A Citizen’s Guide to Global Warming Evidence

Was it only me? I thought Chicken Little dead. After all, when was the last time we heard competent authority shouting “Only the government can stop the sky from falling!”? But there he was yesterday, singing his old song, and from the highest perch in the land.

Since the subject has come up, even though it pains to do so, we have to talk about it. Hence this modified and expanded repost. I’ll also have more in the near future.

Mind! Global warming can be dangerous. But, so far as we know, only politically and financially. Why, your own author lost jobs (and more) because of global warming. So unless you have balls of steel, as I do, beware what you say on this topic. This post originally ran 1 December 2009.

Why are you so scared about global warming? Why do you believe things are as bad as they are? Why is it you feel that the world is coming to an end unless we do something?

Unless you are an actual, God-love-you, bona fide climatologist, it is difficult to see how anybody could raise an interest in the state of the climate given the actual, direct evidence we have for dangerous man-made global warming. But it’s clear our National Nervousness Index is peaking. Why is that?

Chances are, that if you are worked up, it is because you are mistaken. If you are like most people—and most people are—then you have inappropriately thought that certain evidence implied the truth of dangerous man-made global warming (or AGW, for short) whereas it actually does not. You are therefore unnecessarily worried.

Here, then, is a brief FAQ which you can cut and paste on your energy-efficient refrigerator, or pass out to “activist” friends.

  • The Earth’s climate has never been static It has always changed. And nobody—not a soul—knows what an ideal climate is. How can you say it will be bad if you don’t know what is good?
  • AGW is not the only theory of climate change Something caused climate the change, but it may not have been AGW. There are many rival theories, but you have never heard of them. One, or even none, of them might instead be true and could be useful in predicting future climates.
  • The accuracy of historical temperatures is questionable and is in flux We do not have direct measurements for most of the Earth’s history, and have to rely on statistics—-God help us!—to impute the missing records. The records used to compute past temperatures are ever changing, too; thus, so are the imputations. This process is fraught with error and uncertainty—uncertainty which is rarely or never carried through climate analyses, meaning we are too sure of the results.
  • Historical temperature changes are not good evidence of AGW Because it was cooler, or hotter, in the past is not complete evidence that AGW is true. All historical temperature observations are consistent with all known rival climate change theories. Past temperatures are, at best, indirect evidence for many different climate change theories, and not just AGW.
  • Statements of what happens when it is hot outside are not evidence that AGW is true If you heard that a glacier melted when it was exposed to hot air, you have learned what you already knew: ice melts when it is hot. Absolutely no observation of any plant, mineral, or animal is direct evidence of AGW. Thus, every horror story you have heard about small fish whose native waters got uncomfortably warm, about a species of grass that was stressed under the harsh sun, are not direct evidence that AGW is true. They are only statements of what happens when it gets hot out or when it rains or fails to.
  • Every statement about what might happen if AGW were true is worthless as evidence for AGW Horror stories about the evil, wretched future that awaits us once the “tipping point” has been breached are not evidence for AGW. The statements are empty of any kind of proof. “Studies” that claim future awfulness due to AGW are inappropriately and disingenuously used to hint that AGW is true. This naughty behavior is equivalent to the Tokyo scientist who solicits his government for a Godzilla “studies” grant because of the havoc the nuclear-fire breather could cause if he were real. That his grant is awarded is not evidence of Godzilla’s existence. Nor are the string of papers published on crushed bodies, burnt cities, and the like evidence for Godzilla’s existence.
  • The best indirect evidence for AGW is the fit of climate models to historical data AGW climate models can reproduce some of the historical data in some regions fairly well, but only in a statistical sense; they cannot fit data in all times or areas. However, many of those rival climate change theories fit the historical data equally well. Thus, the ability to reproduce historical data to an arbitrary level of goodness is not especially strong evidence in favor of AGW.
  • There does not exist good direct evidence for the truth of AGW The only possible direct evidence would be if the AGW models skillfully predicted future climate data (skill means an improvement over a naive forecast such as persistence or rival theory). These skillful predictions would tell us that the theory underlying the models is likely to be true. AGW climate models do not skillfully predict new data. A forecast of doom is not proof of doom.
  • The level of uncertainty in horrors caused by AGW is higher than thought A scientist writes a paper which states a horror is likely but not certain to occur if AGW is true and if a string of other conditions are met. This announcement is falsely taken as direct proof the horror will certainly occur. But the chance that the horror and AGW are both true and the string of conditions are true is necessarily less. Exaggerated example: it is 60% likely bee stings will increase if AGW true. But there is only (say) 10% chance AGW true. Therefore, there is only 60% x 10% = 6% chance we will see increased bee stings in the presence of AGW.
  • The bandwagon effect is strong Isn’t it odd that researchers predict that warm, fuzzy, cuddly, photogenic species all face extinction risk if AGW is true, but they also say that species that bite, stick, pester, and plague will thrive if AGW is true?

