William M. Briggs

Statistician to the Stars!

Just what are falling temperatures evidence of?

If increasing temperatures are consistent with or are evidence of global warming, what theory is consistent with or evidence of falling temperatures? Global warming, too?

We have to ask this complicated question because it was just reported that this year’s global average temperature is on track to be the coldest in the last eight years. In other words, the temperature has dropped, and has been dropping for a couple of years.

So, do these falling temperatures mean that global warming has stopped or is false?

“Absolutely not,” said Dr Peter Stott, the manager of understanding and attributing climate change at the Met Office’s Hadley Centre.

We also hear from “a team of climate scientists at Kiel University” who

predicted that natural variation would mask the 0.3C warming predicted by the Intergovernment Panel on Climate Change over the next decade. They said that global temperatures would remain constant until 2015 but would then begin to accelerate.

This is going to be complicated, and there are not many ways to make this topic easy to understand, so hold on.

We have to explore what it means for evidence to be “consistent with” of “inconsistent with” a theory, what it means for a theory to be wrong or right, and what it means to be probably right or probably wrong.


Suppose, then, that the theory of anthropogenic global warming claims, among other things, that the temperature will certainly rise year by year. The temperature did not rise and in fact fell. This evidence is inconsistent with the theory and so the theory is false because it made a prediction that said that falling temperatures were impossible. If you like, we can say that this theory has been falsified (Popper’s term of very little utility; a topic to explore in full another day).

Our cartoon theory has been proven false. It can thus be dumped, forgotten, ignored. Skeptics may rejoice! Indeed, any theory that makes a prediction that says “X will certainly occur (in such and such circumstances)” and in fact “not X” occurs, has been falsified, which in plain English means that it is wrong. (“not X” means “Any circumstance that is certainly not X.”)

However, the actual theory of anthropogenic global warming (AGW) makes no such claim like “The year-by-year temperature will certainly rise.” Instead, it makes claims like this: “The year-by-year temperature will probably increase.” We can go further and say that nearly all the claims of that theory are statements of this kind, that is, probability statements.

There is only one claim of certainly in the AGW theory and it is that “Mankind influences climate.” That statement is trivially true. It is impossible for mankind not to influence climate. Every action you take, every breath you make, changes the climate. In fact, we can broaden the claim and say that “All organisms influence the climate” and it remains true. Since this is trivially true, the only interesting questions are (1) “How much does this or that organism influence climate?”, (2) “In what part are these influences helpful or harmful?”, and (3) “Can the helpful aspects be magnified and can the harmful effects be mitigated?”

Climatologists spend most of their time with (1), the first part of (2) is usually ignored, and “activists” make their business the last part of (3), the first part also being ignored. But we are getting away from our original goal. What do falling temperatures mean to the theory of AGW?

Let’s examine the claim: “The year-by-year temperature will probably rise.” What observations, if any, are inconsistent with that statement? None. There are no set of circumstances that can arise which directly contradict it. Temperatures may rise and they may fall; they may fall for each year from now until the year 3000 and that statement remains standing.


This is another way to state the the AGW theory is not falsifiable. But wait! I do not imply that this is a weakness of the theory. Any theory that makes probability statements cannot be falsified. Thus, it is a mistake—and one I often see—to attack the AGW theory by claiming it is not falsifiable. Of course it is not! How many theories are like this, that is, not falsifiable? Besides mathematical dictums, and not wanting to get to far into this, all theories that are of practical interest to mankind. Any theory that is forced to make probabilistic claims cannot ever be falsified. And, simply put, this is most theories that we ever work with (in real life). Since this is the case, we have to understand what a probability statement means, and what can we mean by data “consistent” and “inconsistent” with such statements.

Now, we are right to suspect a theory that makes a claim that “X will probably happen (in such and such circumstances)” and X does not in fact occur. We have not proven the theory is false, but we would be rational to give increased weight to the idea that it is false. Thus, it is not irrational to weaken our belief in the AGW theory in the face of falling temperatures. Further, Dr Stott is wrong—not probably mistaken, or likely wrong, but flatly wrong—if he says “Absolutely not” to the question “Given the falling temperature, is AGW less likely to be true?” But he would be right—exactly right—if he said “Absolutely not” to the question “Given the falling temperature, is AGW proven to be false?” Given the way newspapers report, we have no clear way of knowing which of these two questions Dr Stott was asked.

I told you this was going to be tricky! It’s now going to get worse, but stay with me.

What Claims Are Being Made?

It is very difficult to keep in mind the exact claims made by a complex theory, which is why when new evidence arises, we have so many different arguments about what this evidence implies. Proponents of controversial theories are usually happy to be vague about the claims they are making because of this. This way, no matter what evidence arises, arguments for the theory can be found within it. We discussed this the other day when we noted that precisely quantified predictions are hard to come by in global warming.

We might hear that “Temperatures will increase” but this is a vague statement because when temperatures do in fact fall in a location, the proponent can say “I meant it will go up elsewhere” or “I meant it will go up on average” or “I did not mean it will always go up.” This is how the Kiel University climatologists could claim that “natural variation would mask the 0.3C warming predicted by the Intergovernment Panel on Climate Change over the next decade” and that temperatures will start increasing in 2015. Their explanatory statement is impossibly vague (saying what is “natural variation” at least means you can exactly quantify the amount of change caused by the existence of mankind), but they have at least made a semi-quantifiable prediction starting six years from now. The IPCC, too, has made quantifiable predictions of global average temperatures, though they seek to introduce vagueness by calling their predictions “scenarios”, a weak attempt at evasion. They also do not explicitly attach probability to their predictions, which makes it harder to say how wrong or right their predictions were.

To judge how likely a theory is to be true requires explicit predictions. For example, suppose the AGW made one of these two statements: (A) “The global average temperature will likely increase”, and (B) “The global average temperature will probably increase.” Our new evidence is that temperatures have fallen. For which of these claims, A or B, would you have less certainty that AGW is true?

