific case would be *beyond the slightest bit of reasonable doubt*, and if no other thinkable mechanism could be proposed challenging it without at the same time, say, challenging energy conservation or the second law of thermodynamics, and if it were a namecalling thread, then yes, this would be a conspiracy thread. But simply asking in a critical way of what exactly is the proof beyond doubt that CO2 is the sole, main origin of dramatic heating is, I would think, legitimate, no ?

Who is saying it is beyond all reasonable doubt? Even climate scientists admit that they do not fully understand all of the factors that affect the Earth's climate.

All anyone is really saying is that increased CO2 and other IR asborbing gases will result in more heat radiating from the surface being trapped in the atmosphere AND that we are putting more CO2 and other IR absorbing gases in the atmosphere. That will tend to cause the temperature of the Earth surface and the atmosphere to rise. Whether there are other effects that will come into play that will reduce or nullify the heating effect of additional greenhouse gases, or that will accelerate the warming is a matter of ongoing study.

AM

 

[Andre]

Who is saying it is beyond all reasonable doubt? Even climate scientists admit that they do not fully understand all of the factors that affect the Earth's climate.

All anyone is really saying is that increased CO2 and other IR asborbing gases will result in more heat radiating from the surface being trapped in the atmosphere AND that we are putting more CO2 and other IR absorbing gases in the atmosphere. That will tend to cause the temperature of the Earth surface and the atmosphere to rise. Whether there are other effects that will come into play that will reduce or nullify the heating effect of additional greenhouse gases, or that will accelerate the warming is a matter of ongoing study.

AM

One should take more factors into consideration, for one we have discussed convection and diurnal variation and putting more CO2 in the atmosphere also increases the outradiation into space. Which causes cooling again. Another factor that has not been discussed is the quantitative heat transportation and specific heat capacity of the out radiating atmosphere. Perhaps that Chiligar's increased convection rate also increases the energy flow to the average effective emission altitude, causing the increased 'trapped' heat to be vented out at comparable rates again. Just pondering about why all evidence suggest no detectable variation in temperature with variation in greenhouse gas concentration.

 

[vivesdn]

That will tend to cause the temperature of the Earth surface and the atmosphere to rise

Some years ago, three engineers were playing with their new toy: a computer. Instead of crashing cars, they were designing and testing a new structure with it. At a given moment, a crash of the current structure had still high damage on legs for rear passengers. Well, the T (inverted) junction between front and rear doors was to be reinforced, obviuosly. But one of them asked to retest it on the computer. At the end, they did it, even when it was obvious that the junction needed to be strengthened. But the computer told them the opposite: the junction needed to be weaker to allow a *correct* deformation to protect passenger's legs.

Given this real story and its moral:
* Are you sure that increasing CO2 will increase air temperature?
* Are you sure high albedo will increase Earth temperature?
* Are you sure that CO2 increase is coming from higher rates of production and not from lower rates of sinking?
* Being water a high performing GHG, will more humidity feed an increase of temperature or will cloud formation imply a descend of temperature?

None of these questions should be considered obvious. And finding reasonable proof for any of them is a hard task.

 

[Andrew Mason]

One should take more factors into consideration, for one we have discussed convection and diurnal variation and putting more CO2 in the atmosphere also increases the outradiation into space. Which causes cooling again.

This does not cause cooling. If the outradiation from the atmosphere increases, the temperature of the atmosphere must have increased. So, increased outradiation has to be associated with a temperature increase.

AM

 

[Andrew Mason]

Given this real story and its moral:
* Are you sure that increasing CO2 will increase air temperature?
* Are you sure high albedo will increase Earth temperature?

Increasing albedo will increase reflectivity of the Earth and decrease the temperature of the earth.

* Are you sure that CO2 increase is coming from higher rates of production and not from lower rates of sinking?

What matters is whether there is a human cause of increased CO2.

* Being water a high performing GHG, will more humidity feed an increase of temperature or will cloud formation imply a descend of temperature?

We don't really know. What we do know is that increased atmospheric temperature will increase the vapour pressure of water and this will have an effect on climate.

