Bishop Hill The mind-boggling coincidence hypothesis
Feb 27, 2014 Also hot off the press is a new paper by Gavin Schmidt and colleagues. Doug McNeall reckons I'm not going to like it, but having taken a look (it's open access for registered users of the Nature website), I have to say I think it's lots of fun.
Schmidt and his colleagues are looking at the hiatus in surface temperature rises and considers why the CMIP5 ensemble all got it so wrong. In their new paper they explain that the reason for this is not – as wild-eyed readers at BH might think – that the models are wonky. In fact it's all down to an incredible, incredible coincidence
Here we argue that a combination of factors, by coincidence, conspired to dampen warming trends in the real world after about 1992. CMIP5 model simulations were based on historical estimates of external influences on the climate only to 2000 or 2005, and used scenarios (Representative Concentration Pathways, or RCPs) thereafter4. Any recent improvements in these estimates or updates to the present day were not taken into account in these simulations. Specifically, the influence of volcanic eruptions, aerosols in the atmosphere and solar activity all took unexpected turns over the 2000s. The climate model simulations, effectively, were run with the assumption that conditions were broadly going to continue along established trajectories.
Apparently, if you go back and rework all the forcings, taking into account new data estimates (add half a bottle of post-hoc figures) and 'reanalyses' of old data (add a tablespoon of computer simulation) you can bridge the gap and explain away the pause.
We conclude that use of the latest information on external influences on the climate system and adjusting for internal variability associated with ENSO can almost completely reconcile the trends in global mean surface temperature in CMIP5 models and observations. Nevertheless, attributing climate trends over relatively short periods, such as 10 to 15 years, will always be problematic, and it is inherently unsatisfying to find model–data agreement only with the benefit of hindsight.
So, with the benefit of hindsight, the climate modellers can fit their square peg into a round hole. It wasn't that the models were running too hot, it was just that nature has got it in for climate modellers.
Of course, they still have the problem that the energy budget estimates of TCR are all pointing to much lower climate sensitivity than the GCMs. These studies are, of course, strongly suggestive of the "mind-boggling coincidence" hypothesis being incorrect and the original supposition - that the models are overheated - is right. However, Schmidt and his colleagues make no attempt to address such minutiae, waving them aside, with characteristic bonhomie, as mere speculation:
We see no indication, however, that transient climate response is systematically overestimated in the CMIP5 climate models as has been speculated8, or that decadal variability across the ensemble of models is systematically underestimated, although at least some individual models probably fall short in this respect.
Told you it was fun, didn't I?
Reader Comments (182)
Lord Beaverbrook
CMIP5 RCP's - projections commence in 2007, after only 3 years observations are breaching the bottom of the stated confidence level:-
CMIP5 near-term global temperature projections: updated from IPCC AR5 Fig. 11.25
Still there 3 years later. I am told this because "they only aim to simulate the multi-decadal trend, not shorter-term…" If that was the case I wonder why the chart shows a greater degree of confidence in the short term than it does in "the multi-decadal trend"? Should the short term not show a lesser degree of confidence? I wonder just how well that would be received?
We are approaching the time when the goalposts will be wider than the pitch.
If I rolled a 1 twice in a row I would suspect coincidence. Three times then I would be concerned. If i rolled it for 17 years an never threw anything above a 3 I would suspect that either it wasn't a dice or that it was loaded
Noel,
More arm waving on your part does not illuminate anything, but that is not your purpose.
The divergence between predicted outcomes and reality is now statistically significant.
That is why Gavin & gang are looking for dogs to blame for their lost homework.
It is annoying when AGW hypesters brush off 17 years while grabbing onto single storm events or a rainy season as *proof* of the CO2 crisis. If integrity was a concern for the AGW promoter/explainer, he would take trouble to reign in high level government leaders who are deceitfully claiming weather events as proof of something that is by Gavin's own admission not happening now.
But that is not very likely, is it?
"If you had a six-sided dice and you threw two 1's in a row, you wouldn't attempt to claim that the average score of a six-sided dice is 1, not 3.5."
If you had a pair of dice and you threw a thousand times and never got 1,1 you might be inclined to wonder whether the dice were good. If you had a bunch of climate models and ran them a bunch of times and none of them ever produced a series which matched the actual temperature record, you might wonder whether the models were good. Or why the worst ones were not relegated out of the ensemble.
