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Quantifying Uncertainties in Climate Science

Another date for your diaries - the Royal Met Soc's meeting on uncertainty in climate science.

Climate models produce different projections of future climate change under identical pathways of future greenhouse gases. This meeting will highlight recent studies that have attempted to quantify those uncertainties using different approaches.

Time No. Presenting author Title
Prof Reto Knutti, (ETH Zürich) Projection uncertainties: The multi model perspective.
Dr Paul Williams, University of Reading. Climate models: The importance of being stochastic.
Dr Jonty Rougier, University of Bristol Background and philosophy
Dr David Sexton, UK Met Office UK climate projections.
Dr Tamsin Edwards, University of Bristol Palaeo-constraints on climate sensitivity.
Dr Lindsay Lee, University of Leeds Constraining aerosol models.

Details here.

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Reader Comments (224)


Comparing Richard Betts and Tamsin Edwards with Mark Serreze and Al Gore seems a little harsh. Only two of them are on the make, so far as I can see, and the other two engage on here, despite the insults.

Dec 3, 2012 at 12:58 PM | Registered Commenterjamesp

There is another public Royal Met Soc meeting a few days later on Dec 17th, on "The Mathematics of Extreme Climatic Events". This might be of interest to those in the Cambridge area, like Don :)

It says it is suitable for ages 14+, despite the fact that it involves a wine reception.

Dec 3, 2012 at 1:04 PM | Registered CommenterPaul Matthews

Dec 3, 2012 at 12:57 PM | Don Keiller

Don, that really is just venting though, rather than something that might stimulate any rational debate. I think it is good if the discussion remains a bit more 'scientific' in nature.

Dec 3, 2012 at 1:22 PM | Unregistered CommenterRob Burton

BH pub meet? I'd like to invite myself along (though if it's that evening I can't make it)....

Thanks to all that stuck up for me here. But if I need to "prove" myself to others...

I (and my colleagues) consider myself a mainstream climate scientist: e.g. see Richard Betts' statements about AGW and impacts. But I do try to point out misrepresentations in the media when I can, and I believe I'm more vocal about this than most others at my (relatively early) career stage. In other words, I do try to stick my head above the parapet relative to both "sides".

a) Richard Tol will vouch that I spoke up in this Planet Under Pressure conference session of scientists and media (chair: David Shukman, BBC) about the validity of high end, "semi-empirical" estimates of sea level:

I was shaking with adrenalin afterwards. I'm relatively new to glaciology (previous post-doc was in palaeoclimate) so it wouldn't normally be seen as "my place" to criticise experts...

And Barry can vouch that I emailed a comment about the same thing to Katharine Hayhoe, because of this slide on her webpage (though she didn't change it):

(I also emailed that the "1bn dependent on glacier water" estimate had been revised downward)

b) I can't remember if I played a very active role in the Times Atlas errors, but I did tweet about it and (I think) pointed out at Bishop Hill that the glaciology community were being very proactive in addressing them.

c) Fairly recently I corrected Marcus Brigstocke on the record Greenland melt story:

d) Bish can vouch that when I came to the Met Office, I joined Jonty in criticising palaeoclimate reconstruction uncertainty estimates (because of my experiences in the SUPRAnet research network), and recommended to the Met Office scientists they read The Hockey Stick Illusion because it contained valid criticisms of the statistics.

e) I've agreed with Paul Matthews that using ever-shortening trend lines (past 30 years, past 20, 10) for the IPCC AR4 global mean temperature graph is a misleading comparison.

f) I've just agreed to contribute to (about climate sensitivity), which is a site that tries to promote civil conversations between people of different views on various topics of climate science - to clarify why they disagree.

g) I called my blog All Models Are Wrong, and my main aim there is to talk about climate model uncertainties!

Is that clear enough that I am not biased/activist/money-grabbing? And if you're still not convinced, I'll buy you a pint and try and convince you in person!

I dunno, I stick my neck on the line for you guys and whaddoIget? Well, more content for my slide about online insults anyway ;)

Thanks again to those that stuck up for me.

Dec 3, 2012 at 1:29 PM | Unregistered CommenterTamsin Edwards

Note that I counted you one of us in the first comment on this thread Tamsin. I'm sorry others can't help themselves. Foolish and counterproductive, as the Bish has said.

Dec 3, 2012 at 1:34 PM | Registered CommenterRichard Drake

Sorry, Tamsin, I have had a bad week or so. I apologise.

