U.S. Senate Report: Over 400 Skeptical Climate Scientists

The U.S. Senate Committee on Environment & Public Works has released an addendum to its list of 400-plus scientists who express some level of skepticism about man-made global warming. I highlight this because, well, it turns out that my name has made its way onto the list, so I now have to explain why and what it means to be a “skeptic.”

I should first explain that I am on this list reluctantly, because, as I have been quoted as saying, “Most scientists just don’t want the publicity [associated with speaking out on climate matters] one way or another. Generally, publicity is not good for one’s academic career.” I do not think, then, that my being on that list, and starting this blog, will bring a tremendous boost in my own professional life. Scientists like to see discussions about uncertainty in their methods and results kept inside peer-reviewed journals and not dragged through the press. They have strong opinions on this. Witness the scorn heaped up the physicists Fleishman and Pons when they first released their “cold fusion” theory to the press and not to other scientists; for example, see this article which says that what the pair did was a “‘classic’ example of what not to do as” scientists. Actually, this is an odd statement because the incident ended well—because it was the initial public announcement that spurred the flurry of research that showed that cold fusion was false.

The only reason that I have been able to think of about why research should be confined to journals is that it is in these places that scientists expect to find new results. Scientists are not in the habit of scanning the newspaper or trolling the internet looking for press releases. There just isn’t the time to do so.

But climatology has, unfortunately, become a different sort of creature. Far too much speculation shows up in the headlines. Prominent scientists have taken to using the press as a bludgeon to discourage reasonable dissent. An example: R K Pachauri, Chairman of the IPCC, and now co-recipient of the Nobel Peace Prize, has compared anybody that dared question mad-made climate change to those who believe in a flat earth.

“Well, there will always be some skeptics,” Pachauri said. “As you know, there is still in existence something called the Flat Earth Society. There are people — a very limited number, thank God — who believe the Earth is flat.” Source: Washington Post

These excruciating comments are asinine and irresponsible, and they must be answered publicly.

I am not skeptical that man causes changes in his environment; in fact, I argue man must cause changes (see this post). I am only skeptical about the extent of these changes and about our ability to understand them. I am skeptical of the results from climate models that are used to posit large and harmful shifts in the earth’s temperature.

The vast majority of pronouncements about climate change are based on forecasts, guesses made about the future which are conditional on the multitude of assumptions underlying the models being true and on the forecasts having only small error. My specialty is in forecast evaluation (not just climate models, but any kind), and I do not feel that climate models have shown their ability to make accurate predictions thus far. This is why I said that the “error associated with climate predictions is also much larger than that usually ascribed to them; meaning, of course, that people are far too sure of themselves and their models.”

Overconfidence is a common human trait, and it holds in scientists just as much as it does with civilians. Typically, however, the excessive surety of scientists is tempered by the peer-criticism process, which has the effect of reducing, but never eliminating, prediction error. But this service won’t work well if experts are made to feel squeamish about making their critiques because of a public browbeating by autocratic scientists, politicians, and “activists.”

There is also a shade of “groupthink”—bandwagon research—not so much with climatologists, but with the mass of secondary and tertiary investigators who use climate model output as input to their own models of economics, public health, sociology, and so on. These models invariably show what they were programmed to show: that climate change of any kind is bad. This is, of course, physically impossible; but these are not physicists who are making these remarks—which of course quickly find their way into the press—and thus they are not held accountable in that sense.

Of course, if global climate models eventually show skill, then I will believe what they have to say.


  1. Norm

    There is an interesting demographic statistic to the climate change issue. Around 1980 the defintition of the greenhouse effect was changed to promote the AGW agenda eliminating the concept that clouds were responsible for most of the greenhouse effect (77%).
    Anyone under 45 years of age would have completed their formal education after this change so their perception of the greenhouse effect would be limited to atmospheric gases which are responsible for no more than 23% of the greenhouse effect and CO2 is only responsible for less than 40% of this 23%. (the total greenhouse effect is 33?C so CO2 is responsible for no more than 3?C. the radiative band that CO2 captures is alraedy at least 2/3 saturated so there is only 1?C of further warming possible from CO2 regardless of the concentration)
    It would make an interesting statistic to compare the age of people to their position on global warming with a cut off of 45 years.
    Most of the skeptics that I know are over 45 and most of those firmly convinced that the IPCC models are correct are under 45.
    Perhaps the Climate Change issue is nothing more than a measure of the ability to indoctrinate through education (similar to the clerics teaching the terrorist version of Islam)

    Norm K

  2. Doug

    I admire your courage Mr. Briggs. I am a government employed environmental professional who is also skeptical of models.