And that is why the pause is significant. It brings into question the validity of the models. And the fact that some scientists and modellers cling to the models as they are brings their stance into question too. You can't write a paper on that. 'The models are not very good' is not appropriate substance of a paper or a comment. But you can sure say it here and see what response you get from modellers.
"The Soon / De Freitas debacle shows a perfectly proper defence of academic standards after the publication of some manifestly bad science from Soon et al which would almost certainly have been rejected if it had been properly peer reviewed."
Gotcha Noel, you've never read the Soon and Ballanius paper. As papers go it wasn't exactly a ground breaker, but simply a review of published, peer reviewed, papers that supported the existence of the MWP. The paper had four reviewers all of whom passed muster with the Editor of the journal.
On topic, this has to be some sort of sketch from MPFC, with John Cleese being interviewed by Eric Idle?
EI: "So the recent storms have been caused by climate change then Chief Scientific Officer?"
CSO JC: "Yes there is definitely a link to climate change."
EI. "Aren't other scientists saying it has been caused by the Jet Stream moving south?"
CSO JC: "That's correct they're cause by a southerly lying Jet Stream which has been caused by climate change."
EI: "But your deputy says there's no link between the Jet Stream and climate change."
CSO JC: "And he's correct but climate change is making the storms more intensive."
EI: "But aren't scientists saying that there is no evidence that the storms are more intensive, in fact the storm intensity has dropped over the last 20 years."
CSO JC: "That's correct, but we're getting more storms because of climate change, there's definitely a link."
EI: But aren't we getting less storms worldwide according to scientists."
CSO JC: "That's correct, but there's definitely a link to climate change."
EI: Is that parrot dead?
CSO JC: "No I took it back to the shop and the vendor told me it was rigid because of climate change."
EI: Thank you Chief Scientific Officer.
Bishop, it is well known that the CMIP5 models for AR5 were projections from about 2005. This means that they used historic forcings up until 2005 and estimated forcings (based upon historical averages) thereafter. If the actual forcings from 2005 differed from the estimates the models will not project correctly, even if they are perfect (yes, I know you think they are not, but that is not relevant). I have discussed this before here and elsewhere and I sure as hell didn't deduce it on my own - it is common knowledge. Were you unaware of this fact or is it something you prefer to ignore?
Given that it is a characteristic of the models (indeed perhaps of any model that has variable, unpredictable, inputs, even the economic ones you favour), why is it such an "incredible, incredible coincidence" that once the correct forcings for 2005 onwards are used the results are more accurate? Isn't this exactly what would be expected?
If for example your favourite gas price model was based upon 'normal' economic cycles and it turned out that the last ten years hadn't been 'normal' and the predicted prices were wrong, would you consider it an "incredible, incredible coincidence" that once the correct economic cycle was used the results were more accurate?
If we have to deal with the crusty old "why don't you write a peer reviewed paper" nonsense of the same vintage, then yes, we have to reference the source which documents what a scam the whole thing is.
To save time and avoid rehashing ancient ground, can we just take as read such classics as "out of context", "enquiries" and all the other excuses of the day?
In other words the models are incomplete and inaccurate
Chandra
Gavin is changing forcings pre-2005
Green Sand
The CMIP5 RCP's are simulating the expected coincidence of a positive PDO with strong positive ENSO conditions and an active solar maximum.
Dr Richard Betts is into models. He will be able to tell us if Gavin's paper has any remote grounding in science, or even reality.
Lord Beaverbrook
But, but, but, I thought the combined, never mind the individual effect of each, was considered to be so insignificant as to be deemed irrelevant?
Or am I being so last century?
Hansen wrote this a few years ago:
The deadly European heat wave of 2003, the fiery Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year can each be attributed to climate change. And once the data are gathered in a few weeks’ time, it’s likely that the same will be true for the extremely hot summer the United States is suffering through right now.
These weather events are not simply an example of what climate change could bring. They are caused by climate change. The odds that natural variability created these extremes are minuscule, vanishingly small. To count on those odds would be like quitting your job and playing the lottery every morning to pay the bills.
These all happened well past 2000. He's arguing they cannot be from natural climate variability. His buddies are now arguing that the pause is due to natural climate variability. They can't both be right. They can both be wrong.
Bishop,
> Gavin is changing forcings pre-2005
The same argument clearly applies, but if you like I'll spell it out, changes in bold:
So why is it such an "incredible, incredible coincidence"?
As they say - if you torture the data long enough it will tell you anything you want it too.