A difficult question! Let’s try to understand it. You can see that A and B differ only in the words “likely” and “probably”. Suppose that, to you, “likely” means “at least 90%” and “probably” means “at least 50%”. It’s clear that claim B is thus weaker than claim A. So that when contradictory evidence arises you would suspect that the theory that gave rise to A was more suspect than the theory that gave rise to B. The terms “likely”, “probably”, “might” and so forth, do not mean the same thing to every person. For example, I might say “likely” means “at least 50%” and “probably” means “at least 90%”, and so I would come to the opposite conclusion about the truth of the underlying theory as you did.

All this means is that the more precise a prediction is, the easier it is to judge it. The vaguer a claim is, the harder it is to dismiss or accept the theory that gives rise to it. Not every claim can be exactly quantified, but any prediction of importance can be made clear in terms of decisions or actions we would have to make given the claim is true. So it is no excuse to say “The problem is too hard to give an exact prediction.” Because if that were true, then the theory has no practical consequences, and so can be ignored. To be clear, AGW theory does make claim to have practical consequences, and so its proponents should be able to give us more exact predictions.

Like I said, precise claims from AGW are not always to be had—though of course they sometimes are—but let us suppose that the theory makes the claim that “There is a 90% chance that the year-by-year global average temperature will increase.” For the last several years the temperature has fallen. The theory is not falsified because the claim only mentioned a probability, one which is consistent with falling temperatures. We are rational, however, to decrease our belief in the truth of the theory.

Now suppose that a group of climatologists offer a rival theory called “Business as usual” (BAU) which makes the claim “There is a 50% chance that the year-by-year global average temperature will increase.” For the last several years the temperature has fallen. The theory is not falsified because the claim only mentioned a probability, one which is consistent with falling temperatures. We are rational, when offered a choice between the two theories, to increase our belief in the truth of the BAU theory over the AGW theory because the BAU’s predictions were closer to what actually happened. The temperatures fell, but saying there is a 50% chance of this happening each year is closer than saying their is only a 10% chance of this happening (10% = 100% – 90%).

The best theory, which is not on offer, is the one which predicted that the temperatures would fall for the last couple of years. So let us offer that theory—call it the Baby, it’s cold outside (BICO) theory—which makes the claim “There is a 10% chance that the year-by-year global average temperature will increase.” This is the best of the three theories in the sense that its probability statements were closest to what actually happened. The BICO theory says there is a 90% ( = 100% – 10%) chance that temperatures will fall.

It’s about to get tricky once more. Be sure you understand everything so far before reading more.


We do not just judge theories about how well they predict future data, but also by how well they explain already observed data. The BICO theory does not explain all the previous data we have very well, as you might guess. Proponents of the AGW theory say that their theory does. The BAU theory does a reasonable but imperfect job explaining historical data. Now, it is true that just because a theory explains past data well it does not mean that it will explain future data well. This is because it is always possible to create a theory that explains past data perfectly or as close to perfect as we want to be. Memorize this (especially if you read any paper which uses statistical results). Of course, any theory that does well on future data will also do well explaining historical data. Thus, given reasonable performance explaining historical data, the real test is always on how well a theory predicts data we have not yet seen (which is defined as data that was not used in any way to create the theory).

Realistically, the BICO model is out of contention because of its exceedingly poor performance on historical data. The two competitors left are AGW and BAU (I do not mean to imply that these are the only competitors in real life, just the they are the only two we are considering here). The contest is how well each model does on predicting future data.

There is some math that says that if we have two (or more) competing theories, the one that is calibrated is better than the other in the sense that anybody who acts on information from the calibrated theory would do better than had he acted on information from the other theory. Calibration means that if a theory says “There is a Y% chance that X will occur”, then on Y% of the times X could have occurred, it actually did. Neither the AGW nor the BAU theories are calibrated in this sense.

But there is the sense that the BAU theory is simpler than the AGW theory. The BAU theory requires no advanced “degrees” to understand, nor does it require suites of multi-million dollar computers, nor does it need panels of bureaucrats to meet yearly to discuss it. The AGW theory needs all these things and more. It is a sophisticated theory (I am not using this word sarcastically).

We would hope, given all the time, effort, and money that goes into the sophisticated AGW theory that it could beat the BAU theory in its predictions. If not—if the BAU theory routinely beats the AGW theory—then we would be rational to give more weight to the truth of the BAU theory.

Right now—as far as I am able to see—the BAU theory does beat the AGW theory in predictive ability. Actually, a modification of the BAU is what routinely wins. That modification states something like “There is a 90% chance that the global average temperature will do what it did last year.” This is technically called persistence (BAU(P)). When a sophisticated theory cannot beat either the BAU or BAU(P) theory, it is said not to have skill. If a theory is not skillful, it should not be used; that is, one should not base any decisions with respect to that theory. So far as I am able to see, the AGW theory is not skillful.

My caveat is “so far as I am able to see.” I am constrained by the inexact nature of the AGW theory’s predictions. The BAU and BAU(P) theories are certainly precise enough. It might be the case, for example, that I have mis-quantified the AGW’s predictions, or misunderstood exactly what physical variables the predictions are referring to, or that I have mischaracterized what the AGW predictions imply. For example, I have been taking them to mean that “There is a 90% chance that the year-by-year global average temperature will increase.” I welcome correction on my characterization. In fact, we all would welcome the correction and look forward to the issuance of precise statements and predictions.

Just What Are Falling Temperatures Evidence Of?

So how about it? Since temperatures have fallen, what are we to believe? It is not true that the AGW theory has been falsified, but neither have the BAU or BAU(P) theories. Given our characterization of the AGW theory, it is rational to say that our belief in it, given the contradictory observations, should be lessened. The BAU theories remain as true as ever—that is, we do not really increase nor decrease our beliefs in them based on this new evidence.

It might be, as I have admitted, that our characterization of the theory’s statement is wrong. Another characterization was offered by the Kiel University group who are probably claiming that temperatures will likely fall or remain constant until 2015, after which they will likely increase. I say “probably” because it’s not clear what their exact claim is. However, this is likely a fair summary of it.

