Bishop Hill New Scientist on the AR5 leak
Dec 16, 2012 Climate: solar New Scientist covers Alec Rawls' leak of the AR5 draft, and more particularly the resulting focus on the solar influence on climate. The article can be seen here. Now solar is not really my thing, so I'm feeling my way here somewhat, but it seems to me that the New Scientist piece doesn't really address the argument made.
Rawls' case was based around the following statement from Chapter 7.
Many empirical relationships have been reported between GCR or cosmogenic isotope archives and some aspects of the climate system (e.g., Bond et al., 2001; Dengel et al., 2009; Ram and Stolz, 1999). The forcing from changes in total solar irradiance alone does not seem to account for these observations, implying the existence of an amplifying mechanism such as the hypothesized GCR-cloud link. We focus here on observed relationships between GCR and aerosol and cloud properties.
OK, so if I understand correctly, the climate changes in line with cosmic rays. Cosmic rays change in line with the sun's output. But the changes in output are insufficient to explain the changes in climate, so the deduction is that these changes must be amplified in some way - in other words that there is a direct and an indirect effect of TSI on climate. One possibility is that the indirect effect is that variations in solar output affect the number of cosmic rays' reaching earth which affects cloud formation. However, the paragraph above implies that it is possible that it could be something else too.
Chapter 7 then goes on to say that the cosmic ray/cloud link is too weak to be responsible. This would seem to me to leave open the possibility that the amplification is caused by "something else".
Rawls, however, notes that Chapter 8 seems to contradict this obvious conclusion, by ignoring the inconvenient correlation between climate and cosmic rays, assuming that most of the changes are anthropogenic.
The New Scientist rebuttal of Rawls quotes extensively the comments of Joanna Haigh, a scientist at Imperial College London:
They're misunderstanding, either deliberately or otherwise, what that sentence is meant to say," says solar expert Joanna Haigh of Imperial College London.
Haigh says that if Rawls had read a bit further, he would have realised that the report goes on to largely dismiss the evidence that cosmic rays have a significant effect. "They conclude there's very little evidence that it has any effect," she says.
Fine. So it's "something else" causing the correlation between climate and cosmic rays then?
Well, New Scientist isn't saying. The "many empirical relationships" discussed in Chapter 7 are never addressed. We only hear more from Prof Haigh on the impossibility of the cosmic ray/cloud effect being responsible.
So we have a mystery. But more importantly we have a contradiction at the heart of the report that needs to be addressed.
Reader Comments (80)
In support of Keith (10.31am) a feature of the GCR-climate hypothesis is the potential to test it over timescales ranging from 10^-2 year through to 10^9 years. At the short time scale the GCR flux is modulated by the solar wind and solar activity. However, on longer time scales one expects to see much greater variation in the GCR flux as a result of the solar system moving in and out of the spiral arms of the galaxy and corresponding greater variations in climate. Shaviv and co-workers have demonstrated an empirical correspondence between the phase and frequency with which major cold stages in Earth history occur and the clustering of cosmogenic exposure ages of iron meteorites. Taking an alternative approach Svensmark estimated the GCR flux over a 500 million year period by considering star formation rates estimated from existing star cluster catalogues. Both approaches yield very similar correspondences between Earth surface temperature and the supposed GCR flux.
Over the same period that astrophysicists have begun to look at a possible GCR-climate link a number of workers, notably Jan Veizer and colleagues, have suggested that Earth surface temperatures are decoupled from atmospheric CO2 levels. They have used the oxygen isotope record of marine carbonates to estimate temperature and point to major glacial episodes such as that at the Ordovician-Silurian boundary (which is also a major extinction phase) which occurred under periods of very high atmospheric CO2 levels.
The linking of the GCR estimates with Veizers palaeotemperature record led to the Shaviv and Veizer paper in which they suggested that changes in the magnitude of the GCR flux could account for as much as 66% of estimated temperature changes.
