control knob – Climate- Science.press

New Study: Human Contribution To Enhancement Of Earth’s Greenhouse Effect A Negligible 0.2 Percent

“[T]he contribution of CO2 to the greenhouse effect is 4% – 5%. Human CO2 emissions represent 4% of the total, which means that the total human contribution to the enhancement of the greenhouse effect is 0.16% to 0.20% – a negligible effect.” – Dr. Demetris Koutsoyiannis (2024)

From NoTrickZone

By Kenneth Richard

New research exposes the vacuousness of the “imaginary world” models proclaiming CO2 the dominant regulator of the Earth’s climate.

A CO2-less or CO2-only atmosphere…an imaginary-world thought experiment

An oft-heard claim is that, due to the prominence of CO2 as the Earth’s climate “control knob” (see Lacis et al., 2010), the greenhouse effect could not exist – indeed, it would collapse – if there was no CO2 in the atmosphere.

Image Source: **Lacis et al., 2010** and **Schmidt et al., 2006**

However, it should go without saying that this CO2-less atmospheric condition itself is an imaginary-world conceptualization. Thus, fantasizing about what would happen if the atmosphere was comprised 0 ppm CO2, 1,000,000 ppm CO2, 0 ppm water vapor…are all just untestable, never-observable thought experiments. They cannot be subjected to the scientific method. Thus, they are unfalsifiable.

CO2’s climate effects are undetectable

Of course, this very unfalsifiable thought experiment is what believers in the CO2-is-the-climate-control-knob narrative rest their case on. But even if we do use this imaginary-world premise, the existing models (MODTRAN, HITRAN) that allegedly support the CO2-controls-climate orthodoxy actually undermine it.

For example, as Dr. Koutsoyiannis points out in his extensively-referenced paper, the MODTRAN data show that the Earth’s temperature remains at the default greenhouse-effect value if the water vapor scale is adjusted upwards slightly, by just 30%. The greenhouse effect does not “collapse” as claimed by Lacis et al. disciples – the control-knob believers.

The HITRAN database also indicates the imaginary-world condition of doubling CO2 from 400 to 800 ppm would only alter the radiation flux at the top of the atmosphere by -1.1%, a hypothetical realization that could not even be detected in future macroscopic measurements (if the atmosphere ever were to reach a CO2 concentration of 800 ppm).

MODTRAN models further affirm that (1) there is only a 1% temperature difference between either doubling (800 ppm) or halving (200 ppm) the atmospheric CO2 concentration, and (2) the change in the downwelling radiation resulting from an increase from 300 ppm (1900) to 420 ppm (2023) is only 0.5%. These tiny changes “could not be discerned by observations.”

CO2 has not been detectably reducing the outgoing longwave radiation

As a “control knob” for the climate, CO2 is believed to be the principal reason why the Earth’s outgoing longwave radiation (OLR) should be reducing (Dewitte and Clerbaux, 2018).

“…the increase of Greenhouse Gasses (GHG) primarily CO2 reduces the OLR”

However, despite the increase in CO2 concentration in recent decades, OLR has been increasing. Any reduction in OLR from the CO2 effect is not detectable.

Image Source: **Dewitte and Clerbaux, 2018**

Likewise, the MODTRAN clear-sky results (i.e., an atmosphere where no clouds exist and CO2 and water vapor are the main greenhouse effect agents) show OLR has increased by +0.38 to +0.60 W/m² from 2001 to 2022, consistent with the increase in temperature.

According to the data reviewed by Dr. Koutsoyiannis, any record of decrease in OLR “can hardly be attributed to increased CO2, but it can be related to water vapor and cloud profiles,” as the “effect of CO2 is trumped by the effect of clouds, which is consistent with the major role of water on climate and the minor one of CO2.”

95% of the greenhouse effect (downwelling radiation) is from water vapor, clouds

Per the MODTRAN calculations, CO2’s contribution to the planetary greenhouse effect is only 4% to 5%, and the contribution from water vapor and clouds is 87% (outgoing radiation) to 95% (downwelling radiation). The CO2 contribution to greenhouse effect changes over the last century, as CO2 increased from 300 ppm to 420 ppm, is only about 0.5%. This quantified percentage is “below any threshold to make it observable.”

Worse, when we consider that human CO2 emissions are only 4% of Earth’s total CO2 emissions, and that the CO2 contribution to the greenhouse effect is just 4% to 5%, “the total human contribution to the enhancement of the greenhouse effect is 0.16% to 0.20%.”

