Bishop Hill Where there is harmony, let us create discord
Jul 3, 2014 Climate: Statistics Climate: Surface My recent posts touching on statistical significance in the surface temperature records have prompted some interesting responses from upholders of the climate consensus, with the general theme being that Doug Keenan and I don't know what we are talking about.
This is odd, because as far as I can tell, everyone is in complete agreement.
To recap, Doug has put forward the position that claims that surface temperatures are doing something out of the ordinary are not supportable because the temperature records are too short to define what "the ordinary" is. In more technical language, he suggests that a statistically significant rise in temperatures cannot be demonstrated because we can't define a suitable statistical model at the present time. He points out that the statistical model that is sometimes used to make such claims (let's call it the standard model) is not supportable, showing that an alternative model can provide a much, much better approximation of the real world data. This is not to say that he thinks that his alternative model is the right one - merely that because it is so much better than the standard one, it is safe to conclude that the latter is failing to capture a great deal of the variation in the data. He thinks that defining a suitable model is tough, if not impossible, and the only alternative is therefore to use a physical model.
As I have also pointed out, the Met Office does not dispute any of this.
So, what has the reaction been? Well, avid twitterer "There's Physics", who I believe is called Anders and is associated with Skeptical Science, tweeted this:
Can @MetOffice clarify their position wrt statistical models - in a way that @aDissentient might understand?
A response from John Kennedy appeared shortly afterwards, which pointed to this statement, which addresses Doug Keenan's claims, noting that there are other models that give better results and suggesting that the analysis is therefore inconclusive. Kennedy drew particular attention to the following paragraph:
These results have no bearing on our understanding of the climate system or of its response to human influences such as greenhouse gas emissions and so the Met Office does not base its assessment of climate change over the instrumental record on the use of these statistical models.
I think I'm right in saying that Doug Keenan would agree with all of this.
Anders has followed this up with a blog post, in which he says I don't understand the Met Office's position. It's a somewhat snide piece, but I think it does illuminate some of the issues. Take this for example:
Essentially – as I understand it – the Met Office’s statistical models is indeed, in some sense, inadequate.
Right. So we agree on that.
This, however, does not mean that there is a statistical model that is adequate.
We seem to agree on that too.
It means that there are no statistical models that are adequate.
Possibly. Certainly I think it's true to say that we haven't got one at the moment, which amounts to the same thing.
Then there's this:
[Statistical models] cannot – by themselves – tell you why a dataset has [certain] properties. For that you need to use the appropriate physics or chemistry. So, for the surface temperature dataset, we can ask the question are the temperatures higher today then they were in 1880? The answer, using a statistical model, is yes. However, if we want an answer to the question why are the temperatures higher today than they were in 1880, then there is no statistical model that – alone – can answer this question. You need to consider the physical processes that could drive this warming. The answer is that a dominant factor is anthropogenic forcings that are due to increased atmospheric greenhouse gas concentrations; a direct consequence of our own emissions.
Again, there is much to agree with here. If you want to understand why temperature has changed, you will indeed need a physical model, although whether current GCMs are up to the job is a moot point to say the least. (I'm not sure about Anders' idea of needing a statistical model to tell whether temperatures are higher today than in 1880 - as Matt Briggs is fond of pointing out, the way forward here is to subtract the measurement for 1880 from that for today - but that's beside the point).
All this harmony aside, I hope you will be able to see what is at the root of Anders's seeming need to disagree: he is asking different questions to the one posed at the top of this post. He wants to know why temperatures are changing, while I want to know if they are doing something out of the ordinary. I would posit that defining "the ordinary" for temperature records is not something that can be done using a GCM.
I think Anders' mistake is to assume that Doug is going down a "global warming isn't happening" path. In fact the thrust of his work has been to determine what the empirical evidence for global warming is - when people like Mark Walport say that it is clear that climate change is happening and that its impacts are evident, what scientific evidence is backing those statements up? I would suggest that anyone hearing Walport's words would assume that we had detected something out of "the ordinary" going on. But as we have seen, this is a question that we cannot answer at the present time. And if such statements are supported only by comparisons of observations to GCMs then I think words like "clear" and "evident" should not be used.
Bishop Hill
In my post above I said:
If you want to understand why temperature has changed, you will indeed need a physical model.
