Bishop Hill Some model thoughts
Jun 18, 2013 Climate: Models Climate: Parliament There have been a few interesting bits and pieces floating round on the subject of climate models in recent days.
At WUWT, Bob Tisdale has reviewed the CMIP5 model predictions of Antarctic sea ice and found that they have performed no better than their predecessors.
Judith Curry has focused on a paper by Stevens and Bony that looks at one of the fundamental deficiencies of climate models - their inability to represent clouds - and considers the futility of trying to add complexity in other areas until this basic failing has been overcome.
And then Doug McNeall tweeted the following remarks in defence of the CMIP5 ensemble:
The CMIP5 ensemble is not set up a a calibrated probabilistic prediction system: it doesn't pretend to be one either.
It is just a set of plausible trajectories that the climate might take, given a certain set of forcings.
They're not predictions - just plausible outcomes, and those outcomes have not been borne out in practice. The models have fundamental deficiencies too.
Do the policymakers discussing the Energy Bill in Parliament today understand these issues?
Reader Comments (63)
"It is just a set of plausible trajectories that the climate might take, given a certain set of forcings."
Yeah. All the models (seem to) work using a set of assumptions about 'forcings'. All the models are wrong to one degree or another. Have they considered the possibility that there is an assumption in the forcing thory which does not match reality? That it never will no matter how it is parameterised? Now, if it was me, I'd be finding a way to check and test that assumption which was independent of the models. I dunno, observation maybe. And I'd be looking at it from a point of view that there IS something wrong, not that we are all correct but the numbers somehow are not co-operating.
What is implausible? Was our current weather plausible 5 years ago? 10 years ago? What does the model add to a bunch of people sat in a room saying
"No, no, no! I think it's going to be ......." ?
"Do the policymakers discussing the Energy Bill in Parliament today understand these issues?" I'm not sure most of them even know there are issues, never mind understand what they mean.
but not necessarily the right forcings because one thing is clear; no-one knows what the right forcings are or just as importantly how they interact. So this is a very expensive way of saying that it is pure guesswork. At least we are getting a small degree of honesty from Doug.
This highlights the sleight of hand so beloved of the warmists and what we sceptics have known all along. They have no problem with the world treating their projections as predictions until the predictions are shown to be wrong at which point they revert MAGICCly to projections.
Snake oil anyone?
It is easy to get a false perception of what is going on.
Increased media coverage of a certain type of story, gives the impression that that type of event is more common than it was many years ago wwhen there was less media coverage on the type of story concerned.
In the UK over the past 8 to 10 years we may have had more flooding, and these events have increasingly appeared on the news. But is the increased in flooding truly related to different and/or increased rainfall patterns? people assume so, however, if properly investigated, it may well be found out that the majority of flood events is not linked to different and/or increased rainfall patterns, but due to poor land management and porr town planning and building control.
In London over the last 20, or so, years there has been a tendancy to dispense with fron gardens and tarmac over this area for increased off-street parking. This is a small change, but when added together can have a large impact on the way in which rainfall is absorbed, or forced onto the road onto sewers with insufficient capacity to handle run off water, whhich in turn leads to flooding.
Over the last 40 or so years many new housing developments have been built on flood plains. Of course, this means that when there is heavy rainfall, these developments/new towns/urban spread is prone to flooding. It also means that the water which would normally be absorbed in the flood plain is not quickly absorbed there.
On some of these new developments, flood defences have been built to protect them from flooding. But this leads to consequential problems forcing rivers to back up and flood further up stream simply because they can not flood in there past usual and natural location.
My point is that sometimes becoming increasingly aware of events is not because the event is more common buty rather because it is more frequently reported. Further, it is far too easy to jum to conclusions. My example of increased flooding is one obvious area where the underlying cause can be more complex and may not be due to or entirely due to tyhe cause that most obviously leaps out at one; namely increased rainfall, different rainfall patterns.
In practice, there is much variability in the climate and weather and natural variability is under-estimated, and because we do not understand natural variability, what it consists of, what these forcings are and what are the upper and lower bouunds of each constituent forcing, natural variability is not properly modelled.
Until natural variability is properly known and understood, one cannot begin to seperate climate forcings due to natural variability. The models make assumptions but these are merely hunches. There is no independent verification of the correctness of these assumptions, and since reality is so different from model projections, it appears likely that the assumptions made in the models is incorrect, but of course, the assumptions could be correct save that natural variation is under-estimated and natural variation is the dominant player.