I’m available to speak on this (and many other) topics. See the Contact Page.

This was originally a follow-up to my Pajamas Media piece on What is—and what isn’t—evidence for global warming.


  1. dearieme

    “The Earth’s climate has never been static”: true. It is also true, however, that it seems sometimes to change slowly and at other times to lurch rapidly. As it happens, I can see no evidence worth a hoot that we are lurching at present.

    By way of context, I’d find it useful to have an idea, however approximate, of when people predict the next Ice Age is due. We are assumed to be in an “interglacial”, aren’t we?

  2. Daniel

    Which alternative climate change theories that have skillfully predicted new data? The AGW models are failing, but I’d like to see verification of other models skillfully predicting the data.

  3. Rick Ballard

    Typo alert – it’s Lindzen, not Lindezen.

    Thank you for your work on this. I look forward to future pieces.

  4. Arijigoku

    One solar-based climate change theory I like is described in the book The Chilling Stars by Svensmark and Calder. There is an experiment at CERN called CLOUD which relates to this and you may hear some interesting results from there in the next year.

  5. Nick

    What’s also funny, is that the temperature record has been maniplulated, and the models fit the manipulated temperature record, is that the models have proved something that is wrong.

    The religious scientists on the AGW side know this. They know that if you pull the temperature record card from the bottom of the stack, the whole tower collapses.


  6. Mike B

    I have another one for you, don’t know if belongs as a separate point, but it should at least be emphasized within one of your above items:

    Leading paleoclimatologists have proven to be completely out of their depth in the appropriate use of statistical methods for reconstructing past temperatures using proxies.

  7. kdk33

    seems to me:

    The models include all of the known important natural climate drivers, then are fit to past data by adjusting “human effects”. When used to predict the future they fail, but the excuse is natural variability, which is a natural effect, so the models don’t include all the natural effects, so the fitted human effects must be wrong. (deep breath).

    Or put another way, is anybody seriously claiming we’ve identified all important natural climate drivers. If no, then models are necessarily incomplete.

    I’m probably missing something.

  8. Mariwarcwm

    This is not about honest people trying to work out honest answers to what is happening to climate, or CO2. I read today that Governments have spent billions on Carbon trading, bankers and politicians are raking it in. Just check out hhtp://joannenova/com.au for a brisk description of the corruption that lies behind all of this.

    Like you I was a trusting citizen until I recently did a bit of reading about the carbon trading business. I find it frightening because the amounts of money to be made are so large. The naive population will pay for it all with higher energy bills. The great Copenhagen gravy train will thunder on, thanks to George Monbiot (I am in England) and his friends. I don’t think that he understands what he is doing by supporting warmists.

  9. Ray

    “The best indirect evidence for AGW is the fit of climate models to historical data.”

    I disagree. Fitting a curve to existing data is not prediction, it is curve fitting. I used to do that for a living and I have several computer programs that do curve fitting by different error criteria. One program minimizes the absolute error, another the squared error, another minimizes the maximum error (minimax criterion) and one will draw a curve thru all the data points by calculating a Lagrange interpolating polynomial. You can also do a spline fit if you have to go thru all the data points. There are lots of ways to fit a curve to data.