As I put it in a tweet to Anders, he and I are in glorious harmony.
He has just replied:
No, I really don't think we are. If you want to understand GW you need a physical model.
I laughed so much I got cramp in an intercostal.
Reader Comments (307)
The Earth's atmosphere adapts to keep thermalised SW energy = OLR whilst minimising radiation entropy production rate. That means minimising high entropy CO2 15 micron IR to Space by maximising [CO2].
This is why the Earth always tries to enter the interglacial state, defined as life increasing terrestrial enthalpy and [CO2] whilst decreasing terrestrial entropy.
The concomitant rise in GHE is independent of well-mixed [GHG]. The cause is a decrease in interglacial cloud albedo by biofeedback.
The proof is that ice-adapted Neanderthals had bigger eyes to cope with high ice age cloud albedo. This is the mathematical physics of Gaia!
BishopHill says
Anders effectively agrees. I don't. Building a model is a necessary, but far from sufficient, condition towards understanding. It then must be related back to the real world data. Tweeking parameters to make the model look right is not understanding real phenomena, but simply replicating what has gone before in a series of equations. To demonstrate that a particular model shows understanding requires it say something about the real world. The flip side is that some possible situations are excluded. Having said CO2 will cause warming resulting in climate becoming more extreme, we now have CO2 working directly to make climate more extreme. Except of course, when CO2 makes climate becomes less extreme. If that fails, contradictory trends over years are just weather, whilst once-in-a-generation extreme weather events are confirmations of climate change happening. What we are left with are climate models that as much about the real world as a betting model that predicts next year the Grand National will be won by a horse with a jockey on its back.
As my dear wife once complained during a dispute.... "You're using logic and that's not fair!"
Theres physics: While you are here, how about relaxing the ghetto-ization of climate blog commenting and unbanning many of the regulars from here and WUWT who contributed comments to your blog - they were non-abusive, on-topic and non-spamming. Break down the protected silos within which several commenters who would otherwise have a hard time contributing, currently hide.
@ Martin A
"So far as we know, the law of conservation of energy is universally true. It applies everywhere and has nothing to do with whether some system or other is closed or not"
Really?
"The law of conservation of energy is an empirical law of physics. It states that the total amount of energy in an isolated system remains constant over time (is said to be conserved over time). A consequence of this law is that energy can neither be created nor destroyed: it can only be transformed from one state to another. The only thing that can happen to energy in a closed system is that it can change form: for instance chemical energy can become kinetic energy."
https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Conservation_of_energy.html
"What has whether the Earth is a closed thermodynamic system have to do with evolution?"
Just some distant recollection of interminable discussions on usenet (remember that?) - talk.origins air - about how evolution was in breach of fundamental rules of physics because life could not have been created/evolved in a closed system. Can't remember why, exactly.
Not really on topic though. (Yes ... I know that I raised it first, but not intended to be taken very seriously.)
@ There's Physics
"If we continue to increase our emissions, the only physically plausible way in which we could enter a long-term cooling phase is if there were a major asteroid strike, or significant volcanic activity."
How are you defining "long term" for the purpose of this test?
ATTP
You have your radiation "blinders" on. The post is about surface temperature patterns and statistical models for interpreting them. Oceans comprise 70% of the earth's surface, and I simply showed an example of how the Sea Surface Temperatures can be modelled by step changes rather than a linear trend. As for variations around a mean temperature, are you referring the cooling prior to the 1980's? Or maybe the cooling since 2003? Averages relate to time frames. As I said, I am looking at SSTs since the 1980s.
.
John Shade's comment deserves elevation to a blog post and as wide as possible dissemination.
"And then there's physics" writes (emphasis added):
"You need to consider the physical processes that could drive this warming. The answer is that a dominant factor is anthropogenic forcings that are due to increased atmospheric greenhouse gas concentrations; a direct consequence of our own emissions
This is a wonderful example of "radical potentialism," the belief that if something COULD be the case, then it MUST be the case. The term is a family one, by the way--that Marx had a similar term is purely a coincidence.
@ramspace: if GHG-absorbed IR energy were to be thermalised in the gas phase, local absorptivity would be greater than local emissivity. That could only be the case in the absence of Local Thermodynamic Equilibrium.
