Does CO2 really drive global warming?

May 2001 Chemical Innovation, May 2001, Vol. 31, No. 5, pp 44—46 ^ | May 2001 | Robert H. Essenhigh, E. G. Bailey Professor of Energy Conversion, Ohio State University

[E. Pluribus Unum]

Does CO₂ really drive global warming?

I don’t believe that it does.

To the contrary, if you apply the IFF test—if-and-only-if or necessary-and-sufficient—the outcome would appear to be exactly the reverse. Rather than the rising levels of carbon dioxide driving up the temperature, the logical conclusion is that it is the rising temperature that is driving up the CO₂ level. Of course, this raises a raft of questions, but they are all answerable. What is particularly critical is distinguishing between the observed phenomenon, or the “what”, from the governing mechanism, or the “why”. Confusion between these two would appear to be the source of much of the noise in the global warming debate.

In applying the IFF test, we can start with the clear correlation between the global CO₂ profile and the corresponding temperature signature. There is now in the literature the report of a 400,000-year sequence clearly showing, as a phenomenon, that they go up—and down—together (1). The correlation is clear and accepted. But the causation, the mechanism, is something else: Which is driving which?

Logically, there are four possible explanations, but only two need serious consideration, unless they both fail.

• Case 1: CO₂ drives the temperature, as is currently most frequently asserted; and

• Case 2: Temperature drives the level of CO₂.

Both appear at first to be possible, but both then generate crucial origin and supplementary questions. For Case 1, the origin question is: What is the independent source of CO₂ that drives the CO₂ level both up and down, and which in turn, somehow, is presumed to drive the temperature up and down? For Case 2, it is: What drives the temperature, and if this then drives the CO₂, where does the CO₂ come from? For Case 2, the questions are answerable; but for Case 1, they are not.

Consider Case 2. This directly introduces global warming behavior. Is global warming, as a separate and independent phenomenon, in progress? The answer, as I heard it in geology class 50 years ago, was “yes”, and I have seen nothing since then to contradict that position. To the contrary, as further support, there is now documentation (that was only fragmentary 50 years ago) of an 850,000-year global-temperature sequence, showing that the temperature is oscillating with a period of 100,000 years, and with an amplitude that has risen, in that time, from about 5 °F at the start to about 10 °F “today” (meaning the latest 100,000-year period) (2). We are currently in a rise that started 25,000 years ago and, reasonably, can be expected to peak “very shortly”.

On the shorter timescales of 1000 years and 100 years, further temperature oscillations can be seen, but of much smaller amplitude, down to 1 and 0.5 °F in those two cases. Nevertheless, the overall trend is clearly up, even through the Little Ice Age (~1350–1900) following the Medieval Warm Period. So the global warming phenomenon is here, with a very long history, and we are in it. But what is the driver?

Arctic Ocean model
The postulated driver, or mechanism, developed some 30 years ago to account for the “million-year” temperature oscillations, is best known as the “Arctic Ocean” model (2). According to this model, the temperature variations are driven by an oscillating ice cap in the northern polar regions. The crucial element in the conceptual formulation of this mechanism was the realization that such a massive ice cap could not have developed, and then continued to expand through that development, unless there was a major source of moisture close by to supply, maintain, and extend the cap. The only possible moisture source was then identified as the Arctic Ocean, which, therefore, had to be open—not frozen over—during the development of the ice ages. It then closed again, interrupting the moisture supply by freezing over.

So the model we now have is that if the Arctic Ocean is frozen over, as is the case today, the existing ice cap is not being replenished and must shrink, as it is doing today. As it does so, the Earth can absorb more of the Sun’s radiation and therefore will heat up—global warming—as it is doing today, so long as the Arctic Ocean is closed. When it is warm enough for the ocean to open, which oceanographic (and media) reports say is evidently happening right now, then the ice cap can begin to re-form.

As it expands, the ice increasingly reflects the incoming (shorter-wave) radiation from the sun, so that the atmosphere cools at first. But then, the expanding ice cap reduces the radiative (longer-wave) loss from the Earth, acting as an insulator, so that the Earth below cools more slowly and can keep the ocean open as the ice cap expands. This generates “out-of-sync” oscillations between atmosphere and Earth. The Arctic Ocean “trip” behavior at the temperature extremes, allowing essentially discontinuous change in direction of the temperature, is identified as a bifurcation system with potential for analysis as such. The suggested trip times for the change are interesting: They were originally estimated at about 500 years, then reduced to 50 years and, most recently, down to 5 years (2). So, if the ocean is opening right now, we could possibly start to see the temperature reversal under way in about 10 years.