    I believe it was Von Neuman that said if you have enough adjustable parameters you can fit a curve to an elephant.The climate models have lots of adjustable parameters.

  10. Mike B


    I think that’s why Briggs referred to it as “indirect evidence”. Skill in prediction would be “direct evidence.”

  11. Briggs

    Thanks, Rick, dammit. My enemies have once again hacked into my system and changed my orthography. It is a constant menace.

    noahpoah, I canceled my subscription the day after they came out with the Savage Bjorn issue.

    All, Am on my way to the left coast. Will reply in full tomorrow sometime.

  12. Pete

    I will put this on my fridge, but can I change the 1st bullet from “It has always changes” to “It has always changed”?

  13. Dennis D

    I am not sure what to believe but I do know something is wrong when Christmas Day 2008 is 70 degrees and June 2009 never reached 90 degrees. Something is going on but due to these ideology brainwashed scientists we still don’t know .

  14. amicus curiae

    kdk33 models not including Clouds and solar irradiance are…worthless.

  15. Jolly Ranch

    Ray says:

    >> I disagree. Fitting a curve to existing data is not prediction, it is curve fitting.

    I agree with your disagreement. My take on all this is that there was very little to no physical science here. I have yet to see even semi-empirical equations for the “science”.

    That is why Harry didn’t talk about equation audits or system energy balances. Moreover, the quality of the TS 3 model was judged according to its conformance to TS 2.1 outputs. That is one reason for all the “artifical adjustments” in the code. I haven’t seen any discussions about improvements in the underlying science. At this point I’m hard-pressed to see ANY science behind the curtain.

    What I do see is a lot of empirical data that purports to be a reasonable temperature proxy. But given the odd results arrived at from very small data sets and the apparent selection bias towards “hockey stick” curve shapes, it is hard for me to to see how these chronologies were not cherry-picked.

    So the “hockey team” engaged in a lot of curve fitting (or “calibration” as they put it) using proxies of dubious quality. The forward predictive capability of their models appears to be not much better than ZERO (random chance). A sure sign of poor data or poor models or both.

    A simple example: If you create a hundred or so “time-series” of dice rolls, you can find some that will fit a given anomaly record after some simple scale adjustments. Now it should be obvious that the temperature measurements and the dice rolls are not related, but that doesn’t mean the two patterns can’t be loosely fit given enough candidates. But outside the “calibration periods” model and data will diverge, just as we see in the real CRU studies.

    Of course, I yield to my betters as I am new to this discussion. If anyone is aware that the CRU models in particular (or AGW models in general) are anything other than just curve fitting, please let me know.

    p.s., Mr Briggs, thanks for your fine work.

  16. Dean

    The best evidence for AGW is not the models, not the hockey stick, it is the physics.

    The second best evidence for AGW is that if our knowledge of the best evidence is wrong, then there wouldn’t have been any recent ice ages.

  17. kdk33


    the hockey stick is bogus
    models are garbage (no clouds or solar irradiance)
    speculation on consequences is… well, speculation
    the instrument record is probably doctored

    sea level rise isn’t accelerating
    hurricanes aren’t rampaging the coast
    nobody was ever killed by an angry melting glacier
    CO2 is plant food
    polar bears aren’t dying

    …or put another way, all climate prognostication aside:
    The earth has beem warming ~200 yrs, CO2 has been rising ~100 yrs, and the observational data suggests human prosperity has never been better. Think I’ll turn up the thermostat, right after I drive my SUV around the block.

    Back to the really technical stuff, sorry for the interuption.

  18. Bernie

    I am not sure I understand your two statements.

  19. James Gibbons

    An interesting analysis of some CRU emails relating to SO2’s cooling effect which might explain the “divergence” in temperature:


    It seems that some of them noticed the cooling ability of pollution but Phil Jones didn’t believe it.

    I get the feeling these people don’t really know what they are doing, but they sure don’t give that impression to the press.

  20. DAV

    Godzilla’s not real? Never had you pegged as a Godzilla-denier, Briggs. Next you’ll be claiming the IPMC report was orchestrated around by a clique of “scientists”.

