Bishop Hill A chat with Leo and Doug
Jan 11, 2012 Climate: other I had an interesting exchange of views on Twitter last night with the Guardian's Leo Hickman and the Met Office's Doug McNeall. I was pressing them on the issue of climate models and their reliability and more specifically the fact that their ability to predict temperature is unvalidated.
Leo rather ducked the issue, noting that he wasn't qualified to comment, but I think that Doug and I came to a meeting of minds. Doug draws some comfort from the fact that other aspects of the global climate can be validated - we mentioned tropospheric fingerprints and I'm assuming ENSO would be another one. We didn't go into the question of just how much of a model/data match there is in these areas and I realise the fingerprints are hotly disputed. Let's therefore park these questions for the minute.
What was more interesting was that Doug and I agreed that unknown unknowns are a big problem for climate models. I think this recognition does take the debate forward so I'm gratified for Doug's input. Now I think we have to ask ourselves whether this ignorance has been properly relayed to the public and to policymakers.
On a related question, Doug and Leo asked what it would take to convince me of the validity of the models. Scientifically, this is an easy question. You need a lot of out-of-sample data. This will clearly take time, but it's the only way to do it. Pretending otherwise is simply to fool yourself. That said, I think if we had had some sort of a match between data and models since the IPCC projections in 2001, I would probably have moved a long way towards Leo's "convinced" position. When you think about it, it's remarkable that this failure of the models doesn't appear to have dented Leo's confidence in them at all.
Bishop Hill
Leo tweets:
I didn't say I was confident in models or not. I was talking about about basic principle tht rising CO2 causes warmng and that we'd b foolish to ignore that risk.
Interesting stuff.
Reader Comments (63)
Id prefer it if they just published the unaltered raw data rather than putting out the model projections, or maybe if they placed the raw data next to what the models projected and report on the difference.
Of course Leo's faith remains indented, we are dealing with a religious belief system and nothing else.
Mailman
I know you really didn't want to talk about it (and perhaps sneaking it in under "what do the public and policy makers know") but how well is the bias in the IPCC GCM runs known - absolute global temperature from the runs range over 4 degrees C in a nonlinear system. It is only when you take anomalies that they roughly line up. And then there's the clouds, ENSO (in what sense does that work?) and all the other things you don't want mentioned.
Having said that they have their place, but need to be kept in it.
The Genie is out of the flask, Leo, and into the atmosphere, where it is disobeying your wishes.
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If Leo is unqualified to comment on the issue of climate models, what is he qualified to comment on? One issue he is clearly unqualified to comment on is about basic principles, such as the hypothesis that rising CO2 causes warmng.
Still, being unqualified has never got in the way of journalists - take the example of the BBC science and environment correspondents. Not one qualification between them.
I agree with Mr Hickman that it would be foolish to ignore the CO2 risk.
But it is even more foolish to set expensive and ineffective policies as if the unknowns do not exist.
It is very odd that the proponents of catastrophic warming never seem to distinguish between two propositions. One is that increased CO2 in the atmosphere has a warming effect. The other is that any warming effect from any source leads to positive feedback of a given magnitude.
It is really quite extraordinary, and scientifically illiterate, to think that the thesis that increased CO2 will lead to catastrophic warming depends solely on the first of these propositions. Most people here probably believe that if you raise atmospheric CO2 levels, you do indeed in effect apply warming to the planet. They probably do not believe that this applied warming will result in much if any heating however.
It is, or could be, a bit like applying extra heat to a boiling pan of water. The temperature of the water does not rise. Yes, turning up the gas results in more heat being applied to it.
The question to ask Leo might be: does he think all elements of this chain of reasoning are equally certain and rest on the same evidence? If he says yes, he really is scientifically illiterate. If he says no, then what he needs to do is spell out the argument and the probabilities. The probability that doubling CO2 will warm, in an amount great enough to produce a 1 degree C rise in temperature IF NOTHING ELSE CHANGES is 100%. It would be interesting to know what readers think will happen next however.