I have little doubt that to the layman, they view model outputs as predictions, not projections. Infact, I consider the distinction to be disengenuous when (i) there is not a caveat placed upon every projection making it clear that it is not a prediction and that it is based upon unverified assumptions and will only have some resemblance to reality if and only if the assumptions made are correct and bearing in mind that the assumptions have not been independently verified; and (ii) where model output is intended to influence government policy on the basis that what the models output will come to pass unless the government instigates policies which will prevent the model output coming to pass.
If model output is projection only, there should be stark caveats. These should include not only the aabove but should also include a note that the model itself is unverified and list all areas that we know that the model deals with poorly, eg., clouds.
Further to my post above, the 9th para should have read: "Until natural variability is properly known and understood, one cannot begin to seperate climate forcings due to non natural variability ..."
It is all very well to show accuracy with "hindcasting" as the models (generally) do. However, as the models (and modellers) are finding; "Prediction is very difficult, especially if it's about the future." - Niels Bohr.
Policy makers (and modellers) should note this statement.
noTrophywins - I'm sure they have all the right forcings... but not necessarily in the right order :)
and Doug says "it doesn't pretend to be one either"
Pity no-one told Vicky Pope
http://www.youtube.com/watch?feature=player_embedded&v=WyDmdcPw7Uw
unless my ears deceive me she starts off this lecture with the words 'we are predicting'
and her predictions have not come to pass (yet) and nor will they
we still seem to have plenty of snake oil in stock!
Well, I have my doubts about this - I'm not even sure I understand them completely! But here's something they might be able to understand ...
Since Dec. 2012, the United Nations Development Program (UNDP) has been conducting a "Global Survey" of (heretofore never consulted) ordinary people inviting them to select 6 (of 16 - or 17 if you count the "write in") priorities for a post-2015 world.
"Action taken on climate change" is one of the options. It is defined/explained as follows:
With 623K+ "votes" cast to date, the "world" ranking for this "priority" is ... 16th.
And since they're discussing an Energy Bill, they might also be interested in knowing that for the U.K. and Northern Island, the ranking of the 16,760 "voters" for "Reliable energy at home" did not fare much better, currently standing at 13th. Although this could have been affected by the definition/explanation:
I could be wrong, but "sustainably generated" might have caused some to not be too thrilled about it.
[Background and links at: NEWSFLASH! Action on climate change voted bottom of world’s priority heap]
So McNeal deploys the Mystic Meg defence of climate modelling.
Uh you know guys it's just crystal ball gazing really [Snip - raise the tone please]
The GCMs seek to model a change in diurnal equilibrium, caused by anthropogenic CO2, based upon a radiative imbalance that they calculate to be three orders of magnitude less than TOA insolation. Unless the effect of albedo (clouds) can be modelled to the same accuracy the radiation calculation is meaningless. AFAIK the effect of albedo is as much as an order of magnitude greater. Furthermore, conduction, convection and other phase change effects are also far greater uncertainties in the coupled, non-linear thermodynamic calculation.
The radiative imbalance model has failed, with the inability to predict the last 17 years of flatlining temperatures (hindcasting doesm't count). The "missing heat" (hiding in the deep oceans) excuse is pathetic.
We need Josh,
I have in my mind a picture, I imagine a cartoon where a Wile E coyote character who represents the political elite in Parliament................... is out on a rocky ledge, he is furiously cutting rock [er grant me some poetic license here!] - using a big saw - with a label attached with "Energy bill" written upon it, the cliff represents economic and financial stability/prosperity and the rocky ledge is Britain. Of course, Wile E. coyote is kneeling on the ledge and of course is on the wrong end of it..........................the thin rock ledge is cracking and down below is the economic abyss....................on Wile E coyote saws on and maniacally at that.
Back to fundamentals, chaos theory, butterflies and tornados (why does that metaphor always annoy me?)
Precisely because it has been proven that long-run climate prediction is not possible, it is inappropriate to attempt to state that there is a “consensus” that “global warming” caused by increased greenhouse-gas concentrations will be dangerous if it continues. Scientific dissent on the question of climate is and will always be legitimate, because it is settled, proven science that long-run prediction of the behavior of mathematical objects such as climate is not possible unless the initial climatic state at any chosen moment is known to a fineness of detail that is in practice impossible to attain, and unless the processes for the subsequent evolution of the object are also known in detail, which they are not…
As Lorenz (1963) put it in the landmark paper with which he founded chaos theory –
“When our results concerning the instability of non-periodic flow are applied to the atmosphere, which
is ostensibly non-periodic, they indicate that prediction of the sufficiently distant future is impossible by
any method, unless the present conditions are known exactly. In view of the inevitable inaccuracy and
incompleteness of weather observations, precise, very-long-range weather forecasting would seem to be
non-existent.”