This work is not without controversy. There are many issues associated with the interpretation of oxygen isotope records in marine carbonate deposits and fossils. Not least of these is how has the oxygen isotope composition of the oceans evolved throughout geologic time. This is currently widely debated.
Further, more recent work by Came et al. has suggested that Veizer's temperature estimates are wrong and that in fact CO2 and temperature are coupled. Clearly much more work requires to be done in resolving the issues and refining the debate.
I hope to add more to this debate over the coming months and years as we embark on an ambitious programme to try and resolve some of the issues associated with estimating Earth surface temperatures and ocean isotope composition over the past 10^9 years.
Finally, Shaviv has estimated climate sensitivity over a range of different time scales ranging from 10^8 years to 10's of years and finds that if you include a putative GCR flux together with CO2 into the overall forcings that the overall sensitivity at all time scales is the same and on the order of 0.35K/W/m^-2. Such an observation is very attractive in that it is a very parsimonious description of the response of the Earth system to forcings over time scales ranging in length of more than 10^6.
JK,
Although it is getting off-topic, in short I think the IPCC reports are too blunt an instrument when it comes to science where there is a lack of knowledge or contradictory findings. The evidence can speak for itself and a lack of evidence should be allowed to do likewise. The artificial pressure from policy makers to have certainties that can inform policy decisions is a corrupting influence.
Very informative post by Paul Dennis.
I fear I may have to change my sour and prejudiced view of the UEA - maybe it is not all Socialist Worker cells a la Nurse, nor Alarm Sustaining cabals a la Jones, nor PR Funders and Proponents a l'Acton.
Hurray!
Since Popper has shown that the logic of science is and must be a process of conjecture and attempted refutation, and that belief and consensus proves absolutely nothing as to truth, then theorists should simply state their name and their theory and, in order to aid the process testing to attempted destruction, provide a list of other scientists working with, on, and against, the same hypothesis.
That many agree on some explanation makes it a moral duty for others to seek out a rival one - even if they doubt that the establishment opinion is incorrect. (I speak of establishment because although no theory is ever established it is all too plainly the case that an idea come become an idee fixe.
This went straight down the Bore Hole at RC (what a surprise) but pleasingly collected number 1111:
"A propos the Alec Rawls kerfuffle, does climate science recognise a significant unexplained correlation between sunspot activity and global temperature (or not)?"
Richard C: ‘Other key words are "such as". Alec and other commentators certainly didn't misread those two...’
The phrase ‘such as’ means, ‘what follows is an example’. In this case the example is the ‘hypothesized GCR-cloud link’. ‘Hypothesised’ means that somebody has offered an explanation, but one that requires some more supporting evidence.
In that light, the writer is in effect saying: Some scientists have claimed a GCR-cloud link, but the claim is problematic because observations do not account wholly for the claimed effect.
The writer is discussing a scientific claim. To do that, he needs to summarise the claim. That does not necessarily mean he supports the claim.
"If this is anything to go by, GCR as a driver of cloud cover is still a hypothesis under investigation."
The same could be said of AGW couldn't it?
Dec 17, 2012 at 7:17 AM | geronimo
Yes. Unfortunately the experiment (Let's double the amount of CO2 in the atmosphere and see what happens) started with the Industrial Revolution and the results will not be in until the end of this century, when our descendants can look back and work out who was right.
Until then we are condemmed to argue possible futures, with only limited evidence and probability estimates.
Anyone being dogmatic at this point, accepter or sceptic, is going beyond the evidence.
The IPCC authors realise this. They are trying to deliver a fair summary of the complex current state of the science, while being pressured by politicians demanding simple certainties that can be used for decision making.
Brendan, however you parse the commentary in the released AR5 document it is not possible to parse the empirical observations. I'd be very interested in your thoughts on the following paper amongst others:
Shaviv, N.J., 2008. Using the oceans as a calorimeter to quantify the solar radiative forcing. J. Geophys. Res, 113(A11), pp.A11101–.