What we have here is a sufficient mechanistic explanation for the dominant temperature fluctuations and, particularly, for the current global warming rise—without the need for CO₂ as a driver. Given that pattern, the observed CO₂ variations then follow, as a driven outcome, mainly as the result of change in the dynamic equilibrium between the CO₂ concentration in the atmosphere and its solution in the sea. The numbers are instructive. In 1995, the Intergovernmental Panel on Climate Change (IPCC) data on the carbon balance showed ~90 gigatons (Gt) of carbon in annual quasi-equilibrium exchange between sea and atmosphere, and an additional 60-Gt exchange between vegetation and atmosphere, giving a total of ~150 Gt (3). This interpretation of the sea as the major source is also in line with the famous Mauna Loa CO₂ profile for the past 40 years, which shows the consistent season-dependent variation of 5–6 ppm, up and down, throughout the year—when the average global rise is only 1 ppm/year.

In the literature, this oscillation is attributed to seasonal growing behavior on the “mainland” (4), which is mostly China, >2000 mi away, but no such profile with that amplitude is known to have been reported at any mainland location. Also, the amplitude would have to fall because of turbulent diffusive exchange during transport over the 2000 mi from the mainland to Hawaii, but again there is lack of evidence for such behavior. The fluctuation can, however, be explained simply from study of solution equilibria of CO₂ in water as due to emission of CO₂ from and return to the sea around Hawaii governed by a ±10 °F seasonal variation in the sea temperature.

Impact of industrialization
The next matter is the impact of fossil fuel combustion. Returning to the IPCC data and putting a rational variation as noise of ~5 Gt on those numbers, this float is on the order of the additional—almost trivial (<5%)—annual contribution of 5–6 Gt from combustion of fossil fuels. This means that fossil fuel combustion cannot be expected to have any significant influence on the system unless, to introduce the next point of focus, the radiative balance is at some extreme or bifurcation point that can be tripped by “small” concentration changes in the radiation-absorbing–emitting gases in the atmosphere. Can that include CO₂?

This now starts to address the necessity or “only-if” elements of the problem. The question focuses on whether CO₂ in the atmosphere can be a dominant, or “only-if” radiative-balance gas, and the answer to that is rather clearly “no”. The detailed support for that statement takes the argument into some largely esoteric areas of radiative behavior, including the analytical solution of the Schuster–Schwarzschild Integral Equation of Transfer that governs radiative exchange (5–7), but the outcome is clear.

The central point is that the major absorbing gas in the atmosphere is water, not CO₂, and although CO₂ is the only other significant atmospheric absorbing gas, it is still only a minor contributor because of its relatively low concentration. The radiative absorption “cross sections” for water and CO₂ are so similar that their relative influence depends primarily on their relative concentrations. Indeed, although water actually absorbs more strongly, for many engineering calculations the concentrations of the two gases are added, and the mixture is treated as a single gas.

In the atmosphere, the molar concentration of CO₂ is in the range of 350–400 ppm. Water, on the other hand, has a very large variation but, using the “60/60” (60% relative humidity [RH] at 60 °F) value as an average, then from the American Society of Heating, Refrigerating and Air-Conditioning Engineers standard psychrometric chart, the weight ratio of water to (dry) air is ~0.0065, or roughly 10,500 ppm. Compared with CO₂, this puts water, on average, at 25–30 times the (molar) concentration of the CO_2, but it can range from a 1:1 ratio to >100:1.

Even closer focus on water is given by solution of the Schuster–Schwarzschild equation applied to the U.S. Standard Atmosphere profiles for the variation of temperature, pressure, and air density with elevation (8). The results show that the average absorption coefficient obtained for the atmosphere closely corresponds to that for the 5.6–7.6-µm water radiation band, when water is in the concentration range 60–80% RH—on target for atmospheric conditions. The absorption coefficient is 1–2 orders of magnitude higher than the coefficient values for the CO₂ bands at a concentration of 400 ppm. This would seem to eliminate CO₂ and thus provide closure to that argument.