AM

 

[DEMcMillan]

Andrew Mason wrote “So I guess you can explain Venus' surface temperature without reference to CO₂ content of its atmosphere.!?‘
Venus has a very hot surface and a complete cloud cover. The atmospheric pressure at its surface is 93 times that of Earth. A 1991 Magellan rocket recorded its atmospheric temperature; the recording stopped at 34 km altitude. http://www.datasync.com/~rsf1/vel/1918vpt.htm This figure extends its last recorded temperature to Venus’ surface using four lines to intersect at four surface temperatures reported later. The dry adiabatic lapse rate for Venus has been calculated by NASA to be 10.5 ^oK/km compared to 9.8 ^oK/km for Earth http://pds-atmospheres.nmsu.edu/education_and_outreach/encyclopedia/adiabatic_lapse_rate.htm
The difference is mediated by Venus’ slightly lower gravitational force and higher atmospheric mean molecular weight. The lines argue that Venus’ lower atmosphere is adiabatic, not heated by radiation. Venus’ temperature at 58 km altitude is 260 ^oK. This is the top of its sulfuric acid cloud. Below the cloud top, Venus’ temperature rises continuously to about 730 ^oK at the planet’s surface. Earth’s stratosphere has a peak temperature of 262 ^oK at 50 km mediated by ozone, but its temperature at 10 km is only 217 ^oK, rising to 298 ^oK at its surface. Venus’ outward radiation is determined by the temperature at its cloud top. 260 ^oK means 259.1 W/m2. The cloud reflects an albedo of 0.65 to lower the planet’s net downward solar radiation to 228.8 W/m2. The reduction in outward loss needed for radiation balance is 39.7 W/m2. The balancing temperature without a greenhouse effect would be 252 ^oK, 8 ^oK lower. Venus’ surface is ~730 ^oK because of its dense atmosphere. CO₂ contributes 8 ^oK at the top. It is the massive nature of Venus’ atmosphere that acts adiabatically over a wide altitude range to make it so hot.

 

[vanesch]

Who is saying it is beyond all reasonable doubt? Even climate scientists admit that they do not fully understand all of the factors that affect the Earth's climate.

All anyone is really saying is that increased CO2 and other IR asborbing gases will result in more heat radiating from the surface being trapped in the atmosphere AND that we are putting more CO2 and other IR absorbing gases in the atmosphere. That will tend to cause the temperature of the Earth surface and the atmosphere to rise. Whether there are other effects that will come into play that will reduce or nullify the heating effect of additional greenhouse gases, or that will accelerate the warming is a matter of ongoing study.

AM

Ah. Well, that's also the statement I subscribe to. I would even add that "there are indications that it is possible that these effects are amplified through feedback and could potentially lead to much stronger heating than just the optical effect of the greenhouse gasses". But that's not really what is said everywhere in scientific circles, and it is certainly not the impression you get when you read the IPCC summary reports. There the tone is more that it is now "scientifically established" that there is going to be a strong heating, and the only thing that is left is an uncertainty of how much: 90% chance between 1.5 and 6 degrees, with a most probable value of 3 K.

 

[vanesch]

This does not cause cooling. If the outradiation from the atmosphere increases, the temperature of the atmosphere must have increased. So, increased outradiation has to be associated with a temperature increase.

Yes, of upper layers in the atmosphere. The point is that convection can change the temperature profile of the atmosphere, and depending on that profile, you have a different radiative balance. That is the same as changing the resistivities in a resistive chain, will change the potential distribution along that chain, and will also change the overall current, for the same overall potential difference.

 

[vivesdn]

Increasing albedo will increase reflectivity of the Earth and decrease the temperature of the earth.

Ok. And low albedo will increase temperature? Sure?

What matters is whether there is a human cause of increased CO2.

The origin of CO2 matters if CO2 plays a role on climate change. But again, increase of CO2 is due to increased sources (human cause) or due to low sinking?

We don't really know. What we do know is that increased atmospheric temperature will increase the vapour pressure of water and this will have an effect on climate.