Rhoda
"Quaking in my plimsolls." Does that lead to "stamping your tiny feet" ?
Noel Darlow
You are a blast from the past, aren't you. Soon and Climategate? The important thing about Climategate is that it is all on record and publicly available. You may have noticed that the media are slowly and sporadically becoming aware that there are many views and many motives in the debate.
We already have major participants reconsidering the views that they expressed when they were young, fervent and less wise. Serious money has been made. Landscapes have been ruined. Power bills have doubled, and will double again.
We have 3/4 of a million years of ice core data showing temperature varies and causes later CO2 variation. We have CO2 still rising but temperature static for two decades.Temperature readings from the 1930's suddenly need adjustment. Deep sea temperatures never before measured are now shown to have a rising trend. The IPCC has a long documented record of mendacious behaviour. The more research we do, the greater complexity we see in the behaviour of sun, wind and water.
There are now so many dots that it is impossible not to connect some. Climategate emails are a positive feedback waiting to happen. They show the connections in all their mundane, tawdry, career enhancing, it's just business, detail. If you read them, then the various enquiries are obvious white-washes. they show the institutions and governments in a very unflattering light.
I could continue for a loooong time, but life awaits.
I don't think they've taken into account ALL the coincidences.
Global surface levels of gold (apparently a highly reflective metal) have also been rising recently: see http://en.wikipedia.org/wiki/File:World_Gold_Production.png
The cooling effect of gold must be enormous.
Surely?
It seems highly questionable to me even as an explanation of why climate models haven't got the temperature trend right over the last 15 years.
Its statement that "We see no indication, however, that transient climate response is systematically overestimated in the CMIP5 climate models as has been speculated" [a reference to the Otto et al paper, of which I am one of the authors] can only be a reflection of Schmidt putting a telescope to his blind eye, like Nelson. The energy budget analyses in Otto et al depend on changes over 100+ years, not 15 years. And repeating them using the actual AR5 forcings dataset - rather than (as Otto et al. did) using forcings diagnosed from CMIP5 models and adjusting their aerosol forcing to try to match AR5's - gives almost the same transient climate response (TCR) estimate, and a lower equilibrium climate sensitivity (ECS) estimate.
Gavin Schmidt, the modelling community and its supporters should face up to the fact that, based on the IPCC's latest estimates of aerosol forcing and heat uptake in AR5, the odds are high that the CMIP5 climate models used in AR5 are on average too sensitive both in terms of ECS and TCR - probably substantially so. Good scientists wouldn't try to deny this, although they might argue aerosol forcing is more negative than the IPCC concluded . Schmidt's co-author Shindell in fact published a paper before the AR5 cut-off date that estimated aerosol forcing as more negative than the -0.9 W/m2 best estimate in AR5. The aerosol and cloud specialists who wrote Chapter 7 of AR5 will have given careful consideration to Shindell's work when deciding on their best estimate and uncertainty range for aerosol forcing.
A perfect lull then
Alan Reed
That, Sir, is pure Magic!
It banishes the pause, the hiatus, the slowdown et al into the long forgotten past!
Lol!
The part of the paper on the influence on updated external forcings seems perfectly reasonable to me - Schmidt et al show how some forcings probably exerted a stronger cooling influence than previously thought, and they back this up with references. Seems fine.
The part on estimating how the CMIP5 simulations would have looked if they'd simulated ENSO as it occurred in reality is more challenging. This is extremely hard to do as ENSO is a complex phenomenon, but the authors make a good attempt. They do seem to recognise that there are uncertainties in this - they say their conclusions "may explain most of the discrepancy" (my italics). I don't see any reason why any of this is wrong, but the ENSO part in particular should be viewed as an estimate rather than being a definitive answer. Nevertheless, I think this paper makes some important contributions to explaining the "pause".
It's a shame (but not particularly surprising) to see the Bish and many others here resorting to cynicism rather than reasoned argument. (How many people here have actually read the paper? It's available free.) Bish, why say "explained away" instead of just "explained"? Also, you say "with the benefit of hindsight" as a criticism, but isn't offering explanations of what has happened in the past exactly what scientists are supposed to do?
PS. Alan Reed - nice one, very good!
Noel Darlow
Okay, so what was wrong with the Soon & Baliunas paper? And how serious where its shortcomings compared, say, to the MBH publications?
