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Discussion > Evidence, confidence and uncertainties

Paul Matthews @ Dec 2, 2011 at 5:35 PM

Hi Paul,

Richard is a professional scientist and so should be amenable to rational argument. As he says, he is not an expert in paleo, and this explains his lack of awareness about recent studies in that area. As you say, Richard was a lead author on AR4, on the chapter dealing with radiative forcing. Despite this, it is clear from earlier postings that Richard was unaware of TSI reconstructions published both before and after AR4 which conflict with the earlier reconstructions used in the AR4 attribution studies. This is far less understandable IMO. I pointed these studies out to him in an earlier discussion thread in which the author of one of the reconstructions added comments to confirm the situation. I was therefore surprised to read the following comment from Richard on this current thread:-

Estimates of the various external forcings of the climate system (radiative forcing, ie: the perturbation to the Earth’s energy balance) suggest that the net anthropogenic forcing is extremely likely (95%) to be substantial and positive, and likely (66%) to be at least five times larger than the natural radiative forcing (solar). The evidence for this is presented in the IPCC AR4 Radiative Forcing chapter on which I was a lead author . Since then, further evidence has emerged than the solar forcing may actually be smaller than that used in AR4. [my emphasis]

This is misleading for two reasons.

1/ Some of the reconstructions previously pointed out to him were published prior to AR4.
2/ He points out the implication that these reconstructions suggest higher sensitivity during the early 20th century, when it is at least as reasonable to draw the implication that models are not validated by 20th century temperature observations.

This disingenuousness is entirely consistent with your suggestion that Richard will never admit that claims in AR4 are unjustified. I find it especially disconcerting, since he should not need to have the literature on this issue repeatedly pointed out to him on a blog. As I've said before, I'm not a sceptic and I completely agree that decarbonization is needed. However, I'm also sick and tired of seeing science used as political pawn in all of this (especially by scientists), and to be honest I'd thought and hoped that Richard was better than this.

Dec 2, 2011 at 7:32 PM | Unregistered CommenterPhilip

Dec 2, 2011 at 12:53 PM | matthu

Ah, sorry, I think we've been talking at cross purposes.

When I agreed that your statement:

at least some of the impact is likely caused by CO2 emissions

was part of what "virtually everyone who knows about the science can agree on", I thought we were including sceptics in that. When I said "everyone" I really did mean everyone. My understanding is that even most sceptics agree that CO2 has at least some impact. So I thought we were talking about a statement that anybody who has thought seriously about the issue could agree on.

However, when you talk about "consensus" you seem to be referring to the "mainstream" (ie: that which sceptics do not consider themselves to be part of!).

On the specific issue we are discussing here (relative importance of CO2 radiative forcing), no I don't think the "mainstream" opinion has particularly changed.

(However other conclusions from AR4 probably have evolved - see the SREX for example, with downgraded statements on hurricanes and drought for example. Science does move on!)

I think getting too hung about definitions of consensus is a bit pointless though. It leads us down the road of argument from authority, rather than evidence. The entire point of this discussion thread has been to discuss the evidence itself, not who does or does not agree with it! :-)

Dec 2, 2011 at 7:36 PM | Unregistered CommenterRichard Betts

BBD
I take your point, honest.
But as long as scientists are saying "we can't explain the MWP", there must remain doubts over the late 20th century warm period.
If you're all so damn sure that MWP wasn't due to CO2 but you don't know what it was due to, it's also possible that you've missed that element this time.
I'm not saying it is so or even likely but a little more awareness of the limitations of our knowledge would be welcome. Climatology, as someone said earlier today, is still only in its adolescence (I would say 'infancy' personally). We don't know it all and it's the ones who pretend they do that create scepticism.
And perhaps miss the real answer, assuming we haven't found it yet.

Dec 2, 2011 at 7:45 PM | Unregistered CommenterMike Jackson

Paul Matthews

Paul,

I certainly don't think anything I can say is likely to shift Richard.But I think Steve McIntyre could tear even more holes in that confidence level of 66% based on that awful list of citations provided by Richard.

I had a look at the Ljungquist paper mentioned by Philip above. It contains the Esper 2002 Polar Urals series. McIntyre did a comparison of the results from the Polar Urals series when analysed by Briffa 1995 and by Esper 2002. They were nothing like each other. No one, not even McIntyre could account for that.

Mann 2008 has been thoroughly dissected by Steve McIntyre and the well-informed readership he has. There is much more amiss with Mann 2008 than I mentioned.

I take the answer to my first question to be that there is sound scientific evidence to support the IPCC
2007 claim but, by the standards of the IAC, the conclusion is, nevertheless, of little value. So, how much of the 20th century global warming do you attribute to mankind.? I say 49%. The science was worse than we thought.

And how likely is it that the IPCC will embrace all the IAC recommendations?