And referring water vapour, then we should clarify this first, shouldn't we?

 

[vivesdn]

This does not cause cooling. If the outradiation from the atmosphere increases, the temperature of the atmosphere must have increased. So, increased outradiation has to be associated with a temperature increase.

AM

Consider an oven at a given inside temperature. Outoor temperature won't change significantly due to the oven. Between inner and outer walls will exist an stationary temperature gradient as thermal energy flows from the hotter inside to the cooler outside. The thicker the wall, the smaller the gradient, and less heat will be lost.
Now, inside the hard wall or even the vacuum wall (Dewar's flask) you have a coil with some fluid that goes from inside surface to outside surface and comes back on a closed loop. A pump keeps the fluid moving.
For sure you'll have increased the heat flow as you transport the hot fluid in contact with inner surface directly to the outer surface, were it will radiate and transfer far more heat as it will be much hotter than the wall would have been if heat was to travel due to temperature gradient through the wall.

 

[baywax]

Just found this article... they're calling these Brown Clouds a mask for Global Warming because of their reflectivity creating a cooling affect(?)

"Imagine for a moment a three-kilometer-thick band of soot, particles, a cocktail of chemicals that stretches from the Arabic Peninsula to Asia," Achim Steiner, UN undersecretary general and executive director of the program, said during a news conference on the findings.

"All of this points to an even greater and urgent need to look at emissions across the planet, because this is where the stories are linked in terms of greenhouse emissions and particle emissions and the impact that they're having on our global climate," he said.

The brown clouds have darkened 13 cities in Asia, including Beijing, Shanghai, Bangkok, Cairo, Mumbai, New Delhi and Tehran, "dimming" sunlight in some places by as much as 25 per cent.

The brown clouds, produced by the burning of fossil fuels, wood and plants, form particles like black carbon and soot that absorb sunlight and warm the air, enhancing the greenhouse effect.

Scientists, however, said the brown clouds also "mask" the warming impacts of climate change by an average of 40 per cent because they contain particles that reflect sunlight and cool the Earth's surface.

http://ca.news.yahoo.com/s/cbc/081113/world/technology_brown_clouds_1

Yetch.

 

[kasse]

This thread offends people of reason, and should be locked.

 

[Andrew Mason]

Yes, of upper layers in the atmosphere. The point is that convection can change the temperature profile of the atmosphere, and depending on that profile, you have a different radiative balance. That is the same as changing the resistivities in a resistive chain, will change the potential distribution along that chain, and will also change the overall current, for the same overall potential difference.

Certainly convection changes the temperature profile of the atmosphere. It moves heat from the surface to higher up in the atmosphere and reduces the temperature gradient. But convection exists now. It is not caused by the air absorbing IR radiation from the surface. It is caused by air being warmed by contact with the surface. It also does not change the radiative balance. That is determined by the amount of solar energy absorbed by the earth. That changes only with a change in the Earth's emissivity.

My original question was: how does an increase in CO2 increase convection? Or, looking at it another way, how does adding CO2 to the atmosphere increase convection beyond what adding the same amount of nitrogen or oxygen to the air?

AM

 

[Andrew Mason]

Consider an oven at a given inside temperature. Outoor temperature won't change significantly due to the oven. Between inner and outer walls will exist an stationary temperature gradient as thermal energy flows from the hotter inside to the cooler outside. The thicker the wall, the smaller the gradient, and less heat will be lost.
Now, inside the hard wall or even the vacuum wall (Dewar's flask) you have a coil with some fluid that goes from inside surface to outside surface and comes back on a closed loop. A pump keeps the fluid moving.
For sure you'll have increased the heat flow as you transport the hot fluid in contact with inner surface directly to the outer surface, were it will radiate and transfer far more heat as it will be much hotter than the wall would have been if heat was to travel due to temperature gradient through the wall.

I don't follow your analogy. If the energy supplied to the interior of the oven is constant and if the temperature is constant, the amount of energy being removed from the oven has to equal the amount of energy being supplied to the interior of the oven. If you increase the rate at which heat energy is removed, the temperature of the oven will reduce until the rate at which heat is removed exactly equals the rate at which energy is being supplied to the interior of the oven (ie. exactly the same rate as before).