The abstract closes with:
"We find that the total radiative forcing associated with solar cycles variations is about 5 to 7 times larger than just those associated with the TSI variations, thus implying the necessary existence of an amplification mechanism, although without pointing to which one."
Are you saying that the review in AR5 also discounts the empirical observations as well as the evidence for a physical process which may account for these observations?
I'm at the beginning of my own exploration of Earth surface temperatures covering the neo-Proterozoic through the Phanerozoic. As best I can tell the evidence for a GCR-climate link on such time scales is at least as strong as that for CO2. At shorter time scales, for example over the solar cycle there is empirical evidence for an amplification mechanism. Given the growing evidence in support for the GCR-climate link on geologic time scales it is appropriate that such links on shorter time scales are explored through theory, observation and experiment. I'm not aware of any conclusive observations yet that rule out the GCR-cloud-climate process.
Brendan H
"such as" means one such possibility (GCR-cloud) has been selected to investigate but there are OTHER such possibilities to explain the discrepancy that haven't i.e. the admission of a knowledge gap remains for those not investigated.and it (the gap) is not necessarily GCR-centric.
However (for other eyes now), even the WG GCR investigation conclusions are premature and not nearly as black and white as they would have us believe. I've provided links to CCG up-thrread of my cursory scan of the literature they cite to support their case (e.g. Agee 2012) and some analysis of the murkier aspects (esp. the uncertainty in Agee and Agee vs Marsh and Svensmark) but the best resource is an annotation of links to all the papers in the GCR section by Gail Combs (thanks to Glenn Tamblyn) at WUWT here:-
http://wattsupwiththat.com/2012/12/13/ipcc-ar5-draft-leaked-contains-game-changing-admission-of-enhanced-solar-forcing/#comment-1173566
It is worthwhile running a fact check on the WG interpretations and use of those papers I've found and it is not an exhaustive compendium either.
Paul Dennis: ‘Brendan, however you parse the commentary in the released AR5 document it is not possible to parse the empirical observations.’
I’m not trying to parse any empirical observations. I’m challenging the claim that AR5 contains a ‘game-changing admission of enhanced solar forcing’.
What has happened with the sceptic commentary over this case is that we have been presented with two conflicting claims:
• AR5 contains a game-changing admission of enhanced solar forcing
• AR5 is falsely dismissive of enhanced solar forcing
It seems to me that sceptics are throwing two pies at the target in the hope that at least one will stick, but are doing so at the price of coherence and credibility.
‘I'd be very interested in your thoughts on the following paper amongst others… Are you saying that the review in AR5 also discounts the empirical observations as well as the evidence for a physical process which may account for these observations?’
I’m not a scientist so am not able to comment on the science, but from the text the author doesn’t seem to be dismissing observations, such as for a GCR-cloud link. But nor does he seem to be confirming them so much as noting that many empirical relationships have been ‘reported’. That sounds to me like a description, ie an introduction leading to a discussion.
Richard C (NZ):’ …"such as" means one such possibility (GCR-cloud) has been selected to investigate but there are OTHER such possibilities to explain the discrepancy…’
Yes, we agree on the meaning of ‘such as’. As for other possibilities, there are often other possibilities, but so what? The fact that you have a particular view is not a compelling reason for others to consider that view.
Brendan,
thank you for your comments. I agree with your analysis of the debate over this particular aspect of the leaked AR5 document. I'm not really interested in the politics and publicity debate but rather more concerned with the science. I encourage you, as a non-scientist, to also look at some of the science. Apart from anything else we are at a very interesting stage where we have two competing hypotheses. Currently we have the paradigm in which CO2 exerts a dominating control on Earth's climate. This paradigm is pervasive and has been used to explain features of Earth climate throughout much of geologic time. There is a relatively new kid on the block that involves GCR's and admits strong extra-terrestrial, indeed extra-solar system influences on climate and Earth surface temperatures. How this plays out will be fascinating for students of science and philosophy.