Now, since predictions of “likely falling or remaining constant until 2015” are the same as the predictions made by the BAU and BAU(P) theories, it is obvious that the Kiel University (and similar) theories do not yet have skill. It is true to say that it might—but we won’t know until after 2015.

I for one am happy to wait before doing anything until then.

(To anticipate the counter to this conclusion, which we’ll discuss more fully at a later date—meaning I don’t expect this short reply to answer fully the counter: since you haven’t proven skillful, why should I do anything? If you say the consequences are too horrible if we do not, I ask you why you also refute Pascal’s argument.)


  1. You take for granted that all your critics will refuse Pascal’s wager. Pascal was a smart guy, and yet, he didn’t refuse it :). Yes, yes, I know, it’s an invalid wager. But at least, AGW theory is a little bit more quantifiable than PW, is it not?

    And while all you said is true and I agree, you didn’t exactly make any skill test. So we are left with vague words (even vaguer than AGW theory), where numbers would be far better arguments. If anything, it sounds like an appeal to ignorance, because everything is possible.

    I enjoyed reading it. A little too big. Nice to learn that AGW is unfalsifiable in a Popperian way, and why it’s so.

  2. AGW Falsification

    It seems to me that AGW makes ever so many predictions, most if not all, falsified:

    * A doubling of CO2 leads to a 2.5C increase of the Earth’s average temperature; 8C according to one of Hansen’s papers (the true figure according to recent work appears to be closer to 1C)

    * The higher the latitude, the greater the temperature increase (“global” warming appears confined to Siberia & northern China)

    * Higher temperatures lead to decreased summer soil moisture (measurements of soil moisture in Siberia & China indicate that this has increased with increasing temperature)


    Not to mention retrodictions:

    * The Medieval Warm Period was confined to Europe & N. America (elephant seals were breeding on the Antarctic Coast during the MWP; it’s too cold today)

    * Britain was no warmer than today during the MWP (so where did the Medievals get the sucrose, or vacuum distillation apparatus needed for wine production 9 years out of 10?)

    * Greenland was no warmer during the MWP than today (so where did the Greenlanders get the JCBs needed to dig graves in the fozen ground?)

    Apropos Blaise Pascal:

    “Before entering into the proofs of the Christian religion, I find it necessary to point out the sinfulness of those men who live in indifference to the search for truth in a matter which is so important to them, and which touches them so nearly.” — Pascal’s Thoughts on Religion and Other Subjects

    Pascal’s formulation of the Precautionary Principle requires a “search for truth”. The Precautionary Principle is advocated by ever so many climate “scientists” who actively discourage the hoi poloi from seeking the truth; they merely make thinly disguised Appeals to Authority. For a rational sceptic, this will never be anything other than a logical fallacy.

  3. Interesting. You might find this of some interest:

    “Towards the Probabilistic Earth-System Model”, Palmer.T.N.


  4. Briggs

    December 8, 2008 at 2:35 pm


    No, no appeal to authority or ignorance anywhere here. You can compute the skill of the IPCC forecasts just as easily as I can for the last few years. There is no need to get formal and produce a single number to quantify the lack of skill. Not in this venue, especially.

    It is long, though. If I can figure out a way to make it shorter, I will.

    Mr Git,

    It’s true that you often hear predictions phrased in the yes/no fashion you list them, but I don’t think many argue that all these predictions are certainly true or certainly false. There is always some uncertainty there, perhaps implicit, but lurking as part of the pronouncements.

    Anyway, I can already see that I’ll have to regret having mentioned Pascal at all!

  5. Popperian Falsification

    It’s important to distinguish between Popperian falsification and naive falsification. Popper did not state that a failed prediction necessarily led to the rejection of a theory. What he stated was that we should prefer those theories that required the least number of auxiliary hypotheses. We should also prefer those theories that lead to successful predictions.

    He gave for an example the orbit of Neptune falsifying Newtonian mechanics. The auxiliary hypothesis was that there was a planet beyond Neptune influencing its orbit. Newtonian mechanics predicted its approximate mass and location, leading to the discovery of Pluto. Newtonian mechanics was strengthened by this discovery. Had there been no such planet, the theory would have been weakened.

    By contrast, Freudian psychology and Marx’s theory of history need frequent rescue by auxiliary hypotheses that introduce no useful new tests of those theories. The same would appear to be true of AGW.

    Popper never argued for certainty in our scientific theories; rather he was after what should guide our preferences when selecting among competing theories. It’s amusing that your argumentation for preferring BAU over AGW, or BICO was one that Popper might have made 🙂

  6. The sun did it, and will keep on doing it.

  7. What the recent cooling trend proves is that there are other factors which are at least comparable, in size of effect, to AGW.

    Of course, this was already proven by the global cooling scare of the 1970s. However, AGW proponents tend to only admit it when forced. Most of the time, they talk as if confounding factors are negligible. So it’s good to make them admit it as often as possible.

  8. Briggs

    What is AGU? I got confused when that TLA popped into the piece.

  9. Briggs

    December 8, 2008 at 5:13 pm


    Typo. Idiotically repeated many times. Two reasons: my slowness, and “AGU” also stands for “American Geophysical Union”, a group to which many of us belong, and which I was probably thinking of.

  10. Luis:
    Please don’t think I’m being antagonistic this time I’m not, Promise!
    Since when were numbers better arguments than words or sentences? Each argument should be taken on it’s merit.
    If people are to understand about Global warming, it is important for them to understand some basic ideas. Just imagine, most of the people out there who’ve not read about this subject, know as little as me! It might be a scary thought, but that’s reality.
    (and I will never admit how much I know about this subject but I’m happy to be considered ignorant if that is in any way helpful to this debate.
    There is a bigger picture to be considered here.

  11. I think you might be a bit hasty in throwing out the BICO with the bathwater here.

    After all, we know that the earth was pretty hot about 4billion years ago and that it’s cooled considerably since then. Of course there have been ups and downs along the way – good old natural varation – but from observation it’s pretty clear that on average each year has been cooler than the last.

