Bishop Hill Lewis on Shindell
Mar 10, 2014 Climate: Models Nic Lewis has a post up at Climate Audit, looking at the new paper by Gavin Schmidt's colleague Drew Shindell.
Shindell, the lone author of the paper, looks at CMIP5 models and claims to show that there are distinct differences between the climate's sensitivity to different forcings. Once these are taken into account, and once a lot of adjustments are made to them too, it is possible to show (allegedly) that low climate sensitivity to carbon dioxide is not possible.
These adjustments are not trivial, as Lewis explains:
One of those adjustments is to add +0.3 W/m² to the figures used for model aerosol forcing to bring the estimated model aerosol forcing into line with the AR5 best estimate of -0.9 W/m². He notes that the study’s main results are very sensitive to the magnitude of this adjustment. If it were removed, the estimated mean TCR would increase by 0.7°C. If it were increased by 0.15 W/m², presumably the mean TCR estimate of 1.7°C would fall to 1.35°C – in line with the Otto et al (2013) estimate. Now, so far as I know, model aerosol forcing values are generally for the change from the 1850s, or thereabouts, to ~2000, not – as is the AR5 estimate – for the change from 1750. Since the AR5 aerosol forcing best estimate for the 1850s was -0.19 W/m², the adjustment required to bring the aerosol forcing estimates for the models into line with the AR5 best estimate is ~0.49 W/m², not ~0.3 W/m². On the face of it, using that adjustment would bring Shindell’s TCR estimate down to around 1.26°C.
The analysis also relies on the CMIP5 models' representation of climate and the various forcings being realistic, and Lewis has taken a detailed look at the individual models and the multimodel mean. These do not exactly encourage confidence. The scaling factor - the amount by which you have to alter the model estimate to get a match with the observations is of the order of 70%. When you look at the individual models it's even worse:
To summarise, four out of six models/model-averages used by Shindell are included...in AR5 Figure 10.4 ... none of these show scaling factors for ‘other anthropogenic’...that are consistent with unity at a 95% confidence level. In a nutshell, these models at least do not realistically simulate the response of surface temperatures and other variables to these factors.
It's rather amusing really. Read the whole thing.
Bishop Hill
Reader Comments (37)
Where's Entropic Man? Go and read the post at CA, note especially the issues of scaling factors and non-physicality of the models and tell us why you have such blind faith in their hopeless predictions? 50% higher on average than actual temps, arbitrary scaling.
Useless. As rgbatduke points out, throw away all the ones that don't agree with reality. That looks like all of them.
And don't forget none of the models simulate absolute temps. So how do they get albedo correct, which relies on the freezing point of water to get snow cover right?
Our Bob is always gilding the lily?
Maybe we should call him Bob The Gilder :-)
This really is becoming a discussion approaching the scientific relevance of efforts to prove how many angels can stand on the head of a pin.
You can not determine what TCR reality is by interpreting the impact of changing the input parameters of models whose output does not even resemble the observed world.
I doubt it worth the time and effort to even read the nonsense written by this man ( other than for a laugh of course).
Stacey
I like that, it made me chuckle.
"Can we fix it? No, you can't!"
Thinking Scientist
Surely the models must use absolute temperatures? How else could they handle radiative transfer?
Can anyone explain what qualifications Jeremy Grantham's mouthpiece has that enable him to comment with any sort of reliability on Shindell — or for that matter anything else to do with climate?
Weird to me is that Shindwell is the sole author. Usually every man and his dog has his name on a paper.
Mar 10, 2014 at 10:43 PM | Jimmy Haigh
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He's the kite being flown by the Team ?
I cannot get CA on my android mobile. Does anyone know a fix for this?
Paul,
CA on android-type smartphones is a bit dodgy. Assuming you can see an incomplete version of the website, scroll all the way down and you should see a link something like "view complete website".
Click on that. Sometimes it takes several times and a reconnection to the URL.
Paul Matthews
Try - Go to CA site, select android Menu, (top right next to Tabs) then check "Request desktop site"
Hope it helps, if it does remember to un-check when leaving CA.
One personal observation that has made me so sceptical of this farce is that of night-time conditions. It is probably fair to say that the concentration of CO2 can be assumed to be constant throughout the lower atmosphere: a variability of 10% of 0.04% can be considered insignificant. However, the concentration of water, in vapour or suspension of liquid or solid form, does vary, to degrees that can be discerned visually. When the night-time sky is cloudless, the temperature plummets; the drier the atmosphere, the greater the fall (hence ice can form in Arabian deserts during the night); while the CO2 levels are unlikely to be vastly different from other areas, this displays that the heat-retention by CO2 is negligible. When the sky is overcast, the temperature fall is greatly reduced, indicating that water can have a tremendous heat-retaining effect in the atmosphere. The greater the levels of water, the greater the effect, so showing that water has far more effect than CO2 on heat retention (or “greenhouse effect”).