Most would probably say that the temperature of the planet will most likely rise very little, if at all, as a result.
Giving a model the "ear" of a politician, or receptive journalist or committed activist isn't difficult.
And complexity and "teraflops" galore may impress these people, but means nothing,
I look at these models as an engineer and think: "Shit there are so many inputs missing, and many of those that are present are best guesses. Nice exercise but not much use for anything. Not if it wasn't politicised."
It is a 4 billion year old non-linear chaotic system for christ's sake...
But what do I know I am not a climate "scientist"...
There you have it. That was also the ultimate argument from Bob Watson at the Guardian debate, boiling down to, "If something is happening that might possibly cause some danger, we can't ignore it".
Why do such people ever get on a plane, or even a car? The risk of death is certainly there.
What about dioxins? There was a panic about dioxins contaminating the food chain by accumulating first in soils, then food, then milk, etc - so incinerators got heavily regulated. Well, every single motorbyke and passenger car on a motorway running through agricultural fields is also contributing to dioxins in the food chain - why aren't we worried about tha risk, too?
And, of course, the ever-present, frequently mentioned risk of an asteroid hitting the Earth. Why aren't the world governments investing on that? That would arguably be easier to justify.
Addendum
I'll stick to putting quotes in speech marks, rather than trying this computalingo stuff!
"Now I think we have to ask ourselves whether this ignorance has been properly relayed to the public and to policymakers."
To the general public, who don't read the likes of yourself & WUWT or Booker's & the likes columns, no.
As for the policy makers, those at the top are well aware, I've no doubt, but if the green taxes are to continue to flow, they won't be raising these doubts in public.
Leo tweets:
I didn't say I was confident in models or not. I was talking about about basic principle tht rising CO2 causes warmng and that we'd b foolish to ignore that risk.
Bish - if you could be so kind, please ask Leo to have a look at the following items:
1. The map of Glacier Bay in Alaska, which clearly shows that the glacial retreat in the last 50 years (which is always put down to CO2) is actually very small fraction of the total glacial retreat since the end of the Little Ice Age.
2. Likewise I would be very interested to hear if Leo (or Doug) could identify the CO2 signal in the following graph.
Because I can't and I don't know anyone who can. If CO2 is warming us up it is having a very negligible effect.
There is an interesting WUWT article relevant to last nights chat..Ie a new paper that would seem to agree with Pat Michael that higher IPCC projections of temp, are unlikely..
http://wattsupwiththat.com/2012/01/10/the-climate-science-peer-pressure-cooker/
From the Abstract of Gillet et al.:
Our analysis also leads to a relatively low and tightly-constrained estimate of Transient Climate Response of 1.3–1.8°C, and relatively low projections of 21st-century warming under the Representative Concentration Pathways.
So the answer to Leo, and questions of 'risk'.
Yes CO2 warm the atmosphere.. HOW much is the important bit, to quantify risk..
IF lots a big risk...if nor so much a smaller risk..We then act accordingly...
Or we could just waste trillions on pointless decarbonisation.. bcos of unknown fears of 'high risk' Meanwhile 22,000 children die a DAY, because of poverty, diseases, etc. all fixable NOW.. and EVEN IF CAGW were true, then measure to help those people NOW, would prevent future CAGW deaths..
MY thoughts are of the 'risk', of NOT helping those people now, because of a CAGW delusion, vs a rather smaller amount of AGW, or even aGW (ie not much). There is only so much political time and will available. focussing on one thing to the detriment of all others is ridiculous
It's incredible that scientists still stick to this religion of CO² heats the atmosphere when there is absolutely no empirical proof.
It is a religion, it's definitely not science.