This overall position can be summarized by saying that water accounts, on average, for >95% of the radiative absorption. And, because of the variation in the absorption due to water variation, anything future increases in CO₂ might do, water will already have done. The common objection to this argument is that the wide fluctuations in water concentration make an averaging (for some reason) impermissible. Yet such averaging is applied without objection to global temperatures, when the actual temperature variation across the Earth from poles to equator is roughly –100 to +100 °F, and a change on the average of ±1 °F is considered major and significant. If this averaging procedure can be applied to the atmospheric temperature, it can be applied to the atmospheric water content; and if it is denied for water, it must, likewise, be denied for temperature—in that case we don’t have an identified problem!

What the evidence shows
So what we have on the best current evidence is that

• global temperatures are currently rising;

• the rise is part of a nearly million-year oscillation with the current rise beginning some 25,000 years ago;
• the “trip” or bifurcation behavior at the temperature extremes is attributable to the “opening” and “closing” of the Arctic Ocean;
• there is no need to invoke CO₂ as the source of the current temperature rise;
• the dominant source and sink for CO₂ are the oceans, accounting for about two-thirds of the exchange, with vegetation as the major secondary source and sink;

• if CO₂ were the temperature–oscillation source, no mechanism—other than the separately driven temperature (which would then be a circular argument)—has been proposed to account independently for the CO₂ rise and fall over a 400,000-year period;
• the CO₂ contribution to the atmosphere from combustion is within the statistical noise of the major sea and vegetation exchanges, so a priori, it cannot be expected to be statistically significant;
• water—as a gas, not a condensate or cloud—is the major radiative absorbing–emitting gas (averaging 95%) in the atmosphere, and not CO₂;

• determination of the radiation absorption coefficients identifies water as the primary absorber in the 5.6–7.6-µm water band in the 60–80% RH range; and
• the absorption coefficients for the CO₂ bands at a concentration of 400 ppm are 1 to 2 orders of magnitude too small to be significant even if the CO₂ concentrations were doubled.

The outcome is that the conclusions of advocates of the CO₂-driver theory are evidently back to front: It’s the temperature that is driving the CO₂. If there are flaws in these propositions, I’m listening; but if there are objections, let’s have them with the numbers.

References

1. Sigman, M.; Boyle, E. A. Nature 2000, 407, 859–869.
2. Calder, N. The Weather Machine; Viking Press: New York, 1974.

3. Intergovernmental Panel on Climate Change. Climate Change 1995: The Science of Climate Change; Houghton, J. T., Meira Filho, L. G., Callender, B. A., Harris, N., Kattenberg, A., Maskell, K., Eds.; Cam bridge University Press: Cambridge, U.K., 1996.
4. Hileman, B. Chem. Eng. News 1992, 70 (17), 7–19.
5. Schuster, A. Astrophysics J. 1905, 21, 1–22.

6. Schwarzschild, K. Gesell. Wiss. Gottingen; Nachr. Math.–Phys. Klasse 1906, 41.
7. Schwarzschild, K. Berliner Ber. Math. Phys. Klasse 1914, 1183.
8. Essenhigh, R. H. On Radiative Transfer in Solids. American Institute of Aeronautics and Astronautics Thermophysics Specialist Conference, New Orleans, April 17–20, 1967; Paper 67-287; American Institute of Aeronautics and Astronautics: Reston, VA, 1967.

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Robert H. Essenhigh is the E. G. Bailey Professor of Energy Conversion in the Department of Mechanical Engineering, Ohio State University, 206 W. 18th Ave., Columbus, OH 43210; 614-292-0403; essenhigh.1@osu.edu.

[Excellence]

Thank you. I just read a few lines; I’ll read the whole thing soon. But two things jumped out at me. One is that CO2 from fossil fuel burning is being differentiated from CO2 from all other sources, by some, almost giving it more influence than it deserves. The other is regarding water in the atmosphere as a vapor rather than a gas. In the letter I wrote to the editor I emphasized water’s influence as a gas, not a vapor. So it would appear I got that point correct for what it was worth. The bottom line of my point was that interglacial global warming is an inexorable juggernaut, an overwhelming force that cannot be removed by prayer-or carbon credits. Unless proved otherwise, I’m going to continue to run with that point. Thank you so much for taking the time to refer me to this paper.