However given my previous treament at the hands of climate "scientists".
(Professor Phil Jones tried to get me "silenced", before saner minds prevailed),
perhaps you can understand my frustrations?

Dec 3, 2012 at 2:00 PM | Unregistered CommenterDon Keiller

I did Richard! Very happy to see that the majority of people here trust me (even if they don't agree with me). It's good to have met a few of you in person now too.

Don, I don't abuse, denigrate, marginalise or ridicule anyone - and I don't think it helps to add to that pile. I'd also rather not be called perverse or anti-human, or have my scientific output described as "faith", thanks. If you have a specific criticism of some science I've written or presented, let me know.

I think we're all coming to a much better understanding of each other's concerns by appreciating that there *is* a spectrum of views among both "dissenters" and scientists, and that all of us can learn or thing or two from each other (from spotting mistakes, to reading more widely, to improving our critical thinking and explanations).

Far better that than treating this as a game of Us vs Them, of polar opposites that can never agree on anything or even be civil to each other. Surely we left that behind in the playground? I agree many people out there do take this approach... but there's no need to sink to their level.

Anyone that has talked to me about the subject of climate scepticism/dissent knows that I defend you, often. I might not agree with everything you all say, but there are many valid criticisms, concerns and viewpoints that (most of you know) I take seriously in considering, or listening to, or acting on.

Dec 3, 2012 at 2:00 PM | Unregistered CommenterTamsin Edwards

Thanks for the apology Don. I'm not having the greatest year myself.

I do understand your frustrations. But please do keep an open mind - climate scientists, like climate sceptics, are not a homogenous group. There is an obvious difference between the debates being had in the US and UK. And Richard Betts has also wondered if there is an old guard / new guard split...

Dec 3, 2012 at 2:06 PM | Unregistered CommenterTamsin Edwards

Tasmin, I do remember several of your comments here that addressed issues well, not one sided. Though, I don't know that a grant grabbing approach is so bad, otherwise, we might not get a chance to read your comments and have benefit of your knowledge. ;) So, perhaps you will appreciate that I hope you grab more grants.

Knuttti writes quite well and fairly. I imagine that with Knutti/Tasmin and the stats people, it should be quite an informative meeting. Perhaps those predisposed should go or read before making negative comments.

Dec 3, 2012 at 2:17 PM | Unregistered CommenterJohn F. Pittman

I don't have the background or experiences of many commenters on climate science issues, but I always think that civility when talking with/about any 'reasonable' and 'civil' climate scientists like Tamsin Edwards and Richard Betts is very important. Their commitment to a wider range of dialogues than the agitators would allow is exemplary. Rather than view their public engagements as "too little, too late" for climate science, I see them as more thoughtful, careful, and open minded than many in climate related fields. They cannot be responsible for every word and deed from anyone in their field, but they do engage with a wider public far better than most of their colleagues. If Tamsin or Richard were only mindful of career and grants they would not even be talking to us!

Dec 3, 2012 at 2:43 PM | Registered CommenterSkiphil

Tamsin, I appreciate your comments.
However the traffic on climate change has essentially been one way for 20 years now and those who had the temerity to question have been crushed. Many have lost their jobs. I myself have had climate "scientists" discuss how to "silence" me and "make it difficult" for me at my place of work, simply because I asked questions of them.

You say that climate scientists are not "homogenous". Unfortunately with very few exceptions- you may be one of them, that has not been my experience.

Dec 3, 2012 at 2:49 PM | Unregistered CommenterDon Keiller

Tamsin Edwards indeed spoke about the pitfalls of semi-empirical estimates of sea level rise at said conference.

Dec 3, 2012 at 2:55 PM | Unregistered CommenterRichard Tol


Even so, there's no need to start the cycle again with (innocent!) new scientists. Visiting the sins of the father, etc. Better to give people the benefit of the doubt, to assume they have good intentions until they indicate otherwise.

Calling a post-doc names could be seen as a mild form of making things difficult for me in my own work. The internet lasts a long time. I'm not trying to say it's of the same magnitude as discussions of being silenced, of course. But as people have said already, I have no reason to be here, no career gain to be made. In fact in many ways it could be seen as detrimental to my work - time better spent on publications, on writing (ahem) grant proposals, on having a decent work-life balance... I happen to see it as fruitful, not only because I think people have a right to accurate information about science on which policies are made, but also because of the other reasons I mentioned above (it's useful to me too).