Barry Woods; you also have to remember that the Gilet paper is based on constraints by observed temperature rise, in turn the implicit assumption that most post-industrial temperature rise has been CO2-AGW. There is no proof of that. Much could have been natural
Therefore the data shown in the paper are upper bounds. As there is increasing evidence that the 2nd AIE is a form of AGW and Arctic melting is a natural, cyclical GW process, there will be a spectrum for CO2-AGW going down to zero, or if there is self-absorption near CO2 IR band saturation, sub zero.
And when I read today of Lacis justifying the claim of 33 K present GHG warming from modelling, I saw red because that figure convolves true GHG warming and the lapse rate cooling up to the composite emitter position in the upper atmosphere.
This is Alice in Wonderland science by activists promoting exaggerated claims.
May I respectfully point everybody also in the direction of the "unknown knowns", the facts that everybody should know but many refuse to acknowledge...
...such as for example the absolute symmetry between these days' predictions of climate disasters due to warming with the 1970's predictions of climate disasters due to cooling. Certain geographic areas are also especially popular among the catastrophologists of all eras.
We should also be perfectly familiar why it should be so (disasters usually befall the poor...no prize to forecasting a major loss of Bangladeshi lives in the next decade, for example), but alas that is an unknown known as well.
Stephen Richards: The empirical proof is supposed to be in a paper by Harrier et al 2009 to be found on the oxymoronically titled skepticalscience. That is the only paper I've ever had cited to me that purports to show empirically that CO2 was causing extra heating. It got shredded in the comments, but as is the way with skepticalscience the shredding posts have now disappeared.
Bish, perhaps you could ask Leo whether the fact that the sun rises in the morning and causes warming, concerns him as well?
And you might mention that it is just as foolish to assume a risk where none exists, as to ignore a known one
Peter B
Your comment about dioxins reminded me of something. Just at about the time that we were all starting to be told that landfill was "bad" and incineration was a possible way forward for the non-recyclables was when the usual suspects started the dioxin scare running.
One statistic that caught my eye (no reliable link though I'll keep on looking) was that the UK pumped more dioxins into the atmosphere from fireworks on November 5) than all the incineration plants in Europe in a full year.
How accurate that is I couldn't say but the Greenies have always been very good at distorting or hiding the truth to further their agenda. For another take on the same argument see the Yes Minister episode The Greasy Pole.
On the main issue, when is somebody going to explain to this ignoramus why it is taking so long to determine whether feedbacks are positive, negative or non-existent? It would appear that — politics aside — that would determine the extent to which we need to emulate Corporal Jones or Private Fraser!
I've read the abstract of Gilet et al and have (cynically) come to the conclusion that a number of researchers are not really interested in a solution, merely in further discussion of the problem.
Leo:
There's a little parable in the second sentence, where Hickman felt he had to shorten 'that' to tht, warming to warmng and be to b. In fact, he'd repeated the word about. If he'd realised that there would have been no need to shorten anything.
And which of us spotted the word he'd repeated? Likewise, it's hard to detect which piece of a person's world view is surplus to requirements, the removal of which will lead to balance.
Here's a very good description of the difference between the IPCC predictions of 1990 and reality: http://www.sciencebits.com/IPCC_nowarming
One of the differences between the Alarmists and Skeptics is in the degree of absolutism displayed by many of the former. "The science is settled. The debate is over. We must act now to save the plant. Don't argue," where as skeptics tend to be a bit more flexible.
So if some of the Absolutists are emerging from their bunkers to engage in civilised debate, that is surely something to be encouraged.
Because once they become aware of their Absolutism, they cease to be Absolutists -- their worldview has widened in an irreversible way. (This is why cults try to keep their adherents uninformed and ignorant).
So I applaud the Bish for engaging with these folks (and kudos to them in turn) in the hope that reasoned debate can be restarted, without the precondition that "the science is settled."
@Jan 11, 2012 at 8:44 AM | lapogus
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lapogus
As you point out, there is no correlation between CO2 levels and temperature anomalies during the instrument record. Further, and this is important, nor is there any correlation between CO2 levels and temperature on a geological time scale (there are periods of high CO2 levels when it wass cool.conversely low CO2 levels and it was warm, rising CO2 levels yet falling temperatrures, falling C02 levels yet increasing temperatures). Given the lack of correlation, it is difficult to support the statement "...basic principle that rising CO2 causes warmng and that we'd be foolish to ignore that risk."