    Too much of what passes as science today is derived from models and policy makers are far too trusting of these quantified guesses.

    While GCM’s of 2008 are certainly more sophisticated than those that were developed in the 1960’s, a close look reveals that they still do not adequately incorporate some of the most important climate variables, such as water vapor and ocean currents.

    Your point about the secondary and tertiary studies is one that I very much agree with. The proliferation of these derivative and often wildly alarming studies is problematic in that they are wholly dependent on the models being right. They very much put the cart before the horse.

    In many ways the next few years (5?, 10?) will be very intersting for climate science. The warming effects associated with sunspots and the positive El Nino are no longer part of the climate mix. If these prove to be as important to climate as some skeptics have postulated, the models as currently configured will be empirically falsified.

    Until then, I remain skeptical.

  3. David Brunfeldt

    So, if you are a bureaucrat, politician, journalist, high school biology teacher, social scientist, or other non-physics-based person of the planet, how are you going to understand AGW?

    You don’t understand radiative transfer, frequency, wavelength, color, or any aspect of heat, energy, temperature, or any of the physical rules of the game.

    Most of these people have a hands-on skepticism of their computer’s operating system, word processor, etc. But they are willing to believe a much more sophisticated program called a GCM. I think that most people are engaged in some kind of climate mea culpa, quasi-religious guilt trip, unrelated to rational thought.

  4. Administrator

    David, your question is excellent, and I want to take the time to answer it right. So come back in a day or two and look for posting with a title something like “How Can I Know”?

  5. Luke

    William – a fair and reasonable position on the surface, but many of the skeptics are much more than skeptics – they have move into the area of activism and political involvement. And of course there are many skeptcal theories but one rarely sees skeptics being skeptical of each other – or even critical – just the IPCC.

    Indeed it would be wonderful if the CO2 issue turned out to be unimportant as an issue, as to do anything about it practically will be a most difficult social, economic and technological undertaking on a global scale.
    But this should not deter us from evaulating the risks.

    However the issue is not one of certainty – governments have to make decisions on the basis of risk management and imperfect data. There is a certain amount of evidence collated by the the IPCC placed before us which skeptics are skeptical of.
    How skeptical? 100%, 10% , 50% or what? You could do the 2 way payoff tables of being right and wrong and the consequences thereof. But it is an issue of risk management – how much action should humanity take on this issue and when? None, some, a fair bit or major reform? Call for more information?

    As you are a statistician you have a most difficult problem – all our time series data have problems and limitations – paleo climate proxies, surface temperature data, sea surface temperatures, satellite data on temperature, cloud, radiation, storm and hurricane records etc.
    Given natural variability exists, if there were a greenhouse signal, presumably it would intitially hard to detect that signal emerging from a fog of natural variation. A job for statisticians. Frankly this fuzzy signal probably looks like what’s in front of our noses.

    As for models your mention of skill worries me – one could use LEPS, ROCS, probability distribution or chi square type measures on seasonal climate forecasts. But that’s not the sort of modelling they are undertaking. The models ar not trying to simulate the climate of 28 July 2035 exactly and never will. They are trying to simulate the variability of a climate in transition and in equilibrium with changing levels of CO2 forcing. New “background average climates” in a statistical sense not a forecast of precision.

    Not knowing how humanity will respond to greenhouse or what will happen technologically in the future, greatly affects the prime driver of the simulation – the pattern of future CO2 growth. So as Trenberth has reminded us these GCM model runs are not forecasts, they are only scenarios and can only ever be scenarios. And it is the only technology available to us given we don’t have a spare planet Earth to play with a few thousand years to experiment with different aspects. So I’m not sure how skill testing would work in such an area – and I am not saying on the other hand that some form of validation is not required.