To obey Kirchhoff's Law of Radiation there can be no gas phase thermalisation of that energy and no 'back radiation', the excess energy being re-emitted in random directions to be thermalised at condensed matter.
State this basic physics to a Climate researcher and their eyes glaze over, then they scream 'denier'.
Really?
(...) Jul 3, 2014 at 5:39 PM | Unregistered CommenterWFC
WFC - Here's a better expression of the law of conservation of energy than what you quoted.
"The law of conservation of energy is a law of physics that states that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another. "
As I said, the law applies without any reference to whether some system is closed or not. It's one of nature's conservation laws that does not need to have some system defined to state it. The definition you quoted seems to have needlessly confused you by referring to "an isolated system" as if conservation of energy depends on such a concept.
I took a look at Lectures on Physics (vol 1) By Feynman, Leighton, Sands. Always good for getting to the fundamentals of any question involving physics. Feynman was a bongo player and amateur artist as you probably know.
Chapter 4 is titled Conservation of Energy. Here's an OCR of the opening paragraphs which may help you get a feel for it...
I hope that helps a bit. They key thing is that it applies always and in all situations. It does not depend on having "an isolated system".
John Shade's comment deserves elevation to a blog post and as wide as possible dissemination.
Jul 3, 2014 at 6:17 PM | Unregistered CommenterPeter Dunford
Done. See Discussion > Hall of Fame, Bishop Hill (comments)
ATTP says.....
(Quoting Doug Keenan) "Based on what we currently know, it is plausible that Earth will enter a cooling phase during the next several decades."
But then you respond [my bold]:
"...indicates a significant misunderstanding of radiative physics. If we continue to increase our emissions, the only physically plausible way in which we could enter a long-term cooling phase is if there were a major asteroid strike, or significant volcanic activity."
Tell me, ATTP, do you understand the phrase: "Post hoc, ergo propter hoc"? 'Cos you have demonstrated it very well here - and not just in the post I quoted. Of course, it may well be that you have managed to falsify the Null Hypothesis - and we just haven't heard about it.
@ Martin A
Thank's for that - although the amount of energy could presumably vary in an open system? (Not through creation or destruction, but through coming and going.)
"I took a look at Lectures on Physics (vol 1) By Feynman, Leighton, Sands. Always good for getting to the fundamentals of any question involving physics"
For anybody who doesn't know, the lectures are on-line here:
http://www.feynmanlectures.caltech.edu/
DougK: "I am saying that a cost–benefit analysis makes an extremely strong case for increasing the hardware budget tenfold or more."
Really Doug? I would say that spending Umpty billions on Climate "Science" has so far achieved the square root of b*gger all and shows no sign of changing any time soon.
In the eternal game of allocating scarce resources it is a crying shame that this palpable nonsense gets anywhere near the top of the pile for consideration. What a monstrous waste.
So in contrast I would take the computer they've already got and put it on ebay.
> While you are here [...]
Nice move, shub. Let me see if I can use that one. Let's see:
While you're here, dear Douglas, have you asked Richard Muller before releasing your correspondence with him?
Also, if you have any comments about his accusation of “statistical pedantry,” that would be nice.
***
If you'd acknowledge that your endorsement of Very Tall's master argument may not lead where you thought it would, that would be nice.
Anders said "All I'm really saying is that statistical models - alone - cannot tell us what physical processes are causing the warming. Therefore you can't use the inability of statistical models to do this, to then argue that we don't know what's causing the warming. Of course, Bishop seems to be suggesting that all that's really being suggested is that statistical models cannot provide empirical evidence for warming. Well, since the surface temperatures today are higher than they were in 1880, we have warmed, so this would seem to be wrong."
I see what you are doing there abs to be honest if you were a genial from East Germany called Nadia you would win some serious weight in gold medals for mental gymnastics to completely get the Bish and Dougs positions so spectacularly wrong.
Mailman
ATTP
If energy comes in many forms, which cannot be quantified, how can you be certain it's increasing? There have been many instances of evidence which turned out to be evidence of something else entirely.
Harry Passfield
If the null hypothesis is that conditions have not changes since 1880, you can consider it falsified.
Global temperature, CO2 concentration, total ice volume and sea level have all changed by statistically significant amounts in the direction predicted by the cAGW hypothesis.