Whilst it may be the case that in laboratory conditions and in isolation CO2 may exhibit warming when subjected to IR, however, in the real world atmosphere that is planet Earth, the net effect may not be the same (e., it may lead to an increase in evaporation from the oceans leading to net cooling, or changes in convection patterns leading to cooling etc). The fact is that we simply do not know what effect increasing CO2 levels may have, but that said, there does not appear to be cause for alarm. Given the rate of warming in the period say mid 1970s to 2000 is not statistically different to the rate of warming between say 1910 and 1940 and given the present hiatus to the warming post 1998, one cannot have confidence that as a matter of basic principle an increase in CO2 leads to warming.
Jan 11, 2012 at 9:49 AM | geronimo
My point exactly. I just cannot understand why so called scientists, of which I was proud to be one, can persist with this stupidity. I wouldn't mind if they said there is no empirical evidence but radiation/ quantum theory suggest it might. I just totally detest this conerie that comes out of the Met Off et al about 90% this and 90% that. It is unadulterated religious cr@p.
I too applaud the Bish for his open-mindedness, for his ability to communicate and contact both sides of the community. It's what makes his blog readable. SteveMc is very similar but comes from the more technical side and for me that is perfect because we have the perfect balance. WUWT provides the intermediate level and journalistic perspective. This combination is what the religious freaks lack.
I was talking about about basic principle tht rising CO2 causes warmng and that we'd b foolish to ignore that risk.
This is just classic religion. It might be true but do you want to risk the punishment.
The recent discovery of how widespread seafloor vents are should give pause for thought.
The basic principle is that outgassing from within the Earth causes Global Shrinking and we'd be foolish to ignore that risk.
Jan 11, 2012 at 11:01 AM | Rick Bradford
Of course the science isn't "settled", if it was we (the scientists) wouldn't be here!
We are confident about some aspects but not other aspects.
On models, the same models are of course tested out of sample every day as they do the weather forecast as well as climate projections. OK this isn't always right, but the general principle that the models largely do the right kind of thing on those timescales is one reason why we think it's reasonable to assume they do the right kind of thing on other timescales.
Of course the key issue for AGW is the influence of rising CO2 on long-term conditions, and as BH says this requires running the models in advance and then waiting long enough to see if they agree with what happened in reality, so by definition you can only test old models. As I've mentioned before, the earlier climate models used in the 1970s were used to make estimates of warming over the next 30 years which were fairly close to what happened - which reminds me that is the subject of Philips question in the "Evidence" discussion thread so I really must address that, sorry...! BH asks for tests of the projections made 10 years ago, but the problem is that with internal variability in the system you need longer than that to test the models, unless you specifically initialise the models with the conditions of (say) 2001 using data assimilation techniques, and that kind of thing was not available then, we only started doing it 5 years ago.
So yes, out of sample testing on timescales relevant to GHG rise is an important point but by definition difficult with the latest models!
IMHO climate models should be regarded as encapsulating the various strands of theory and exploring the aggregate effect of that. Jonathan Jones on twitter quite rightly picked up on the phrase "evidence from models" - models are theory and evidence requires actual data. However, while they are still theory, the predictive skill of many aspects of the theory are tested on a daily basis and found to be useful.
Of course like all areas of science we need to further refine the theory by continual testing against data.
Richard
Has anyone assessed the 1970s models with actual CO2 (and other) forcings? i.e. have we discounted the possibility that there are compensating errors from forcings and model?
Richard Betts -
The First Assessment Report of the IPCC (1990) projected temperature rise of 0.2 K over the decade 1990-2000, and 0.3 K/decade for the following decades. Would you say that that the length of time, and the deviation from the actual trajectory, is sufficient to call that particular model falsified?
postscript to above at 1:34 PM -
I should add that this was the business-as-usual projection, lest there be any confusion.