    Anyway my summary – be skeptical – but evenly skeptical. The sceptics cannot have their own camp if they are fair dinkum. And for society it is an issue of risk management with imperfect information. Someone has to make some decisions.
    How many of the 400 list are “fair dinkum” and how many are simply political activists.

  6. Mike Davis

    I have a problem with the fact that the methods and procedures they use for arriving at the historic temp. record has not been properly audited. It appears that they are using best guess methods that match their theory. Thus they are supporting this data with the GCMs and using this to support the GCMs. Maybe this is just modern science at work and I am too old to understand modern science.

  7. Administrator

    Luke, you are right on the money. Too many skeptics take the position that “man-made global warming is impossible.” Of course, it is possible, and the only trick becomes assessing how likely climate changes are caused by people, and how much of an influence there will be.

    After you have those numbers in hand, you still have the other big question which you rightly emphasize.: How likely will our potential interventions modify our influence?

    Now, briefly, my argument is this (I’ll expand this later): the predictions that are used to make decisions (these are initially based on climate models, and modified, by a long chain of people, to become the forecasts used by politicians) are too sure by about a multiple of 2. That is, take the given “plus or minuses” and multiply that by 2 (well, I think the minus should be bigger, the plus is about big enough). That’s just for the forecast for climate warming regardless of mankind’s influence.

    Then do the same for the estimated fraction of climate change that mankind causes. And again do the same for what we can do about it, which, given what we know about history and world-scale political events, should lead us to multiple the error bounds by an order of magnitude or two.

    In short, there is a large class of people who are far, far too sure of themselves, their estimates of the risk are inflated by an enormous amount, and their pronouncements that the “debate is over” is premature.


  8. Norm

    AGW, to the extent promoted by the GCM models, is actually physically impossible because the Earth does not radiate enough energy in the capture band of CO2 to raise the global temperature any more than 1degree C.
    The GCM models use only the physical properties of CO2 without taking this limit into consideration, and are therefor able to predict much larger temperature rises from increases in CO2 than is physically possible.
    The simple observation during the ten years of the Kyoto Accord that CO2 emissions increased by about 340megatonnes/year for the first 5 years with the temperature going up by about 0.01degree C/year, but in the last 5 years CO2 emissions have increased by 800megatonnes per year yet the global temperature has been dropping on average for these last 5 years by 0.01 degrees C, shows first of all that global warming ended 5 years ago, and secondly there is no direct relationship between CO2 emissions and global temperature.
    If the GCM models were based on the proper definition of the “Greenhouse Effect” that includes clouds as the major component, instead of the current approach that uses CO2 as the major component and uses clouds as a “feedback” to justify the focus on CO2, there would be no justification for the AGW premise from the GCM models.

    Norm K

  9. Roger

    What a great sense of humour Luke has – It’s the Scepics who are the political activists?

  10. Michael Smith

    Dr. Briggs,

    Thank you for having the courage to speak out on this important issue. Your area of expertise is most urgently needed in the global warming debate to counter the IPCC’s attempt to convince the public that “the science is settled and the debate is over”.

    What the public doesn’t realize is that the models relied on so heavily by the IPCC — the GCMs — vary tremendously in their outputs. For instance, in their projections of tropical tropospheric warming — which is supposedly the place where the greatest warming will occur — the models predict everything from a warming trend of .6 degC/decade down to .01 degC/decade, with some even predicting a COOLING trend above a pressure level of 200 mb! This little tidbit came out when a paper was published showing that the small warming seen so far in the tropical troposphere does not match the model’s predictions. To counter that paper, the web site RealClimate pointed out that the authors were only looking at the AVERAGES of the model’s predictions — and that when one considered the range of all the individual predictions, the lack of tropospherical warming could not be said to contradict the models. In other words, they have a model for almost every outcome! And if ANY of the models matches reality, they must ALL be considered valid! Read about it and see the range of model outputs here:


    Now here’s the really fun part. What does the IPCC do with the fact that the model outputs are all over the map? Does this make them skeptical of the models? Does this make them question their utility? No. Instead, they treat the models as if each run was a valid, random sampling of the climate — as if the model’s variability reflects the climate’s variability. They then take these results and run traditional statistical analysis, computing averages, standard deviations, medians, etc and project “confidence intervals” based on these statistics.