Supporting evidence for CO2’s negligible role

Another set of sources supporting the contention that CO2’s greenhouse effect contribution is only 4% to 5% comes from the notorious Trenberth radiation budget charts. First, notice the 333 W/m² value identified for downwelling radiation from greenhouse gases (lower right).

Image Source: **Trenberth and Fasullo, 2011**

Now consider the estimated greenhouse effect (downwelling radiation) contribution from CO2 alone as shown in Schmithüsen et al., 2015.

Notice it ranges from about 0 W/m² (or less) near the poles, about 10-15 W/m² at mid-high latitudes, and about 25 W/m² around the tropics. Averaged over the globe, it would appear the total mean CO2 greenhouse effect contribution is about 13 to 15 W/m². If CO2 indeed accounts for ~14 W/m² of the 333 W/m² downwelling radiation from greenhouse gases, its contribution is 4.2%. The other ~95%, or ~320 W/m², is necessarily from water vapor and cloud.

Image Source: **Schmithüsen et al., 2015**

As shown in the Koutsoyiannis review of results from HITRAN database, a doubling of CO2 from 400 to 800 ppm only produces a ~1.1% perturbation to the radiative flux at the top of the atmosphere (3 W/m²), which is not discernible. This is consistent with Chen et al. (2024), who assess that a doubling of CO2 produces a negative top-of-atmosphere (TOA) forcing (-1 W/m²), and a positive TOA forcing of just +2-3 W/m² in the mid-high latitudes and tropics.

These papers further establish the negligible role of CO2 in the Earth’s greenhouse effect.

A Curious Paleo Puzzle

Hmmm, sez I … looks like an interesting study. Paleo CO2 levels back to about 65 million years ago, which peaked at about 2000 ppmv.

From Watts Up With That?

Guest Post by Willis Eschenbach

I was wandering through the fabled land of X yesterday and came across the following post:

*Figure 1. Post on X showing a shortened version of the original Figure 6 from the paper linked below.*

Hmmm, sez I … looks like an interesting study. Paleo CO₂ levels back to about 65 million years ago, which peaked at about 2000 ppmv.

I was reminded of an earlier graphic I’d done, showing paleo CO₂ levels over a much longer time span. Figure 1 above only covers the Tertiary and Quaternary ages, the far right two boxes on Figure 2 below.

*Figure2. Full history of CO2 since the Cambrian Explosion of life.*

So I went to the source listed in Figure 1, a study yclept “Atmospheric CO2 over the Past 66 Million Years from Marine Archives” by Rae et al. The graphic below is a shortened version of Figure 6 of the Rae et al. study.

*FIgure 3. Panels a) and c) of Rae et al., Figure 6*

The authors have fully bought into the “CO₂ Roolz Climate” theory, saying inter alia:

Changing levels of atmospheric CO₂ have long been implicated in the well-documented cooling of the climate through the Cenozoic; however, outside of a handful of well-studied climate transitions, it has been hard to make a close link between CO₂ and climate. Our new combined marine-based CO₂ compilation shows, more clearly than in previous studies, a close correlation between CO₂ and records of global temperature (based on either geochemical reconstructions and/or the state of the cryosphere) through the entire Cenozoic (Figure 6).

…

Nonetheless, it is clear, even with these caveats, that atmospheric CO₂ and temperature are closely coupled, both across the data set as a whole and within shorter time windows. While the data set as a whole suggests a relatively high climate sensitivity, much of this temperature change is apparently accomplished by jumps between different climate states.

Hmmm, sez I … I wondered why they didn’t mention the value of what they claim is “a relatively high climate sensitivity” for the data set as a whole. So I figured I’d take a look at their data.

For the CO₂ data, that was easy. They provide it in an Excel file in their Supplemental Material.

For the temperature data, the total opposite. They say “Surface temperature estimated from the benthic δ18O stack of Westerhold et al. (2020), using the algorithm of Hansen et al. (2013)” … except they don’t give you the relevant links to the data or the algorithm.

Grrr. I did that, dug out Westerhold’s data, found and applied the Hansen algorithm, links above, and dang, it took a while.

In any case, here’s their CO₂ data.

Figure 4. Paleo CO2 levels to 66 million years ago

Our current levels are far from the highest even in just the last 5 million years, let alone 60 million years. (Note that I haven’t added a LOWESS smooth of the data as they did, because that effectively invents tens of millions of years of data.)

So my next question, of course, was how well the temperature corresponds with the log of the CO₂ levels. Figure 5 shows that relationship.

*Figure 5. Paleo temperatures, and linear fit of the base 2 log of the CO₂ levels.*

I have to say that is a very good agreement by climate and paleo standards, where measurements are always uncertain.