Sandy S
Actually you can quantify the energy budget.
The energy required to increase sea level by thermal expansion, to increase ocean heat content, melt ice and warm the air can be measured and calculated from measurement s. Their sum is the amount of energy needed to produce the observed warming.
Satellite measurements of energy flow allow the energy imbalance to be calculated.
Experimental measurement of the radiative physics of CO2 allow calculation of the forcing due to increasing CO2, confirmed by observation of downwelling radiation and outward longwave radiation.
Empirical evidence from the three strands, temperatures, energy budgets and CO2 converge on the same value for the energy gain by the climate system - 6 * 10^22 joules/year.
willard, you have successfully disqualified yourself from passing judgements on blog commenting and moderation with the rachelsquirrel moderation fiasco you created.
I've been pondering what you mean by a statistical model. I assume something akin to the methods used in statistical mechanics where the "average behaviour" of a large number of particles approximates to the behaviour of say a gas and is used to predict thermodynamic behaviour etc.
Such a method works well when the basic physical/chemical processes are understood and can be quantified and individual particle behaviours can be written down as equations of motion and constraints etc eg gas in a box with known sinks and sources for say heat and gas gain or loss.
The physics/chemistry has to come first before the statistical theory (other than a guess) can be built.
With climate, essentially an open system with emergent properties eg clouds, photosynthesis, DMS CLAW feedback positive or negative?, albedo change, chemical erosion of rocks, etc there is a mass of quantification that is not understood even though lots of the basic physics/chemistry is understood.
Hence any reasonable model, physical or statistical looks to be a way off and that's before the challenges of chaos kick in.
"If the null hypothesis is that conditions have not changes since 1880, you can consider it falsified."
Why would anyone consider that to be the null hypothesis? Is there something special about the climate of 1880 that it should have been expected to last forever, unchanging and static?
Shub,
Part of me would quite like to do that. However, I doubt it would go any better now than it did before. Given that, I don't really have the desire, energy or inclination to have to moderate very contentious comment streams again.
WFC,
I mean multi-decade. As others have pointed out, internal variability does mean that we can have periods of cooling, but a multi-decade cooling period, while we continue to increase our emissions, would essentially be a scenario in which a system that was out of equilibrium moved further out of equilibrium, which seems physically implausible.
Ron C.,
You can't really separate surface temperatures and radiative forcings. The surface temperature essentially determines our outgoing flux (the rate at which we're losing energy). If, prior to an El Nino event we're in equilibrium (Ein = Eout) and the El Nino acts to increase surface temperatures, then if there is no change in radiative forcing, we will be in a state where Eout > Ein and we will lose this excess energy in a matter of months. On the other hand, if the surface temperatures do not drop back down after an El Nino event, there are two plausible explanations. The system was not in equilibrium prior to the El Nino event (Ein > Eout) and the El Nino has acted to drive us closer to equilibrium, or the El Nino event itself can produce a change in radiative forcing. There is, however, no evidence for the latter possibility. Therefore El Nino events are probably simply acting to drive the surface temperatures towards equilibrium, with the system being out of balance because of anthropogenic forcings.
ramspace and Harry,
Let me try and rephrase what I mean. If we consider all the known physical mechanism that could contribute to our warming, the most likely scenario is one in which anthropogenic influences dominated after about 1950 and contributed a non-negligible amount prior to 1950. If you want to propose a different scenario, you will need to discover/explain physical mechanisms that are currently unknown.
SandyS,
I didn't say that. Most of the energy is in the form of heat (as opposed to kinetic, for example). Therefore measuring the temperature and density, and knowing the equation of state of the different parts of the system, is sufficient to determine the energy.
Apologies for the lengthy comment. It's also getting a little late, so I think I will call it quits for now.
@entropicman: the 'forcing' concept fails to understand that it is an Irradiance, a potential energy flux to a sink at absolute zero. The real energy flux at the surface is the vector sum of Irradiances. The 6.10^22 J/Year term is maginary, the result of a perpetual Motion Machine of the 2nd Kind. In reality, mean enthalpy accumulation is near zero.
Sigh. More than 100 comments here arguing about minutiae, or reinforcing beliefs, whereas the real battle is elsewhere.
