Discussion > Let's get real about climate models
Attp - please would you say briefly what you mean by "boundary conditions" - I think you may be referring to something other than what I use the phrase for.
Jan 16, 2016 at 4:52 PM | Registered CommenterMartin AI haven't actually read this yet, but it may answer your question.
Jan 16, 2016 at 5:07 PM | Unregistered Commenter...and Then There's PhysicsAttp - Thank you but I don't see how an article that *you have not read* can tell me what *you* mean by "boundary conditions".
I have the impression that you use the term for something quite different from its normal use in maths and physics as constraints that the solution of a differential/partial differential equation has to satisfy. Am I surmising correctly?
Jan 16, 2016 at 6:40 PM | Registered CommenterMartin A
Attp - if you are still hanging about - I'm still interested to know what you mean by "boundary conditions". The fact that you evidently consider "initial conditions" as being something different (rather than just a boundary condition for t = 0) seems to indicate that, for you, they are something different from what is normally understood in formulating systems of partial differential equations (which, essentially, is what a GCM is).
Martin A
Simon, you surprise me; you believe that the global warming is anthropogenic! Mind you, you do not specify by how much; is it that you think it is ALL, or just a proportion? (Also, there is the point that there has been very little warming for nearly 2 decades; whose fault could that be?) You also say that CO2 is increasing exponentially, yet all the evidence I have seen is that it is more or less linear – however, the human consumption of fossil fuels, hence emissions of CO2, has increased exponentially.
Martin: the circular logic of the Believers never ceases to amaze me.
Radical Rodent
Interesting that a discussion about models vs observations over at Steve McIntyre's blog seems to arrive at the same conclusions.
I'm waiting for someone in scientific public life to point out that in the normal science world, all CMIP5 models would be considered to be failed models because they all run hot compared with observation.
In the climate science world it seems normal to ignore the failure of the models and regard the observations as somehow being wrong.
How long can these people get away with this?
Schrodinger's Cat
Simon Hopkinson
To make that claim would be to deny the past 20 years of exponentially increasing CO2 and an absence of significant warming.
Thank you, a chance to test the AGW Paradigm against observation and your description of the last 20 years.
The Holy Climate Law (☺) should be able to approximately predict product the warming over the 20 years from 1992 to 2012, the latest year for which a 5-year average is available. CO2 increased from 355 to 395ppm. Assuming climate sensitivity of 3, 3.7W/C and no lag the maximum temperature expected is 5.35ln(395/355)3/3.7=0.46C
Over that period the GISS 5-year average increased from 14.33C in 1992 to 14.67C in 2012. That is an increase of 0.34C in 20 years.
95% cnfidence limits for the GISS data are +/-0.09C. The difference between two means become statisticically significant when the 95% confidence limits no longer overlap forat 0.18C. The difference between 1992 and 2012, 0.34C, is statistically significant.
On the basis of this observed data the AGW paradigm is making a better job of describing the last 20 years than you are.
Entropic man
In the climate science world it seems normal to ignore the failure of the models and regard the observations as somehow being wrong.How long can these people get away with this?
Jan 17, 2016 at 1:47 PM | Unregistered CommenterSchrodinger's Cat
How long have you got? They won't stop while they are still being funded for being wrong.
michael hart
EM - To start with:
- Yes, no question that the radiative properties of radiative gases in the atmosphere are well understood and have been measured in detail and with precision.
- No question that *in principle* total outgoing radiation and total incoming radiation can be measured. However, I have (somewhere) a paper co-authored by Hansen where he states that the difference between the meqsured quantities is not credible - "so we have to rely on results from models" (or similar words). Presumably the situation has not change since, or it would have been shouted from the rooftops.
- I think that you use the term "radiative forcing" to mean "difference between total incoming and total outgoing energy", rather than the IPCC definition. Am I right on that point? Because it is "radiative forcing" according to the IPCC that is inherently impossible to measure. (See below).
To deal with your points...
Firstly, the absorption spectra of greenhouse gases are well known from laboratory measurement. We know both the spot absorbtion frequencies and the effects of band spreading in a well mixed atmosphere. Forcing can be calculated from theory using this data and radiative physics.