Dec 3, 2012 at 3:19 PM | Unregistered CommenterTamsin Edwards

It seems like the same ones that went to the Royal Society meeting.

I would go, but having spent much of the last year not working, I've decided that I can't fund further trips like this out of my own pocket.

And I'll say this seriously. If the government want to engage with sceptics they are going to have to pay sceptics to engage - like they do for all the green NGOs.

Good policy comes from engaging with all the relevant parties and sometimes that costs money and if the government are not prepared to fork out the money, they are not going to get good advice.

Dec 3, 2012 at 3:34 PM | Registered CommenterMikeHaseler

Leave by train 8.30am, arrive back 12pm cost of the ticket about £120.
800 miles round trip by car at least £160 (And there was no one else from a Scottish institution last time so no hope of a lift)
Is there a webcast?

Strange how the only climate meetings I've ever seen webcast are sceptical? Perhaps this shouts louder about the real motivation for their meetings?

Dec 3, 2012 at 3:45 PM | Registered CommenterMikeHaseler

I find getting Tamsin two cups of tea works really well, and also makes Adam Corner speaking about Lewandowsky much less annoying.

Bish, you have my email, you know my face, let me know if you'd like me to buy you both a pint on the hypothetical pub evening.

Dec 3, 2012 at 3:48 PM | Unregistered CommenterRoddy Campbell

Well I'm glad that's all cleared up then :-)

Best wishes Prof Edwards professionally and personally, wish I could make both the drinks and the talk, though most of it would probably be over my head. Best wishes to all over Christmas.

Dec 3, 2012 at 4:01 PM | Unregistered CommenterSwiss Bob

Tamsin, Richard, many thanks for contributing.

I find the “uncertainty” a total blind. To me it is meaningless until it becomes quantifiable. The number of variables in climate science must be mind boggling and each and they will each have an inherent degree of “uncertainty”, let alone the interactions that can result in further degrees of “uncertainty”.

How you handle this is well beyond my comprehension, but looking at how an “ensemble mean prediction” is performing against actual observational data is not.

Whilst I am utterly convinced that “we” are improving our awareness, but is that resulting in improved skill?

I have asked Richard on quite a few occasions why the MO does not publish updates of their “DePreSys Decadal Forecasts” simple straightforward ensemble mean prediction against actual? There is an annual prediction made starting in 2005, short term I know but are we getting better with our predictions? Would expect any forecast to be more accurate at the beginning than at its conclusion.

I understand the position that Richard is in and frankly I do not really expect him to go championing my cause with his employer.

Tamsin, Richard, the above is very simplistic; however I belong to the simple masses who are paying for the reactions our politicians are having to your science. “Uncertainty” doesn’t mean anything to me, or our politicians they are certain enough, so please with respect somebody at least show me that “our” forecasting skills are improving.

PS I concur with many more, it should be possible to express disappointment about a situation without causing offence.

Also Tamsin or Paul, if you get time could you please expand on:-

“e) I've agreed with Paul Matthews that using ever-shortening trend lines (past 30 years, past 20, 10) for the IPCC AR4 global mean temperature graph is a misleading comparison.”

All trends are relative and intereactive

Dec 3, 2012 at 4:04 PM | Registered CommenterGreen Sand

OK, Tamsin. Ceasefire.

Dec 3, 2012 at 4:21 PM | Unregistered CommenterDon Keiller

Good idea, Don. Both of you have better things to do with your time, I feel sure.

Dec 3, 2012 at 4:33 PM | Unregistered CommenterJohn Shade

Dec 3, 2012 at 10:08 AM | Don Keiller

until the likes of Richard Betts and Tamsin Edwards speak out against the wilder flights of fancy and doom-mongering delivered daily by the Beeb and The "Guardian", why should I not "tar them with the same brush" as the charlatans at CRU that I had a 3-year legal battle with?

Hi Don,

Do you mean like:
this when I challenged the BBC, or
this when I challenged the Guardian, or
this when I expressed my disappointment with the Times Atlas, or
this when I called out a stupid article on ThinkProgress? :-)

You talk about people trying to "silence" you - well, I've asked you several times if you would consider being an Expert Reviewer for the IPCC 5th Assessment Report, particularly my chapter on terrestrial ecosystems. I genuinely do want to hear your views on what my co-authors and I are writing, at a time when it can be useful in getting the chapter right as opposed to when it's too late to make a difference. At one point you agreed, but then sadly you changed your mind. Please reconsider - we are writing the Second Order Draft now (which I why I am not blogging much at the moment), and it will be out for review in March. This is your chance to make your views known, and for them to go on official public record along with our responses.