    Even when old Sol goes red giant on us, the effects will only be temporary. Eventually our old friend entropy will have his way.

  12. Baron Fishpaste

    December 8, 2008 at 6:55 pm

    I would say that falling temperatures are a clear case of coldness – anyone can see that – it’s hardly rocket science, is it.

  13. Oh what a tangled web is weaved
    When first we’re cautioned to believe
    What learned scholars have conceived
    As theories that are best believed
    By lesser citizens like me.

    Love the post, professor.

  14. “If you say the consequences are too horrible if we do not, I ask you why you also refute Pascal’s argument.”

    Good one!

  15. Rising temperatures indicate catastrophic anthropogenic global warming. Falling temperatures indicate climate change. Got it? Now get with the program Briggs!

  16. Briggs

    December 9, 2008 at 6:13 am


    I know we’ll have to cover Popper in more detail later, but for now I’ll remind us of an extended quote from Stove’s Scientific Irrationalism (mine is by Transaction Publishing, 2001; read all p. 169-182; quote starts on p,. 172). Before I begin the quote, we can remind our readers that the words true and false are extremely strong words; in fact, there are none stronger. Thus, when you say a theory is false—not just improbable, but false—you are making the strongest claim possible. The quote:

    Let us call the conjunction of Newton’s law of motion with his inverse-square law of gravitational attraction, “Newtonian physics”. And let us consider the question whether Newtonian physics is this sense falsifiable; the question, that is, whether there is any observation-statement which is inconsistent with Newtonian physics.

    …[I]t is obvious enough that the answer to this question is “no”. There can be no observably non-Newtonian behavior, on the part of billiard balls or of anything else…That Newtonian physics is unfalsifiable, is also evidence from the fact that, however oddly billiard balls might behave on a given occasion, Newtonian physics could form part of the deductive explanation of this behavior, by being conjoined with other propositions, perhaps about hidden masses, or about the presence of forces other than inertia and gravitation.

    Newtonian physics (in our sense) is evidently a scientific theory. This fact, along with its unfalsifiability, is a refutation of Popper’s famous thesis that falsifiability is a necessary condition of a theory’s being scientific…

    Popper’s reply is given in the following paragraph, “…assume…that we construct a gun that fires ballistic missiles which consistently move in a clearly non-Newtonian track…almost any statement about a physical body which we may make—say about the cup of tea before me, that it begins to dance…would contradict Newtonian theory.”

    That Popper’s reference to missiles which move in a “clearly non-Newtonian track” was a flagrant begging of the question, I need hardly state…But the principal defect of the paragraph just quoted is much more simple and amazing than this. Consider the proposition: “There was no whirlwind about; the apples which had fallen from my tree rose from the ground and began to dance around…” [I]t is not only obvious, it is blazingly obvious, that this propositionis not inconsistent with Newtonian physics The same is true, and equally obviously true, of the proposition: “The cup of tea in front of Popper began to dance, without spilling the tea.” …Yet he brazenly asserts that any of these propositions, and indeed “almost any statement about a physical body which we make … would contradict Newtonian theory.

    One can scarcely believe one’s eyes while reading this paragraph of Popper. What beginning student of deductive logic would not be ashamed to assert such transparent logical falsities as these?…It is difficult, in fact, to imagine a more brutal contempt for deductive logic than is displayed by this impudent list of so-called falsifiers of Newtonian physics…

    Newtonian physics, [Popper] says, is actually inconsistent with Kepler’s laws. It “formally contradicts” them; “from a logical point of view, Newton’s theory, strictly speaking, contradicts both Galileo’s and Kepler’s…”

    [I]t is obvious that this answer too is false: strictly speaking, and formally, Newtonian physics is not inconsistent with Kepler’s laws.

    [Kepler’s propositions are] so far from being inconsistent with Newtonian physics, that [they] could be deduced from and explained by Newtonian physics, in conjunction with certain contingent assumptions about the forces to which planets are subjected, the mass of the planets…and so on. Some at least of these auxiliary premises would of course be false in fact. Their conjunction with Newtonian physics would therefore be false in fact too. But that conjunction, obviously, need not be logically false…

    A very long quote. It would be better to rush out, buy, and then read Stove’s book. Like I said above, this is not a subject which lends itself to brevity.

  17. The sun heats the Earth during daylight hours and the Earth cools at night by radiating thermal energy.
    Atmospheric components, primarily clouds and to a lesser extent water vapour and CO2 slow down the rate at which the Earth cools by blocking this thermal radiation in the case of clouds and retarding it in the case of water vapour and CO2.
    All of these components are essentially passive insulators and add no heat to the system so none of them actually warm the Earth, all that they do is to slow down the rate of cooling.
    CO2 is responsible for less than 10% of this effect and at a concentration of 300ppmv it has slowed down the cooling by about 95% of its capacity to do so.
    The Earth is about 34°C warmer because these components slow down the cooling enough over night to the point that there is still some heat left over when the sun returns and warms things up again.
    The effect from CO2 is less than 10% of this or 3.4°C and since there is less than 5% of this effect remaining the maximum future effect from increases in CO2 can be no more than 5% of 3.4°C or just 0.17°C!! (In actual physical tyerms this value is only one tenth of this amount.)
    The AGW hypothesis is based on a causal relationship between CO2 emissions and global temperatures that does not physically exist, so it is meaningless to either try and prove it or falsefy it by observed temperature and CO2 relationships.
    On the other hand just the fact that this direct causal relationship does not even exist should be enough to falsefy the whole theory itself.

    Norm K.

  18. I would say that the problem is that AGW is not a “theory” in the sense of customary scientific meaning. Rather it seems like cases described, I think, in “Supercrunchers” by Ian Ayers, in which proponents skip the untidy step of forming a hypothesis to test against the data. The approach seems to be instead, let’s put all the data (setting aside reasonalbe questions regarding the quality and consistency of such data) into a correlation analsyis and see what can explain the variation. “Let’s just let the data speak for itself”. So I am not sure whether parsing Popper more finely will help us. I think the more interesting question is what to do about the growing tendency to skip the theory and go direclty from data to public policy, a problem covered nicely in “Science and Public Policy” by Ainsley Kellow.