The observations are that there is a strong coherence between oceanic heat uptake and the solar cycle suggesting an amplifying process, whatever that may be.
Over millenial time scales there is a strong coherence between proxies for GCR flux (e.g. cosmogenic isotopes including 14C and 10Be) and proxies for climate change (e.g. d18O in speleothems)
Over time scales of 10^7 to 10^9 years there is strong evidence for a changing GCR flux experienced by the solar system with a periodicity of ca. 150Ma (e.g. cosmogenic 41K in iron meteorites and estimaes based on star cluster catalogues - two different approaches that yield the same periodicity and phase relationship). This record is strongly coherent with estimates of Earth surface temperatures based on geologic and geochemical evidence (though considerable more work needs to be done).
Finally, on slightly longer time scales one needs to account for the early faint sun paradox. The geologic evidence is strong that for most of the Archaean period water existed as a liquid. However, estimates of the early sun irradiance is such that we might expect Earth to be too cold for liquid water. Snowball events in which Earth is frozen have been postulated, and the geologic evidence could be described as strong for such events in the neo-Proterozoic (say between 630 and 800Ma) and the early palaeo-Proterozoic (2.3 billion years ago). However there is a 1.5 billion year gap between these events. Again a possible GCR link has been found that could explain this distribution.
Such observations naturally draw one to want to explore possible links between them. For example, is there a parsimonious hypotheses that can explain all these observations. One of the founding principles of geology is uniformitarianism and the search for a process that could possibly account for these different observations is entirely consistent with this principle. In this way the situation is not unlike that during the early 1960's when plate tectonics evolved as a unifying hypotheses that linked many different geophysical and geological observations.
This is especially so as one cannot apparently find the same coherence between CO2 and Earth surface temperature over geologic time. The data is sparse but we do know that there are periods with relatively high CO2 yet evidence of major global glacial events. I indicated above the Silurian-Ordovician transition but there are others too.
The scientific debate is fascinating and how it develops will make for an exciting time for geology, astrophysics, atmospheric physics and chemistry and climate science. Just as an illustration of this excitement I recommend that you, and others, read: Svensmark, H., 2012. Evidence of nearby supernovae affecting life on Earth. Mon. Not. R. Astron. Soc., pp.1–21.
There are many points to debate in this paper, errors and issues I have with it, but it is a very elegant attempt to develop a hypothesis that can explain the GCR-climate link and it's effect on life on Earth.
Oops. I hate it when I re read my posts and see a typo. The last line contains 'effect'. I meant 'affect'. There are probably other typos too for which I apologise.
Thanks, Paul. Oh, were your contribution on this page a head post somewhere.
=============
I think 'effect' was right the first time. It is usually a noun, whereas 'affect' is usually a verb.
John,
you're right. I re-read the posting after I made my correction and then wanted to withdraw the correction.
Paul, I know the feeling.
Also, I meant to thank you for your posts on this thread which I have found very instructive and engaging.
Paul Dennis: ‘I'm not really interested in the politics and publicity debate but rather more concerned with the science. I encourage you, as a non-scientist, to also look at some of the science.’
I have looked at the science, but like most non-scientists my understanding is at the level of basic rather than advanced. I’m also a text person, and when my eyes encounter the squiggly things they tend to jump to the next portion of text, and I don’t think that habit will change in the near future.
As such, I am dependent to a large degree, although not totally, on the scientific views of others. Therefore, in order to gauge credibility, I need to use other types of analysis, and one of these is to gauge how well a commentator presents on related issues, in this case a critique of another scientist’s views.
In this instance, Rawls doesn’t come out very well. In claiming an ‘admission’ he is both/either displaying cognitive bias and/or a disregard for accuracy.
In other words, on the ‘politics’, he has performed below par. That doesn’t make him worse of a thinker than other players in this field, but nor does it make him better. So for the time being the rational position for me is the status quo, although of course that could always change.
Brendon
>"The fact that you have a particular view is not a compelling reason for others to consider that view"
I would have thought it was the responsibility of the IPCC to investigate ALL known possibilities and admit that there is the possibility that there are unknown mechanisms operating.