[Update: just saw your "ceasefire" comment after I posted this. This is not intended to inflame a new argument, just to point out that I do believe I am doing the things you suggest in (a) challenging outlandish statements and (b) encouraging openness and constructive dialogue. No need to respond - but I do hope you will feel able to consider reviewing the next draft of my IPCC chapter :-) ]


Dec 3, 2012 at 4:49 PM | Registered CommenterRichard Betts

This figure I think has something interesting to say regarding uncertainly in climate science. It shows changes in mass balance for various polar regions, from the recent Shepherd paper, and each of the 3 or 4 methods used has a nice error region shown either side of the central figure.

Since in most cases there is little if any overlap between the methods, isn't it abso-bloody-lutely OBVIOUS that the error bars are WRONG? So why was it published, and why is it taken seriously by climate scientists?

Dec 3, 2012 at 5:55 PM | Registered Commentersteve ta

"In the most likely scenarios, the Met Office climate change predictions for the Government forecast temperatures in the UK to increase from the 1961 to 1990 average of 10 to 17C in the summer to 15 to 22C by 2080."

Really? A 5C increase is the "most likely scenario" by 2080? This was apparently Richard Betts' "correction" to the BBC that he has linked to above.

Dec 3, 2012 at 6:02 PM | Registered Commentersteve ta


Careful with your source there - you're quoting the Telegraph, not me. We don't say that's the "most likely" scenario, it's the highest of three emissions scenario, and we don't make any judgements on which is more likely. Louise has got mixed up I think :-)

Dec 3, 2012 at 6:11 PM | Registered CommenterRichard Betts

I am glad that Don has apologised to Tamsin, there is always the danger of any scientist commenting, has the percieved sins of the whole filed heaped upon tnem. This happened to Judith Curry initially.

And Tamsin and to some extant Ricahrd are NOt in leadership roles.

Don criticism might sit better directed at various cheif scientists and presidents of various societies, that get to speak publically (ie newpapers, mainstream media and television) and privately to politicians which Tamsin does not, nor does Richard

Howver I also agree with Don about the 20 years, if i was an acdemic like Don, i would be very concerned to be in desmog blog deniers database, labelled a disinformer, denier, misinformer and in the pay of the denial machine. That is shameful. And it is up to the leadership of science to protct science from that sort of polticised behaviour. And the silence of the leadership is damming

And Don experience with his legal battles with cru, is damming of the science establishment, which is not attacking 'science', but sadly few amongst the science leadership see the difference.

Richard and Tamsin backed me up with Peter Gleick, and when i pointed out to Katie Hayhoe that 300 k climate deaths claims (GHF) was not rigorous science. Katie changed it after Ricahrd joined in.

Tamsin was even brave enough to tackle Marc Morano on one occasion, and Marc was of course polite back(one or two other were not)

BUT and it is a big BUT, who challenges Greenpeace, 10,10 and al those other eco groups that use that false claim. Who challenges the Guardian John Vidal when he promotes the GHF report, or the dozen other articles in the Guardian saying action needed because of 300k climate change deaths. I have had a tonne of abuse fron eco groups, grenpeace,foe, etc for trying to point out things like that. I'm just a member of the public, with sod al time and money. I shouldn't have to

Dec 3, 2012 at 6:49 PM | Unregistered CommenterBarry Woods

Dec 3, 2012 at 6:11 PM | Richard Betts
"Careful with your source there - you're quoting the Telegraph, not me. We don't say that's the "most likely" scenario"

Not quite 5 degrees but a different source

Dec 3, 2012 at 6:56 PM | Unregistered CommenterRob Burton

Steveta: your graphs showing non-overlapping error bounds for different methods shows up one of the difficulties of estimating uncertainty. A comment was made further up the thread about "quantifying uncertainty". Whilst a laudable objective it is nigh on impossible, as it requires knowledge of the true answer which is only known after the fact (post hoc).

As some of you may have gleaned, I work in uncertainty of very large models (not climate) and I work with attempting to make uncertainty estimates using stochastic methods (including spatially dependent methods). I was at a major conference last week and this week I am running a training course on the topic for around 18 industry attendees.