Yes, that is what the Myhre paper reports. And that paper is where the Holy Formula comes from. I still remember my disappointment on learning that it had not been derived from theory, but merely by curve fitting to computed results from their model.
Secondly, the outward radiation spectrum and intensities are monitored from orbit. At the absorption frequencies relevant to each greenhouse gas one can measure the decrease in energy output relative to the black body spectrum. Integrating these values gives the radiative forcing for the gas.
I think there are some oversimplifications there but it would take too long now to explain why I think that. (It's to do with the lapse rate and the mean height at which final radiation to space occurs.)
Thirdly, the intensity and spectrum of downwelling radiation is monitored from the ground. Once again calculating total energy at the emission wavelengths for each gas gives the radiative forcing for that gas.
That tells you about the amount of energy being repeatedly shuttled back and forward between the ground and the lower atmosphere but that does not tell you about how much is making its final escape to space. So it does not seem relevant to even your definition of "radiative forcing".
You still have this belief that radiative forcing is not measurable.(...) It exists as a measurable phenomenon, despite your lack of belief.
As the difference between "difference between total incoming and total outgoing energy", yes in principle it can be measured. Although it does not yet seem to have been done with believable results - please correct me if my information is out of date.
HOWEVER. According to the IPCC radiative forcing is defined as follows:
"The radiative forcing of the surface-troposphere system due to the perturbation in or the introduction of an agent (say, a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long-wave; in Wm-2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropo-spheric temperatures and state held fixed at the unperturbed values".
This is not the definition of a measurable physical quantity. You can't measure the change in the radiation balance at the troposphere *after* the stratosphere has readjusted, but with the surface and tropospheric temperatures *held fixed*. The troposphere itself is an indeterminate thing. So yes, radiative forcing (as per the IPCC) cannot be measured. It can exist Only in climate models. It seems very strange that one of fundamental concepts of climate science cannot exist in the physical world only in computer models.
Deterministic.
EM I asked you to say what you mean by "deterministic" but I don't think you did. Please would you do so - hard to respond when I don't know what you mean. I think you may mean "evolves according to physical laws" - have I guessed right there?
On a planetary scale and over geological timescale these processes are deterministic. Repeat the conditions and the physics produces the same equilibrium. This is deterministic.
Even on geological timescales, that seems to me to involve some quite drastic assumptions. But I now understand that you are not saying it applies over timescales relevant to the present discussion.
Martin A
Radical Rodent:
Simon, you surprise me; you believe that the global warming is anthropogenic! Mind you, you do not specify by how much; is it that you think it is ALL, or just a proportion?
That, detective, is the right question! ;) I accept Arrhenius' proposition that adding CO2 to the atmosphere enhances its ability to retain energy. By his math, I accept his ~1.2C climate sensitivity. I accept that we are burning fossil fuels and releasing CO2 into the atmosphere.
What I don't know, and what it's becoming clear I'm not alone, is the net effect of our additional CO2. The climate has NOT responded according to EM's AGW paradigm.
(Also, there is the point that there has been very little warming for nearly 2 decades; whose fault could that be?)
Indeed! I don't pretend to have the answers.
You also say that CO2 is increasing exponentially, yet all the evidence I have seen is that it is more or less linear – however, the human consumption of fossil fuels, hence emissions of CO2, has increased exponentially.I think I was unclear or misspoke. Over the period of industrialisation to date, the CO2 curve has been exponential, not linear or logarithmic. However, we also know that CO2's warming effect is logarithmic, not linear or exponential.
The interplay of the rate of CO2 entering the atmosphere and its effectiveness in retaining heat could mean that we've already seen pretty much all the warming that CO2 can muster. I don't know that this is the case, but I know that nobody else does either. And I know that GCMs are not where we'll find out. ;)
Martin: the circular logic of the Believers never ceases to amaze me.
Most, if not all, Believers' arguments seem to me to rely on logical fallacies.
EM:
[...]On the basis of this observed data[..]
GISS extrapolates, with added assumptions, temperature data for enormous areas in the polar regions. Your confidence in their "observations" is not shared here. But given that I'm a Popperian, I'm sure that won't surprise you.