[E. Pluribus Unum]

I neglected to place this link in post #75. It appears in post #77, but here it is in case you missed it.

Link to Dr. Essenhigh's latest article.

[E. Pluribus Unum]

The bottom line of my point was that interglacial global warming is an inexorable juggernaut, an overwhelming force that cannot be removed by prayer-or carbon credits.

That's a keeper!

[E. Pluribus Unum]

As I suspected, there is much evidence that your holy "peer-reviewed" journals actively suppress research that contradicts anthropogenic global-warming dogma:

Leading scientific journals 'are censoring debate on global warming'

[M. Dodge Thomas]

That's a very poorly conducted survey.

Oreskes finding was: "Without substantial disagreement, scientists find human activities are heating the earth’s surface”.

The survey question was: to what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?

"Mostly the result" is of course a much stronger claim, and framed as a quite ambiguous question (how much is "mostly"?) as well.

More generally, a lot of the critics of anthropogenic warming just don't seem to recognize that virtually all adherents to the theory are perfectly willing to acknowledge that other processes are important in determining global climate, and that some of these processes are undoubtedly also active at the moment.

Those concerned about anthropogenic warming are modeling climate behavior over a geologically very short (100-200 year) time-frame, and their point is that within that period anthropogenic warming is going to effect change in addition to whatever mechanisms may also be changing it.

And that's what's really worrisome - if these other factors tend to counter anthropogenic warming its effects may be attenuated, but if there are independently acting to warm the earth, and we were going to experience 1-3C warming anyway, and we add 2-3C anthropogenic effects to that... well, then you have very significant disruptions to human life, let alone the rest of the biosphere.

[E. Pluribus Unum]

I’m going to repeat one of my points from above, since you chose to ignore everything except the fluff comment.

Is it not true that the global temperatures in all the general circulation models drift upward or downward over time because their feedback models are deficient?

Isn’t it reckless to then say that this is what is going to happen in the real world?

[M. Dodge Thomas]

Isn’t it reckless to then say that this is what is going to happen in the real world?.

All you can ascribe to such models is a confidence level over some period of time. We make decisions - big decisions - on this sort of such basis all the time.

IMO the rational discussion in this case - and I believe this will increasingly come to be seen to be the case by most people like yourself over the next few years - is given that we have a pretty high and increasing confidence level that CO2 is a significant climate driver, what are the reasonable (and reckless) things to do about it. That, I think, is the really interesting and significant question.

[E. Pluribus Unum]

IMO the rational discussion in this case - and I believe this will increasingly come to be seen to be the case by most people like yourself over the next few years...

I get it.

That means that you charlatans are going to claim that the totally expected rise in global temperatures caused by the approaching solar activity peak in 2010-2012 is due to anthropogenic CO₂, right?

NASA Solar Storm Warning

IMO, if you float that lie, people are going to see once and for all that the Anthropogenic Global Warming Emperor has no clothes, because people like me are going to make sure that they do.

Maybe you have realized that the jig is about up and you have decided to go for broke, eh?

[M. Dodge Thomas]

OK. Had time to track this down over the weekend.

Peiser’s paper as submitted to Science contained significant errors, they were brought to his attention, and he has withdrawn his claim that he had demonstrated widespread skepticism of AGE among climatologists. He remains a global warming skeptic, but now states that:

“I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact.”

What happened?

Oreskes obtained her list of publication for the ISI Web of Science by searching the database for peer-reviewed papers; Peiser used the samedata base but an unrestricted query, which produced many additional articles from popular publications. With *one* exception, it was this latter group of publications that were skeptical of the presence of AGW.

As a result Peiser has stated that:

“Only [a] few abstracts explicitly reject or doubt the AGW (anthropogenic global warming) consensus which is why I have publicly withdrawn this point of my critique.”

And when further pressed, he eventually reduced the list to one.

http://www.abc.net.au/mediawatch/transcripts/s1777013.htm

These problems were discovered in part during the review of Peiser’s letter to Science – irrespective of anything else, this would have been enough to trigger rejection, though I don’t know it this was the only reason.