I particularly noted Tamsim's comment earlier : "All models are wrong", but we should add the remainder of this quotation which is "...but some are useful".

Models help us to understand physical processes. With regard to uncertainty though, most uncertainty models look at the residual around the model proposed, not the uncertainty associated with the model itself being wrong, which is very difficult to do. This, to some extent, explains Steveta's observation concerning the non-overlapping error bars using different predictions. The uncertainty is unique to the model, not to the family of possible models. This is a particular interest of mine. One of the fundamental issues is the stationarity assumption of the model. An assumption of stationarity (or non-stationarity) forces the model in a certain direction, and any uncertainty is then essentially the uncertainty around that non-stationary model: it is not a measure of the validity of the model. The problem with stationary or non-stationary (read "trends") is that the predcition accuracy then depends heavily on the reliability of the assumed trend behaviour and no amount of uncertainty modelling will then bracket the true answer if the assumed trend model is wrong.

This meeting on 12 December sounds interesting. I think I am in London that day, but I am not sure I can make it. I would particularly be interested in the paper by Paul Williams on stochastic modelling. Its a shame there is currently no abstract for it.

Dec 3, 2012 at 7:00 PM | Unregistered CommenterThinkingScientist

Barry [typos corrected]:

I am glad that Don has apologised to Tamsin, there is always the danger of any scientist commenting has the perceived sins of the whole field heaped upon them. This happened to Judith Curry initially.

Key point. Without that kind of self-control (and common sense) we risk snuffing out all internal dissent and going back to fruitless polarisation. Any dissent from real scientists using their real names is always going to be a shade more low-key (to put it mildly) than the latest BH nym who has read a few web pages and has nothing to lose in offering the most extreme interpretations and encouraging others to do the same.

There's a happy medium somewhere around here, I feel sure. :)

Dec 3, 2012 at 7:04 PM | Registered CommenterRichard Drake


one of the (many) problems for climate science is the way it has been infiltrated by activists from Greenpeace and the other enemies of democracy.

Richard and Tamsin you, and the climate establishment, need to distance yourselves from these people starting with the IPCC process. It is entirely wrong for NGO's to have any involvement in the IPCC.

Richard this is the point you made on the Think Progress site linked to above - association with unelected activists undermines the science and contrary to your belief the science needs all the support it can get.

PS the output of computers is not science. I hope we are all agreed on that?

Dec 3, 2012 at 7:06 PM | Unregistered CommenterDolphinhead

But Dolphinhead, Richard and Tamsin, despite their legendary strength, cannot single-handedly eject every activist 'from Greenpeace and the other enemies of democracy' from climate science and politics worldwide.

One of the great ironies of the little world of Bishop Hill is that mostly we rage against a massive foe that wouldn't dream of arriving here in person to answer for its crimes. So if someone has the cojones to turn up, which in itself shows how different they are from the norm, we take all of our frustration out on them. It's not the only screwy thing about the culture here but it's in the top five.

But I still am fond of BH and of Betts and Edwards. But then I'm widely known to be a little unhinged :)

Dec 3, 2012 at 7:14 PM | Registered CommenterRichard Drake

I am on Richards and Tamsins side, always have been, i susoect that they may not see this yet.

The backlash against all science when it comes, concerns me. The politicians and media will dump all over science. Jonathan has made similar noises and others.

I've spent three years being nice and patient, two things i am very bad at.
I wil treat people as i expect to be treated. But activists like Lewandowsky, George Marshall, Corner and Pidgeon, activist press like the bbc, monbiot and hickman, i think desrve the full delingpole(contempt and riicule) ie I agree with Don. All those mug, acticvist non science people with massive mecia privledges and the ear if the establishment need a wake up call.

Leo outing Ben, purely personal, Adam outing my real name in the Guardian comments,Adam popping off to Australia to attack sceptics and tories in print, calling Delingpole 'far right' just shows utter activist with the protection of an academic under attack from nasty sceptics, when he feels like it, these people however well intentioned and sincere they are about 'saving the planet', they I think are partly responsibly for the poltical, polarised climate that prevents rational debate about anything climate related, especially energy policy, which is ruinous

Or the delusions of saving the planet from 300k climate deaths, when 22,000 children die every day from poverty, and cagw has totally distracted away ftomtakling that, which perversly, if tackled would prevent the mythical future climate deaths as well. Weather kills the poor.