Simon Hopkinson
EM, I remember that a year or two back, after I commented that "radiative forcing" cannot be measured, you kindly referred me to a paper whose title and abstract implied that the authors had made measurements of "radiative forcing".
It turned out that they had measured downwelling radiation from the atmosphere arriving at ground level and that was what they termed "radiative forcing".
Could you easily find the reference and post it please? If I kept the article, it's lost on a computer somewhere. I'd like to re-read it.
Martin A
A Popperian? Wiki says this:
Logically, no number of positive outcomes at the level of experimental testing can confirm a scientific theory, but a single counterexample is logically decisive: it shows the theory, from which the implication is derived, to be false.If someone were to maintain that there has been very little warming for nearly 2 decades, a Popperian might look at this graph and conclude that this is a clear counter example and that this "very little warming" was therefore disproved. You would doubtless wriggle and writhe, seek to finesse the meaning of "very little" or of nearly 2 decades to find a period that you could feel happy with, or claim that the indices are wrong or that the scientists are all crooked and that we can't believe surface measures or claim that the lower troposphere, where nobody lives, might be different. You would, in short, find any way to reject any counterexample; you are no Popperian.
Raff
Ack! I forgot for an instant that the people I was interacting with, who objected so vehemently to my "gotcha" of attp and climate models, would - as they always DO, because it's all they CAN - seize upon any imprecision as if it were ultimate proof that there is no validity to an argument. How could I have forgotten that I'm dealing with such pond scum?
There is a world of difference between my gotcha and Raff's. My gotcha isn't a trick.
Replace my "20 years" with "the pause", and FFS grow up.
Simon Hopkinson
If there ever was a "pause" it is well and truly over. My graph stops in June 2015, since when the line goes off the top. So even if you start your "nearly 2 decades" at the peak of 1998, as non-Popperians like to, there is a clear counterexample to your suggestion. And Popper would require only one. You are no Popperian.
Raff
How could I have forgotten that I'm dealing with such pond scum?
To be fair, I often forget too, but then they inevitably do something to remind me. Thanks.
...and Then There's Physics
Raff, does GISTEMP incorporate the latest NOAA "pause-buster" adjusted data? LOL
[edit] to be clear about this, if you want to hold me to the vastly superior Popperian standards, you can't do so using vastly inferior and tainted pseudoscience. I can be persuaded to change my view only by work which is performed to the highest standard. I have good reason to not trust GISS data is at that standard.
Simon Hopkinson
Simon it is you who is pretentious enough to claim to be a "Popperian" and implicitly asks to be judged as such, despite not recognizing an "experiment" when you see one. I had to look Popperian up. You dodge only by invoking that favourite conspiracy catch-all, namely "fraud" ("tainted"), that conveniently expands to encompass all that would induce a real Popperian to reject your conclusions.
I presume you take RSS and UAH to be superior and untainted, despite Mears saying they are not and despite there being a vast difference between UAH v5.6 and UAH v6.x. Doubtless you'll consider UAH/RSS to be superior although the models used are not validated, while without a trace of irony you'll decry GCMs for not being validated. I notice nobody wanted to vote in my poll: how many people no longer trust UAH and RSS now that they know their models have not been validated?
Raff
Ah ATTP - you're back. Care to say what you mean by 'boundary conditions'? As I said, I have the feeling that you mean something different from the normal sense in which the term is used.
Martin A
Raff, you're not only out of grace in your interactions here, you also patently have no grace. You presume to know what I think of UAH/RSS and presumably HadCRUT too. You don't.
The disparities between series casts doubt on ALL series. Because you're a True Believer, you presume to "know" that I, as your antagonist, am some form of Heretic- a believer in the antithesis of your position. You repeatedly ignore my statement, that I am Agnostic. Some data series I'm absolutely sure is untrustworthy, and apparently you're convinced the others are similarly afflicted. Therefore I concede that there is insufficient good data to draw a conclusion, because the uncertainties are overwhelming.
Your belief sweeps you along like a Pooh Stick. You judge everyone by the reflection of your own deficiencies, in some measure oblivious to the truth that you are deficient. Obviously not completely oblivious. Nobody could be that stupid.
