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Discussion > Where's my best evidence?

Sorry, it did not occur to me to look up the concept of best evidence. Below is a wiki quote, and I ask you to compare what is written here with the IPCC reports. I think there is a problem.

The best evidence rule is a common law rule of evidence which can be traced back at least as far as the 18th century. In Omychund v Barker (1745) 1 Atk, 21, 49; 26 ER 15, 33, Lord Harwicke stated that no evidence was admissible unless it was "the best that the nature of the case will allow". The publication ten years later of Gilbert's enormously influential Law of Evidence,[1] a posthumous work by Sir Jeffrey Gilbert, Lord Chief Baron of the Exchequer, established the primacy of the best evidence rule, which Gilbert regarded as central to the concept of evidence. The general rule is that secondary evidence, such as a copy or facsimile, will be not admissible if an original document exists, and is not unavailable due to destruction or other circumstances indicating unavailability.

Jun 24, 2012 at 8:15 AM | Registered Commenterrhoda

How very odd that the BBD entity should come to the rhetorical "rescue" and support of the BB entity. Some might conclude that BBs who pray together - with their oft recycled recitations and invocations of the tenets of IPCC generated propaganda - stay together. But I couldn't possibly comment.

Jun 24, 2012 at 10:18 AM | Registered CommenterHilary Ostrov

bb and bbd sound very similar.

I ran into a post yesterday where bb was spewing out energy consumption figures for the UK left and right.

I find it hard to believe that the measurements you seek don't exist. They must! However, instead of asking you to go looking for it, I'll continue to search. Maybe we can email some famous climate scientists?

Jun 24, 2012 at 1:21 PM | Registered Commentershub

Shub, I recognise that telling it simply has no artistic effect, but 'spewing out... left and right' is rather an exaggeration for one sentence: Net oil imports were 80 million barrels in 2010 implying a cost at current prices of around $8bn. This is net oil imports, not consumption. It dwarfs any green spending, wouldn't you say?

Jun 24, 2012 at 3:12 PM | Unregistered CommenterBitBucket

Shub, if it does indeed exist, why would 'they' not include it in their literature? Why would no knowledgable warmist put a link up right here, or have done so in a thousand other posts on a hundred other blogs?

My conjecture is that when they went looking they could not find it. Do you really think that if an outfit like CRU found contrary or even inconclusive facts that they would publish it? Or suppress it? No, nor do I.

Jun 24, 2012 at 3:38 PM | Registered Commenterrhoda


I assume you are still, after all this time, waiting for your best evidence.

A posting by Marion [ Jul 8, 2012 at 12:56 PM Marion ] prompted me to put down my understanding (as a bystander) of "the best evidence". If I've got it wrong, no doubt someone will correct me.

Here is my own understanding of the "evidence". I have the impression that the evidence can be sumarised as follows:

(1) The world has been warming.
(2) Atmospheric CO2 levels have been rising and this is due to fossil fuel use and land use change.
(3) The rising CO2 levels have caused the observed warming.
(4) CO2 levels will continue to cause warming in the future.

(1) is shown by the instrumental record and, prior to the instrumental record, by analysis of proxies such as tree rings.

Marion has listed the issues I was vaguely aware of with the instrumental record.

I had read about issues such as "the original data has been deleted (UEA)", "the homogenisation has been done by undocumented methods", "the quality of many instrument sites is in serious doubt (next to air conditioner outputs etc) - WUWT". To me, even a single one of such issues would mean that the instrumental record would have to be regarded as unfit for purpose. But I have read that studies by climate scientists have shown there is no need to worry about these things.

The use of proxy data (eg tree rings) has its "convergence problem" . It also has the problem that records that don't correlate with the temperature record are, apparently, excluded from the analysis. Climate scientists don't seem to see that as a problem. Who am I to say otherwise?

(2) The rising CO2 levels are shown by Mauna Loa data since around 1960. (Before then, I don't know. Ice records, perhaps?). This has been caused by fossil fuel use and land change use is confirmed by common sense and the close match between annual anthropogenic emissions and the rising atmospheric levels - one is consistently around 45% of the other. Probably by C12/C13 arguments too, though I am ignorant about that.