  19. Briggs

    December 9, 2008 at 11:13 am


    Thanks for reminding us of the Kellow reference. But I can see that I won’t be buying it. It’s listed at $110 at Amazon! And it’s only 180 pages!

  20. I know. Maybe he will barter for copies of your book, signed, of course! Still it is an incredible (in the sense that it challenges the credibilty of the logical foundations of AGW) book and a very enjoyable read.

  21. Noblesse Oblige

    December 9, 2008 at 5:44 pm

    Einsteinian gravity is preferred over Newtonian gravity because it is more consistent with observation (e.g., light bending, the precession of the orbits of planets). Natural variations, with at most a small AGW component, is preferred over “strong AGW” as espoused by the IPCC, because solar variability and decadal/multidecadal ocean cycles do a better job of explaining the historical record. The former preference is very strong. The second will become so.

  22. Briggs

    December 9, 2008 at 5:55 pm


    Yes! Exactly! We prefer Einsteinian gravity over Newtonian because the predictions we make with Einsteinian gravity are better!

    But it is a mistake to say that we have falsified Newtonian physics, or that the observations are logically inconsistent with it.

    Right now, which makes better predictions (on data not used in any way to create the model/theories): AGW or BAU(P)?

    Either way, the observations are not logically inconsistent with either theory.

  23. Norm K:

    In your previous comment, you stated “Atmospheric components, primarily clouds and to a lesser extent water vapour and CO2…”. I have to applaud your statement, especially since the observable effect of cloud cover appears to be either missing or severely underrepresented in the models in favor with the IPCC crowd.

  24. Noblesse Oblige

    December 9, 2008 at 8:10 pm

    In the same way that gravity can be generalized to a scalar-tensor theory from the simplest scalar theory of Einstein to allow for effects not included in Einsteinian gravity, one can generalize BAU(P) to allow for an anthropogenic component.

    In gravity, we can write symbolically G = (1-b) S + b T , where S is a scalar theory, T is a tensor theory, and b is a constant = 0 in Einstein. The new theory G must reduce to Newtonian gravity when it is consistent with observation. Then one can go ahead and test whether a particular b>0 actually improves agreement with observation, relative to the simple Einstein theory. For example Jacob Bekenstein proposed in 2004 that such a modified theory might explain observed anomalous galactic rotation without resorting to mysterious dark matter. The point is that the starting point is the simplest explanation known to be consistent with observations. Then the scientific process seeks to extend it to encompass a larger set of obervations that ‘don’t fit.’ This is how we got from Newton to Einstein in the first place. The process never stops, and no one says the ‘science is settled.’

    In the same way one can write symbolically for a theory of climate C:
    C = (1-b)BAU(P) + b AGW. Now what value of b>0 gives the best agreement with observation, and what is the uncertainty in b. Instead, what we are given is the a statement something like “very probably” b>0.5, without demonstration of how this determination was arrived at, or any sense of the ‘spread’ in its value. Furthermore because of this determination, and appealing to the precautionary principle, we need to enact policies as soon as possible.

    The point of all this is that no one has objectively considered the full body of observational data to develop a more rigorous determination of b. Instead we are told the science is settled, and the precautionary principle reigns. Well, in addition to sloughing over the ‘b’ issue, the appeal to the precautionary principle is flawed because it considers only environmental risk, while ignoring economic risk. Bjorn Lomborg aggressively addresses this flaw by comparing investments in mitigation with other possible investments of social value and is excoriated for it. Integrated assessment models (e.g., William Nordhaus) consider the economic effect of various policy options within the framework of mitigation. But both of these approaches take the IPCC as a scientific ‘given.’ Therefore, to address the overall climate issue, one ought to develop and include uncertainty in ‘b’ in an integrated probabilistic view of overall risk.

  25. Good read.

    If one is to exam the long term trend, then I say that only time will tell. Also, without knowing the uncertainty of a prediction, I don’t see how one can conclude that the prediction is incorrect.

    Mr. Noblesse Oblige,

    If I understand you correctly, the idea and the reasoning of a linear combination is the same as, e.g., diversification in investment that minimizes the risk from any one investment. Though I haven’t check into details and the math behind the weather ensemble predictions in which (I think) such idea is employed. If one is to take the average of all scenarios, then an equal weight has been placed on each scenario.

    The coefficients (b) could be estimated by minimizing a certain criterion. And once the problem is “well-defined”, the minimization should not be terribly difficult. I would think such idea has been well explored…of course, I could be wrong. Live and Learn!

  26. Briggs

    December 10, 2008 at 10:40 am


    Excellent point. If some prediction says “A will equal X”, then, at first, we have to take it that they mean A will equal X. If A does not in fact equal X, then the forecast has failed.

    There are, of course, many ways to evaluate predictions given this kind of excess certainty, but they all come back and say, “You know, it would have been better had you stated your prediction in probabilistic terms.”

    Forecasters should follow that advice. Particularly since (as those who read that magnificent work Breaking the Law of Averages well remember) climate forecasts are contingent events whose probability is something between, but never equal to, 0 and 1. That is, they should say things like “There is an 80% chance that A will equal X.”

  27. In defense of Newton, it is a common misconception that Einstein’s theory had superseded Newton’s. However Newtons equations in their original form allowed for Einsteinian calculations because he was canny enough to have a variable mass. It was the later simplifications of Newton’s work by others that were incompatible.