No doubt lots of typos, resorting to smartphone, all computers have children attached :-)

I have little patience left with the climate elite, political establishment, the beddingtons, Nurses, media etc

Dec 3, 2012 at 7:33 PM | Unregistered CommenterBarry Woods

Barry [typo-reduced]:

Or the delusions of saving the planet from 300k climate deaths, when 22,000 children die every day from poverty, and cagw has totally distracted away from tackling that, which, perversely, if tackled, would prevent the mythical future climate deaths as well. Weather kills the poor.

No doubt lots of typos, resorting to smartphone, all computers have children attached :-)

I have little patience left with the climate elite, political establishment, the Beddingtons, Nurses, media etc

Awesome. All kids attached to your phone should know what a privilege it is. :)

I'd only add "Weather and poverty kills the poor - and so-called mitigation increases poverty." It's obviously what you meant. Nobody anywhere is claiming that any carbon control is going to eliminate bad weather - and the fact there's no correlation between extreme events and warmer temperatures means we have no idea if these policies will even reduce it. But they will certainly make the poor poorer than they would otherwise have been. We're back to Erhlich in the 1960s and managing the population by making sure the poorest perish.

This rightly infuriates. But it remains vital we do not take out that frustration on the few scientists that turn up here, as if they were Erhlich himself. They're many steps better than that, just from what we've seen them write.

It's amazing how important courtesy remains despite the vastness of the problems we seek to grapple with. Or perhaps because of them. It reminds us of the importance and value of every human being, as our host continues to exemplify.

Dec 3, 2012 at 8:05 PM | Registered CommenterRichard Drake

Is it possible to not have a 'nym discussion' everywhere?

Dec 3, 2012 at 8:20 PM | Registered Commentershub

For one Ehrlich, there are a hundred baby Ehrlichs.

If I read the output of environmental journalists and activists, it would seem that to be a scientist in the environmental sciences, hatred of human beings is du jour

Dec 3, 2012 at 8:22 PM | Registered Commentershub

Dear ThinkingScientist,

I do hope you can come, so I can thank you in person. It was your thoughtful comment (Sep 13, 2011 at 6:20 PM) that inspired me to start a blog, to give myself a space to answer the questions you raised. I haven't crossed paths with you since, so I haven't been able to let you know.

Thank you,


Dec 3, 2012 at 8:26 PM | Unregistered CommenterTamsin Edwards

And Richard Drake, I'd quite like to give you a hug.

Dec 3, 2012 at 8:27 PM | Unregistered CommenterTamsin Edwards

Where am i taking anything out on the scientists here?

Noone, as tamsin has pointed out (rightly, ages ago) amongst he majority of working scientists, know we exist, nor cares.
My wife keeps asking me, for example, which side is Delingpole on again, or Mcintyre, or something similar, the public don't know we exist either.

Courtesy is what I try, but it doesn't get you anywhere meaningful, the establishment, media science institutions just treat anybodyy sceptical with contempt. Look at Newbery, Montford submission to Steve Jones BBC or to Levenson, or Don's treatment by CRU.

Politically, i have to say it, Morano or Delingpole, North, etc are probably right in to challenge the horrors of intolerrant environmentalism and an activist establishment, by confrontation. Though i have little energy or time for it, from now on

Dec 3, 2012 at 8:35 PM | Unregistered CommenterBarry Woods

Oceans of notions...

- The notion that if different models could be made to agree, the uncertainty in their predictions would be eliminated.

- The notion that, if models reproduce past climate variations, this validates their ability to predict future climate variations.

- The notion that the non-increase of global average temperature over the past ten or twelve years temperature was in fact predicted by the models, as it lies in the expected range of variation of their predictions.

- The notion that feedback effects betwen CO2 concentration and resultant warming are well enough understood for the results of models including these effects to be useful.


- The notion that economic models driven by the outputs of climate models produces something meaningful.

Dec 3, 2012 at 8:45 PM | Registered CommenterMartin A

I agree with most of what you said above. Except for one thing. The establishment may look upon sceptics with contempt. But that is because they are ignorant of the power of ideas. That is what sceptics, or scientists, represent.

I never used to bother much with Lewandowsky. The Australian government apparently is in his thrall. It was owing precisely to work by you, geoffchambers and others in this blog that attention was finally turned on his output, at least in these quarters, to reveal the kind of utter garbage it constituted.

Imagine if the Austrialian government listens to him, and continues to listen to him and others like him. What do you think the outcome would be? You can see it coming a mile. The others can't. I can, thanks to you. That is a difference right there.