Jan 11, 2012 at 1:14 PM | Richard Betts
"On models, the same models are of course tested out of sample every day as they do the weather forecast as well as climate projections. OK this isn't always right, but the general principle that the models largely do the right kind of thing on those timescales is one reason why we think it's reasonable to assume they do the right kind of thing on other timescales."
What makes a good weather forecast is not related to what the 'global average temperature' will be in 2100. The only thing that really matters in the temperature prediction is the energy balance in the system, something which GCM's have traditionally been really bad at. Whether 1W per M2 leaks out of the weather forecast model won't effect it at all but would be crucial when trying to tell us the temperature in 90 years time. And the most important variable effecting the energy balance (sunlight in and IR out) is the water cycle evaporation, convection, condensation and cloud formation which we still don't understand at all and getting just cloud wrong by 1% will totally change any future temperature prediction.
Richard, do the UK weather forecasts use a global or just a hemispheric(NH) model these days?? I'd guess a global model is used to model the entire world.
I don't think you would ever be able to convince me that GCM's are a valid tool for determining future temperature due to the unknowns and historically more energy conservation. They are good for short term forecasting but basically useless after that, apart from being an interesting toy to produce charts that do look very realistic...
Nobody seriously doubts that CO2 has the ability to raise temperature do they?
The real doubt is the extent and as far as I am aware, no climate sensitivity study based on empirical data suggests high sensitivity. Only studies based on models suggest high sensitivity.
I'd trust empirical over guesswork any day of the week
"As I've mentioned before, the earlier climate models used in the 1970s were used to make estimates of warming over the next 30 years which were fairly close to what happened"
Do you have a link to paper for this? Of course this is the time where a linear increase over time would have a been a reasonable approximation.
Richard,
Accepting for the purposes of discussion that the models have proven useful predictive competence up to a week, but not on slightly longer timescales, a month, I can't see that it follows that any amount of short term performance supports the idea that they have predictive skill on a timescale of decades, and there are many reasons why this should not be so. e.g. ocean heat oscillations which change little over the course of a few days.
Richard Betts
Would I perhaps be right in thinking that that is where the science breaks down?The earth's climate is not predictable in the sense that the liquefying point of a solid is predictable or that the law of gravity and what flows from that is predictable or that the speed of sound through various media is predictable.
Weather forecasts are pretty good up to about five days. Seasonal forecasts are usually not bad within certain wide parameters (though there have been a couple of blunders). Beyond that it's guesswork.
As Richard Verney has pointed out there is a disconnect between CO2 and temperature as often as there is a relationship. There is still a battle going on between the "science is settled" supporters (forgive the shorthand, Richard) and the "no, it's not" supporters. Every week someone is publishing some piece of work which supports this hypothesis or undermines that hypothesis yet through it all we keep on hearing the strain, "our models are fine; we're confident in their output; no, we're not listening to any theories that don't fit the CO2 meme; anyone who disagrees with us is a denier; and so on".
I come back to what is going to be my favourite quote for 2012: Ed Cook's "what we know is that we know f*** all".
And we're wasting trillions trying to "combat" something that we dignify with the name 'climate change' but is actually probably only weather.
Herding cats would be child's play by comparison!
MangoChutney
You are mistaken. The most likely value for climate sensitivity appears to be about 3C for a doubling of CO2. Various lines of evidence converge on this value (Knutti & Hegerl 2008).
From IPCC AR4 WG1:
Hansen & Sato (2011) Paleoclimate implications for Human-Made Climate Change is an empirical study which finds a value of ~3C for CS.
Annan & Hargreaves (2006) takes a different, but also non-model-based approach and estimates a value of ~3C. (Discussion on Annan's blog here).
Knutti & Hegerl (2008) is a short review paper which examines the various different approaches to estimating climate sensitivity. See their Fig. 3 panel A.