I suppose that it makes commenters feel good. Net effect = zero.
Sometimes being here is like being on the Greenpeace website.
EM says: "If the null hypothesis is that conditions have not changes since 1880, you can consider it falsified."
If??? That's one hell of an 'if'. The fact that your interpretation of the Null Hypothesis is a load of blox is neither here nor there. Try again.
ATTP: [my bold] "ramspace and Harry,
Let me try and rephrase what I mean. If we consider all the known physical mechanism that could contribute to our warming, the most likely scenario is one in which anthropogenic influences dominated after about 1950 and contributed a non-negligible amount prior to 1950. If you want to propose a different scenario, you will need to discover/explain physical mechanisms that are currently unknown."
ATTP: You really haven't twigged that you need to falsify the Null Hypothesis for the bolded part of your comment to be true - or even worthy of being considered. You have nothing that can make the 'most likely scenario' even a contender.
...the amount of energy could presumably vary in an open system? (Not through creation or destruction, but through coming and going.)
An "open system" is presumably one where energy can enter and leave, so the energy it contains can vary.
For anybody who doesn't know, the lectures are on-line here:
http://www.feynmanlectures.caltech.edu/
Jul 3, 2014 at 7:00 PM | Unregistered CommenterWFC
Many thanks for the link. That's really useful to know about.
Harry,
And maybe you should start by defining your null. Also, we're not starting the whole statistical game playing thing again, are we? I thought we'd agreed that you need physics to understand the processes underlying changes to our climate.
ATTP: "And maybe you should start by defining your null [Harry]."
My null? Now you're playing stupid games, ATTP. If you're in this debate you know full well what the Null Hypothesis is. Don't play the fool, I figured you for better than that - otherwise, I'm wasting my time.
Harry,
Okay, let me explain how one may do this. Consider what would happen if we included all possible physical processes, except anthropogenic ones. If we do this, the resulting surface temperatures profiles are not statistically consistent with observations. If we add the anthropogenic influences, they are statistically consistent. More strongly, there is no known way to develop a physically motivated process/model that both ignores anthropogenic influences and is statistically consistent with observations.
Now, are you going to explain your thinking with regard to the null hypothesis?
"I doubt it would go any better now than it did before. "
You can do that, theresphysics. I won't comment there. Nor I believe will too many others as well.
No ATTP, I will not let you 'explain how one may do this'. There is only one Null Hypothesis and you have not falsified it, let alone accepted that it exists outside of your tenuous definitions. The fact that you insist - still - in accepting that 'anthropogenic [processes]' have equivalence to (known) physical processes puts the lie to your argument. As I said earlier, you have decided that "after this, therefore because of this" - a logical fallacy.
Anders
your comment at 8:20 pm assumes that 'we' know and understand all physical processes. We don't.
You will be aware that the rate of increase in global average surface temperature between 1975 and 1998 was similar to the rates of increase observed between 1860 and 1880 and between 1910 and 1940 (approximately 0.16 C° per decade). And yet only the last one is blamed on manmade emissions. Odd.
ATTP
I was right--it's your radiation blinders. You are so stuck on your radiative global warming paradigm that you cannot see anything else. Surface temperatures are entirely the function of the heat transfer processes operating in the lower troposphere: namely conduction, convection and evaporation. Radiation only matters at the TOA. But that's a whole different subject. I won't participate in your attempt to hijack.
Harry Passfield
Please state your null hypothesis. You have rejected my definition and responded with rudeness when ATTP asked.
All we can presume from your relies is that you do not know what the null hypothesis is, and are unwilling to admit it.
If you want us to falsify your null hypothesis, we need to know what you think it is.
Headless Chicken,
Okay, that one may sounds that way, but I've been using all "known" physical processes up until then. We may not "know" and "understand" all physical processes, but that doesn't mean that it is particularly likely that we'll suddenly discover some unknown physical process that allows us to conclude that our current understanding is wrong in some significant or fundamental way.
And if you actually looked at the forcings during those different periods, you would discover that we can largely explain both periods as a response to external forcings. In the latter period, anthropogenic influences dominate. In the former, there is a bigger contribution from solar and (I think) volcanoes. Just because they show similar rates of increase does not mean the underlying physical processes were the same.
turnedoutnice, you say, "the 'forcing' concept fails to understand that it is an Irradiance, a potential energy flux to a sink at absolute zero."