Dec 2, 2011 at 7:48 PM | Unregistered Commentersam

So,
nothing on how confirming model results from more model results, is not correct?

Let me assure you, circular reasoning is not isolated to modeling alone. In genomic research with microarray data, people develop diagnostic and prognostic tests. Some even reach commercialization. Circular reasoning is rampant, but hardly anyone notices. When commercialization of an assay is deemed 'success', everyone thinks someone else has done the due diligence. It is really surprising.

Dec 2, 2011 at 7:53 PM | Unregistered CommenterShub

I would still like to see a 'sceptical' run on the Met Office GCM computer. If both extremes of input were used we might see if there is either an unbreachable gap between mainstream and sceptical positions or that we're 'too close to call'.
Keeping the 'ball' to prevent fair play isn't cricket......

Dec 2, 2011 at 8:40 PM | Unregistered CommenterDave_G

Dave_G

This video might provide some insights about your question. The answer I think is 'too close to call', not that it's likely to help much.

Dec 2, 2011 at 8:55 PM | Unregistered CommenterPhilip

Wow, Richard!

Without in any way wishing to be rude, because I do appreciate your frankness, you certainly seem to be backing away from what you had previously agreed. I originally asked you:

Richard -
Are you able to state what you consider to be the most recently formulated statement that is regarded to represent the so-called "consensus of opinion"?

I had thought that it was something along the lines of

1) global warming is real (whatever that means)
2) man is having an impact
3) at least some of the impact is likely caused by CO2 emissions

Is there another similarly brief way of expressing the totality of the consensus?

Now to me, that is self-explanatory. I talk about a formulated statement and I talk about the consensus - something that has been referred to often enough by mainstream people like Beddington, Nurse, Brian Cox and so forth that I did not think there could be any ambiguity.

But now you are telling me that there are really two consensuses?

One (the one I outlined above) that is designed to include everyone including sceptics, and another (presumably much narrower) 'consensus' that is designed only to include mainstream scientists (is that the same as scientists who believe in "the cause"?)

No wonder people argue about what scientists are saying when they backtrack like that!

Dec 2, 2011 at 9:42 PM | Unregistered Commentermatthu

Paul, Philip, Sam,

Sorry if you get the impression that I have an unwavering loyalty to AR4 as a matter of principle. This is completely untrue. I thought I'd made it pretty clear that I was willing to read the papers I've been told about (in fact I already did read some of them). Also, there are actually some parts of AR4 I disagree with - we just haven't talked about them here!

Philip, when I said "more recent evidence has emerged" I was referring to Lief Svalgaard's powerpoint presentationthat you pointed me to, and the TSI reconstructions mentioned within that, and mentioned in our 20C Attribution thread, which as far as I remembered became available after AR4 was written. Did I miss any that were not cited in AR4 but were available by mid 2006?

I can assure you that I am not being political here!

Dec 2, 2011 at 10:18 PM | Unregistered CommenterRichard Betts

Dec 2, 2011 at 9:42 PM | matthu

Are you a lawyer or something? :-)

I think it's a pointless debate to try to over-define "consensus". Let's talk about the actual evidence, not how many people agree with it or how we categorise them!

Dec 2, 2011 at 10:27 PM | Unregistered CommenterRichard Betts

Dec 2, 2011 at 8:40 PM | Dave_G

Interesting suggestion. What would be your definition of a "sceptical model run"?

Dec 2, 2011 at 10:28 PM | Unregistered CommenterRichard Betts

Hi Shub

Sorry, I didn't get chance to pick up on your earlier post.

Please can you be a bit more explicit about where I've confirmed model results from other model results?

Dec 2, 2011 at 10:49 PM | Unregistered CommenterRichard Betts

Richard,

AR4 was released in 2007. The paper by Preminger and Walton was published in 2006 and that by Krivova, Balmaceda, and Solanki in 2007. Your original comment about this that caught my eye was to a posting on this blog in September of this year. The thing that bothered me the most was that you were still pushing the same AR4 story in 2011, even though it is not supported by the most up to date research, and even though you should have been aware of the research because of your involvement in that Chapter in AR4. I'm not familiar enough with the paleo topics to comment strongly, but I can see that Sam's frustration is palpable in his comments and is in some ways similar to mine. On related topic, I'm also very interested to find out how IPCC people would synthesize the research from Lovejoy's group.

Dec 2, 2011 at 10:49 PM | Unregistered CommenterPhilip

Thanks Philip

Preminger and Walton was received by the journal in October 2006, and Krivova et al in November 2006, both a few months after the cutoff date for papers to be accepted for inclusion in AR4. That's what I meant by "since AR4".

I thought I did agree with you in the 20C Temperature Attribution thread that this issue of the new TSI reconstructions was important. Our runs for AR5 used the Wang et al reconstructions, ie: a smaller rate of change of TSI in the early 20th Century than that used for the AR4 runs - admittedly not as small as Lief's though.