Next I looked in detail at the cluttered area at the lower right. That’s the time of the “ice ages”, periods of glaciation followed by periods of warmth. Figure 6 shows the ice ages.

*Figure 6. Paleo temperatures, and linear fit of the base 2 log of the CO₂ levels. I’ve added lines between the temperature and fitted CO₂ values for each measurement time.*

Once again, by the standards of paleo and climate, these are good fits.

So … what’s not to like? Does this actually show that CO₂ at 0.04% of the atmosphere is really the secret global temperature control knob as the authors claim?

Perhaps not.

Let’s start by looking at the math. I’ll divide the math off so as not to bother folks who are math-averse … for you, just jump over this section. Here is the summary of the linear fit of log2(CO₂) and temperature.

Coefficients:

             Estimate   Std. Error   t value    P-value
(Intercept)    7.4810     0.1954       38.3      <2e-16
log2_CO2       6.3137     0.1087       58.1      <2e-16

Residual standard error: 2.468 on 644 degrees of freedom
Multiple R-squared: 0.8398, Adjusted R-squared: 0.8395
F-statistic: 3375 on 1 and 644 DF, p-value: < 2.2e-16

“log2_CO2” is the base 2 logarithm of the change in CO₂. The “Estimate” of 6.3 in bold above is the climate sensitivity, the estimate of the temperature change corresponding to a doubling of CO₂.

So yes, as the authors say above, this does show a “relatively high climate sensitivity”. The climate sensitivity of 6.3 is the third highest of 172 various past estimates of climate sensitivity. Here’s a look at previous estimates.

*Figure 7. Estimates of climate sensitivity from theory and reviews, observations, paleoclimate, climatology, and GCMs.*

Another problem, beyond the climate sensitivity being one of the highest of the 173 estimates, is the much higher CO₂ values earlier in the past shown in Figure 2. If climate sensitivity is 6.3°C per doubling, that would put the global average surface temperature at around 40°C in the Cambrian and around 36°C in the Devonian … seems unlikely.

However, there’s a larger problem. The CO₂ theory is that a rise in CO₂ absorbs more upwelling longwave radiation. This causes an imbalance in the net radiation at the top of the atmosphere by redirecting some of the upwelling longwave back to the surface. The amount of this increased downwelling radiation is called the CO₂ forcing.

The surface temperature then warms, increasing the upwelling surface longwave radiation to restore the balance.

Figure 8 below shows the difficulty factor. When the earth’s surface warms, it emits more radiation following something called the Stefan-Boltzmann equation. Figure 8 below shows the increased forcing due to increased CO₂ levels in the past, along with the corresponding increase in surface upwelling longwave radiation from the temperature increases.

*Figure 8. Changes in upwelling surface longwave radiation, and downwelling atmospheric longwave radiation due to CO₂.*

Yikes. So there’s the perplexitude—we’re told to believe that a change in CO₂ forcing of 13 W/m2 causes a corresponding 128 W/m2 in upwelling surface longwave radiation.

But where does the extra energy come from? Seems like the tail is wagging the dog. After allowing for the 13 W/m2 of CO₂ forcing, there’s another 115 W/m2 of extra energy leaving the surface … but where did it all come from?

By comparison, solar energy absorbed by the surface is 164 W/m2. So the surface needs to be getting another three-quarters of a sun’s worth of energy from … somewhere …

It would have to be some extraordinarily large feedback to the warming if that’s what caused more warming. The feedback factor would have to be ~ 0.9 … and if the feedback factor is greater than 1.0, it grows without end. And that would suggest that at some point in the past, the natural fluctuations in this feedback would have led to endless growth.

And it’s difficult to think of a physical process that would supply that 115 W/m2 to the surface. For example, total cloud albedo reflects about 75 W/m2 back to space. So if the positive cloud feedback led to the complete disappearance of the clouds, that would only increase the surface absorbed solar by 66 W/m2 after adjusting for increased surface reflection … and we’re looking for 115 W/m2.

The same is true for the positive water feedback. The numbers aren’t big enough. The IPCC AR6 WG1 Chapter 7 Section 7.4.2.2 estimates a combined water vapor and lapse rate feedback at 1.12 W/m2 per °C of warming. The warming back to 60 million years ago is about 15°C. So water vapor+lapse rate feedback would be on the order of 15°C * 1.12 W/m2 per °C = 17 W/m2 … and we’re looking for 115 W/m2.

What else … the paleo temperature or paleo CO₂ might be incorrectly calculated, in which case none of this shows anything.