They claim to be able to tell us what will happen in the future. Forgive us if we find it a bit suspicious that they can only do so after it has happened. A sort of retrospective forecast, if you will.
"We see no indication, however, that transient climate response is systematically overestimated in the CMIP5 climate models as has been speculated8, or that decadal variability across the ensemble of models is systematically underestimated, although at least some individual models probably fall short in this respect."
Furthermore, we hear no indication of any of these things. LA-LA-LA-LA-LA-LA-LA!!!
So if the models have to be updated every 6 years or so (because they always 'fight the last war') we should get the 2100 projection right in about 2094.
Isn't climate science wonderful?
... and for RB; the cynicism has been truly earned.
I can't believe this is still hanging out there:
"A(nother) miracle just happened."
Andrew
At the 95% confidence level, how likely is it that all these factors will co-incidentally line up to create a pause in the warming?
Isn't it more likely that the models are simply wrong? At the 95% confidence level.
isn't offering explanations of what has happened in the past exactly what scientists are supposed to do?
=============
there are an infinite number of explanations for the past, with 1/infinity odds that any specific explanation is correct. Pretty long odds when it comes to believing someone is correct.
However, the future has an infinite number of possibilities and the change of guessing is 1/infinity. So if you do manager to predict the future the odds are pretty good that you are onto something.
So, predicting the past - useless. Predict the future - also useless unless you happen to get it right. Explaining why your prediction was wrong - worse than useless. It is excuse making.
Bullshit.
To paraphrase Tallbloke:
"If the negative coincidences of natural variations are sufficiently geo-effective in the 21st century to cancel the alleged effect of extra airborne co2 on surface temperature, how much did positive coincidences contribute to the warming of the late 20th century?"
Just tell me again, which people are in denial?
It reads as though Dennis Lee or Uri Geller were co-authors on this.
"Also, you say "with the benefit of hindsight" as a criticism, but isn't offering explanations of what has happened in the past exactly what scientists are supposed to do?"
The problem is Richard that there is a scientific community that looked at the relationship between CO2 and temperature in the late 20th century and asserted that the rise in CO2 was the cause of the rise in "most" of the 20th century rise in temperature and then went on to say that if the rise in CO2 continued then the temperature rises would continue and that untold disasters would occur. They followed up this forecasting with models that showed an almost linear response between CO2 and temperature. There was not the remotest uncertainty in these forecasts, no "ifs and buts" CO2 would cause the temperature to rise. CO2 has continued to rise for around 17 years now and there's been no rise in temperature. What should the scientists do in that case? Well there are at least two scenarios:
1. They could have re-looked at their theory that CO2 was the major driver of warming n the 20th century - they did this by increasing their certainty that it was from 90% to 95% in AP5. As far as I'm aware there is no scientific body of evidence to support this assertion because no scientific work has been done to check the theory that CO2 was the major driver of warming. To put it more succinctly, the observations don't fit the hypothesis but the hypothesis remains true without being tested. So almost as a body, but after some 10 -12 years of denying there was a pause at all the scientific community moved on to 2 below;
2. They could redouble their efforts to proving CO2 as the major driver of temperature by finding natural causes that, however tenuously, could explain the pause they had previously denied. So this is what they've done. The hypothesis remains sacred. Now Gavin Schmidt a scientist famous mainly for setting up a heavily censored web site to protect Michael Mann's hockeystick graphs, with open contempt for scientists who challenge the (daily changing) consensus position comes up with just such a paper, probably the first of many, and Richard thinks we're being cynical deciding that the paper has little worth and is not adding to the scientific knowledge.
Richard whether you like it or not the widespread perception of climate science is that there are 97% of the scientists beavering away trying to prove a hypothesis right. Each paper that comes even tenuously close to keeping the hypothesis alive is greeted as though it were the final say on the subject by the compliant 97% peers. In most other branches of science papers are published with the intention of laying out scientific research so that peers can try to replicate it and find the flaws. Not so with climate science papers, from these sources at least, are written to prove the hypothesis and get rid of awkward headlines in the MSM. Before this paper becomes remotely acceptable it should be tested and replicated by other scientists not bruited as a reasonable attempt at explaining the "pause".
If you haven't already done so you can now add me to your list of cynics on this site-:)
@Andrew 5:42 PM
As any good carpenter knows, if you want a square peg fit in a round hole, use a very big hammer
Or enlarge the hole.
Richard Betts
Your statement does come across as hypocrisy to those of us that have been telling you for years that the models were running too hot.
