How MINISCULE is the Anthropogenic Greenhouse Effect ?

This post is to highlight conclusions from a 1998 paper by Sherwood B Idso in Vol 10: 69-82 of Climate Research, "CO2-induced global warming: a skeptic’s view of potential climate".


Sherwood Idso finds that a consensus of 8 natural experiments he describes is that for a doubling of carbon dioxide to 600ppm, the global temperature might rise at most by 0.4 degrees C.
To save blog space the links below take readers to the relevant sections of an html version of Sherwood Idso’s paper.


ABSTRACT

1. INTRODUCTION
2.1. Natural Experiment 1
The first of the unique meteorological situations investigated  was the change in atmospheric water vapor that typically occurs at Phoenix, Arizona, USA, with the advent of the summer monsoon.

2.2. Natural Experiment 2
With respect to the phenomenon of naturally-occurring vertical redistribution of dust that occurs at Phoenix, Arizona, each year between summer and winter, (Idso & Kangieser 1970), Sherwood Idso had previously demonstrated that the restriction of airborne dust to a much shallower depth of atmosphere during winter does not alter the transmittance of the atmosphere for the total flux of solar radiation, but that it increases the atmosphere’s downwelling flux of thermal radiation at the Earth’s surface by
13.9 W m –2 (Idso 1981b).

2.3. Natural Experiment 3
The annual cycle of surface air temperature that is caused by the annual cycle of solar radiation absorption at the Earth’s surface was studied  at 81 locations within the United States.

Discussion 2.4. Initial implications

2.5. Natural Experiment 4
The first of two 2 global-equilibrium natural experiments consisted of simply identifying the mean global warming effect of the entire atmosphere and
dividing it by the mean flux of thermal radiation received at the surface of the Earth that originates with the atmosphere and which would be non-existent
in its absence.

2.6. Natural Experiment 5
The second global-equilibrium experiment made use of the annually-averaged equator-to-pole air temperature gradient that is sustained by the annually-averaged equator-to-pole gradient of total surface-absorbed
radiant energy (Idso 1984).

Discussion 2.7. Intermediate implications

2.8. Natural Experiment 6
Considering what could be learnt from our nearest planetary
neighbors, Mars and Venus.

2.9. Natural Experiment 7
The same result may also be obtained from the standard resolution of the paradox of the faint early sun
(Sagan & Mullen 1972,

2.10. Natural Experiment 8
A final set of empirical evidence that may be brought to bear upon the issue of CO2 -induced climate change pertains to the greenhouse effect of water vapor over the tropical oceans.

3. RISING CO2 AND THE GLOBAL WARMING OF THE PAST CENTURY

4. COOLING THE GLOBAL GREENHOUSE

5. SUMMARY AND CONCLUSIONS

33 thoughts on “How MINISCULE is the Anthropogenic Greenhouse Effect ?”

  1. “There is no controversy surrounding the claim that atmospheric CO2 concentrations are on the rise; direct measurements demonstrate that fact. The basic concept of the greenhouse effect is also not in question; rising carbon dioxide concentrations, in and of themselves, clearly enhance the thermal blanketing properties of the atmosphere. What is debatable, however, is the magnitude of any warming that might result from a rise in the air’s CO2 concentration. While admittedly incomplete and highly approximate general circulation models of the atmosphere predict that a 300 to 600 ppm doubling of the air’s CO2 content will raise mean global air temperature a few degrees Celsius, natural experiments based upon real-world observations suggest that a global warming of no more than a few tenths of a degree could result from such a CO2 increase. Which conclusion is correct?”

    I like this – the more up to date studies have put climate sensitivity:

    “A vast array of thought has been brought to bear on this problem, beginning with Arrhenius’ simple energy balance calculation, continuing through Manabe’s one-dimensional radiative-convective models in the 1960’s, and culminating in today’s comprehensive atmosphere-ocean general circulation models. The current crop of models studied by the IPCC range from an equilibrium sensitivity of about 1.5°C at the low end to about 5°C at the high end. Differences in cloud feedbacks remain the principal source of uncertainty. There is no guarantee that the high end represents the worst case, or that the low end represents the most optimistic case. While there is at present no compelling reason to doubt the models’ handling of water vapor feedback, it is not out of the question that some unanticipated behavior of the hydrological cycle could make the warming somewhat milder — or on the other hand, much, much worse. Thus, the question naturally arises as to whether one can use information from past climates to check which models have the most correct climate sensitivity.”

    from www.realclimate.org/index.php?p=229

  2. may I emphasize the alarmist nature of the above quote:

    it is not out of the question that some unanticipated behavior of the hydrological cycle could make the warming somewhat milder — or on the other hand, much, much worse.