That doesn't even make any sense, and you're using it to claim that people don't understand radiative physics. Why?
Ron C.,
No, they're not, but I would guess that if you have been involved in this debate for quite some time and still think as you do, nothing I say will change you mind. Again, I do wonder why the blog owner doesn't pop in and clarify these misconceptions. I'm sure he agrees - or, at least, I thought he did, with the fundamentals of the greenhouse effect.
If the null hypothesis is that conditions have not changes since 1880, you can consider it falsified."
Why would anyone consider that to be the null hypothesis? Is there something special about the climate of 1880 that it should have been expected to last forever, unchanging and static?
Jul 3, 2014 at 7:44 PM | Unregistered CommenterBloke in Central Illinois
I chose1880 is a useful starting point for two reasons.
1) It is the approximate starting point for the Increase in CO2 observed in the Law Dome ice core, described in the 19th century chemical literature; and estimated from rates of fossil fuel consumption.
2) It is the starting point of useful worldwide temperature data.
Feel free to suggest alternatives.
Harry,
Following on from Entropic Man's insightful comment, no there is not only one Null Hypothesis. The null hypothesis is typically that there is no relationship between two datasets/sets of observations. Maybe you could elaborate as to what your ONE null hypothesis is.
"Okay, we agree that we need a physical model to understand what drives changes in our surface temperature (at least I think we do)."
Rubbish. This is the common alarmist argument for belief: "you must explain it otherwise you must accept what we believe.
ATTP (Jul 3, 2014 at 8:48 PM) sais "And if you actually looked at the forcings during those different periods, you would discover that we can largely explain both periods as a response to external forcings. In the latter period, anthropogenic influences dominate. In the former, there is a bigger contribution from solar and (I think) volcanoes."
Have you a reference to support this statement?... and what about the forcings since ~2000AD that explain 'the pause'?
"you would discover that we can largely explain both periods as a response to external forcings"
No. Not true. You can ask Judith Curry. Secondly, the models' response to either period does not match measured temperature rise rates.
Anders
let me say kudos for coming here to fight your corner but as Ron C points out you are obsessed with radiative physics at the expense of the many other drivers of climate. Reading your posts, your argument boils down to 'CO2 is a greenhouse gas. We are increasing the amount of CO2 in the atmosphere. Warming must follow. Any warming that has occurred whilst CO2 increased can be attributed to that increased CO2.' Any evidence that contradicts this view is rejected or rationalised away. A true scientist would be asking what on earth can be counteracting the hypothetical extra forcing of all that extra CO2 such that surface temperatures have been stationary for well over 17 years? And if this continues, where does that leave the hypothesis? At what point in time do I need to re-think my position?
As an aside Judith Curry has a post on the over-confidence of climate science. I think you suffer from the same malaise. Adieu.
Anders: "Okay, we agree that we need a physical model to understand... "
MikeHaseler: "Rubbish. This is the common alarmist argument for belief: "you must explain it otherwise you must accept what we believe."
Really, it's more like "you must be able to explain the underlying physics in order to explain the changes".
Statistical models cannot explain complex systems very well, if at all. There's an obvious problem with statistical models, based on "correlation =/= causation", but an even bigger problem here is that we'd need at least thousands of years of data to be able to build a really solid statistical model of climate change.. and we just don't have that.
EM's "insightful comment"? Oh pullease, ATTP. You and EM have been around this block so many times that you are being deliberately disingenuous about admitting to the the knowledge of what makes the Null Hypothesis. You're just a pair of NH deniers, really. (Was that too rude for you EM, you sensitive being?). I know, and I believe everyone commenting on this blog KNOWS what the NH is. But you have just too much invested it your own doctrinaire beliefs that you can't even admit to knowing the NH, much less falsify it.
Joanna,
The simple solution is to not take part in discussions here.
Entropic,
Isn't there a forum somewhere missing it's fracking expert?
Anders,
The fact you have got the bish's and Dougs question so spectacularly wrong just reinforces the point that you are your big standard alarmist incapable of rational discussion. Although to be honest, if you stopped to pull your foot out of your mouth you would deprive us all of plenty of entertainment :)
Mailman