    How could one not weep at this outrage suffered by this endearing creature?

    Here’s proof of Godzilla’s reality (Quote: “History shows again and again
    How nature points up the folly of men”):

    You want more proof? Go to Wikipedia.

    Godzilla’s is real. It’s about time you Mothra-lovers faced reality.

  21. Briggs


    This is a very important point: it does not matter whether the “hockey stick” is correct or not. If it is, then it is not direct evidence for AGW: it is at best indirect evidence for it, but it is also indirect evidence for many other alternate climate models. If it is not correct, then again, it says nothing directly about AGW, or other climate, theory (it might have something to say about psychological theories).

    And the same thing goes for observed sea level rise, etc.

    These are just things that happen, and their happening is consistent with many models of climate (change).

    The most important test of AGW (or any) theory is that it can make skillful predictions. These are what we are still awaiting.

  22. Michael

    the questions i’ve never heard asked are:

    if satellites can determine the earth’s temperatures, can we determine the temperatures of other celestial beings within our planetary system? can we look at the temperature variations of said planets – and compare them to our planet?

    if solar energy is the main culprit in our ecosystem, shouldn’t the same effects be seen on other planets/ moons?

    if a correlation can be drawn, doesn’t AWG become debunked?

    we need to think simply. the truth is usually the simplest explanation.

  23. Welcome to the Land of Fruits and Nuts. Notice how much warmer it is here? Notice how much nicer it is to be warm?

    All the foofrah and panic about the slim possibility that the global might get a degree or two warmer over the next 100 years is misplaced anxiety. I mean, so what? It might be a GOOD THING if it it got a little warmer.

    All those folks living in warm regions seem to think so. Otherwise they would move somewhere colder, like Alaska. Many (most) people migrated to CA precisely because of the warmer climate.

    All of which says nothing about the validity of AGW theory. But it does demonstrate the instinctive two-facedness of our anxiety-prone species.

  24. stan


    I would like to offer you another category of evidence — evidence of incompetence and fraud which tends to prove that purported expert witnesses lack credibility.

    Catastrophic AGW is a theory which has been pushed onto a gullible public for the purpose of making enormous policy changes. The burden of proof should be on those pushing the change. Those pushing the change have trotted out various arguments to support their claims regarding the science. You are correct in noting that many of the AGW arguments rely on things which really are not evidence of AGW. However, it is perfectly appropriate for skeptics to demonstrate the falsity of such arguments for the purpose of impeaching the credibility of those witnesses. For example, the hockey stick is not evidence of AGW. But the alarmists and their experts said it was. Proving that it is wrong and likely fraudulent is an appropriate way to demonstrate the falsity of their claims (and way of thinking) and destroys the credibility of those alarmists who perpetrated the fraud and those who cited it.

    Further, since one of the biggest of their arguments asks the people to rely on the experts as all-knowing authorities, impugning the credibility of those experts is perfectly appropriate. Appeal to authority may be a logical fallacy, but it is widespread and even widely used in our legal system. When those supposed experts are exposed as frauds, it impugns their credibility. When the massive incompetence underlying so much of the scientific work is exposed, it demonstrates how unfit they are for their roles as authorities.

    The vast majority of the people are in no position to evaluate the science. They have no choice but to try to discern who are credible expert witnesses and rely upon them. So even if some of the arguments rely on facts which aren’t really evidence of AGW, it is perfectly appropriate to defend against the implementation of the proposed policies by exposing the falsity of the purported facts and the lack of credibility of the purported experts.

    We all use past experience to determine what credibility to lend to others. If they have lied before or committed fraud before or been shown to be incompetent before, we are making sound judgments when we choose to ignore them or discount what they tell us. Yes, this time they might be right. But life’s too short and shorthand methods to determine credibility are all we have. Knowing this, skeptics should address the alarmists on the ground the alarmists have chosen to fight, even when the alarmists’ proffered arguments themselves fail to constitute valid evidence.