    I suggest you read the uncensored debate on climate sensitivity on the ukweatherworldforum
    www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=25003&start=1
    Tom Rees and I reached a consensus that transtent sensitivity is approximately 1 K/2xCO2 in the climate model used by the dutch weather service KNMI.

    And it’s transient sensitivity that counts not equlibrium sensitivity which has a relaxation time of more than a century.

  3. “While there is at present no compelling reason to doubt the models’ handling of water vapor feedback…”–note that this is no compelling reason in the view of the writers at realclimate. Less biased observers have their doubts. After all, the majority of that claimed 1.5-5 deg C warming is really due to water vapor feedback. This is convenient: we have historical observations of CO2, but not of water vapor.

  4. No historical data on water vapour? – no wonder they can’t model clouds in their CGM’s. But surely relative humidity measurements have been collected over a long enough period to produce some data?

  5. because they severely censor their blog, they let pass adhoms to skeptics, they reject scientific arguments they don’t like.

  6. Louis,
    I’m sure there are historical humidity measurements. As I understand it (and if I’m wrong someone should step in), those measurements are going to be almost all limited to very close to the Earth’s surface, whereas the broader distribution of water vapor in the atmosphere is what’s driving the greenhouse feedback. The bulk quantity of CO2 in the atmosphere is very easy to gauge because CO2 is well mixed. However, bulk H2O is much harder to gauge because it is highly variable in time and space (goes in and out of water bodies, clouds, vegetation, etc. on a timescale of hours). There is a high uncertainty just in the modern average atmospheric H2O content for the atmosphere as a whole. I suspect this makes it challenging to observationally constrain its effects in models.

  7. Robert,

    Yes agreed – but the point is that if measuring the distribution of water vapour in the atmosphere historically, as you correctly show, is an extremely difficult activity then effectively we have no data, really, to describe the behaviour of water vapour/clouds. As the Greenhouse effect is dominated by this factor, it actually means the GCM’s are next to useless.

  8. This seems as good a place as any to mention that the Fox News career of junkscientist Steve Milloy may be coming to an abrupt end due to a slight defect in full disclosure: scienceblogs.com/deltoid/2006/01/the_big_shill.php. Warwick’s prominent link to Milloy’s stuff says that his “huge site debunks all manner of Green and Govt. myths and lies.” Possibly a note should be added on Milloy’s conflict of interest problem, which extends far beyond the tobacco issue. Be careful of the company you keep, Warwick.

  9. Steve,

    Does the tobacco industry, ExxonMobil, etc. funding cause scientists to alter their opinions or are they funded because their opinions match the donors interests? You claim it is the former and I contend it is the latter.

    If you are concerned that funding causes a change in opinion then why aren’t funds from government and environmental organizations just as suspect? It certainly is in big governments interest to scare the electorate in order to arrogate more power.

    Attacking the source of funds is red herring that only impresses the naive and uninformed. Unfortunately, that is the majority.

  10. Reid – “Attacking the source of funds is red herring that only impresses the naive and uninformed. Unfortunately, that is the majority.”

    The question is that why would ExxonMobil fund climate science? Why does the research that ExxonMobil funds all come out contrary to the majority position of science? Can you name one study funded by ExxonMobil that supports the AGW position.

  11. Ender,

    I think the reason is obvious – the Greenies want to destroy ExxonMobil, so what do you expect ExxonMobil to do when confronted with that spectre?

  12. Ender, Because they produce oil? Which is evil? I notice in contrast that no one objects to the Saudi’s oil production, though. Or Iran’s for that matter. Only US companies.

  13. Note how Steve Bloom changes the discussion by engaging in ad hominen attacks. Steve, when you start playing the man rather than the ball, the natural inference is that you have concluded your team is losing the game. Where are the specific criticisms of each of Idso’s arguments relaying experimental evidence on the size of the climate sensitivity to changing CO2? Show us the errors in his calculations. How can so many lines of experimental evidence yielding the same conclusion be wrong? Why should we instead believe the predictions of GCM models that, contrary to the advertising of AGW proponents, are not solely built up from tried and tested physical principles? In particular, where the underlying processes are chaotic the relevant equations cannot be derived from first principles, and the GCM models instead contain ad hoc "parameterizations" for the relevant critical features. Isn’t it a fundamental principle of science that theories are not trusted until they agree with experimental evidence and, furthermore, that the more different types of evidence there are that are consistent with the theory the more believable it is? Has not the evidence that Idso presents in this paper told us that at least some of the ad hoc paremeterizations in the GCMs must be wrong? A legitimate question to ask, if the mutually reinforcing Idso calculations are correct, is what else can explain the temperature rise of the last century that has been greater than his calculations would imply if the change in CO2 has been the only relevant forcing factor? A substantial body of literature published since he wrote his paper suggests that changes in solar activity (both irradiance and the positively correalted strength of the sun’s magnetic field) provide the missing explanation. The idea that the sun and associated cosmic ray flux have been the primary drivers of climate change on earth has also been shown to be consistent with an extremely wide range of evidence covering all geological time periods and collected using different measures and methodologies.