    Another question of logic I present alarmists with when they tell us that extreme weather events will surely increase under global warming is that the conclusion that global cooling should then reduce extreme events is implicit. Houghton and others have a variation on this where they state boldly that global warming causes wet areas to be wetter and dry areas to be drier, ie an overall nasty. This again has the inbuilt conclusion that we should all be jolly happy with a cooling planet. As it turns out, we’ve seen a cooling planet these past two years and it seems a whole lot colder, wetter and generally nastier than the relatively warm period before it. This experience even concurs with what certain scientists were telling us about the effects of the coming ice age in the 70’s. Warming is a tough sell – people really prefer to be warm. Clearly hurricanes haven’t stopped people moving to Florida and rising sea levels haven’t stopped certain prominent green-washers from buying property by the sea. Hence duplicity has become routine among the activist-scientists. Of course, the only logical outcome for extreme events is that some might increase while others might decrease. At that point said alarmist will then mention the acidification of the ocean (much scarier than just becoming less alkaline or more neutral) and so the circus continues.

  28. About Popper, and Freudian psychology and Marx’s theory of history.

    It probably was not social science, Popper was talking about.

    And not climate stuff.

    If you are dealing with intentions of human beeings, falsification is out of the way.

  29. Briggs

    December 10, 2008 at 12:29 pm


    Actually, it was partly the nuttier ideas of Freud and Marx that convinced Popper that falsifiability is what makes a theory “scientific.” He was rightly irritated that proponents of these loony ideas would interpret anything, absolutely anything, that happened as positive evidence for their beliefs. In other words, there wasn’t anything that could prove them false. Talk to an ardent Freudian or Marxist now and see if this still isn’t the case.

  30. Briggs, I agree. A probabilistic statement is a better way to present the best answer that the science can deliver with imperfect evidence. However, correct probability reasoning is not easy.

    Some sciences also have to go through the test of repeatability, which is one of the reasons why publication of research results is important. Once an article is published; it’s subject to further review by other scientists who try to build on the results. This is not the case in climatology though since many conditions are just not replicable.

  31. AGW does not predict that temperature will consistently rise year on year, but rather that over time it will rise. I’m a fan of technical analysis in the stock market and a basic rule is that nothing goes straight up and nothing goes straight down. There are bounces in a declining market and retraces in a rising one. Movement in the opposite direction does not necessarily mean the trend is broken.

    Instead, you have a trend line. If the price pattern is above the trend line, you have a rising trend regardless of whether the price has gone up or down in the short term. A trend is not broken when the price moves in the opposite direction a bit, it is broken when the trend line is crossed.

    Same with AGW, so long as the temperature stays above the trend line, the rising trend is intact. The nut of it is what peroid you use to make your trend line. In the stock market, each trader is free to choose his own trend line based on his own experiences and risk tolerance. There is no objective right or wrong, there is just what works for you and what doesn’t.

    I would argue that an appropriate trend line in temperature is one that draws on past data in such a way that it would show when the data diverges from normal variation (an oscillator rather than a line). My biggest complaint about AGW is that there has been no data presented yet showing that climate is behaving unsually. That would be a first step; before we can identify a cause, we have to identify a problem.

    So far as I can tell, there is roughly zero resouces dedicated to answering the question, “is there anything unusual about current climate behavior.”

  32. Isn’t one of AGW’s few testable predictions a hotspot in the trophospere at higher latitudes?

    If this hotspot is not there, is this not evidence to fall back to the null hypothesis (BAU)?

  33. Briggs

    You cannot “remind” me of the Stove quote as I have yet to read the book (I do have it as a PDF) so I will set to and do so.

    You are correct that any discussion of Popper is likely to be long and so I will at this point restrain myself. Hopefully, when we do discuss him at length, we will both learn much. So far you have proved a most excellent teacher 🙂

    I will remind you that I mentioned Stove’s son explaining his father’s irrational hatred of Popper as being due to their close physical resemblance. I suspect there’s more to it than that, but save my speculation for later. Rafe Champion (Popper’s Roger Kimball) might know somewhat of this issue.

  34. Briggs and your response to Ekat

    It was precisely Popper’s perceived need to demarcate pseudo-science from science that provided the impetus for the development of his ideas.

    Briggs re Popper

    He wrote in the preface to “Conjectures & Refutations” that “The way in which knowledge progresses, and especially our scientific knowledge, is by unjustified (and unjustifiable) anticipations, by guesses, by tentative solutions to our problems, by conjectures. These conjectures are controlled by criticism; that is by attempted refutations, which include severely critical tests. They may survive these tests; but they can never be positively justified; they can neither be established as certainly true nor even as ‘probable’ (in the sense of the probability calculus).

    I imagine it’s the last sentence you disagree with.

  35. Pascals wager failed because he had no idea what god he was going with, based on his precautionary principle. What if you chose the wrong god?

    The whole AGW theory is based on, and would not exist without, the physical basis. We know exactly what ‘god’ it is we are referring to, we have ironclad, physical evidence it does what it is claimed to do. CO2 is a greenhouse gas, it warms the atmosphere by absorbing and re-emitting radiation in random directions.

    Big difference.

  36. Bug,

    When you say,
    “in random directions” What do you mean?

  37. Briggs

    December 11, 2008 at 6:59 am


    Hmm. I wonder what Popper himself would say about the idea that Stove didn’t like their similar looks?

    But you’re right. I do not agree with that last sentence. Think about mathematics, which are nothing but provably true statements (ultimately conditional on axioms that are not provably true, of course).

    And what would you say of the “18th floor defenestration” theory? “Probably” true that you turn to goo if you try it? Popper would have to say no.

  38. “When you say,
    “in random directions” What do you mean?”

    Randomly. I think that is pretty clear.

  39. Crystal clear!
    Next question, what is the olecranon process and what bearing does this have on the ischial tuberosity?

  40. But it is a mistake to say that we have falsified Newtonian physics, or that the observations are logically inconsistent with it.

    This is not correct .
    The Newtonian gravity theory can’t be wronger than it already is .
    Why ?
    Because it is not Lorentz invariant .
    In simpler words it tells us that interactions propagate with infinite speed .
    In even simpler words it tells us that the speed of light is infinite .
    All this has been falsified long ago and the observations are definitely logically inconsistent with the notion of an infinite speed of light .
    Obviously if Newton had understood that the speed of light is finite , he’d have discovered relativity which is a completely different theory from the one he proposed .