The fact that there have been scientific studies on the PDO, ENSO and the Sun that have been regularly welcomed and discussed by those of the non '97%' persuasion is testament to refute the coincidental cooling proposed. All of this has been ignored by 'the consensus' until after the fact and then you have the audacity to suggest that we are cynical of the scientific process.
The new clime down from CO2 is the one and only true forcing, which this paper is adding to, is very welcome but it is only the start and there is a lot more ground to cover before most of us will be happy that the 'science' is heading in the right direction.
Look to your own, especially the publicly vocal, before passing judgement on the unqualified public.
Genuine question here. I was under the impression that ENSO and like processes EMERGE from a GCM. Not so? If they do, you ought not to just go back and plug observed ENSO into the model which did not see that emergent phenomenon.
I repeat the suggestion that the Met get Bob Tisdale over to tell them how he thinks it works. He's available. Otherwise the impression that we are completely at the mercy of the oceans and we have no clue how they work will prevail.
Noel Darlow,
So is just 26 years of statistically significant warming in the period 1980's to 1990's sufficient to "prove" the entire edifice of AGW? Because that's all there is (you could maybe push it to 29 years at a pinch, with a dose of cherry picking).
I am looking forward to the time when the hiatus approaches 20 years in length. There are several high profile climate scientists who have already confirmed that no climate models produce standstills of that length.
Not long to wait...
Chandra Wrote:
"Bishop, it is well known that the CMIP5 models for AR5 were projections from about 2005. This means that they used historic forcings up until 2005 and estimated forcings (based upon historical averages) thereafter. If the actual forcings from 2005 differed from the estimates the models will not project correctly, even if they are perfect (yes, I know you think they are not, but that is not relevant)."
Exactly Chandra, if you tell the models what the weather has been like, they will tell you what the weather has been like, but not very well.
And what are these useful for?
Nial, LMFAO.
Dr. Phil Jones -CRU e-mails-7May,2009-
"Bottom line: the "no upward trend" has to continue for a total of 15 years before we get worried ".
Gavin Schmidt on Real Climate -December 2007-
Daniel Klein asks at #57:
"OK , simply to clarify what I've heard from you.
(1) If 1998 is not exceeded in all global temperature indices by 2013, you'll be worried about state of understanding.
(2) In general,any years global temperature that is on trend should be exceeded within 5 years ( when size of trend exceeds weather noise).
(3) Any ten year period or more with no increasing trend in global average temperature is reason for worry about state of understandings......
Response: (1) Yes
(2) probably , I'd need to do some checking
(3) There is no iron rule of climate that any ten year period must have a positive trend..... Right now the modelled expectation is for trends in the range of 0.2 to 0.3 degrees /decade and so that's the target."
Something is awry since 1992! Is this what he is saying?
As the late Gerry Rafferty sang:
"Clowns to the left of me, jokers to the right. Here I am, stuck in the middle with you"
AGW is like a bad smell that just won't go away. Basically a cat fart.
Thank God for peer review by the way. We can look back at these great papers in a few years and think just how far science had come.
So if Schmidt is right, where did huge amount of heat now buried in the deep ocean come from?
@ Noel Darlow
...The same error is made when people talk about the "temperature increase" as a significant climate event. Even if we hadn't detected any global warming, a period of fifteen years is far too short to say anything meaningful about climate. We know there is a large amount of year-to-year and decade-to-decade variability. The climate trend is a long-term average which by definition is not affected by short-term variability - just like the average dice score of 3.5 is not affect by a run of 1's, or 6's, etc.
Attttribution of the temperature increase is an interesting problem but not one which has any bearing on the long-term climate trend.
The only reason it is talked about at all is because it gives climatologists some ammunition to make unscientific claims, and a lot of money. Model runs frequently throw up periods of faster than average or slower than average warming although of course they can't predict the precise timing of every random climate event. The increase just isn't that interesting unless you have a job riding on the AGW theory....
There. Fixed that for you...
It is the "learned" first stage of panic. It will no doubt increase with pausing/cooling times.
I get the part where they argue they are just unlucky.
I don't get the part about how that manages to constitute the basis of a scientific article.
I may have got the wrong end of the stick here, but are they saying here that natural phenomenon have had more influence over the temperature than what they thought anthropogenic CO2 emissions would cause?
I thought the whole point of AGW was that manmade CO2 are trumping all other kinds of influences on temperature. So how come natural phenomena are suddenly allowed to be considered?