  14. Loius – these greenies you speak of have a lot of resources. Fancy inserting false IRS reports into the US taxation system to discredit ExxonMobil.

  15. Ender, I like most here have no idea what you are rabbiting on about with false IRS reports etc. Greenpeace is a multi billion dollar entreprise funded by its supporters, and to continue receiving funds, Greenpeace needs to keep you lot scared out of your wits to keep the money coming in. Greenpeace management have a lifestyle which you and your fellow travelers have to keep funding.

  16. Greenpeace billions, Louis? Be serious. Peter, our friend Steve Milloy is in trouble for violating a basic rule of journalistic integrity; i.e., failing to tell his employer that he received money from a third party for promoting certain views that ended up in a column written for the employer. Do you have a problem with that? As for the Idso piece, why waste my time? It’s a decade old and it’s not clear to me that Idso hmself would defend it now.

  17. Steve I am very serious about Greenpeace. This report focuses on Greenpeace, arguably the most recognizable and visible name in the nonprofit world and the most egregious offender we reviewed. Greenpeace’s organizational structure consists of multiple corporate entities that engage in blatant self-dealing, laundering funds through Greenpeace’s tax-exempt corporation. These funds are then passed to other Greenpeace corporations that use them for non-exempt – and often illegal – purposes. Such actions carry severe legal implications, specifically in the context of federal tax law that governs non-profits. Source

  18. Steve: "As for the Idso piece, why waste my time? It’s a decade old and it’s not clear to me that Idso hmself would defend it now." I wasn’t asking you to speculate on Idso’s current thoughts on the matter. I was asking you to tell me where the errors are in his calculations. You have eight independent calculations to invalidate. On the other side, can you show me even one piece of empirical evidence validating the ad hoc parameterizations in the GCM’s correspond to reality? By the way, I am not using "ad hoc" here as an aribtrary term of abuse. Rather, as the dictionary defines the term, it means "improvised" or "concerned with one specific purpose". Some parameters in the GCM equations are not derived from fundamental physical principles validated in laboratory tests (since the relevant equations are too complicated to solve), but have been chosen to give an overall desired sensitivity of average global temperature to an assumed increase in the CO2 content of the atmosphere. The only way of validating these parameter choices is through experimental evidence of the sort dsicussed by Idso. Are you saying that such evidence is more consistent with the sensitivity calculated by the GCM’s than with the numbers calcuated by Idso. If so, I again ask, where are the mistakes in his calcualtions?

  19. Peter, you are inviting me to spend quite a bit of time going over that document (and I’m still not done with two other detailed responses relating to this blog). I’m willing to do it since I’ll learn some things along the way, but given the age of the piece and the general marginality of Idso’s views I think there’s a good chance he no longer defends at least some of it. I don’t think it’s asking too much for you to confirm that first.

  20. Sure, Warwick, but our understanding of the truth is a work in progress, or so science tells us. Anyway, as you’re the one who posted it perhaps you know whether Sherwood remains ready to defend all of its contents.

  21. Steve, go to Sherwood Idso’s website at www.co2science.org/scripts/CO2ScienceB2C/subject/c/subject_c.jsp, and search his site on the matter. The link will take you to letter C (for everything related to CO2 and other things beginning with “C”.

    There is also an email address for you to ask Dr. Idso if he still backs his old (?) study. Try it and I am sure that the Idsos will answer your question. They have answered many of my questions, so I don’t see why they wouldn’t answer yours. Don’t be shy.

    Speaking of “old” I have seen at the top of this blog Enders posting a quote from Real Climate (“…beginning with Arrhenius’ simple energy balance calculation,…”) as if Arrhenius was a proof for the “greenhouse effect”. Isn’t Arrhenus a little “older” than Idso’s study? Why Arrhenius’ more than 100-year old claim is worth more than Idso’s 10 year claim? Somebody has lost his sense of proportions.

  22. Well, here we are in April … Steve Bloom’s threat to actually read and comment on Dr. Idso’s paper has not materialized.

