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« Orlowski on the GWPF report | Main | Sherwood's fabrication »

Myles' model mystery

The Science Media Centre has put out a response to the GWPF report here. I was struck by Myles' Allen's contribution:

Their [TCR] prediction of 1.35 degrees C is, even if correct, only 25% lower than the average of the general circulation models used in the IPCC 5th Assessment.  A 25% reduction in TCR means the warming we might have expected by 2050 might take until the early 2060s instead.  Their 5-95% range of uncertainty in TCR (kindly provided by Nic Lewis) is 0.9-2.5 degrees C, almost exactly in line with the range of the models shown in their figure (1.1-2.6 degrees C).

Compare this with what is said in the Lewis/Crok report (long version, p. 49):

CMIP5 climate model TCRs are on average 35% higher than 1.35◦C, at 1.8◦Cor so,with the TCR for particularly sensitive models substantially higher than that (the UK Met Office HadGEM2-ES model has a TCR of 2.5◦C).

So is it 25% or 35%? Here's Lewis/Crok's Figure 6 (which is based on Table 9.5 of AR5), which provides some perspective on the figures:

But this is not the only problem with Myles contribution. As is pointed out in the Lewis/Crok report (long version, p.49), the amount of warming produced by the CMIP5 models is actually much higher than you would immediately expect from their TCR figures.

Using data on simulated warming over similar periods for all the CMIP5models analysed in Forster et al. (2013),model average effective TCRs of 2.0◦C over the instrumental period, and 2.2◦C from the 2000s to the 2090s, can be estimated.

So in practical terms, the model TCRs are of the order of 50% higher (2.1/1.35=1.5) than the observational studies.


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Reader Comments (33)

Myles Allen the 11 degree kid! How he has the brass neck to make any prediction of future warming is beyond me!

"Biggest-ever climate simulation warns temperatures may rise by 11 ºC."

Oh ClimatePrediction makes a "Tiny Mistake"

Why on Earth would anyone believe Myles Allen?

Mar 6, 2014 at 4:17 PM | Unregistered CommenterCharmingQuark

"So is it 25% or 35%?"

I bet it is both: 1.35*1.35=1.8225

Think profit on cost and profit on return.

Mar 6, 2014 at 4:24 PM | Unregistered Commentergraphicconception

@ CharmingQuark

"Why on Earth would anyone believe Myles Allen?"

Because he says what they want to hear.

Mar 6, 2014 at 4:26 PM | Unregistered CommenterPeter C

So is it 25% or 35%?

The two quotes are consistent, because the first says the models (1.8) are 25% higher than the Lewis figure (1.35), whereas the second says Lewis is 35% lower than the models. The difference is 0.45, which is 25% of 1.8 and about 35% (well actually 33.3333%) of 1.35. So the percentage difference depends on where you start from - high or low.

Mar 6, 2014 at 4:28 PM | Registered CommenterRichard Betts

So, does Myles stand by his 11 degree prediction/scare-monger/will-this-wind/fantasy?

I suppose it makes a real scientist, like Richard '4 degrees' Betts, look like some kind of crazy-eyed denier. Maybe that's why Richard was chosen to come here: he was the sanest one they could find at the Met.

Mar 6, 2014 at 4:29 PM | Unregistered CommenterStuck-Record

Richard, Graphic

Ah yes - me being dim!

Still leaves us with the other issue.

Mar 6, 2014 at 4:43 PM | Registered CommenterBishop Hill

"Expert reaction" by the "Science" Media Centre (who else?). Circle the wagons chaps. Now who decides these people are experts? We all know the definition of these self-proclaimed experts with their "settled science".

Mar 6, 2014 at 4:56 PM | Registered CommenterPhillip Bratby

Lewis and Crok seem to have stirred up a lot of opposition. They are all out trying to preserve their disaster story estimate which is not far from the IPCC range. Full court press, it looks like. It works a whole lot better as a PR effort than a proper scientific response. Why would proper scientists resort to this hip-shooting nonsense. Lord knows they criticize non-scientist lay bloggers for it often enough. Lewis and Crok do not even undermine the CAGW meme, merely delay the catastrophe for a while. Why must they be so vigorously opposed? Does even this mild change uncouple the gravy train?