Similarly, the energy which the Earth radiates is determined not by the nature or motion of the atmosphere (assuming there is no change in reflectivity/emissivity), but by the amount of radiation incident upon the Earth (ignoring the heat emerging from the interior of the earth). The total amount of radiation emanating from the Earth is completely independent of convection occurring in the atmosphere or the oceans for that matter. The rate at which energy is radiated from the Earth has to be exactly equal the insolation: the rate of radiation energy incident upon it. If this is not the case, the Earth's temperature would self-adjust until the incoming radiation matched the outgoing radiation.

So increased convection cannot increase the amount of radiation emanating from the earth.

The CO2 problem is an insulation not an insolation problem. If the CO2 concentration of the atmosphere increases, more of the outward IR radiation from the surface is absorbed by the atmosphere and half of that is reradiated back to the surface. This means the surface has to heat up in order to balance outward and total inward radiation. Although the total radiation from the Earth does not change, the temperature at the surface of the Earth has to increase.

AM

 

[vanesch]

My original question was: how does an increase in CO2 increase convection? Or, looking at it another way, how does adding CO2 to the atmosphere increase convection beyond what adding the same amount of nitrogen or oxygen to the air?

I have no idea how CO2 can influence convection all by itself. But what is true is that an increased CO2 content will increase the "opacity" of the atmosphere to IR, and hence as such redistribute absorbed and emitted power fluxes. This can have an influence on the temperature distribution in the atmosphere, which by itself is responsible for the drive behind convection.

But that is not the main point. IMO, the main point is that convection is a negative feedback mechanism (independent of whether there is CO2 or not) for radiative forcing of the surface, in that if the radiative forcing increases, then the surface temperature will also increase, and this will drive more convection, which will allow for a larger heat flux to transit through the atmosphere than when no such convection were present.

You are of course right that the total outward flux must equal the inward solar flux that is not reflected directly as visible light (albedo). So the total outward IR flux is fixed (at fixed albedo), and this, independent of what is the composition, and what are the heat transport mechanisms in the atmosphere. At least in a simple 1D model.

So we know (for fixed albedo) what is going to be the outward radiant IR flux. However, what we are interested in, is the total temperature gradient in the atmosphere needed to obtain that IR radiant flux. This net flux is everywhere going to be the same, at every point in the atmosphere. It will of course be composed of different partial fluxes: a radiant upward flux, a radiant downward flux, heat convection, and heat conduction. But the total balance, at every point in the atmosphere, must equal the same, fixed, outward IR flux. As such, the atmosphere (and even the vacuum) act as a kind of "resistor" in which a radiant flux is driven by temperature differences. For the "vacuum", that "resistor" is simply given by the black body formula: for a certain temperature (difference: with the CMB, but that's neglegible), we have a certain outward radiant flux. The atmosphere adds "resistance" to this: we need a bigger temperature difference to obtain the same radiant flux. That extra resistance is the greenhouse effect. It is due to the partial absorption and re-emission of IR radiation by layers of the atmosphere, which cause also a downward IR flux, and hence we need a higher upward flux to compensate, and arrive at the same net outward flux.

As such, we can think of heat to "make its way" through the atmosphere, and needing an extra "delta-T" each time it crosses a layer of atmosphere. The more the atmosphere absorbs, the more delta-T there is, and that's the basis of the extra greenhouse effect due to greenhouse gasses.

Also, these "delta-T"s will influence the temperature differences in the atmosphere itself.

So radiatively speaking, heat gets emitted from the Earth surface, is radiated a bit upward, then a bit downward, then a bit upward again, etc... and makes its way all the way up to the highest layers, where it is eventually emitted in space. The sum of all these final contributions must make up the fixed outward radiant flux. The more opaque the atmosphere, the "more difficult" this outward way is, and the higher the overall delta-T that establishes it. Hence, heating of the surface. Each atmospheric layer is a thermal resistor that increases a bit more the overall thermal resistance of this atmosphere.