    I was impressed by the eight natural experiments analyzed. Steve, can you disprove, or even dispute, any of the paper’s calculations or conclusions?

    w.

    PS — I suppost this will bring out the trolls and ad hominem experts again … don’t feed the trolls …

    PPS — The paper just had its eighth birthday (April 9,1998). I don’t understand how its age is any issue at all … unless someone believes that the temperatures measured in Phoenix have gotten stale with age or something. For example, take this experiment:

    The first of these 2 global-equilibrium natural
    experiments consisted of simply identifying the mean
    global warming effect of the entire atmosphere and
    dividing it by the mean flux of thermal radiation
    received at the surface of the Earth that originates
    with the atmosphere and which would be non-existent
    in its absence (Idso 1984). Calculation of both of
    these numbers is straightforward (Idso 1980, 1982),
    and there is no controversy surrounding either of the
    results: a total greenhouse warming of approximately
    33.6°C sustained by a thermal radiative flux of
    approximately 348 W m–2. Hence, the equilibrium surface
    air temperature sensitivity factor of the entire
    planet, as defined by this problem,
    is 0.097°C/(W m–2).

    I fail to see how the fact that this statement was made eight years ago changes anything about the calculation.

    w.

  23. Well, here we are in April … Steve Bloom’s threat to actually read and comment on Dr. Idso’s paper has not materialized.

    I was impressed by the eight natural experiments analyzed. Steve, can you disprove, or even dispute, any of the paper’s calculations or conclusions?

    w.

    PS — I suppost this will bring out the trolls and ad hominem experts again … don’t feed the trolls …

    PPS — The paper just had its eighth birthday (April 9,1998). I don’t understand how its age is any issue at all for the calculations themselves … unless someone believes that the temperatures measured in Phoenix have gotten stale with age or something. For example, take this experiment:

    The first of these 2 global-equilibrium natural
    experiments consisted of simply identifying the mean
    global warming effect of the entire atmosphere and
    dividing it by the mean flux of thermal radiation
    received at the surface of the Earth that originates
    with the atmosphere and which would be non-existent
    in its absence (Idso 1984). Calculation of both of
    these numbers is straightforward (Idso 1980, 1982),
    and there is no controversy surrounding either of the
    results: a total greenhouse warming of approximately
    33.6°C sustained by a thermal radiative flux of
    approximately 348 W m–2. Hence, the equilibrium surface
    air temperature sensitivity factor of the entire
    planet, as defined by this problem,
    is 0.097°C/(W m–2).

    I fail to see how the fact that this statement was made eight years ago changes anything about the calculation. Draw your own conclusion now, in 2006, from this calculation.

    My conclusion is that current sensitivity would be less than the ~0.1°C/(W m-2) determined by this natural experiment, because thermal losses rise with either delta T or delta W depending on the type of loss. Thus, losses at the current warm temperatures are larger than at a smaller delta T. This reduces sensitivity to a change in forcing, as some of the increased incoming energy is not converted to surface temperature rise.

    w.

  24. Hi,
    1. Steve Bloom Says:
    January 30th, 2006 at 12:49 am
    Peter, you are inviting me to spend quite a bit of time going over that document (and I’m still not done with two other detailed responses relating to this blog). I’m willing to do it since I’ll learn some things along the way, but given the age of the piece and the general marginality of Idso’s views I think there’s a good chance he no longer defends at least some of it. I don’t think it’s asking too much for you to confirm that first.
    2. Warwick Hughes Says:
    January 30th, 2006 at 11:09 am
    Sherwood says, “Truths are truths, no matter their age”. I doubt that is backing away Steve.
    Hugh R’s comment:
    Sherwood Idso’s 1998 paper reviews and summarises a number of earlier results which he had published, some alone, others with co-authors, in peer-reviewed papers from around 1980 onwards. Perhaps Idso’s views remain ‘marginal’ because people like Steve Bloom (sorry to be personal, Steve, no offence meant, I’m glad that you have contributed to this discussion) have preferred either not to read Idso’s 1998 paper or to ignore its contents. Steve’s stated reason for declining to read it (too old) seems rather weak, given that the 2007 IPCC report still contains references to many pre-1998 publications.