All this raises the question: why the obsession with CO2? The only conclusion I can come to is that it is a gas that it can easily be shown to be produced in large quantities by humans; in doing so, fear can be generated, and, by manipulation of that fear, greater control can be exercised over the general population. This way, greater power can be achieved by those wishing it – and almost all the present political classes are quite blatant in their quest for power.
All these “learned papers” [sic] are mere straw in the wind, piffling waste that may blind the eye with commanding statements, impressive figures and acronyms, and confusing statistics, in desperate attempts to conceal the truth.
This sort of tripe is what we mere tax payers are supposed to build (and fund) our future on?
Slightly OT, Sir Richard Branson wants denialists to "get out of the way".
I wonder if Burt. Rutan, his rocket designer, will take him up on that request?
http://rps3.com/Pages/Burt_Rutan_on_Climate_Change.htm
I have yet to be convinced that there is a good reason for assuming that this model-abstracted 'climate sensitivity' concept, transient or otherwise, can be assumed to behave as a monotonic function.
In a dynamic non-linear system with feedbacks, tipping points etc, you may not know where your starting point is with respect to either an equilibrium, or a steady state. Given that CO2 both radiates and absorbs IR it seems entirely plausible that you may be sitting on an energy landscape that looks something like this or this (picking two visual examples almost at random from other fields).
You may think you are going uphill, or down, and traversing a smooth landscape, but it could actually change abruptly at any moment. Climate sensitivity could in principle be negative if you have no idea where you are starting from.
Bob Ward promoting this paper is like Baghdad Bob promoting the great victory of the Iraqi army.
Bob,
geld his lily?
Normal practice for climate 'science' torture the data until it tells you what you want to hear .
Paul, another option is to bookmark this address:
http://climateaudit.org/?ak_action=reject_mobile.
David Stainforth?
Wasn't he, with Myles Allen, a co-founder of Climate Prediction dot com? He was there at the time of the "Laurel & Hardy" 11 degree prediction!
He is well known for his stance on CAGW and believing that the debate is over.
Great credentials.
Well if you have Bob Ward ranting you must be doing something right.
Stainforth is another person who thinks that climate model runs are experiments. The following from his website says all you need to know about him.
Is this another paper that looks like it was tailor-made in response to cries from political activists? Something along the lines of
too many people are noticing what a pile of junk the computer models are, and we're hurting real bad - we need something fresh for obfuscation work or we face a serious setback.
I daresay these would not be the exact words used, but I think the message they carry would have been there, by dog-whistle or by rambling eco-speak or by some other code.
Re 'experiments' and computer code. Statistically-designed experiments can be an excellent way of investigating complex software by imposing patterns of changes to adjustable parameters in the code, and using associated techniques to extract estimates of the effects of these parameters, and some of their interactions with each other, on one or more response variables. Climate campaigners and unscrupulous scientists may seek to use the term 'experiment' to try to benefit by association with experiments in the physical world. We have seen such speciousness used with, for example, 'climate change' presented as something their critics do not believe in, ha ha. It is shameful to deceive others in such ways, but of course when you are busy saving the planet, Schneider's Directive is there to support such dishonesty.
Has Bob Ward every done anything other than offer instant, unqualified support for any pro-agw paper? He's neither neutral or fair; he's biased and deals in propaganda, simple as that.
Cheshirered , ture but that is his job as 'paid shrill' , the amazing thing is that he is so bad at it and yet still Graham hands him buckets of cash.
Cheshirered , ture but that is his job as 'paid shrill' , the amazing thing is that he is so bad at it and yet still Graham hands him buckets of cash.
First Drew assumes climate models gives useful results then.....well after that false assumption there is no point reading any further, is there?
The troiuble here is the risk/reward ratio. Being grossly pessimistic gets you papers published immediately, awards from other politically correct pseuds, invitations aplently, promotion, grants and being lauded as a planet-saver. Being honest and realistic means you will be very lucky to be published at all, may lose your job, be uniformly disinvited regardless of your previous work and vilified as a killer of unborn children. Congrats Drew - you took the easy choice.