Dec 3, 2012 at 8:46 PM | Registered Commentershub

Hi Tamsin, That's very flattering and I am glad you found my comments constructive. I am still waiting for replies to those questions I posed though...:-).

I have some interesting insights from those questions in my own discipline, where reservoir engineers fit the "hindcast" by what is known as history matching. The thoughts and comments from presenters at the conference I attended last week have direct relevence for climate models. Too long and technical probably to discuss here though.

Dec 3, 2012 at 9:20 PM | Unregistered CommenterThinkingScientist

You're right, no answers yet - chase me up on that :)

I thought you were in reservoir modelling. My colleague Jonty used to do a bit of that, or is certainly familiar with it. Think I meant to read a paper about emulation of reservoir models recently - probably something to do with Jonty's colleague Michael Goldstein. If I wasn't supposed to be doing something else right now I'd look it up for you... but again, do chase me if you're interested.

Dec 3, 2012 at 9:38 PM | Unregistered CommenterTamsin Edwards

Hi Tamsin,

I am a geophysicist with a second expertise in geostatistics. I help facilitate the building of the large scale (multi-million cell) 3D static geocellular reservoir models. These contain geophysical and geological measurements and stochastic representations of geology. They form the static model uncertainty. The static model is then initialised and used for dynamic fluid flow simulation by reservoir engineers. The reservoir engineers are essentially my end users and I work a lot with them.

Although I don't live there now, Bristol is my home town. I also teach a little once a year at IC to post graduates.

Dec 3, 2012 at 9:55 PM | Unregistered CommenterThinkingScientist

Geckko quoted:
"The effect of global aerosols on clouds is one of the largest uncertainties in the radiative forcing on the climate1."

In fact, uncertainty as to the magnitude of the indirect effect of sulphate aerosols on clouds seems to have been much diminished by recent observational satellite-based studies. The conclusion is that such cooling is much smaller than had generally been thought, and that which is built into typical climate model simulations.Total negative effective aerosol forcing looks to be below, probably some way below, 1 W/m^2 (compared with positive forcing of +3.7 W/m^2 for a doubling of CO2). (See, e.g., Myhre et al, 2009 and Lebsock et al, 2008.) In fact, Prof. Graeme Stephens, the lead scientist on the NASA CloudSat mission and an expert on the aerosol indirect effect, reckons that the best estimate for it is zero, which would put the best observational estimate of total negative aerosol forcing below 0.5 W/m^2.

By comparison,the IPCC AR4 report gave a best estimate for total negative aerosol forcing of 1.3 W/m^2 in 2005, since when it has if anything declined slightly. Hansen's NASA GISS Model E climate model uses an even higher total negative aerosol forcing, of 2.4 W/m^2 in 2010, cancelling out much of the greenhouse gas warming. That allows the model to give a realistic simulation of 20th century warming despite it having a high climate sensitivity. A similar, if less extreme, situation very likely pertains in relation to many other climate models.

I think that when eventually the climate modellers are forced to reduce their aerosol forcings to conform with observations, they will have to retune their models to much lower climate sensitivity levels, resulting in substantially reduced projections of future warming, sea level rise, etc. In the meantime, I would expect that an increasing number of studies will incorporate the latest aerosol forcing data and produce best estimates for climate sensitivity below the bottom of the IPCC 2 to 4.5 C 'likely' range.

Dec 3, 2012 at 9:59 PM | Unregistered CommenterNic Lewis

Tamsin: The hug, if it goes ahead, must be fully public! But reservoir modelling clearly takes precedence. All the best with all that flows from next Wednesday and on the blog(s) supporting it.

Dec 3, 2012 at 10:05 PM | Registered CommenterRichard Drake

Nic: fascinating about the latest aerosol measurements. A cooling of zero? What happens now the GCMs no longer have the fudge factor they needed to retrodict the past? Lower sensitivity, as you say. It's a joy you're following all this. Thanks.

Dec 3, 2012 at 10:14 PM | Registered CommenterRichard Drake

As for raging about anybody, please do not feel I'm raging against anybody at Bishop Hill.

I wrote to Morano, and Heartland concerned about PeterGleicks personal welfare, asking them to tone everything down, as I was concerned that a professional tradegy might turn into a personal one for his family. I don't think anyone else here or elsewhere did that.