[M. Dodge Thomas]

That means that you charlatans are going to claim that the totally expected rise in global temperatures caused by the approaching solar activity peak in 2010-2012 is due to anthropogenic CO2, right?

On the evidence, 30% would seem to be the about the upper boundary for solar influence:

http://www.agu.org/pubs/crossref/2003/2002JA009753.shtml

[I got the rope]

Hmmm...Solanki seems to be saying the opposite in a later paper.

http://cc.oulu.fi/~usoskin/personal/2004ja010964.pdf

[M. Dodge Thomas]

On a quick read I don't see that the authors are addressing the the relative importance of iridescence and cosmic ray flux relative to other inputs (such as rising CO2 levels) as was done in the first paper I cited.

[E. Pluribus Unum]

On the evidence, 30% would seem to be the about the upper boundary for solar influence:

Uhhh... what would the temperature on earth be with no sun, but a 100% CO₂ (100% greenhouse gas! Oh my!) atmosphere?

[M. Dodge Thomas]

Uhhh... what would the temperature on earth be with no sun, but a 100% CO2 (100% greenhouse gas! Oh my!) atmosphere?

And your point is?

The paper cited is about our current planet, orbiting its current star, at the the present and in the recent past, and unless unless I missed something that star has neither been extinguished or gone nova during the last few hundred years, nor is our atmosphere 100% CO2.

The questions to which we need answers are related to the effects of functions in solar luminosity and cosmic radiation on terrestrial climate in our actual situation.

The paper cited attempts to estimate them.

On empirical grounds and without recourse to modeling it arrives at an estimate that effects related to variations in solar output are responsible for a maximum of around 30% of observed climate change in recent times.

Likely within the next few years, this estimate will be further refined.

IMO, almost certainly, based on the information available at the present time, such refinement will continue to demonstrate that the majority of recently observed climate change is the result of AGE.

IMO, conservatives need to be thinking about the longer term implications of that.

[E. Pluribus Unum]

IMO, conservatives need to be thinking about the longer term implications of that.

We are thinking about the long-term implications of pseudo-scientific apocalyptic propaganda and the soothsayers who spread it.

[M. Dodge Thomas]

We are thinking about the long-term implications of pseudo-scientific apocalyptic propaganda and the soothsayers who spread it.

"Apocalyptic propaganda" - present on this issue on the left and and the right - is a problem whether AGW is real or not.

[E. Pluribus Unum]

"Apocalyptic propaganda" - present on this issue on the left and and the right - is a problem whether AGW is real or not.

Some apocalyptic propaganda is more dangerous than others.

Anthropogenic global warming is one of those, because the agenda of its proponents is to implement a global tax and an unaccountable, all-encompassing global bureaucracy to address it.

[M. Dodge Thomas]

"Anthropogenic global warming is one of those, because the agenda of its proponents is to implement a global tax and an unaccountable, all-encompassing global bureaucracy to address it."

So? The fact that bad solutions are proposed to a problem does not mean it's not real, or that better solution are not needed.

If AGW is in fact a problem, then some sort of international agreement will be necessary to address it. And if conservatives don't like the prospect of an an "unaccountable, all-encompassing global bureaucracy" to do so, then conservatives need be presenting proposals that better accord with conservative principles while achieving the same ends - not maintaining against the weight of increasing evidence that there is zero chance there is a problem because they don't like any of the proposed solutions.

[E. Pluribus Unum]

And if conservatives don't like the prospect of an an "unaccountable, all-encompassing global bureaucracy" to do so, then conservatives need be presenting proposals that better accord with conservative principles while achieving the same ends - not maintaining against the weight of increasing evidence that there is zero chance there is a problem because they don't like any of the proposed solutions.

Or, preferably, we could prove that the current "global-warming crisis" is a perfectly natural stage in the Ice Age/Interglacial cycle that has occurred numerous times.

As a matter of fact, there is every reason to believe we are on the cusp of the next Ice Age, which may well have been delayed by any anthropogenic global warming there might be.

Exactly what global temperature (a fraudulent measurement to begin with) are we supposed to hold the earth at?

Will it be the job of geniuses like you to regulate the production of greenhouse gases to make sure the earth is not to hot and not too cold but just right?