    As it happens and not surprisingly so , using the galilean approximation in the correct theory (general relativity) one finds the same formula as in the incorrect theory (Newtonian) .
    But this is no indication about the validity of the Newtonian theory which is fundamentaly wrong .
    This also doesn’t mean that the newtonian gravity is an “approximation” of the general relativity what one often hears .
    After all by using suitable approximations in the general relativity , one would find the predictions of the epicycle theory which is also as wrong as wrong goes even if it has the “right” formula in some cases .

    It is important to distinguish the skill and the validity .
    It can never be excluded that a wrong theory makes in some cases the same predictions as the correct theory despite totally wrong assumptions that were necessary to derive it .

  41. No, Tom, if Newton had understood that the speed of light is finite, he might have given up physics altogether and taken up sailing.

  42. Briggs

    December 11, 2008 at 12:33 pm

    (I weep! I had typed most of a long reply to Tom, when my damn browser crashed. Now, I haven’t the heart to re-type the whole thing.)


    I don’t agree. See this paper for an argument that Newton was not so wrong as you think.

    And we still have to answer the dancing tea cup example. It is logically possible that there might exist hidden forces and masses that cause the cup to jig, so that if we saw the cup do so it would not be a refutation of either Newtonian or Einsteinian mechanics.

    I am using the word consistent in its logical and not in the various colloquial senses.

    I think that we’ll have to revisit this topic on a new thread.

    (Damn browser.)

  43. Tom

    We really need to distinguish here between Theory (explanation) and Law. A law is an analytic statement, usually with an empirically determined constant. A theory may contain a set of laws, or a theory may be implied from an empirically determined law.

    Newton’s Law of Gravitation states that the gravitational force between two objects equals the gravitational constant times the product of the masses divided by the distance between them squared. Even though this has been “falsified” by GR, it remains “true” (sufficiently accurate) for most sensible purposes.

    Newton’s Theory of Gravitation according to Newton was that he didn’t have one. Of course his Theory of Light: that it was infinite in speed and entirely corpuscular in nature has been falsified.

    Currently, we have two main theories of gravitation: GR and QM, that are mutually incompatible

  44. Briggs: ‘And what would you say of the “18th floor defenestration” theory? “Probably” true that you turn to goo if you try it? Popper would have to say no.’

    Under certain given conditions you will almost certainly turn to goo. While it’s true that every verifiable instance has turned the defenestrated into goo, Popper says we can’t assume that the next instance of the event will result in the same outcome because we don’t know that the Law of Gravitation is universal (as Newton believed). Indeed, Inflation Theory in Cosmology is all about the laws of physics changing over time.

    Popper believed that repetitions of defenestration could not be said to affect the probability of them resulting in the defenestrated turning to goo just because there is potentially an infinite number of them that have yet to be observed. This is really straightforward David Hume.

    Briggs: “I think that we’ll have to revisit this topic on a new thread.”

    You’re the boss 🙂

  45. On Newton.

    Is Newton’s gravity wrong? Well, it depends on what you mean by ‘wrong.’ It is true that Newton is Lorentz covariant. And it also violates the equivalence of inertial and gravitational mass. So since these properties are BELIEVED necessary for a ‘correct’ theory, Newton is wrong in that sense. But there are at least two ‘buts.’ One is that we don’t really know if these two properties are correct everywhere and under all circumstances in our universe; they are in fact assumptions that agree with a lot of observation. Second, from a predictive point of view, Newton agrees very well with observation in many practical situations (ask NASA). And under this multitude of circumstances we cannot distinguish between Newton or Einstein.

    But this is really too pedantic. What Einstein taught us is how to think about space and time in an entirely new way that Newtonian theory could never do. Therefore I prefer the word ‘inadequate’ for Newton. (I suspect Isaac himself would prefer to be wrong than inadequate).

  46. William

    I have imposed myself the strict disciplin to copy a post everytime before submitting it . It is a useful rule that has helped me often and I recommend it . Amusingly last time it served was my post above

    As my origins are QFT , I read the draft you linked . It says 2 , possibly 3 things out of which none seems to relate to the question whether Newtonian gravity theory is right or wrong . But perhaps I missed something .
    First thing is trivial – QM is indeed deterministic and rigidly so . The wave function is defined and solution of the Schrödinger’s equation which gives its time evolution given some initial conditions .

    In the second thing it goes orbital using the Multiverse picture and referring to Bohm .
    The Multiverse picture is not a scientific statement (that’s why I say picture and not theory) because by definition there cannot be any experimental evidence proving or falsifying the existence of the “parallel Universes” .
    Talking of “analogues of myself doing experiments” hits in the “set of all sets” kind of paradoxes . Indeed in this picture there is an uncountable number of Universes with analogues of myself doing experiments with different outcomes . But there is also an uncountable number of Universes where analogues of myself don’t exist and another uncountable number of Universes where no matter exists , etc .
    So what could be the value of a ratio Uncountable infinity / Uncountable infinity ? About anything .

    Third thing seems to be a finer philosophical point about the differences between a probability and a frequency and beyond that what being Bayesian means . Those questions are certainly interesting and relevant in the statistician community but I wouldn’t dare to step in that particular kitchen .
    As physicist what I do in QM is to measure frequencies , so frequencies are what is interesting for QM . If it was helpful , I’d happily censor the word of probability in QM and replace it by the word frequency – btw there are QM papers where the authors insert the caveat that the numbers used are defined as frequencies .

    Btw the hidden local variables interpretation of the QM has already been falsified – QM is definitely non local whether we like it or not and the quantum entanglement is an experimental fact .