(3) My understanding of the evidence that the warming to date has been caused by CO2 Is as follows:

- It must have been that because we don't know what else could have caused it.

- Climate models, including the Met Office model, run with CO2 switched off do not show the full warming 'observed'. But, with CO2 switched on, the observed warming is reproduced. That confirms it. This also confirms that the Met Office models can be relied on to predict future climate.

(4) CO2 hangs around a long time - part of it forever, for practical purposes. This is described by the "Bern model" which is referenced by the IPCC. I don't know how the Bern model has been validated.

In carbon cycle modelling, there is discussion on "adjustment time" vs. "residence time" which, from my viewpoint as a bystander, has not yet been resolved and is relevant to calculating future CO2 levels.

In a nutshell, that is my understanding of the "best evidence". I somehow feel you have been waiting for something a bit more convincing than that. Either: (a) It does not exist, (b) I have got it wrong.

Jul 8, 2012 at 4:57 PM | Unregistered CommenterMartin A

Yes Martin, exactly. I go along with the CO2 increase being due to our emissions. I don't buy the ice cores alone, they look so stable that one would be inclined to a null hypothesis of CO2 movement within the ice. Likewise the CO2 residence time, I fell that is being spun to look scary. And the heat in the pipeline. Pure fantasy.

But models and tree ring? Is that all they have? No emphasis on IR measurements and albedo observations which we know have been done but no-one bothers to bring up? That Chang paper Richard sent me has been cited twice. Twice. Hundreds of CO2 in bottle studio demos, but no proper experiment in proper conditions. And I keep wondering, climate scientists being what they are, whether they have done this work and found it fails to support or even refutes their hypothesis and has been suppressed.

Jul 8, 2012 at 5:57 PM | Registered Commenterrhoda

Sorry, not Chang, It was Wang and Liang. Who to my mind did too much but didn't provide enough graphs. Their emphasis on total downward LWIR has to be done, but between the error in measurement they acknowledge and the role of H2O in the result doesn't say much about CO2. When they do mention it, they calculate the effect based on IPCC formulae, which is no help to me. And again the rush to the average. When you have fourth power terms in the equation, you can't average it out and stay secure in your result.

Anyhow, they find downward LWIR to be increasing by 2.2 watts per square metre per decade. Which is massive, isn't it?

Jul 8, 2012 at 6:32 PM | Registered Commenterrhoda

And to the Harries et al paper (Pretty Sagoo is a name to conjure with). They seem to have found a lot more effect from CH4, CFCs and O3 than from CO2. No measurable effect in 27 years and 50-odd ppm? Maybe I am not understanding it, because I would be totalling the energy in LWIR form the earth not slicing it into different wavelengths. I know its only a letter to Nature, but I'd expect to see more, again.

Is that all they got?

Jul 8, 2012 at 6:56 PM | Registered Commenterrhoda

Hi rhoda

Thanks for taking the time to read the papers.

I'm not sure why you think Harries et al did not find much CO2 effect. I wonder if you have looked at Figure 1c and seen the area of the difference spectrum around wavenumber 970-980 cm-1 labelled "CO2", which does indeed show only a small difference, but not noticed the other CO2 label between 710 and 740 cm-1 (on the left-hand side of that panel) which does show a large difference?

The reason they look at different wavelengths is because it is the different strength of absorption at different wavelengths that gives the characteristic signature for the presence of different gases, and changes in their concentrations. See this post by Jeff Condon at the Air Vent for a nice figure on the absorption spectra for different GHGs.

The same principle is used by astronomers to find out what elements are in stars. Apologies if you know this already.



Jul 9, 2012 at 10:53 AM | Registered CommenterRichard Betts

OK, what threw me was the presentation. I did indeed see the CO2 change. I guess that the integral of this equates to some energy retention. It would be nice to see that in energy units of some kind. Then one would have to find out what happened to that energy, which is really the question. Not the way Jeff Id puts it, exactly. It was never a question for me that CO2 absorbs and retransmits in the stated bands. It is a question of what happens next. I suppose the Harries paper cannot address H2O. It would be there in numbers far higher and more variable than the others, I am sure. In fact it would swamp them. That is why I'd rather see total energy budget rather than worry about this or that band. Neither paper answers that question or aspires to. Not their fault, of course. Making some progress, I think.