Mar 6, 2014 at 4:59 PM | Unregistered Commenterrhoda

At the recent hearings organised by the House of Commons, Allen seemed inordinately excited by his claims of overlap between the lower end of IPCC projections and those presented or conceded as plausible by, I think going by a not very reliable memory, people he might class as sceptics. This was, again as I further recall off the top of my head (it is, metaphorically quite a scarred one as a result of this foolish tendency) a device he seized upon as a means of saying, in effect, we broadly agree and should now move to consider policy issues as the number one priority. In my jaundiced way when viewing such as Allen at work, I thought it was more a straw he might clutch at if observations continue to weaken his case for alarm. A straw with which to build some shred of credibility for some new career direction perhaps? But now I have gone from conjecture about the past to day-dreaming about the future.

Mar 6, 2014 at 5:03 PM | Registered CommenterJohn Shade

Re rhoda's point at 4:59 PM. Think of it from their side. When you have presented yourselves as saviours of the world thanks to your insights into how the climate system works, and have stood on many a real and virtual platform to promote and profit from this glorious notion, it is not unreasonable for you to get a bit jumpy as and when your methods of reaching these insights are effectively challenged.

Mar 6, 2014 at 5:08 PM | Registered CommenterJohn Shade


Only if you believe the Lewis estimate, which as Piers Forster explains, is probably an underestimate.

Incidentally, I think it's misleading for that figure to use the term "observed" - TCR is not something you can actually observe, you can only estimate it from observations of other quantities.

Mar 6, 2014 at 5:35 PM | Registered CommenterRichard Betts

@Richard Betts Yep agree with you about 25%, 35% thing
You beat me to it
Good to see some people are statically literate

Are you ready to agree also that if the UK stopped all CO2 reduction measures for the next 50 years or until fusion power comes online, it will probably make no difference to 2100 temperatures ?
(Would you link your pension to a trend towards the RS/NAS 2.6-4.8C range on a winner takes all basis so that you get nothing if its less than 1.6 in 2050 ?)

Mar 6, 2014 at 5:38 PM | Registered Commenterstewgreen

John Shade.

I think it's the back-up plan, in case the current attempts to silence skeptical views come a cropper, or the weather/reality throws a spanner in the works and refuses to conform to the models.

Then this 'agreement' will be trotted out as, "Look, since we all think [accompanied by lots of hand-waving] it's 2 degrees-ish, let's stop arguing and just have a completely socialist society, with sensible chaps like me and my friends in charge. There, that's settled."

I think the non-lunatic Warmists, the cynical ones who've always viewed it as a means to an end, are crapping themselves at the thought of it getting colder/not getting warmer.

The zealots are still convinced we're all going to BURN, of course.

Mar 6, 2014 at 5:58 PM | Unregistered CommenterStuck-Record

A simple error is pointed out to our host - he responds: "Ah yes - me being dim!" And we move on.

This reader finds it impossible to imagine those refreshingly simple words emerging from Michael Mann's lips.

Mar 6, 2014 at 6:37 PM | Unregistered CommenterPolitical Junkie


For UK emissions, yes I agree it will make little difference in isolation. My understanding is that one of the aims of the Climate Change Act is to set an example to the rest of the world.

No, I wouldn't bet my pension on warming exceeding 1.6C by 2050, but I wouldn't bet it on it staying below that either.

The funny thing about today's GWPF report is that it indicates that the sceptics are more confident than the scientists in predicting the future!

Mar 6, 2014 at 6:48 PM | Registered CommenterRichard Betts

The sceptics ARE the scientists Richard.

Mar 6, 2014 at 6:53 PM | Unregistered CommenterHenry Galt

<I>"My understanding is that one of the aims of the Climate Change Act is to set an example to the rest of the world."

I'm sorry to be so rude, but it is terrifying that anyone closely involved in this process, at any level, is delusional enough to think that, let alone say it out loud in the company of other adults. If that's the view inside the 'bubble' then we are all truly screwed.

