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.

[AlexW]

“I hate to be the one to break it to you, but there isn’t any peer reviewed science out there that effectively debunks global warming. The few things that are published inevitably have corporate backing and don’t survive long when inspected by the climatology community.”

Err, newbie, are you Al Goron in drag?
There are plenty of CERTIFIABLE climate scientist that debunk man made global warming.
As for being in the pocket of big business, that coin has two sides.

Anyway, welcome to FR...You have at least two other FReepers
who will hold your hand on global warming, but they, as well as Al Gore, are not real climatologist, they just play one on TV..I mean internet.

[PeaceBeWithYou]

Ping.

[Fitzcarraldo]

Eventually temperature must go down due to water cloud formation.

[AlexW]

“I am curious to know who these global warming debunked”

You could start with the film, The Great Global Warming Swindle.

As for papers, the great Global Warming grant mill is running full blast, cranking out billions of bucks to feed those leftist printing plants.
There is little money out there for any thoughts of warming to be natural.
That does not fit the template of the socialist.

[AlexW]

“I’m glad you’re not trying to deny that the earth is warming”

I have no doubt that the earth is in a warm period, the same as it was in the MWP, one thousand years ago.
When you can explain that time in history, and explain why
warming in our universe and the planets is caused by the sun, but not here on earth, then I will start to take notice. As for CO2, I will go with the scientist that say
it follows warming, not preceeds it.
In the meantime, I am not interested in the rantings of
grant hungry scientist, or a fat flunkie of divinity school.

[E. Pluribus Unum]

I've done my part - read the original, read the responses, attempted to discover if the author as responded to criticism of the original paper, especially in the last few years (as far as I can determine, he hasn't), and reached the best judgement I can, and pointed you the relevant material I have been able to discover.

The fact that you are unable to defend your beliefs in your own words and choose to defer to your religious leaders' pontifications rather than doing so is proof that you don't really understand what you are advocating, it is just a matter of faith for you.

FAITH = RELIGION

[Excellence]

I just noticed something abut this chart you sent me. The blue label says “Temperature change from 1950 to 1980.” But each line on the chart represents 10,000 years. The time range is over a 160,000 year period, how does one measure 30 years, and who cares what happens in a microscopic 30 year period?! And it looks as if it was even hotter a mere 10,000 year ago. Does this fall under the general heading of obfuscation?

[E. Pluribus Unum]

The blue label says “Temperature change from 1950 to 1980.” But each line on the chart represents 10,000 years.

It actually says "Temperature Change 1950-1980 Mean."

They are using the mean (average) temperature during that period as the reference temperature. In other words, the period 1950-1980 is "0.0" on the Y-axis. The temperatures for all other years are degrees above or degrees below the average temperature for the 1950-1980 period.

There is no obfuscation going on here. They are perfectly reasonable scaling factors.

[M. Dodge Thomas]

Here ya’ go:

For starters, Essenhigh’s assertion that “water averages out as 97% of the thermal trapping” is unsupported in his paper and at wide variance with generally accepted values – he’s able to present these assertions as plausible because he does not understand even the basics of atmospheric physics and chemistry, for example disregards variable absorption rates with altitude. He hasn’t apparently hasn’t even bothered to try to defend this paper since shortly after its publication, and instead has concentrated his criticisms on the economic effects of programs to reduce the rate of increase in atmospheric C02. Nevertheless, the paper won’t die, but surfaces every few years presented in the guise of cutting-edge and well-supported criticism of current consensus views.

Happy now?

Convinced of anything?

I don’t expect so – because the only way to judge the reasonableness and accuracy of such opinion is either to study the question yourself, or to adopt the views of authorities you accept as competent to evaluate them for you.

[TC Rider]

Ruh roh, the global warming mullahs are going to rip through this guy like the Vatican through the Hare Club for Men!

[Robert A Cook PE]

Before we get onto the “ocean CO2 sink issues”, are we in agreement that the portions of this paper centered on discussion of the physics and chemistry of the relative contributions of *atmospheric* water vapor and CO2 are fundamentally flawed?

What’s “flawed” about them?

The relationship, the emissivity comparison, the concentrations are correct?

What’s “flawed” - other than that he destroys (the desired) theory of man-caused global-warming that is needed to destroy the American economy.

[Robert A Cook PE]

Why was the temperature higher 100,000 years ago than it is now? Higher about 200,00 years ago than it is now?

Gore wasn’t putting out his CO2 emissions then.

If average mid-atmospheric temperatures ARE dependent on average CO2 levels (because of reflectivity) why haven’t temperatures gone up since theirpeak in 1998-1999? They’ve just stayed the same for almost 8 years now, but CO2 levels have been gradually increasing the whole time.

[E. Pluribus Unum]

"But when you find an old paper which has attracted fundamental criticisms shortly after publication and has few if any technically competent current defenders, it's generally safe to assume that the critics were right."

More "consensus" science, eh?

Consensus is not science. Consensus is politics.

I contacted Dr. Essenhigh with the information that his paper had been thoroughly refuted. He was genuinely surprised to hear this.

Here is his response:

---

Dear (E. Pluribus Unum)

Very much appreciate your interest.  I didn't know that the article had been refuted.  If the "refutees" (if there is such a word) had a point it would have been a professional courtesy to have contacted me, but nothing like that has yet come my way.  In fact, since the article was published -- 6 years ago (and republished the same year, with ACS permission, in Energy and Environment [12(4), 351 – 355 (2001)] -- I've been getting comments every few weeks ever since, with some questions, but mostly approval and support.

On the matter of more, this is the Attachment, just published last year in another ACS journal, Energy and Fuels, that as a chemist you are probably familiar with.  As you will see, this is more analytical, but it comes up with essentially the same result regarding the (radiative) dominance of water over CO2, and the conclusion that anthopogenic CO2 is unlikely to be possible to have significant impact on global warming.  You will see one change between this and the original article which is setting the (average) water/CO2 absorption/emission properties to about 75-80% for water and 15-20% for CO2 compared with the (original) estimate of about 95%/5%.  The change was taking into account the very much faster drop in water with altitude compared with CO2, but it still sets water as the dominant gas.

If you have time to read it (it is rather long), I'd be interested in your comments.

Thanks again for the interest

Robert H. Essenhigh
E.G. Bailey Professor of Energy Conversion; Department of Mechanical Engineering
The Ohio State University; Columbus, OH: 43210
 
http://rclsgi.eng.ohio-state.edu/~essenhig/
http://rclsgi.eng.ohio-state.edu/~essenhig/ACE.html
http://rclsgi.eng.ohio-state.edu/~essenhig/hier.html
http://www.mecheng.ohio-state.edu/people/essenhig.html

[PeaceBeWithYou]

Ping the list please.

RealClimate.org dishonesty on display.('Mannmade science' strikes again.)

[E. Pluribus Unum]

Link to Dr. Essenhigh's latest article.

[PeaceBeWithYou]

Excellent!

[Excellence]

Ah, thanks for straightening that out.
My first thought is that choosing that time span as a reference point is rather arbitrary. What says this particular reference point is “normal” and everything outside of it is “too” hot or cold?

[Old Professer]

Probably laughed his way through it.