  25. SteveBrooklineMA

    Burning fossil fuels has increased the concentration of CO2 in the atmosphere in a measurable way. By itself, this would lead to increased temperatures through the greenhouse effect. Unless other human activities or natural negative feedbacks have fully offset the effect, the bottom line is that the Earth is warmer now than it would have been otherwise. Increased CO2 is evidence of AGW. Sure, let’s discuss the amount of AGW and its impact, but let’s not question the reality.

    Suppose T(t) represents the temperature T of the Earth at t years in the future. Suppose we have no way of accurately modeling or predicting T in future times; it may be warmer, it may be colder, suppose we just don’t and can’t know. That doesn’t preclude science from predicting that with increasing CO2, future temperatures will be something like T(t)+C(t), where C is some positive function of time. It is not necessary to have a fully working accurate predictive model of the Earth’s temperature in order to be able to predict that increased CO2 will mean an increase in temperature above what it would otherwise be.

  26. Doug

    The very interesting and informative opinion piece below was written by Richard S. Lindzen, professor of meteorology at the Massachusetts Institute of Technology. It originally appeared in the 30 November edition of the Wall Street Journal —

    Editor’s note: I have removed the WSJ content—which is linked at the top of the story. I hate when somebody cut and pastes my entire posts at their web site, and I imagine the WSJ feels the same way.

  27. leg


    You are starting with the assumption that CO2 in the atmosphere contributes to a greenhouse effect. There is no evidence that this happens in the earth’s atmosphere. We just do not have that knowledge yet. Additionally, there are some serious challenges to the whole idea of the greenhouse effect and to assume it is valid belies good science. There are so many questions to be answered that it is either foolishness, hubris, or chicanery to be making climate predictions from what we know – especiallly as it relates to CO2 forcing.
    Studies seem to show that CO2 levels rise following temperature rises with a 100 – 800 year lag time. Is that what we are experiencing right now? What caused the temperature to rise? So many questions, so few answers. It troubles me to see scientists making doomsday predictions from such little knowledge. I would hope it would trouble you.

  28. Snowman

    What is the ideal level of CO2 in the atmosphere? 200, 300, 500ppm or what?

  29. John M

    Dean says:
    1 December 2009 at 10:40 pm

    “The best evidence for AGW is not the models, not the hockey stick, it is the physics.

    The second best evidence for AGW is that if our knowledge of the best evidence is wrong, then there wouldn’t have been any recent ice ages.”

    That’s sort of like saying the best evidence for Derek Jeter being the best Yankee ever is that the Yankees won the World Series.

    The second best evidence for Derek Jeter being the best Yankee ever is that if he he’s not the best ever, then the Yankees didn’t win the World Series.

    I know my logic doesn’t make any sense, but…..

  30. kdk33


    Love the site!

    I was just having a little fun last night…

    I think it’s worth noting, because I never seem to hear, that we DO have observational data for climate change in a warming world and we DO have observational data for climate change in world with increasing CO2. The verdict is in; the science is settled – human prosperity has never been greater.

    …or maybe it’s quadratic and we’re all gonna burn.

  31. Ian B


    Taking your two statements:
    1) Half agree – the physics of radiative heat transfer and particularly the ability of CO2 to slow down the loss of reflected radiation at particular wavelengths (which do not significantly overlap with the wavelengths retained by water vapiour) is a fundamental issue. However, there must also be consideration of the mechanisms of heat transfer (i.e. relative amounts of heat loss from the surface by convection versus back radiation) and the influences of the potential changes in lower atmospheric heat transfer on water vapour and cloud formation

    2) The only scientist who makes the claim that the last glacial was caused by greenhouse gases is James Hansen. Go make the same claim in any geology department and wait for the laughter to subside…

  32. Bernie

    John M
    I had the same problem. We are therefore both either smarter or dumber than Dean. Ian B is obviously smarter than us all, since he seems to understand what Dean said.

    Ian, can you restate what Dean said?

  33. bill-tb

    And the missing Al Gore hotspot is proof that the GCM computer models are all wrong … It falsifies the whole AGW prediction racket.

  34. Marco

    Matt and all the others that might be able to help.

    Your reasoning is logic and reflect my position precisely.