This is too much for my mushy brain to understand. But either volcanoes, the sun and rest of it have an influence or they don't, right? And can't the same be said for the oceans idea?
Having read the Nature Geoscience 'commentary', I believe Nic Lewis (Feb 27, 2014 at 11:35 PM) has hit the nail on the head. They may have reconciled their model forcings but they have not shown that the emergent behaviour supports the high values of 'sensitivity' needed to put the 'C' in CAGW, which is the crux of most sceptics' concerns.
As they make no attempt to estimate this parameter but simply state that they "...see no indication, however, that transient climate response is systematically overestimated...", I have to wonder if this is a case of simple oversight or deliberate misdirection.
Richard
There are several problems with the kind of argument Gavin Schmidt, and especially that the likes of Schmidt should be making them. The basis for climate alarm is predicated on the assumption that a reasonable understanding of the climate system has been achieved, and estimates of its behaviour to various 'forcings' have been worked out. If these were not to be, the IPCC's - almost all of warming of second half of 20th century is due to CO2 - would no longer hold.
"The climate model simulations, effectively, were run with the assumption that conditions were broadly going to continue along established trajectories."
Quite. Which is why they are mostly utterly useless.
Ah, see that's where it went wrong! In making projections about future changes in climate we didn't take into account that climate changes!:-)
I have recently been leading a discussion group with 3rd year students, exploring the history and philosophy of science.
One of the tasks I have asked my students to do is to read "Science as Falsification- Summary"
(Karl Popper, Conjectures and Refutations, London: Routledge and Keagan Paul, 1963, pp. 33-39; from Theodore Schick, ed., Readings in the Philosophy of Science, Mountain View, CA: Mayfield Publishing Company, 2000, pp. 9-13.).
Here are some quotes that I think are particualrly relevant to the whole AGW "debate"
"When should a theory be ranked as scientific?" or "Is there a criterion for the scientific character or status of a theory?"
"The problem which troubled me at the time was neither, 'When is a theory true?' nor 'When is a theory acceptable'?" my problem was different. I wished to distinguish between science and pseudo-science; knowing very well that science often errs, and that pseudoscience may happen to stumble on the truth."
"I knew, of course, the most widely accepted answer to my problem: that science is distinguished from pseudoscience—or from "metaphysics"—by its empirical method, which is essentially inductive, proceeding from observation or experiment. But this did not satisfy me. On the contrary, I often formulated my problem as one of distinguishing between a genuinely empirical method and a non-empirical or even pseudo-empirical method — that is to say, a method which, although it appeals to observation and experiment, nevertheless does not come up to scientific standards. The latter method may be exemplified by astrology, with its stupendous mass of empirical evidence based on observation — on horoscopes and on biographies."
" I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, open your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirmed instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refuse to see it. The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which "verified" the theories in question; and this point was constantly emphasize by their adherents."
"It was precisely this fact—that they always fitted, that they were always confirmed—which in the eyes of their admirers constituted the strongest argument in favor of these theories. It began to dawn on me that this apparent strength was in fact their weakness. With Einstein's theory the situation was strikingly different. Take one typical instance — Einstein's prediction, just then confirmed by the finding of Eddington's expedition. Einstein's gravitational theory had led to the result that light must be attracted by heavy bodies (such as the sun),
Now the impressive thing about this case is the risk involved in a prediction of this kind. If observation shows that the predicted effect is definitely absent, then the theory is simply refuted. The theory is incompatible with certain possible results of observation"
"It is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations.
Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory — an event which would have refuted the theory.
Every "good" scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.
Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of "corroborating evidence.")
Some genuinely testable theories, when found to be false, are still upheld by their admirers — for example by introducing ad hoc some auxiliary assumption, or by reinterpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status.
One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability."
That final sentence sums up everything that is wrong with "Climate Change"- it is a theory of "everything" Flood/Drought, Storm/Calm, Hot/Cold it is all "in keeping" with "Climate Change".
In fact a theory of "everything" that almost daily has to "introduce ad hoc some auxiliary assumption, or by reinterpreting the theory ad hoc in such a way that it escapes refutation".
Does this sound like Gavin's (and Richard's) latest contortions?
In other words it is "pseudoscience" or "climate psience".
By the way this "debate" with the students used the "Wakefield" (Measles vaccine and autism) as an example. Not AGW, although I was sorely tempted :-)