LORENZ, Edward N. 1963. Deterministic nonperiodic flow. Journal of the Atmospheric Sciences 20: 130-141.
And climate, of course, is very-long-range weather.
from: The mathematical reason why long-run climatic prediction is impossible. (SPPI, Monckton 2007)
Poincaré discovered this in the 1880's when working on the three-body problem.
Freeman Dyson tells the story of how he was severely slagged off for using 3 or 4 parameters (guesses) in a model. Climate models contain dozens!
But today's climate modellers say: "just look at the SIZE of our computers."
It just won't do!
Jun 18, 2013 at 10:24 AM | Allan M
What he said.
Perhaps the appropriate collective noun might be a Delusion of Climate Modellers. They'd be the Deluders; we the Deniers.
richard verney
I recently read (and I must start making a note of where I pick up these useful snippets!) that the period 1965-2000 was unusually dry in the UK.
To which my reaction was pretty much as you outlined it above — 35 years is virtually a career lifetime so it's not surprising that even after half that time we had town planners and developers saying, "well, yes, we used to get floods there but we don't any more so it should be safe to build."
And I don't recall any serious opposition coming from hydrologists or insurance companies. From geographers maybe but, hell, what would they know?
And when you add in the extent to which other infrastructure has added to the layers of concrete while maintenance of drainage ditches has tended to be ignored and the fact that Europe does appear at the present to be going through a period that is wetter than the historical average it's hardly surprising that you get more flooding than usual.
Neither, I suppose, should we be surprised that there are people that will interpret these and other phenomena to drive an agenda. Nor, I suppose,should we be surprised that these people include politicians.
The critical forcing we need to worry about is that due to CO2, or 3.7 Wm^-2 per doubling of the preindustrial concentration.
3.7 is about 1% of the external forcing on earth due to solar radiation. 1% at doubling, which is not achieved yet, so the current forcing is less than that.
My question to climate modellers around is:
Are current GCM able to detect clearly a forcing of less than 3.7 W/m^2 ?
and if uncertainty in the estimation of other forcings are higher than 3.7 W/m^2, can GCM say anything sensible about the trajectory of the climate?
The models ignore clouds, which are important as cooling agents but input CO2 content which does not drive climate. Yeah, very good.
No wonder they don't work.
Re: Mike Jackson
It was David Rose's article: Madness of the Met Office Summit meeting to find out why our weather is... normal
Doug McNeall - by his own implicit admission - is not qualified to make statements in the English language.
This is not new (the bit about the models not making predictions) Trenberth had a blog in Nature in which he wrote on 4 June 2007:
"In fact there are no predictions by IPCC at all. And there never have been. The IPCC instead proffers “what if” projections of future climate that correspond to certain emissions scenarios. There are a number of assumptions that go into these emissions scenarios. They are intended to cover a range of possible self-consistent “story lines” that then provide decision makers with information about which paths might be more desirable. But they do not consider many things like the recovery of the ozone layer, for instance, or observed trends in forcing agents. There is no estimate, even probabilistically, as to the likelihood of any emissions scenario and no best guess.
Even if there were, the projections are based on model results that provide differences of the future climate relative to that today. None of the models used by IPCC are initialized to the observed state and none of the climate states in the models correspond even remotely to the current observed climate. In particular, the state of the oceans, sea ice, and soil moisture has no relationship to the observed state at any recent time in any of the IPCC models. There is neither an El Niño sequence nor any Pacific Decadal Oscillation that replicates the recent past; yet these are critical modes of variability that affect Pacific rim countries and beyond. The Atlantic Multidecadal Oscillation, that may depend on the thermohaline circulation and thus ocean currents in the Atlantic, is not set up to match today’s state, but it is a critical component of the Atlantic hurricanes and it undoubtedly affects forecasts for the next decade from Brazil to Europe. Moreover, the starting climate state in several of the models may depart significantly from the real climate owing to model errors. I postulate that regional climate change is impossible to deal with properly unless the models are initialized."
He is wrong! You have to validate the model prior to claiming any plausibility. ie whatever model run was closest to actual conditions is compared to reality. When this is carried out, the model is found to perform badly. Some people may like to argue that models are all we have - but using a bad model for policy because you don't have a better one just leads to bad policy.