Believers are in such a crush to ignore and get past the inherent uncertainties in the system and move on to where everybody is a Believer - by force or otherwise - happy, or otherwise, but at the very least compelled to do whatever is necessary and pay whatever tax to cure the problem that you've heard is "the greatest challenge in human history" or some variant (I am laughing my friggin ass off at you, here).
But the reality is that I'm not attending your Church or willingly putting my money in your collection box or paying tithes because the jury is still out on whether your god or corresponding devil even exists. I'm not closed to the possibility, but as far as I can see you haven't begun to build a strong case for it.
Simon Hopkinson
Therefore I concede that there is insufficient good data to draw a conclusion, because the uncertainties are overwhelming.Oh but you do draw conclusons:
(Also, there is the point that there has been very little warming for nearly 2 decades; whose fault could that be?)You are confident enough to agree ("Indeed!") about a "pause" despite not trusting any of the data. Brilliant! If you don't use data to draw your conclusions, what are you, clairvoyant?Indeed! I don't pretend to have the answers.
Raff
Simon Hopkinson
IIRC there are 35 drift buoys plus manned drift stations, ships and land stations around the Arctic shoreline. Coverage is not as dense as more civilised areas, but it is not absent. The Arctic is, on the basis of the available data, the fastest warming area on the planet. I prefer GISS because they at least try to include the poles,
For the purpose of my calculation any of the surface datasets would do. They all show a similar ∆T.
Martin A
You do have a talent for misinterpreting what I say. Climate and weather are deterministic on all time scales. Unfortunately short time scale variation obscure long term causation.
Entropic man
Entropic man
"Climate and weather are deterministic on all time scales. Unfortunately short time scale variation obscure long term causation."
Of course that implies that you can show that determinism over all timescales. However, can you actually show the determination over any timescales in a rigorous way? That implies a formula that accounts for all temperature movements. I don't think this is possible over 500 years, let alone 30 years or 1 year. Arthur Smith keeps making attempts at annual prediction using deterministic methods and fails badly. I think his knowledge of physics is higher than most on this forum.
diogenes
EM - thank you very much for the references. I'll take another look.
You do have a talent for misinterpreting what I say.
I'm sorry about that. It's not done intentionally (whatever Raff may think/say).
Climate and weather are deterministic on all time scales.
I suspected that was your viewpoint. We need to have a discussion about that (not just now - I'm trying to deal with a backlog of overdue urgent things).
My viewpoint is that there are oodles of things that are:
- governed solely by the (non-quantum) laws of physics
- are random in any normal sense of the word.
I think I remember reading one of Feynman's works (Lectures on Physics?) where he explained it more lucidly, convincingly, and succinctly than I can off the top of my head. I'll see if I can find it. If not, I'll try to explain it myself.
Martin A
Raff
Have you seen this, and this and the most recent sea level data.
Entropic man
Diogenes
"Climate and weather are deterministic on all time scales.
I would be fascinated if you could falsify it above the quantum level. If you could demonstrate that cause and effect does not apply to planetary atmospheres a Nobel Prize would be inevitable.
Entropic man
Martin A
Brownian motion is a process which appears random to a human observer, but iwould be deterministic if you had complete information about the system. The problem is that it is impractical to collect complete information.
More relevant to climate change, turbulent flow appears chaotic because we do not have enough information to see that it is deterministic.
Entropic man
So an outbreak of unanimity, it seems. However, the Met Office does not agree with you two.
On their erstwhile website "My Climate and Me" there was a video in which Met Office senior scientist Dr Kate Willett was asked "How do we know CO2 has caused the warming?". She answered that we know it because in climate models, if the effects of CO2 are turned off, the models no longer indicates warming*.
That little snippet confirmed a couple of things at once:
- The actual evidence [note: *evidence*, not plausibility arguments] that CO₂ caused recent warming must be nonexistent, if that is the best the Met Office can come up with.
- So-called climate science is simply not science if a senior scientist in The Jewel in the Crown thinks that a hypothesis (in the form of an unvalidated model) is evidence.
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* Around that time, a government minister explained that we know CO₂ causes global warming for that reason, so the same misinformation was being fed to the government.