    I was skeptical of whoever pretended to tell the future from the NUMERICAL solution of a system of many coupled ODE/PDE (where the parameter estimation/optimization is at best subjective) long before I engaged in a very large project where the computer was doing all the thinking (imagine that!) in trying to model metabolic systems.

    The approach was very similar:
    1. someone was deciding what was important and what was not,
    2. then some “possible” time evolution were fitted from few scarce data for every deemed-relevant component of the system and
    3. fed altogether into a computer that magically was suppose to tell us the overall time evolution.

    However in that case I could always send back the results as bad since I had the experimental data, or the common sense, to reject them.

    In this case I am still struggling for finding the data you cite. I am aware, for example, of Scafetta et al.’s proposal as well as few other models that seem to work better. However what I think it would contribute a great deal to the debate would be the hard data that show there has not been warming for the past 10 yrs.

    Can anyone please point me to some official database where I can find them?
    This would really help me into decide since, as every decent physicist would do, I trust you but I’d rather see the data for myself.


  35. Barry

    The reason that some models can be fitted to historical climate measures is that they use an infinitely elastic store of aerosols. There is no measure of the quantity of aerosols that could be contributing to “global dimming” at any time, so the modelers have to guess this component.

    After they have done an initial run with their programmed amount of gross warming caused by measured GHG-concentrations (ie actual data) they make an allowance for enough aerosols to reduce their net warming to the known temperatures.

    The whole thing is circular! The actual temp determines the quantity of aerosols which determines the modeled temp which equals the actual temp!

    The IPCC then contends that none of these models could reproduce actual temps without the human -influenced elements (GHGs and aerosols), therefore all other theories are rejected.

    This is certainly not rocket science!

  36. DEEBEE

    Barry, I would go even wider and staet this is not science, when a fudge factor is included.

  37. Noblesse Oblige

    Briggs’ post is absolutely logical. When was the last time you met a logical believer?

  38. Ray


    That’s not a fudge factor. We physics students called it Finagles variable constant. It was commonly used to make the physics lab results give the desired answer.

  39. Briggs, sorry to hear you lost a job over this. Hope your new life is better (although I see you seem to travel a lot more).

    First it was global warming, but in the last 10 years it is global flat-line or cooling. There was global warming on Mars, but no SUV’s to blame, so they blamed it on dark sand heating it up more than the lighter sand of the past. Now some blame the global cooling on the coal burning in China, except another NASA report says aerosols have been decreasing world wide. Now I’m really confused.



    These people will make anything up to satisfy their agenda. The real problem I see is that they own the schools and unfortunately children don’t have very well developed BS detectors.

  40. bob

    AGW is real but it’s no big deal
    I can’t see it any other way
    The Hockey Stick’s dead and the sea is cold
    But the lies won’t go away

    ClimateGate is real and a very big deal
    Jones, Mann, and Briffa are the crooks
    The CRU lied through their teeth about those creeps
    And the Royal Society cooked the books

    Now I know how things will go
    When they pass Cap and Trade legislation
    We will pay and pay and pay and pay
    Until all they bankrupt the nation

  41. Adam H

    Global warming predictions are similar to end-of-the-world predictions. When the time comes to test the prediction, no one cares that the predictions were wrong. A month later, everyone has forgotten, and a new prediction rolls out.

  42. Greg Cavanagh

    Dr. Finagle was a smart man:



    IT WILL.

  43. DAV

    Another blast from the past. Speaking of classics, I just saw Huston’s The Asphalt Jungle. Marilyn’s second or third movie. One thing almost universally true of classics: they don’t make ’em like they used to.

    Another repeat in the news: downtown yesterday a Certain Someone received a second public Swearing-In which sounds as though a public Swearing-Out is overdue and may be in order.

  44. john robertson

    Good summary. You could add that the proposed solution has been the same, cooling=stop using oil.Warming=stop using oil.
    Always the same conclusion, civilization is evil, no matter what the professed evidence.
    The law of unintended consequences has a place in this narrative as well.

Leave a Reply

Your email address will not be published. Required fields are marked *