For a scathing indictment of climate models, watch Murry Salby's Hamburg talk on Youtube. (Skip to the last ten minutes if you are not keen on cross-spectra, diffusion equations and so on.) Lots of:
"Model World", "Real World" comparisons.
http://www.youtube.com/watch?v=2ROw_cDKwc0
Unless his work has a fallacy that I have not spotted, I think it will represent a major turning point for climate science.
[I've typed up the text of his talk for my own benefit. I could post it somewhere if that would be useful. Any suggestions?]
'plausible'- They keep using that word. Wasn't that the word used by one of the reviews to describe Mann's hockey stick result?
plausible- adjective:
1 : superficially fair, reasonable, or valuable but often specious.
2 : superficially pleasing or persuasive.
3 : appearing worthy of belief.
Or as Inigo Montoya in The Princess Bride might say-
"You keep using that word. I do not think it means what you think it means."
For some years my brother gave the models far more credit than I did. When he learned, independently, how badly they simulate clouds his confidence in them evaporated immediately. (Confidence in the models that is, not confidence in clouds.)
He is probably still unaware that they take the postulated CO2 effect and multiply it x3 using the equally uncertain water vapour feedback. The cAGW proponents are really arguing that water is going to cause catastrophic anthropogenic global warming.
Shakespeare could understand it, so I'm sure the non-scientists in Parliament could understand it if they wanted to.
geronimo
And let's not forget that the IPCC was set up with the remit to investigate anthropogenic global warming. Even with the best will in the world and giving them all the benefit of any doubt that might be lurking around there is nothing surprising in their refusal to involve themselves in anything else — that's not what they were for!
And like any governmental or super-governmental organisation they're not likely to come back and say, "we looked at what you asked us to look at and there's nothing of interest so we'll just disband and head for the JobCentre if that's all right with you lot".
Where's the gravy train in that?
Mike, I was simply making the point that the IPCC doesn't do predictions by their own admissions, in the passage I quoted Trenberth slated the models because the "science is settled" theme was taking hold and I guess he sensed the departure of the gravy train without passengers.
What is interesting is that although Trenberth basically rubbishes the models AND says they're not predictions the political classes and the environmentalists, used these "projections" to drive the policy and nobody in the MSM has challenged this.
So what the reader is clearly intended to understand is that, if it were not for uncertainties about future greenhouse gas emissions (and some other unspecified uncertainties), computer models could predict future climate exactly.
But nobody seems to have claimed that the universal failure of climate models to predict climate is due to greenhouse gas emissions not having evolved as expected.
It is all very well to show accuracy with "hindcasting" as the models (generally) do. However, as the models (and modellers) are finding; "Prediction is very difficult, especially if it's about the future." - Niels Bohr (...)
Jun 18, 2013 at 9:41 AM Don Keiller
Murry Salby says much the same thing:
"But reproducing the known change of global temperature is 20/20 hindsight. It's not a strong test of predictive skill. That experiment is called a hind-test.
The real test is a forecast, predicting future evolution. Only then can one be confident that models haven't been tuned to match observed behaviour. That's tantamount to a double-blind test, the standard protocol required in clinical trials of pharmaceuticals. Neither the patient (the model) nor the clinician (the guy running the model) then knows the outcome."
Martin A
But the IPCC has said it isn't possible to predict the climate.
And what you have just quoted is — as almost any sane individual who stops to think about it for two seconds realises — total drivel.
Computer models cannot ever predict the future (and I could stop there!) of a chaotic, non-linear system. There are simply too many variables. In fact the whole thing is a jumble of variables which is what makes it chaotic (duh).
Testing them against the past is totally meaningless. The past is no predictor of the future in almost any aspect of the earth that you care to investigate over any timescale longer than the lifespan of a living organism and then only in relation to that organism.
The only safe prediction about any living object is that it will die; when, you don't know; how, you don't know; where (in the case of any creature capable of independent motion), you don't know. Even the predictions for longevity are so dependent on the age of the subject (the older you are the longer your total lifespan is predicted to be) as to be meaningless.
And at the end of the day all you end up with is theoretical averages which are themselves meaningless.
So either or politicians (and our climatologists) are so stupid they don't understand any of these things or there is some other counter-balancing motive at work.
Or (as is quite possible), I've got it all wrong though nobody has yet seriously challenged my conclusions.
The fundamental question (for me) is why we are still having to argue what ought to be a pretty fundamental truth — climate will never be predictable.
"[I've typed up the text of his talk for my own benefit. I could post it somewhere if that would be useful. Any suggestions?]"
Martin, perhaps a discussion thread on BH? It would need a compact 2 or 3 paragraph precis. Like you, I found Salby's lecture very impressive, but it was a highly mathematical explanation that I doubt many could follow.