From the introduction:
BBD
Your Hansen and Annan links return a 404 error.
I am with Richard Verney on this one. The role of CO2 in the climate system is likely to be modest, and hard to detect because it is, overall, present in such very small amounts. The role may well be complex, with different effects at different latitudes, different times of day, different altitudes, different weather conditions, and different levels of local concentrations, as well as variations due to vertical and horizontal variations in the concentrations of other substances, in particular H2O. What is the impact, for example, of CO2 below a cloud layer compared to say CO2 above it. Are such differences more or less pronounced in associated with tropospheric or stratospheric cloud layers? How does CO2 near the ground contribute to the onset and development of convection, and how does this contribution vary with latitude and surface type? How does the contribution of CO2 vary over in the year in high latitudes where day length varies dramatically. How important is the role of CO2 as a coolant by providing an infra-red source high above the surface for loss of low temperature heat, carried there by convection, to outer space? Our surface weather, and climate, is dominated by the mechanical effects of an atmosphere in rotation and driven from below by diurnal heating of the Earth’s surface by the Sun, with dramatic effects added due to the very large latent heats of water and its abundance in the system. The energy transfers of a trace gas with emission and absorption peaks in a relevant part of the infra-red spectrum is inevitably going to be modest amidst the colossal energies of this great daily turmoil. As far as I can see, in the 30 years of the CO2 scare, these effects remain elusive in terms of hard data. The climate has been behaving in ways that are consistent with the additional CO2 having had a negligible effect overall. But the fraudulently generated scares about CO2 have had appreciable effects on our society in that time, effects which include the display of crass callousness in the deliberate efforts by the previous government to frighten children in their schools and homes as a means of influencing their parents who might otherwise have ignored the ‘crisis’. This corruption of the human spirit was exemplified by the ugly ‘No Pressure’ video. There is also economic damage by actions leading to more expensive energy supplies, damage to the credibility of our political and scientific establishments from their supine responses to well-orchestrated propaganda campaigns by such as the IPCC, and the multinationals such as WWF who have demonstrated great skill in deploying fear for fund-raising as well as for political advantage.
The climate models are modern conceits, equivalent to the intricate epi-cycles of the ancients, convinced that the sun orbited the earth and that all would be clear just as soon as enough epi-cycles were added. Our modern modellers are convinced that CO2 drives climate, and that all will be clear when enough model runs have been made (or another chunk of hardware is paid for). My guess is that their models if left unattended, and especially if allowed freedom to go their own way without constraints such as imposed bounds on temperatures etc, would charge off into absurdity and nonsense and never make contact again with any climate results we might recognise. Of course, they are not allowed such freedom, and with care they can assist with weather forecasting provided they do not look much beyond the lifetimes of existing features such as a cyclone crossing the Atlantic. Where will it go next? How much precipitation from it in the next 24 hours, and where? Will it deepen, will secondary systems develop from it? But let us look at the model runs say 10 days into the future, and we shall see? They will be constrained not to be absurd, so that they might be describing some plausible aspects of a possible future, but they will not show forecasting skill over what I might do with an almanac and a bit of guesswork. They are not models of the climate system, they are short-term extrapolators of the weather system. But, and I continue to speculate, they have been seized upon by some who saw the big political impact of computers portrayed as oracles during the ‘Limits to Growth’ years, and recognised that the same magic in association with the Mauna Loa graph of rising CO2 would be just the ticket for furthering their political ambitions. They were right in that, dramatically right. We are left with the clearing up of the mess they have made.
Mike Jackson
Can this be the very last time that Ed Cook's email is misrepresented here?
Here's a little bit of the vital missing context:
- Cook is not talking about climate science in general
- Cook is not talking about paleoclimate in general
- Cook is talking about specifics - very high resolution proxy reconstructions of Northern Hemisphere temperatures on a millennial scale
This has nothing do with the attribution of modern warming or the estimate of climate sensitivity and pretending that it does is as serious as misrepresentation gets.