Alec Rawls is exposing the latter (the IPCC's admission of the possibility of unknown mechanisms). He is also exposing the fact that the ONLY known mechanism the WG have investigated is GCR and that investigation it turns out is prematurely dismissive, blind to uncertainty in the cloud datasets (Agee 2012), and by no means exhaustive.
He is also exposing the fact that the GCR section is the ONLY solar investigation in the entire report and by the leak he has also exposed the knowledge gap of not only the IPCC but that external interested parties have limited understanding of the solar energy input in general (that is is obvious by the head scratching going on). Joanna Haigh's obvious ignorance of the oceanic heat sink and a requirement for instantaneous cooling from back at 1986 illustrates this perfectly. There are other instances, Foster and Rahmstorf in particular.
Alec Rawls has done a huge service in terms of forcing the solar issue that would be neglected irresponsibly otherwise and raising the overall level of understanding of known solar effects and mechanisms and exposing the realization there could be as yet unidentified (by the IPCC) unknowns (they could for example, think about solar energy accumulation in the ocean).
Richard C (NZ) writes:
'I would have thought it was the responsibility of the IPCC to investigate ALL known possibilities and admit that there is the possibility that there are unknown mechanisms operating.'
I would have thought that it is the responsibility of the IPCC to use its expert judgement to decide on which potential mechanisms are worth discussing in a report of finite length. If you argue that they should not be using their expert judgement then that's an argument against the existence of the IPCC (which is fair enough), not an argument that they have done their job wrongly. As for 'admitting' there might be unknown mechanisms, well they do, don't they?
Richard C (NZ) further writes that Rawls:
'is also exposing the fact that the GCR section is the ONLY solar investigation in the entire report and by the leak he has also exposed the knowledge gap of not only the IPCC but that external interested parties have limited understanding of the solar energy input in general (that is is obvious by the head scratching going on).'
I'm not sure if Rawls has claimed that, but it would seem to be wrong. Chapter 8, pp30-33 contains a three page discussion plus figures (plus reference to supporting informaiton which I haven't checked). Here there is discussion not just of TSI but of UV and spectral irradiance, which seems to me at least as worthy of discussion as GCR.
Also, the level of scientific understanding of solar irradiance is assessed as 'low'. I'm not sure what counts as a 'game changing admission', but for what it's worth the same 'low' assessment was made in AR4.
JK
>"I would have thought that it is the responsibility of the IPCC to use its expert judgement...."
Yes it is but it becomes a battle of wills among experts as the Forest Mims disclosure reveals. The individual experts do not necessarily agree on all counts. There are stark divisions apparent in this new era of (forced and voluntary) "transparency" just as we have seen in similar disclosures from previous reports.
>"As for 'admitting' there might be unknown mechanisms, well they do, don't they?"
Yes they do and I stated as such in my next paragraph but poorly written on my part on reflection.
>"I'm not sure if Rawls has claimed that"
Yes I've probably made a subtle misrepresentation. What I was referring to was this (quoting Rawls):-
"The first sentence here, citing unspecified “empirical relationships” between cosmogenic isotopes (a proxy for solar activity) and “some aspects of the climate system” is the only reference in the entire report to the massive evidence for a solar driver of climate"
http://wattsupwiththat.com/2012/12/16/a-rebuttal-to-steven-sherwood-and-the-solar-forcing-pundits-of-the-ipcc-ar5-draft-leak/
Not sure whether your Chapter 8 refs constitute "the massive evidence for a solar driver of climate" though. I don't know enough of either body of work to identify the deficit Rawls sees let alone debate the point. I only know that the solar papers I've had my head in over the years don't seem to rate highly with the IPCC.
Re "....the level of scientific understanding of solar irradiance is assessed as 'low'".