    This is not science — this is a house of cards based on the assumption that the models have bracketed reality and that averaging them tells you something about future climate. But there is no way at present to know if that is true — there is not even a way, as far as I can tell, to estimate the probability that the assumption is true.

    We need real statisticians like yourself, Dr. Briggs, to audit what the IPCC is doing and keep them honest. You may want to visit the web site ClimateAudit, which is dedicated to doing precisely that.

  11. Papertiger

    Angstrom’s experiment proved beyond doubt that a trace of co2 in the atmosphere, much smaller then the amount that has existed since the beginning of time, is enough to “saturate” the absorption.

    This is solid reproducable proof which falsifies the anthropogenic global warming theory. I have reproduced the test myself. Using two bottles, one filled with co2, the other with plain air, there is no measured difference between the temperatures of the two despite co2 concentration.

    In the web book “The Discovery of Global Warming” by Spencer Weart, this conclusive result is claimed to be invalid because of some undefined property inherent to the atmosphere which Weart (and I presume the rest of AGW advocated) claims isn’t well modeled by Angstrom’s experiment.
    Weart’s claim is – “The greenhouse effect will in fact operate even if the absorption of radiation were totally saturated in the lower atmosphere. The planet’s temperature is regulated by the thin upper layers where radiation does escape easily into space. Adding more greenhouse gas there will change the balance. Moreover, even a 1% change in that delicate balance would make a serious difference in the planet?s surface temperature. The logic is rather simple once it is grasped, but it takes a new way of looking at the atmosphere ? not as a single slab, like the gas in Koch’s tube (or the glass over a greenhouse), but as a set of interacting layers. (The full explanation is in the essay on Simple Models, use link at right.)”

    This is wrong on several counts.
    First the Angstrom test confirms that CO2 is saturated at ground level – this is irrefutable and not a topic for debate.
    Second there is no special property of the upper atmosphere that regulates infrared energy. At the surface as well as in high altitudes heat always obeys the second law of thermodynamics flowing from the source, diffusing out toward areas of lower temperature. Infrared never flows from the lower temperature toward the higher.
    Adding more CO2 makes no difference. Concentration of constituent gases has no effect on the system’s entropy.
    Talk of “layers” in the atmosphere is nonsense.
    Weart knows it too. Look at the way he tries to gloss over the key assertion upon which the theory rests.
    In this multi paged essay he doesn’t bother to support the main contention of the global warming theory with facts tests or observations, instead he directs people to look at some other tract call simple model, where the reader is promised a “full explaination“.
    “Why doesn’t he give the full explaination right here?”, the reader would be right to ask.

    Here is why not. From Simple Models – “Not until the mid-20th century would scientists fully grasp, and calculate with some precision, just how the effect works. A rough explanation goes like this. Visible sunlight penetrates easily through the air and warms the Earth?s surface. When the surface emits invisible infrared heat radiation, this radiation too easily penetrates the main gases of the air. But as Tyndall found, even a trace of CO2, no more than it took to fill a bottle in his laboratory, is almost opaque to heat radiation. Thus a good part of the radiation that rises from the surface is absorbed by CO2 in the middle levels of the atmosphere. Its energy transfers into the air itself rather than escaping directly into space. Not only is the air thus warmed, but also some of the energy trapped there is radiated back to the surface, warming it further.”

    The highlighted segment of that paragraph is impossible. It violates the law of entropy. Just as the flame from a match never flows toward the Earth, likewise infrared energy emitted by co2 molecules never “radiates back to the surface”.


    I am the person who set up the debate between Andrew Dessler and Tim Ball. It was unfortunate that Dr. Ball experienced phone trouble (also highly convenient for the AGW cause). If any of you skeptical scientists can get over your personal shyness long enough to argue the above point with clarity, contact me domaye77542 – at – peoplepc – dot – com.