    If anybody finds their way this far in this blog may I recommend a reading of a much-quoted ‘mainstream’ paper which is a little ‘older’ than that of Idso (1998): Kiehl, J.T. and Trenberth K.E. 1997. Earth’s annual global mean energy budget. Bulletin of the American Meteorological Society, 78, 197-208. Fig 7 of this 1997 paper is reproduced both as Figure 1.2 of IPCC Climate Change 2001 The Scientific Basis and again (with the addition of colour but no other changes except to the caption) on p 96 of IPCC Climate Change 2007 The Physical Science Basis. The 10 intervening years have not, it seems, reduced the 1997 paper’s significance for the understanding of climate change. The diagram deserves careful inspection in its own right, but for proper guidance one should refer back to the 1997 text for Kiehl and Trenberth’s own commentary. The diagram shows that, assuming an albedo of 31%, the sum of incoming shortwave (solar) radiation absorbed by clouds (67 Wm-2) and by the earth’s surface (168 Wm-2) is 235 Wm-2; the same quantity (235 Wm-2 ) is also shown on the diagram as the amount of outgoing longwave radiation leaving the earth’s atmosphere. These two quantities represent the total incoming and outgoing energy and if they were not the same the earth’s surface, atmosphere and hydrosphere would be rapidly heating up or cooling down, which they aren’t. These figures may be subject to some adjustment, but they are not, as far as I am aware, the subject of much controversy.
    The diagram also shows the upward flux of energy leaving the earth’s surface. This is divided into 3 components:
    (a) 24 Wm-2 of ‘thermals’, that is, air warmed by direct contact with the surface and rising under gravity because of its density contrast with the surrounding air; this figure is stated to be the least certain of the 3;
    (b) 78 Wm-2 of evapo-transpiration (the latent heat resulting from transformation of liquid water, including moisture in plants, into water vapour, which also rises under gravity to condense and release its energy higher up within the atmosphere; this figure is well-constrained by the known mean annual global precipitation of about 1 metre per year;
    (c) 390 Wm-2 of long wave radiation from the surface, well constrained on account of the known present surface temperature of the earth.
    (a) and (b) are non-radiative transfers of energy from surface to atmosphere. Ignoring these for the moment and concentrating on (c): if 390 Wm-2 of long wave radiation is leaving the surface and only 235 Wm-2 of long wave radiation is being lost into space then there is a mismatch of 155 Wm-2. Kiehl and Trenberth call this mismatch the ‘long-wave radiative forcing’. This figure can be used in a preliminary estimate of the greenhouse effect. This greenhouse effect is, it should be noted, only partly due to the presence of CO2. Most of the greenhouse effect is due to water vapour, while the non-radiative forcings are not directly taken into account.

    (The following passage makes use of data from IPCC Climate Change 2001 and 2007.)
    Without greenhouse gases, but with its albedo as at present, the earth’s surface temperature would be approx. 255K and the surface would emit longwave radiation at 235 Wm-2(the same as the incoming shortwave radiation). However it emits 155 Wm-2 more than that amount and its temperature is about 288K, 33°C more than the greenhouse-free temperature. The greenhouse effect estimated by this method is thus 33/155 (°C/ Wm-2), or 0.22 °C/ Wm-2. If 3.7 Wm-2 is reckoned to be the thermal effect of doubling the CO2 content of the atmosphere, then a limiting figure for the increase in surface temperature due to such a doubling can be obtained by multiplying 3.7 Wm-2 by 0.22 °C/ Wm-2 to give 0.8°C. Due to the influence of other greenhouse gases, as well as non-radiative forcings, the true doubling figure must be less than this limiting figure of 0.8°C, and presumably closer to Idso’s figure of about 0.4 °C/ Wm-2.

    This estimate omits important factors such as feedbacks as well as non-radiative forcings, but it is at least a starting point for assessing the earth’s climate sensitivity on the basis of established physical science principles and present-day observations. I am an observational scientist, not a physicist, and I would be most grateful for any comments on errors in or suggestions for improvements to the above.

  25. Concerning Hugh R’s statement, I will just comment that I calculated the Earth’s radiation budget on a couple occasions and got similar numbers to what Kiehl and Trenberth got. However, these calculations only give you mean values whereas the greenhouse effect is a partial derivative of the Earth’s radiation budget. Thus, it is only of marginal use in determining the climate sensitivity. It would be nice if all the commentaters on climate change made their own radiation budget calculations – they might learn something.

    Warwick’s comment gives a better place to start. Idso’s calculations of low climate sensitivity have been confirmed recently by Spencer and by Lindzen.

    References:
    Sasamori, T., J. London, and D. V. Hoyt, 1973. Radiation budget of the Southern Hemisphere, in Meteorology of the Southern Hemisphere. Am. Meteor. Soc., Boston, 9, 23.

    Hoyt, D. V., 1976. The radiation and energy budgets of the Earth using both ground-based and satellite-derived values of total cloud cover. NOAA Tech. Rept. ERL 362-ARL 4, 124 pp.

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