Radical Rodent @ 11:38 PM
Exactly the same point about desert night-time temperatures has occurred to me. If CO2 is having such a huge effect on temperatures, this ought to be readily identifiable in scenarios where the other major "greenhouse gas" - water vapour - is not present in the atmosphere to any large degree. In other words, a trend of increased night-time desert temperatures should be present with increasing atmospheric CO2, whether the rest of the planet is warming or not.
I don't know if this is in fact the case. I have searched for such data, but not being a pro in this field, I lack the necessary skills to find any.
Any takers?
To be fair to David Stainforth, he had the job of explaining the background, substance and implications of Drew Shindell's research in two sentences. Not an easy task. And what he wrote was pretty low key and a fair summary of what is said in Shindell's paper. He didn't claim to have validated Shindell's research.
I would also point out that David Stainforth is a author of the Frigg et al (2013) paper "The Myopia of Imperfect Climate Models: The Case of UKCP09" which analyses the official UK climate projections. It states that
"Given the acknowledged systematic errors in all current climate models, treating model outputs as decision relevant probabilistic forecasts can be seriously misleading."
and concludes that
"the aim of UKCP09 was to provide trustworthy forecasts now, and this, we have argued, they fail to do."
We need to start documenting the various excuses by type, focus of excuse, other excuses conflicted with, excuses that are transparently arm waving, etc.
Well if you have Bob Ward ranting you must be doing something right.
Mar 11, 2014 at 7:58 AM | CharmingQuark
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Well, yes - but when does Ward do anything other than rant?
Reposted from Lucia:
I’m curious why I have not seen the following reaction from believers in AGW to Nic Lewis’s paper: “Oh, thank God! I don’t know if this is right, but I pray that it is. It would be such incredible good luck. Mitigation was failing so badly, no one is serious, no one is doing it nearly fast enough. This would be such a gift: it would be like _several_ _successful_ Kyoto accords. Just like that, we have more time, total damage is much less severe. A wonderful reprieve.”
Why do all the accounts look like this: “Lewis’s paper just illustrates one of several possibilities, that climate sensitivity may be _slightly_ lower than we thought.” Take a look – they all add the word “slightly”, or “a little”, or “a tiny bit”. Or, “we’d have an extra _few years_.” Remember that they are describing Lewis’s value which is about a third smaller, and where very high sensitivites are almost wiped out.
Isn’t this (potentially) great news for everyone?
I don’t mean to be cynical. I imagine that they have already set their minds on severe mitigation, and therefore their only reaction is, “Enemy. Trying to stop us. Resist.” They can’t see anything else.
Of course, if some of them really like the de-industrialization that serious mitigation requires, low climate sensitivity would be a really annoying setback.
Thank you, Jack Dawkins (11:20 AM). I was beginning to feel like, if you will pardon the pun, a voice in the wilderness. I feel that this is an important issue; CO2 is perhaps only gas that humans have produced in significant quantities; why has it been selected as the “bad guy” by the global warming fraternity, particularly as the quantities humans have produced are still small fry to what nature itself has produced. The only reason that I can see for this demonising of the gas and its production is to impose severe restrictions on its production – which basically means the destruction of almost all of western industry, and its concomitant civilization. Why this goal should be so avidly pursued by those in office at present does remain a mystery; it appears that they are effectively sawing off the bough upon which they sit.
Stacey
"Bob The Gilder"
That made me smile, too :-)
However...
(Cited by Nic Lewis 11:23)
An astonishing paper.
The easiest and fastest way to read most blogs on mobile is via RSS. Use Play Newstand or Feedly.
ghl asked me:
I posed this (along with other questions on) several BH threads a while back. You can find them at:
http://www.bishop-hill.net/blog/2012/12/2/quantifying-uncertainties-in-climate-science.html?currentPage=4#comments
The questions were directly to Richard Betts (he never answered any of them). However, O. Bothe did post a lot of helpful information in this regard. One of my questions was:
To which O. Bothe responded:
With two references as follows:
http://www.geosci-model-dev.net/5/1009/2012/gmd-5-1009-2012.html
http://www.agu.org/pubs/crossref/2012/2012MS000154.shtml
One of those papers (Mauritsen et al, 2012, Tuning the Climate of a Global Model) contains the following surprising (to me, anyway) statement:
(my bold)
So the range of (arbitrary) temperatures output from models spans a temperature range 4 times larger than the trend of the 20th Century. But it doesn't mater. This is why they show anomalies. So how do you incorporate state change processes such as snow/ice and get the correct albedo?