Jun 18, 2013 at 2:27 PM | Martin A
And Richard Betts claims the MO don't do propaganda. That is the language of the snake oil salesman.
How do the models deal with the areas where we lack scientific understanding? Just to remind ourselves once again what the known unknowns are
Table 2.11 from the Fourth Assessment report of the IPCC sets out the uncertainty assessment of forcing agents. Listed below are the agents and the level of scientific understanding
LLGHGs – high
Stratospheric ozone – medium
Tropospheric ozone – medium
Stratospheric water vapour from CH4 – low
Direct aerosol – medium to low
Cloud albedo effect (all aerosols) – low
Surface albedo (land use) – medium to low
Surface albedo (BC aerosol on snow) – low
Persistent linear contrails – low
Solar irradiance – low
Volcanic aerosol – low
Stratospheric water vapour from causes other than CH4 oxidation – very low
Tropospheric water vapour from irrigation – very low
Aviation induced cirrus – very low
Cosmic rays – very low
Other surface effects – very low
I would seriously like to know how to create a 'reliable' model based on ignorance.
"We can't think of anything else"="We haven't really tried to think of anything else".
"And Richard Betts claims the MO don't do propaganda. That is the language of the snake oil salesman"
That comment could be considered offensive to snake oil salesmen.
"...to remind ourselves once again what the known unknowns are.."
And what are the unknown unknowns? That's what I want to know.
Martin, perhaps a discussion thread on BH? It would need a compact 2 or 3 paragraph precis. Like you, I found Salby's lecture very impressive, but it was a highly mathematical explanation that I doubt many could follow.
Jun 18, 2013 at 2:53 PM Roger Longstaff
Thanks. I'll try to write up a summary of a few lines each section and post that as a discussion item. The text itself amounts to ~13 pages, so that would need to be posted elsewhere. The conclusions of each section can be summarised without needing to go into the maths that is used to produce them.
The last line of his lecture:
A good plan Martin, but the text/video would need to be referenced in order that those who wanted to could check/reproduce Salby's conclusions. I hope that he intends to publish this - do you know if this is the case?
Jun 18, 2013 at 2:31 PM | Martin A
There are pretty much countless number of measurements and physical effects that could be predicted too. It would really help a falsification test if the models consistently predicted localised effects for example. All we ever really see though is a wiggly line of global average temperature for the most part.
Mike J
"We can't think of anything else"="We haven't really tried to think of anything else".
It's worse - they don't want to think of anything else.
@ Rob Burton 4:45 PM
What about precipitation:
http://imageshack.us/a/img14/6786/gcmmodobspcp.png
or regional bias:
http://www.sat.ltu.se/members/viju/publication/airscomp/2007GL030429.pdf
@ Rob Burton 4:45 PM
What about precipitation:
http://imageshack.us/a/img14/6786/gcmmodobspcp.png
or regional bias:
http://www.sat.ltu.se/members/viju/publication/airscomp/2007GL030429.pdf
@ Rob Burton 4:45 PM
What about precipitation:
http://imageshack.us/a/img14/6786/gcmmodobspcp.png
or regional bias:
http://www.sat.ltu.se/members/viju/publication/airscomp/2007GL030429.pdf
@ Rob Burton 4:45 PM
What about precipitation:
http://imageshack.us/a/img14/6786/gcmmodobspcp.png
or regional bias:
http://www.sat.ltu.se/members/viju/publication/airscomp/2007GL030429.pdf
Oops. Apologies.
The page got stuck and when reloading the form was resent too many times. I hope somebody can delete the duplicates. I guess it is better to login, so that posts can be edited
Bish
MO have a post up about todays meeting to examine our weather. Richard Betts was in attendance. Can you see if you can get him to do a guest post?
http://metofficenews.wordpress.com/2013/06/18/meeting-on-uks-run-of-unusual-seasons/#comments
“There is now ample evidence that an inadequate representation of clouds and moist convection, or more generally the coupling between atmospheric water and circulation, is the main limitation in current representations of the climate system.”
Basically, current GCMs are provably crap.
Jun 18, 2013 at 5:54 PM | Patagon
I quick look at those 2 links seems to show the models are very obviously inaccurate about the water cycle.
OT, but the BBC/Met Office have just provided a direct Link to a graph showing a pretty good correlation to global temperatures. They actually show SSTs but easy to see a pretty good match to the familiar temperature graphs.
http://www.bbc.co.uk/news/science-environment-22959578
http://www.cgd.ucar.edu/cas/catalog/climind/AMO.html
Met Office Chief Scientist