Ever since that thread, I don't think I have pushed the point about the models showing warming in the early 20th Century due to solar forcing.

Sorry if I am being frustrating to you and Sam! I'm not being pig-headed - I am just not convinced by the arguments! :-)

Dec 2, 2011 at 11:33 PM | Unregistered CommenterRichard Betts

Dec 2, 2011 at 7:48 PM | sam

Hi sam

I certainly don't think anything I can say is likely to shift Richard.But I think Steve McIntyre could tear even more holes in that confidence level of 66% based on that awful list of citations provided by Richard.

Why are you so concerned about the 66% confidence anyway? That's a long way from being certain. The Met Office issued the infamous Barbecue Summer forecast on the strength of 60% odds, and we all know what happened then :-)

Is your concern not so much with the conclusion but the way it gets propagated onwards with the confidence estimate lost?

Dec 2, 2011 at 11:50 PM | Unregistered CommenterRichard Betts

Richard

Philip has offered a Youtube link that I must first view before I can expand on my 'sceptical model run' as it may answer the question without incurring you any unnecessary work. If the video doesn't clarify my understanding I shall return with a more detailed proposal.

Dec 2, 2011 at 11:50 PM | Unregistered CommenterDave_G

Thanks for the link Philip

Dec 2, 2011 at 11:51 PM | Unregistered CommenterDave_G

Dec 2, 2011 at 4:52 PM | Lord Beaverbrook

Hi, thanks for mentioning the excellent Ineson et al Solar Forcing of Climate Variability paper.

The paper has been well-received. It's quite tantalizing for interannual forecasting - given the difficulties with forecasting internal climate variability, a clear response to a nice predictable external forcing could be a real bonus for forecast skill. Work is continuing on this - the aim is to test its effects on the forecast skill.

Dec 3, 2011 at 12:21 AM | Unregistered CommenterRichard Betts

Richard,

I see that it has been cited over a hundred times already.
It would be interesting to follow up and perhaps have some detail on the response of NAO to UV levels and to what extent this is going to effect us, in the UK.

Dec 3, 2011 at 4:56 AM | Unregistered CommenterLord Beaverbrook

Richard Betts @ Dec 2, 2011 at 11:33 PM said, "Sorry if I am being frustrating to you and Sam! I'm not being pig-headed - I am just not convinced by the arguments!"

Just to clarify, the reason for my frustration is not that you are unconvinced by any particular arguments, but that you were unaware of significant mainstream literature, relevant to your work in WG1, Chapter 2. Obviously I can't speak for Sam, but nonetheless I detected a similar frustration in his comment @ Dec 2, 2011 at 7:48 PM.

Dec 3, 2011 at 9:07 AM | Unregistered CommenterPhilip

Thanks Philip, I'd misunderstood your point.

Happily, thanks to your 20C Temperature Attribution discussion I became aware of the post-AR4 TSI reconstructions and was able to read up on them and check them out. Now, thanks to Sam's questions to me, and the responses of others on this thread, I am in a position to do that with palaeoclimate reconstructions for the last 2000 years.

NB I should just point out that my specific role in AR4 was on radiative forcing due to land cover change, although I did also take an interest in other aspects of the RF chapter and other chapters.

My role in AR5 concerns changes in terrestrial ecosystems, this time in WG2 (Impacts, Adaptation and Vulnerability)

Dec 3, 2011 at 9:49 AM | Unregistered CommenterRichard Betts

Richard,

Thanks for this information. You mentioned earlier that your runs for AR5 use the Wang et al reconstructions, and of course that this reconstruction differs from Leif's and the very similar one published by Preminger. Leif has also said I think that these reconstructions represent the view of a majority of researchers in this area, which raises the question as to why they are not being used by the MO for AR5. Any ideas?

Dec 3, 2011 at 10:42 AM | Unregistered CommenterPhilip

Hi Philip

Lief Svalgaard actually said "I think that my own reconstruction is the best one", so not a majority view (although that's not necessarily relevant - the majority may be wrong!)

As far as I can see, Wang is closer to Svaalgard that it is to Lean, so we're much more towards what you are suggesting. I think Wang et al was thought to be as credible as Svalgaard's (although he clearly disagrees!) and also because, if I remember correctly, the actual TSI reconstruction of Svalgaards's was not published yet. However, I can assure you that Svalgaard was absolutely not dismissed - he is considered credible.

Dec 3, 2011 at 12:31 PM | Unregistered CommenterRichard Betts

Richard,

If memory serves, he made a statement along the lines I said on Climate Audit.

Dec 3, 2011 at 12:52 PM | Unregistered CommenterPhilip

Oh, and of course Preminger is published , and her reconstructions is almost identical to Svalgaard's!

Dec 3, 2011 at 12:58 PM | Unregistered CommenterPhilip