I'm convinced the Rawls leak (ignoring the ethical issues) was necessary to accelerate scientific understanding of all things solar by both the IPCC internally and those scrutinizing their work (us). My impression has been that the solar driver has been unrealistically relegated by the IPCC and because of that the educational value of the reports has been minimal in the solar sense. Up to now, solar education takes place outside of IPCC reports. It remains to be seen if this latest report ups the ante all around but if nothing else, Rawls leak has got people outside the IPCC thinking about the solar driver and extending their knowledge of it.
Re "people outside the IPCC thinking about the solar driver and extending their knowledge of it"
And knowledge of contentious solar issues, the satellite "gap" (Challenger disaster) in particular and closure of it by the respective TSI composite teams. The argument of Joanna Haigh and several others, notably Dana Nuccitelli, relies on adoption of the PMOD TSI composite to the exclusion of ACRIM and IRMB that exhibit different trends. But Scafetta 09 states (page 10):-
"None of the TSI satellite composites proposed by the
ACRIM, IRMB and PMOD teams can be considered rigorously
correct. All three teams have just adopted alternative methodologies
that yield to different TSI composites, but these teams
have ignored the unresolved uncertainty in the data that yields
to an unresolved uncertainty in the TSI composites as well."
http://arxiv.org/pdf/0908.0792.pdf
Scafetta compiled three alternative TSI composites here:-
http://ars.els-cdn.com/content/image/1-s2.0-S1364682609002089-gr2.jpg
Also three different trends.
From 'Total solar irradiance satellite composites and their phenomenological effect on climate', Scafetta (2009):-
http://arxiv.org/pdf/0908.0792.pdf
That paper details the ACRIM vs PMOD "gap" controversy.
See also the followup 'Empirical analysis of the solar contribution to global mean air surface temperature change', Scafetta (2009):-
http://arxiv.org/pdf/0912.4319.pdf
ACRIM vs PMOD (Fröhlich and Lean) from IPCC AR4:-
http://blog.idnes.cz/blog/7317/144075/aa3.jpg
What justification does Joanna Haigh (or anyone else asserting a solar peak around 1986) have to adopt PMOD but exclude ACRIM or IRMB or Scafetta or whatever?
Richard C: ‘I would have thought it was the responsibility of the IPCC to investigate ALL known possibilities and admit that there is the possibility that there are unknown mechanisms operating.’
Presumably because the report dismisses any significant effects from cosmic rays, in fact goes so far as to say there’s very little evidence that cosmic rays have any effect on the climate.
If that is the case, and given that resources are limited, further research in this area would have a lower priority than other areas.
Brendan,
I don't follow your argument. Leaving aside the fact that I don't accept the reports dismissal of evidence for GCR impacts on climate one is still left with the empirical observations of a significant solar amplification factor. This is based on measurements of oceanic heat uptake and loss throughout a solar cycle. The magnitude of the amplification factor is on the order of 6 or 7 according to Shaviv and co-workers. This means that variations in solar irradiance over the course of the 20th century could account for a major component of the total observed warming (e.g. Ziskin and Shaviv, 2011, Quantifying the role of solar radiative forcing over the 20th century, Advances in Space Research, v50, 762-776).
When taking account of the solar amplification one is led to rather low climate sensitivities to the radiative forcing associated with CO2 doubling that are on the order of 1 degree C per doubling. The implication is that there are no net positive or negative feedbacks and thus the IPCC support for estimates of 2 to 4.5 degree C per doubling are very wide of the empirically observed mark.
One suspects that the IPCC is on the horns of a dilemma. Assess and accept the evidence for a TSI amplification factor (by whatever mechanism) then they have to accept a low climate sensitivity that has major implications for the way we are currently structuring society to deal with climate change, or dismiss the evidence for solar amplification and pursue estimates of climate sensitivity that are high and imply a major climate problem around the corner.
Interestingly, Matt Ridley has just written about his conversations with Nic Lewis in which Lewis argues for a lower climate sensitivity of 1.6 to 1.7 degrees C per CO2 doubling. I believe Lewis' estimates were made without taking into consideration an amplified solar irradiance effect.