Mike Jackson
You are right. Lots of things seem to be getting moved around at the moment.
Try this for Hansen & Sato (2011):
http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
And this for Annan & Hargreaves (2006):
http://www.jamstec.go.jp/frcgc/research/d5/jdannan/GRL_sensitivity.pdf
It's the draft, but I'm pretty sure it's more or less as published.
Hi everyone,
Just a quick note, I've noticed that the 'model predictions are useless after about a week' statement keeps coming up.
There are good reasons to believe that weather forecasting and climate prediction are slightly different - the former being an initial condition problem, and the latter a boundary condition (or forcing) problem.
Of course, initial conditions will play a part in short range climate predictions! Ed Hawkins & Rowan Sutton did some really nice work in partitioning the uncertainty - check out the paper, It's open access.
http://journals.ametsoc.org/doi/abs/10.1175/2009BAMS2607.1
Cheers
Doug
Have you just convinced yourself of the difference...
For the sake if discussion, if were to have a further 5 years of stalling, or cooling ( not prove it disprove if agw either way) would it be possible to say sensitivity to co2 is on the low side?.
Similarly. If arrive ice extent increase for a few yrs, not proof either way either, might we ignore that canary.. ie currents, etc, not age..
But, politically, of course either of the above would be a disaster for the climate concerned...
Mike Hulme's climategate email that yes, CO2 is warming, but no, we don't know enough to start reducing emissions, is amazing.
http://tomnelson.blogspot.com/2012/01/wow-in-email-3423-year-2001-uea-warmist.html
Proof of the pudding? Check against the predictions/forecasts:-
"Decadal prediction" 2009
http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/decadal-prediction
"Decadal forecast" 2012
http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/long-range/decadal-fc
Both still in play, just check out the "Observational" as and when the results become available.
For anybody from the MO that might be reading, why has the latest "forecast" been complicated by moving the start date back into an irrelevant period when all this does is truncate the relevant timescale. Also why now include "Observational” GISS and NCDC when the forecast is against Hadley Centre?
It would also appear that the values for "Previous predictions starting from June 1985, 1995 and 2005" have changed between the 2 forecasts? This only by "eyeballing" the data for the charts does not appear to be available.
What fascinates me about climate science modelers is the huge disparity between their claims for their models and the extremely low standards applied to models. They claim for their models the very jewel in the crown of science, namely, successful prediction. Yet when you ask them what standards should be applied to their models you are told that the models are useful for making "projections" for maybe a week.
When you claim that your models can perform as the jewel in the crown of science you are claiming that they can perform as well confirmed physical hypotheses perform. Needless to say, the latter are not limited to making useful "projections" for a week. But ask a modeler to compare the performance of his model to that of well confirmed physical hypotheses and you will get the most dogged silence.
If models can make predictions as well confirmed physical hypotheses do then there is something else that they should be able to do. One characteristic of any new and interesting set of physical hypotheses is that they will imply some future observable phenomena that scientists would not have expected before the hypotheses were formulated. For example, Kepler's hypotheses implied that Venus has phases, as our Moon has phases, an idea that was entirely novel to astronomy at that time. Climate models should do the same. Climate models should expand the range of facts that our climate science comprehends. Climate models fail this test that well confirmed hypotheses pass with flying colors. (The standard that I describe here is central to Karl Popper's thought and to every philosopher of science after him, excepting Postmoderns.)
From the point of view of standards for evaluating science, climate models fail once again because they do not expand the range of facts about climate. Of course models cannot but fail this standard because models do not describe the world but reproduce the world. As reproductions of the world, they cannot be used for prediction.