Mar 6, 2014 at 7:03 PM | Unregistered CommenterStuck-Record

My understanding is that one of the aims of the Climate Change Act is to set an example to the rest of the world.
You're almost certainly correct, Richard. They are setting an example of how to impoverish your children and grandchildren to no purpose, how to fall for every pseudo-scientific scare story that the eco-nuts can dream up (not that I'm suggesting you are an eco-nut, Richard), how to soak the poor in order to further enrich the rich, how to drive industry into the welcoming arms of countries with more sense.
"The rest of the world" (ex the Anglosphere and the EU and the control freaks in the UN) doesn't give a flying f*** about climate change except as another means of milking the developed world for every penny it can screw until we wake up to the fact that "setting an example" (aka "gesture politics") is seen by everyone else as some sort of pathetic joke.
And none of you knows squat about what the temperature is likely to be in 100 years time and none of you has yet produced any evidence to show that the magic 2° figure has any meaning in the real world except as one more stick to beat the sheeple with.
I'm too old to care but if I were 50 years younger I would be prepared to bet (a) that the world is likely to get cooler over the next 25 years, and (b) if I'm wrong and the temperature does rise by 2° over the next 80 the world can only be a better place — at least for those who haven't been starved or impoverished to death in order to keep climatologists in a job.

Mar 6, 2014 at 7:14 PM | Registered CommenterMike Jackson


Lewis and Crok do not even undermine the CAGW meme, merely delay the catastrophe for a while. Why must they be so vigorously opposed? Does even this mild change uncouple the gravy train?

While reading your post, I could not get Mr Spencer's recent post out of my mind...
"95% of Climate Models Agree: The Observations Must be Wrong"

Ironically, (and I didn't remember this until after looking it up to give the link here) within that article he even links to his own study that concluded "El Nino warming reduces climate sensitivity to 1.3 deg. C" (and where have we seen that number again? ...oh yeah, it is the number Lewis & Crok came up with!)

In the "97% of Climate Models..." post, he also verifies what BH said above as the second observation:

And if humans are the cause of only, say, 50% of the warming (e.g. our published paper)
- where "our published paper" is the link to his 1.3degC sensitivity post

And that is probably the reason they are throwing hissy fits over Lewis&Crok. As Spencer points out, a roughly halving of their future predictions to account for 1.3 sensitivity is actually a drastic change that takes us completely away from "Catastrophic" and puts us much closer to "Beneficial"

Mar 6, 2014 at 7:18 PM | Unregistered CommenterDS


Why the differentiation between the "scientists" and the GPWF sceptics?

Are you saying climate sceptics cannot be scientists or worse still, is not calling the GPWF people "sceptics" merely and attempt to deligitimise them?


Mar 6, 2014 at 7:20 PM | Unregistered CommenterMailman


Yes, its called 'the big frost' or glacial discrimination.

Mar 6, 2014 at 7:54 PM | Registered CommenterPharos

It looks to me that, like most sceptics here, the GWPF academic advisory committee is full of good scientists, and many of them are very eminent. Is there a climate scientist of the stature of Freeman Dyson? Lindzen commented something to the effect that climate scientists were mostly second-rate. Good scientists would go into a much more exciting field (even if not so well-rewarded with accolades).

Mar 6, 2014 at 8:01 PM | Registered CommenterPhillip Bratby

Mike Jackson @7:14 PM.

Couldn't agree more. Says it all in just three short paragraphs.

Mar 6, 2014 at 8:16 PM | Unregistered CommenterDavid Porter

"No, I wouldn't bet my pension on warming exceeding 1.6C by 2050, but I wouldn't bet it on it staying below that either."

Then of what value is the number 1.6 to you if you can't see any reason to bet either side of it? Entertainment purposes only?


Mar 6, 2014 at 9:19 PM | Unregistered CommenterBad Andrew

Funny how our politicos are happy to "set an example to the world" wrt climate change, but not wrt nuclear weapons.