I just still fnd it odd, after reading a few emails a few years ago, to find myself on the side labelled antiscience, when my background is physical science (chemistry) and cybernetics. But fir a whim of mine twenty tears ago. I would have been a contemporsry of Richard Betts doimg a phd. I jumped ship at the end of my MSc, computer modelling physical processes for my thesis and got a job. A girlfriend was domg a meteorolgy phd, and i nearly went down the modelling route. Look up cybernetics and Sir James Lovelock ( visiting prof at reading uni cybernetics, and Gaia, and a department with phds doing Daisyworld type work)

I'm on the scientists side, but most sceptics do not see the bulk climate science, they just see policies, an advocacy version, a environmentalist version with an agenda version, or a polticised version of climate science. And i have time and time tried to get that across. How many other sceptics have been at a swimming pool party with IPCc employees and an editor of Tar WG1, yes the one with the hockey stick in it. I have mentioned before I've been very good friends for years with someon with hundreds of mentions and emails in the climategate leak. nothing at all at fault or controversial

So i and others can hapily chat all day long about the science, most scuentists will be interested ehstever the climate dies, up diwn, platea, or fascinating

But, that is where we end up at cross purposes..

Policies and politics have grasped scuence as a shield and use it as a club to push agenda and environmentalism. Nothing sinister. Just environmentalism has fallen to thinking that xatastrophic climate change us just around the cirner, they are saving the planet, these highly emotive inteeligent people think, the world is in denial, and urgent action must be taken, and they lobby hard and hype the science, that could be ruinous and forgets the workds poor. I see Monbiot, George Marshall, lewandowsky, BBC, Guardian and poltician, media all caught up in this cutural phenonomem, and like many others feel uterly powerless to stop it. How did many bystanders feel in the dot com bubble, enron, finance bubble, southsea bubble, tulip bubble, all similar phenonomem, where sceptical thinking was ridiculed.

It is great that richard and tamsin rob, jonathan paul and don and others comment here, they are all a part of the same blog community. But it is all largely at cross purposes to concerns i have about policies, etc,etc. My biggest concern is the intolerance i have come up against, for me just trying to talk ask questions at all amongst the activist community. i will not forget the greenpeace activist saying, ishould not be allowed to pass my views onto my children, nor my daughter(aged 5) coming home from school saying the polar bears are dying because of humans and CO2, after an eco team project, not that in itself, but when i said that I think the polar bears are going to be ok, other scientists are not so worried, she said ok, but didnt want me to tell anybody else about it!

Dec 3, 2012 at 10:20 PM | Unregistered CommenterBarry Woods

Dec 3, 2012 at 7:33 PM | Barry Woods
"The backlash against all science when it comes, concerns me. The politicians and media will dump all over science. Jonathan has made similar noises and others."

This is one of my main concerns too. I'm sure sentiment could change very quickly and the media/politcos would love to have a whipping boy in that situation. Scientists in other fields caught up in any fallout might not be very happy either. I've not been actively involved in science for quite a while now but still think of myself as very much a scientist.

Dec 3, 2012 at 11:04 PM | Unregistered CommenterRob Burton

@Thinking Scientist.

OT but have you had a reply from the BBC Trust and/or your M.P. yet with regards "28 Gate"?
So far the silence for me is deafening.

Dec 3, 2012 at 11:33 PM | Unregistered CommenterDon Keiller

Dec 3, 2012 at 9:59 PM | Nic Lewis

Nic, you are correct that satellite data show the 1st indirect effect* of aerosols to be smaller than assessed in AR4 (in the chapter that I was a lead author on).

However I'm not aware of any papers (or unpublished data) showing it to be zero. Do you have a reference for that, or is it just a "personal communication"? Can you provide a link?

Did you review the RF chapter in AR5 WG1? One of the Coordinating Lead Authors is my friend Gunnar Myhre, who you cite above, and who was also on the AR4 RF chapter with me. He's extremely thorough and objective (and incidentally, Barry, he did his PhD in the Meteorology Dept at Reading too!) I'm sure he will have taken note if you made him aware of a key paper with a further revised estimate of aerosol RF.

*also known as cloud albedo effect, i.e.: effect on cloud brightness

Dec 3, 2012 at 11:36 PM | Registered CommenterRichard Betts


Good to hear you helped Tamsin. I recall you liked my anecdote on a reservoir model ( at Mar 20, 2012 at 3:21 PM ) on

Which helps prove all models are wrong.

Dec 4, 2012 at 12:01 AM | Registered CommenterPharos

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