  12. Papertiger

    I am particularly interested in skeptics within the USA. I have a reasonable doubt that climate change debate will be allowed by the government of Canada.

  13. Administrator

    To Michael Smith:

    I would not say that the way the IPCC looks at model output using classical statistics “is not science.” It certainly is science. But not all science is great science; plus the classical statistics often used too easily lead to overconfidence.

    It is the case, however, that typical forecasts of warming do not fully account for climate model uncertainty. There are attempts to account for the variability across different models, but the level of confidence that each of these model’s outputs are accurate is underestimated, as you suggest. The gist is that the models under-predict actual climate variability.

    There’s lots more work to be done in this area, for sure. And thanks for the tip!

    Oh, it might help to know that I have both a Bachelor’s and Masters in Atmospheric Science, which makes it somewhat easier to understand some of the physics.


  14. Morrie Barembaum

    To Luke,
    You say “…many of the skeptics are much more than skeptics – they have move into the area of activism and political involvement. “.

    However, when we hear that “…there is a consensus…”, and as Mr. Briggs points out that some who subscribe to AGW
    “…compared anybody that dared question mad-made climate change to those who believe in a flat earth.”, what are skeptics to do?

    Just to have the ability to examine the data and theories of AGW in the realm of science (instead of politics or public opinion) requires an enormous resolve — and yes — activism.

    While the consequences of AGW would affect the world population, it is still a question of science that should be studied in that realm. It is not up for a vote — and yet, that is the kind
    of language people are using to prove that AGW exists: consensus.

    Even if there were a consensus about AGW, that does not make AGW true. Prior to Copernicus, there was consensus regarding the Geocentric Theory. Prior to Hubble, there was a consensus that the Universe is static. Both proven wrong.

    Let us rationally study global warming and look at all the data and theories available. That, I’m afraid, has not been done.

  15. Luke

    Morrie – all this stuff about consensus, 2500 scientists, what Al Gore thinks/says is really just blog and press fodder. The real science and government decision making hastens more slowly. Governments won’t push their electorates too hard or they will simply be voted out. As we have seen in Australia in December – does not take very much discontent to give governments the boot even in times of economic prosperity. If AGW is some reasonable degree of risk, the probability of getting individuals, corporations and nation states to move beyond self-interest isn’t that high. And how do you balance the impacts of developed nations versus an emerging China and India.

    Very very difficult problems.

    As for papertiger – don’t argue with us – we’re not worthy- race out and publish your new theories on greenhouse in Science or Nature post haste. If you have debunked the entire existing literature the world surely must be told. Modtran in tatters. Still puzzles me thouigh how using radiometers Philipona came so close to measuring the extra longwave flux as predicted by greenhouse theory. Probably just a lucky break 🙂

  16. Morrie Barembaum

    “…blog and press fodder ,,,”

    “As we have seen in Australia in December – does not take very much discontent to give governments the boot even in times of economic prosperity”

    If it is your contention that AGW had a major impact on the elections in Australia (which I seriously doubt), where did the electorate get their information: science journals?

    Of course it is from the press and blogs. Why has AGW become such a front burner issue? Science journals?
    No, it is the UN’s IPCC (which is not a scientific body) and
    “An Inconvenient Truth”. It is not rational scientific arguments,
    but rather emotional and political argument based on computer modeling that has not been well tested.

    My desire is to have a rigorous review of AGW and the skeptics theory. To allow both sides to present their case —
    as has been done in the past in other “great debates” such as the Curtis-Shapley debate.

    What a novel concept?

    A scientifically rigorous treatment of AGW.

    What if — just what if — climate change is occurring but it is not anthropogenic? What if all the efforts to curb CO2 would have no effect on climate change? We could spend billions and billions of dollars without altering climate change.

    What will we have done to prepare?
    What will we have done to adapt?

    Those who say that AGW is occurring and that CO2 is the sole culprit have put all their proverbial eggs in one basket.
    There could be so many different reasons why climate change is occurring (let us not forget that climate change is the norm, not the exception), that a massive program to curb CO2 will likely not stop climate change.

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