A final possibility, of course, is that the warming has little to do with CO₂ and that the CO₂ levels are a function of temperature and not the other way around …

I titled this post “A Curious Paleo Puzzle”. That’s the puzzle. How can an increase of 13 W/m2 in CO₂ forcing cause an increase of 115 W/m2 of upwelling surface longwave radiation?

All suggestions welcome.

Here on our redwood forested northern California hillside, there’s a small triangle of the Pacific Ocean visible between the far hills on a warm sunny day after a long string of storms. The wind brings us the sound of the surf gnashing and gnawing on the coast six miles (ten km) in the distance. The grandkids, two and four years old, play and laugh in the next room.

With best wishes for sun, rain, and the joys of family in your life,

You May Have Heard This Before: When you comment, I ask that you quote the exact words you are discussing. It avoids endless misunderstandings.

Data: I’ve made two CSV files containing the data used in this analysis so they can be used in Excel or the computer language of your choice. One contains the temperatures, 23,722 different paleo measurements.

The other contains the paleo CO₂ data, 646 measurements. That one also contains the temperatures from the other dataset, interpolated at the dates of the CO2 measurements. This allows for the calculation and graphing of the relationship between the datasets.

The datasets are “Rae CO2 and Interpolated Temps.csv” and “Rae Temperatures.csv“, available at the links from my Dropbox.

Alan Longhurst’s “Doubt and Certainty in Climate Science”

If you are really curious and have that unquenchable desire to learn, get and read this book.

From Watts Up With That?

Book Review by Kip Hansen — 26 April 2023

Finally, a climate science book that readers will learn from. Many readers here are well versed in at least some of the myriad atmospheric and oceanic forces that add up to the complex “coupled non-linear chaotic system” (IPCC TAR Chapter 14) that is the Earth’s climate.

Many readers are frustrated with the continued insistence of political bodies – insistence that is mirrored and echoed in official statements of major scientific organizations — that only the concentration of CO₂ in the atmosphere is of importance in driving the global climate this way or that – some even claiming that increases in atmospheric CO₂are driving catastrophic changes that will lead to the collapse of human civilization.

Many readers will also agree that this focus on CO₂ is a rather naïve short-sighted view of our ever-changing climate.

But how many of us really understand, at a deep and exhaustively thorough level, why we must reject the “CO₂ as climate control knob” hypothesis and thus reject the public policy demands based on it? Having just finished reading Alan Longhurst’s new book – “Doubt and Certainty in Climate Science – 2^nd Edition (2023)” — am ready to admit that I did not.

Who is Alan Longhurst? If you are an oceanographer or a fisheries scientist, then you already know of Dr. Longhurst’s long and illustrious career. If you read Dr. Judith Curry’s blog, Climate Etc. , you will have seen his name at the top of several essays. You may have read Dr. Curry’s review of this book’s first edition, in which she said “This is a remarkable book, a tour de force. There are fresh insights in each chapter, borne of Longhurst’s objective analysis of the data and the literature. The papers he cites are from Nature, Science, PNAS, Journal of Climate and other mainstream, high impact journals. …. However, each of these papers provides a critical link in Longhurst’s reasoning that produces conclusions that do not agree with the ‘consensus.’”

The second edition, now updated through 2022, has just been published this March by Critical Science Press.

It is, indeed, a tour de force.

Unless you have already spent a lifetime studying the complex, complicated and chaotic subjects that comprise climate science, you stand to learn more from this book than from any other contemporary work. Longhurst’s comprehension and recall of the details of hundreds of scientific papers from related and adjacent fields enter into this brilliant synopsis of the state of Climate Science – what doubts we still have and what, if any, certainty we can claim.

I have had this book in my possession since its publication…and have absorbed its contents one chapter at a time. This has turned out to be, for me, a rather monumental task. I read deep and deep takes time, even at only 258 pages. But it has been worth every precious minute.

If you are really curious and have that unquenchable desire to learn, get and read this book.

It is available from the usual sources, in hardback, paperback and eBook.

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Author’s Comment:

Irrespective of your depth of understanding of Climate Science and your personal understandings and biases on various issues involved, you will find things to love, things to hate, things to agree with, and things to disagree with in this new edition of Longhurst’s book. It is, in a single word, breathtaking in its scoop and breadth.

Don’t be childish and quit reading the first time you find something that offends your current understanding. If you do, you will miss out on the insights and understandings of a great mind – one capable of producing this horizon-stretching synopsis.

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Tag: control knob

New Study: Human Contribution To Enhancement Of Earth’s Greenhouse Effect A Negligible 0.2 Percent

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A Curious Paleo Puzzle

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Alan Longhurst’s “Doubt and Certainty in Climate Science”

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