Brendon
>"Presumably because the report dismisses any significant effects from cosmic rays, in fact goes so far as to say there’s very little evidence that cosmic rays have any effect on the climate."
Of course they dismiss it. Their MO is a scary CO2 story, not a boring GCR story. But to do so they have to selectively adopt TSI composite and cloud datasets, misrepresent the papers they cite to support their dismissal (e.g. the cloud dataset uncertainty explicitly stated in Agee 2012 that they cite on trend). ignore other relevant papers and solar controversy e.g. the ACRIM "gap".
>"If that is the case, and given that resources are limited, further research in this area would have a lower priority than other areas."
But as Paul Dennis points out above, the IPCC is left "on the horns of a dilemma". They still have to account (but WGIII and SPM edit it out of consideration) some OTHER amplifying mechanism if they summarily and prematurely dismiss GCR (I'm not advocating GCR as the answer to everything BTW).
Paul Dennis: ‘I don't follow your argument … One suspects that the IPCC is on the horns of a dilemma.’
I’m not sure what argument you are referring to. As for being on the horns of a dilemma, the IPCC author would only be in this position if he accepted the validity and/or import of the observations. He doesn’t seem to be doing this, in which case there would be no horn, and therefore no dilemma.
Richard C: ‘They still have to account (but WGIII and SPM edit it out of consideration) some OTHER amplifying mechanism if they summarily and prematurely dismiss GCR...’
Except that they don’t. The passage in question simply points out a problem with the hypothesis. The writer is not obliged to account for anything if he doesn’t accept the hypothesis.
Where I think you and other climate sceptics are on the wrong track here is in misinterpreting the writer’s remarks to mean he accepts that an amplifying mechanism is actually at work in the atmosphere rather than in the hypothesis.
That’s the significance of the word ‘reported’. The writer is saying that many empirical relationships have been claimed, and then goes on to discuss one of the implications, that there would have to be an amplifying mechanism to account for the observations.
So the discussion is about the hypothesis. Anyone can discuss a hypothesis without necessarily accepting it.
Brendan,
with all due respect I think your reading of the AR5SOD statement seems to me at one end of a spectrum of interpretations that is no more valid than those others have suggested.
The writers make a statement that many empirical relationships have been reported between GCR's or cosmogenic isotopes (which are an excellent proxy for GCR's) and some aspects of the climate system and cites a few of the many studies. The writers are clearly aware of the implications these observations have for an amplification process (irrespective of the mechanism). They then focus on one hypothesis and don't consider others. Refuting that hypothesis (which I don't think they have done with any effect) they do not make any statement as to whether or not they think solar amplification is happening.
It seems to me that you are making the word 'report' into a weasel one which has a meaning different to that which I ascribe to it in this context.
Unfortunately we are now parsing the language and context and I'd much rather talk about the science. Nic Lewis above has started to draw out the consequences of the recent reduction in estimates of the negative forcing effect of aerosols on the climate sensitivity. Similarly, an effect associated with for example solar activity such as modulation of GCR's, clouds and albedo (an amplification process) will also lead to a reduction in the overall climate sensitivity.
I stick with my assertion that the IPCC is on the horns of a dilemma here. It may not have been before the leaked documents but certainly is now.
Paul Dennis: ‘...with all due respect I think your reading of the AR5SOD statement seems to me at one end of a spectrum of interpretations that is no more valid than those others have suggested.’
Perhaps, but as you say, we are talking interpretations here, just as we are with the science.
It’s interesting, mind you, that climate sceptics – not necessarily you – are quickly and easily able to adopt a position of advocacy and strong assertion when the occasion suits.
If the terms ‘sceptic’ and ‘warmer’ refer, in the case of the science, specifically to views about CO2 and its claimed effects – and I think they do – climate sceptics should also transfer their scepticism towards their own views.
That’s possibly too much to ask. Luckily, we still have the scientific method.