But here's my point about convection: if there is a "second way" by which heat can be transported upward through the atmosphere, then it "shunts" part of those resistors. Heat can then, by this second way, reach the higher layers more easily than just by radiation from layer to layer, with each time a partial down radiation. And as such, it will lower the delta-T as compared when there were no such convection.

And now here's my point about feedback. If we look at the purely optical effect of increasing CO2 content of the atmosphere, as calculated by MODTRAN, without altering in any other way 1) the rest of the composition of the atmosphere and 2) any convection or whatever, then we find that for a doubling of the CO2 content, we need to increase the surface temperature by about 0.8K in order to restore the same outward IR flux as before (which, we agree upon, is fixed by the solar influx, and albedo).

Now, if you take it that the atmospheric composition also changes concerning water vapor, and you keep fixed relative humidity (instead of fixed total water vapor), which means that you suppose that at the surface, the wet surface will keep a similar equilibrium as the ratio between partial vapor pressure and temperature in the equilibrium case, but without more cloud formation or convection or anything, then you have, IMO, the maximal possible positive feedback from water vapor. MODTRAN then calculates that you need about 1.5 K surface temperature increase for a CO2 doubling, and the increase in water vapor (due to 1.5 K temperature increase) to have again the same outward IR flux. One would expect the right answer to be somewhere between the two. More water vapor probably means more cloud formation and so on (which increase albedo), but that effect is difficult to quantify. Water vapor is also lighter than air, so this might increase convection (what happens in a cooling tower). This might also decrease the effect of water vapor. Water will not evaporate more than given by the partial pressure equilibrium, so this case is the maximal water vapor feedback. So, without taking into account clouds or convection, according to MODTRAN, a CO2 doubling should result in a surface temperature increase between 0.8K and 1.5K.

Now, convection is a negative feedback which should reduce this needed temperature increase of the surface. I have no idea by how much, but I haven't seen any treatment of this.

But the IPCC talk about an average value of 3 K for CO2 doubling, in an interval of 1.5K to 6K. So there needs to be an extra positive feedback, which is not water vapor, and which is capable to bring this 0.8K to 1.5 K interval or smaller to the 1.5 K to 6 K interval. However, those mechanisms are not really explained. This is where I still have my question marks.

 

[Andre]

My original question was: how does an increase in CO2 increase convection?

Wasn't it mentioned that the Infra red radiative interaction starts in the lowest layers of the atmosphere, at the Earth surface, the primary source of the IR. With more CO2 the lower layers get warmer faster increasing the convection rate.

Also, since the convection is adiabatic it also shows that balancing the temperatures between air parcels by radiation is not a predominant process.

 

[wolram]

This thread offends people of reason, and should be locked.

People of reason should state their reasons why the thread should be locked.

 

[vivesdn]

I don't follow your analogy.

Heat is transferred from inside to the outside through a medium. If the medium is solid, heat is transferred by contact and radiatively layer by layer, creating a T gradient. The greater the gradient the higher the heat flow. But with convection in place, high temperature layers will radiate directly half of its energy to the outside, while in a situation with no convection, lower, high temperature layers will radiate half of its energy to upper layers. So not all of the energy is radiated outwards as upper layers will re-radiate inwards part of the energy

So increased convection cannot increase the amount of radiation emanating from the earth.

It is generally assumed that the temperature decreases at a rate around 2ºC every 300m o 1000 feet. This is the standard atmosphere, based on an standard gradient. But advection and convection have a great impact on this gradient, modifying energy transfer.

 

[mheslep]

...But the IPCC talk about an average value of 3 K for CO2 doubling, in an interval of 1.5K to 6K. So there needs to be an extra positive feedback, which is not water vapor, and which is capable to bring this 0.8K to 1.5 K interval or smaller to the 1.5 K to 6 K interval. However, those mechanisms are not really explained. This is where I still have my question marks.

Off the top of my head they cite surface albedo changes from ice cover losses as one of the other feedbacks.