    But my point about Newton had been of another nature .
    Basically it consisted to say that skillful and right are 2 very different things .
    A wrong theory will sometimes be skillful – actually it is even a precondition for it to live longer than the time one needs to read it .
    A right theory will always be skillful .
    From 2 equally skillful theories based on contradicting premises either one is wrong or both are wrong .
    With the Newtonian gravity vs relativity we are exactly in this situation .
    The premises are contradictory – finite speed of interaction vs infinite speed of interactions .
    Both SEEM equally skillful when one looks at a restricted class of problems (planetary orbits in the solar system not very near to the Sun) .
    But having proven that the speed of interactions is finite , we have proven that the newtonian theory is wrong .
    Really , logically and physically wrong .

    Did it stop being skillfull for some restricted class of problems ? Of course not but now we know thanks to GR HOW exactly restricted the problems must be to benefit of the newoton’s theory skill despite its wrongness (low speeds , low energy density)

    Does it mean that the GR is right ?
    Of course not because we are still left with the case that both theories are wrong .
    It is actually highly probable that it GR wrong too because it breaks down near the black hole singularity or at any extremely high energy density .
    There can be also a premise that has not yet been questionned enough and that will be proven wrong one day .
    So it is highly probable that a fully developped string theory which successfuly quantifies gravity will send the GR to the cemetery of wrong but sometimes skillful theories .

    Yes people laugh often about epicycles but forget that this theory is also skillful in some cases .

    Luckily I did a copy as the post was rejected because of some cookies or not cookies 🙂

  47. Tom

    That was rather well expressed.

    Of course the users of epicycles were only interested in the skill of epicycles, not whether they had a correct theory of planetary movement, or not. The theory they were interested in was astrological correspondence between the heavens and events on earth — a theory in which all educated people believed.

  48. Yet another enjoyable article (I am sure my enjoyment is only coincidental to the fact that I agree with so much of it). 🙂

    A minor annoyance:

    ‘Since this is trivially true, the only interesting questions are (1) “How much does this or that organism influence climate?”, (2) “In what part are these influences helpful or harmful?”, and (3) “Can the helpful aspects be magnified and can the harmful effects be mitigated?”’

    That’s four questions and the article would be better for treating each separately, rather than lumping together both ‘points’ in (3).

  49. Joy–
    You asked what who-zi-whats meant by “randomly”.

    What s/he likely meant was individual photons when emitted may be headed in any direction, and the probability the photon is going in any direction is the same no matter what direction you pick. So, he meant the direction is random with a uniform direction. (Some things can be random but non uniform. For example, many things are normally distributed, meaning the probability distribution functions makes that nifty bell shaped curve.)

  50. Dear Mr Briggs:

    May I translate this article into Spanish and publish it in my blog?, with due recognition and link to the original, of course.

    As you can check in Google, I am on an amateur, non-profit effort to divulgate science (specially astronomy, but including paleontology, geology, climate and philosophy) among Spanish talking people, both by translating from English and by writing my own articles, having published more than two thousand of them in the last few years.

    By the way, I am the one and only “Heber Rizzo” to publish in the world wide web. That’s improbability, isn’t it?

  51. Briggs

    December 14, 2008 at 7:53 am


    Sure, go ahead.

    Improbable? You’re the first “Heber Rizzo” I’ve ever heard of!

  52. Briggs

    December 15, 2008 at 6:55 am

    This is being posted for http://hernadi-key.blogspot.com/, who accidentally posted this on another, unrelated thread. Everything below is his:

    information for you..
    European leaders clash over pledges on global warming !!!

    European leaders gather in Brussels today for a crunch summit, acutely divided over how to deliver on pledges to combat global warming almost two years after declaring they would show the rest of the world how to tackle climate change.

    The EU is split between the poorer east and the wealthy west. Germany says that most of their industries need not pay to pollute, Italy says it cannot afford the ambitious scheme, and Britain says that the package on the table could result in huge windfall profits for companies.

    “There is a very big chasm between the various parties,” said a senior European diplomat.

    Prime ministers and presidents appear to be getting cold feet over key decisions that need to be taken by the weekend to enact laws that will make the climate change package binding for 27 countries.

    Failure is not an option, they say. But Polish veto threats, Italian resistance, and German insistence that it will not jeopardise jobs to help save the planet, suggest that the action plan will be diluted. The risk is the EU will draw withering criticism from climate campaigners and signal weakness and indecision to the US, China, India and other key players in the global warming fight.

    “It’s a question of credibility,” said Jose Manuel Barroso, president of the European Commission who described the summit as the most important of his five-year term. “It would be a real mistake for Europe to give the signal that we are watering down our position.”

    A negative outcome to the talks would moreover cast a pall over the latest round of UN negotiations to secure a post-Kyoto treaty to limit global greenhouse gases.

    But at talks in Poznan, Poland, on Wednesday, EU environment commissioner Stavros Dimas, said: “There are a few issues left but I cannot imagine that we’re not going to get an agreement on Friday. We are going to deliver the targets.”

    The EU package represents the most ambitious legislative effort on climate change anywhere which includes four laws that mandate cuts in greenhouse gases by one-fifth by 2020 compared with 1990 levels, reduce energy consumption in Europe by one-fifth by the same deadline and stipulate that 20% of Europe’s energy mix comes from renewable sources.

    Germany’s chancellor Angela Merkel engineered the deal as EU president in March last year. Since then the EU has been bragging about leading the world in the race to keep global temperatures from rising by more than 2C.

    It falls to Nicolas Sarkozy, the French president, to end his dynamic six months in the EU hot seat with a deal that could see the entire package turned into law before Christmas.

    Sarkozy is staring failure in the face. But he is widely viewed as a consummate fixer who may pull it off. The disputes are fundamentally about costs, a disagreement that has become magnified in the current economic climate. While everyone agrees the headline target of 20% cuts in greenhouse gases by 2020 is sacrosanct, the disputes are about how to get there.

    The heart of the scheme is the “cap-and-trade” or emissions trading system which is to supply around half of the cuts in greenhouse gases. The ceiling for industrial pollution levels is progressively lowered and industries and companies pay to pollute by buying permits in an auction system.see


  53. Thank you Lucia.

  54. Briggs:

    Here you will find my translation of your article:


    I hope that it is only the first of many to come.

    Thank you

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