Mar 6, 2014 at 10:06 PM | Unregistered CommenterAdam Gallon

I'd bet my four pensions that it won't get that warm by 2050. From today's level, not some moving-goalpost base level. 1.6 deg C of which we've seen HOW much already? And the damage so far is? The moved boundaries on the koppen-geiger map so far are? The climate of Oxfordshire is still stubbornly like the climate of Oxfordshire.

Mar 6, 2014 at 10:23 PM | Unregistered Commenterrhoda

Change in a quantity can also be expressed logarithmically using the unit of logarithmic change: the neper (Np). Normalization with a factor of 100, as done for percent, yields the derived unit centineper (cNp) which aligns with the definition for percentage change for very small changes.

The neper (unit symbol Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. (...) Like the decibel, the neper is a unit in a logarithmic scale. While the bel uses the decadic (base-10) logarithm to compute ratios, the neper uses the natural logarithm.

This is a nicely symmetric difference measure. For the TCR difference we would have:

ln(1.8/1.35) Np ≈  0.29 Np =  29 cNp, or
ln(1.35/1.8) Np ≈ -0.29 Np = -29 cNp   as opposed to 25% and 35%.

Mar 6, 2014 at 10:34 PM | Unregistered CommenterAndré van Delft

Any comment on the Forster post?

Mar 6, 2014 at 10:41 PM | Unregistered Commenteranonym

Richard Betts (6:48 PM): "My understanding is that one of the aims of the Climate Change Act is to set an example to the rest of the world. "

Richard Tol wrote, "The UK could be a leader in international climate policy if it would demonstrate that greenhouse gas emissions can be cut substantially without causing economic pain. Current UK climate policy shows the opposite: Climate policy can cause real hardship without making a dent in emissions."

Mar 7, 2014 at 6:17 AM | Registered CommenterHaroldW

Methinks Myles arithmetic is better than yours.

25% lower than 100 is 75. However, 100 is 33% higher than 75, close enough to 35% not to question the difference.

The rest of the more recent statement is more to the point because Myles puts into a larger perspective the results of the models.

0.9-2.5 degrees C range implies 1.7 as a mean, median or mode is a lot less that the catastrophists cite when they hope to frighten us.

Mar 7, 2014 at 9:30 AM | Unregistered CommenterFred Colbourne

This whole report thang makes me feel pretty glum. Reading more posts has left me feeling even glummer about it.
Richard is correct: Even those branded as deniers are now calculating the future to within hundreths of a degree with certainty. The other irony is, is that the report is actually a tacit acceptance of models-for-emissions-scenarios and accordingly an endorsement of mitigation as the primary policy response. A disaster. An own goal.
I think this report will go down as a turning point in the debate about mitigation versus adaptation between sceptics and warmists. Unfortunately, it looks as if it will be lukewarmery that will prove to be the porus argument that let in the tsunami of intervention. You don't need feedback loops, natural GHG will drive the wagon.
Now I'll make my own prediction: Paris 2015 passes a legally binding extension to Kyoto for every significant country on the planet. Milliband - the Uk prime minister - issues his directive for carbon credit cards to be issued to all uk residents by 2018 and ushers in the new technocracy... Enough glummery!

Mar 7, 2014 at 9:33 AM | Unregistered CommenterJustin Ert

In the spirit of making up ones own statistical methods, I grabbed an espresso and started thinking. I believe there is no chance the change in global temps over the next 100 years will be outside the range -10C to +10C, with only a minuscule chance of it not being observed in that range. I'm not too certain about anything really, no fancy models just my gut feeling. Unfortunately there may be someone out there who does not understand what this credible interval means, maybe it is idiocy or convenience that they might choose +10C as the worst likely possibility if we don't change our ways, and discuss this value over all other ones. Good work Dave, great insight into the mind that requires alarm.

Mar 8, 2014 at 9:24 AM | Unregistered CommenterDavid Shaw

But at what point do we get to the 2.5K that marks the end of beneficial warming. I calculate a hell of a lot longer than 2060.

Mar 10, 2014 at 10:20 AM | Unregistered CommenterJamesG

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