If climate scientists are serious about having a science then they must base that science on sets of physical hypotheses that can be used for prediction and they must find some set that proves to be well confirmed. They have the beginnings in Arrhenius' hypotheses which explain how CO2 molecules can serve as something like a blanket over Earth. But these hypotheses have not actually been confirmed in Earth's atmosphere. Then they must develop well confirmed hypotheses covering the various "feedbacks" or "forcings" from clouds, moisture, and whatever. I am sad to say that climate scientists seem to have no energy or inspiration for this kind of work.
Climate models are ingenious ways of extrapolating from lines on past graphs of climate or weather to lines on future graphs of the same. They amount to an ingenious set of hunches. It should surprise no one that they have some ability for "projection" into the future. They are rather good at such projection for the same reason that trained meteorologists are usually better at guessing tomorrow's weather than the man in the street.
I recommend that all climate scientists make a New Year's Resolution to articulate the similarities and differences between their models and well confirmed physical hypotheses. Once they have articulated these matters, they will be able to articulate the standards of evaluation that are appropriate to climate models. Then they can get on with science.
From the paper linked to by Doug:
A final important point to emphasize is that the discussion of prediction uncertainty in this study is based on the variance of model predictions (“spread”) rather than the variance of prediction errors (“skill,” i.e., the difference between predictions and observations).
In other words, our predictions could be dramatically wrong while at the same time enjoying a low 'prediction uncertainty'. A hard one to sell to the practically-minded. Nevertheless, the authors give it a shot: In our view, this work should be a high priority. In the face of changing patterns of risk, quantifying the economic value of progress in climate predictions is an urgent issue for society and for scientists. Finally, our work highlights the importance of targeting climate science investments on the most promising opportunities to reduce prediction uncertainty.
As an aside, I would prefer a definition of skill which compares the model predictions to those of an easier method. e.g. one based on extrapolation of cycles or trends, or even merely 'persistence'. The man in the street can do reasonably well by declaring tomorrow will be similar to today in many weather situations. To be impressive, a weather forecaster has to do better than that at least. Same for climate forecasts.
BBD
Will you please stop yelling at me?
I am (last time I looked) a free man and not beholden to you for my opinions. I know you'd rather I didn't express them but I'm afraid you'll just have to live with it.
This is all futile until we recognise what we are doing (and that include Richard Betts).
A climate model that would match observations for the next year or decade would not only be a miracle, but a direct proof of the existence of God and the triumph of classical mechanics over unimportant things such as quantum physics.
Besides, climate models can only work on the long run, and in the long run they are all obsolete. That is, by the time a model's output can be compared to observations, the model itself will be out of date, due to better modeling and more powerful computers becoming available.
A model doesn't predict the future, it describes what the future would be looking like if nothing else happened apart from what the model expects. That's why it's called projection, and not prediction. And that is why models can only make sense if taken in bunches, providing an indication of how things could turn out...ASSUMING of course the models in the bunch are fairly independent (otherwise it's all re-runs of the same stuff). And of that, I'm fairly sure all models aren't.
So what is a "good model"? It's the one that didn't move the average in the wrong direction. Perhaps it will all start making sense only once the principles of Darwinism will be applied to climate models.
We will then run hundreds of models one day for the following decade, and one decade later forget the bad ones and spawn new models only from the good ones. After half a century or so we should finally be on the right path. But it's a perspective continuously smothered by the rush to make climate models impossibly useful.
Jan 11, 2012 at 3:09 PM | Doug McNeall
Well put Doug. Weather forecasts are very dependent on how good the observations you put into the model are. This is slightly problematic for the UK as most of the weather is off the Atlantic and lots of cloud over the Atlantic can obscure any potential observations you might have underneath the cloud, from satellites for example. (I'm not exactly sure what observations go into the Met Office forecast are). The climate projection problem is pretty much what goes on at the boundary condition at the top of the model, which is radiation in and out. Of course the actual dynamics within the GCM are going to play a a part in this radiation flux, ie cloud creation, but the critical thing in determining the 'global average temperature' in 90 years time is the net flux of radiation across the boundary, which I don't think a GCM is ever able to do accurately, with the lack of knowledge of the important features that effect it.