PS You need never worry about assuming I know anything already. Just assume I don't.

PPS Harries does not seem to address the actual response of CO2 to the change expected according to the increased ppm number. This is so crucial that I wonder at the omission.

Jul 9, 2012 at 1:05 PM | Registered Commenterrhoda

I remember reading that, at one time, the consensus of astronomers was that we could never know the chemical constitution of stars.

Jul 9, 2012 at 1:22 PM | Registered CommenterMartin A

rhoda, I've said it before and I'll say it again. The oceans cover over 70% of the planet's surface; clouds over 60%. As climate scientists seem to admit they don't yet much understand how the oceans or clouds affect climate, so it seems to me that any theories about climate might so far be perhaps just a little premature.

Jul 9, 2012 at 4:32 PM | Unregistered Commentersimon abingdon

Simon Abingdon

Nail on head!

In terms of understanding our climate and all the factors which affect it, we are at "inventing the wheel" stage. The most helpful thing scientists could do would be to tell politicians "we really do not know enough to understand let alone predict climate and you should adapt as best you can until we understand more."

Jul 9, 2012 at 5:06 PM | Registered CommenterDung


The most helpful thing scientists could do would be to tell politicians "we really do not know enough to understand let alone predict climate and you should adapt as best you can until we understand more."

Why not read Spencer Weart's history of the scientific exploration of AGW? This is the timeline, which hyperlinks to the rest of the content on the site.

This 'we know nothing' meme is blinding you to the actual state of knowledge, which is more than sufficient to be sure that AGW is real, and potentially a very serious problem indeed. Retreating into a comforting blanket of ignorance is only an option for those who do not loudly proclaim that they are 'sceptical' of the science. If you are going to do that, you need to be much more conversant with the science you claim to be 'sceptical' about. Especially since you presume to be in a position to tell scientists what they should be telling policy makers.

Jul 11, 2012 at 11:35 AM | Unregistered CommenterBBD


We need to know the sensitivity of the atmosphere to CO2 emissions. To do so needs at least an understanding of how the phenomena of globally ubiquitous cloud formation, precipitation and dissipation can confidently be calculated as they respond to such changes in atmospheric composition as are consequent on increases in the proportions of CO2 not feasibly measurable on any scale coarser than parts per million.

You well understand this problem BBD. So please explain why you are not troubled by this glaring lacuna in our knowledge.

Jul 11, 2012 at 2:37 PM | Unregistered Commentersimon abingdon

simon abingdon

First, definitions. We need to know the sensitivity of the climate system to increased radiative forcing.

We can ask simple questions like: has the climate system ever been warmer than the present? Obviously we know that it has.

We can infer that whatever global changes occurred in cloud formation as the climate system warmed, they did *not* act as a negative or even neutral feedback or the climate system would not be capable of warming up. Obviously. That's what neutral or negative feedback means.

If clouds represented a neutral or negative feedback to increased RF, known past climate behaviour in response to slight changes in forcing would not - could not - have occurred.

Jul 11, 2012 at 9:10 PM | Unregistered CommenterBBD


ask a PHD (there are a few posting on BH) what percentage of all that will ever be known about their subject, do they think they already know. The answer may surprise you.

Jul 11, 2012 at 10:49 PM | Registered CommenterDung

@BBD Jul 11, 2012 at 9:10 PM

Your argument is simplistic as it assumes "other things being equal" on historical timescales and that variables can always be considered in isolation. The ramifications of the multifarious interplays among competing climate effects will continue to defy any attempt at formulating coherent theory.

In science, only one thing really counts and that is the support for a theory provided by observations. The global warming that was earlier predicted with what is now seen as premature confidence has not been realised. Contrary to expectation CO2 increases cannot be shown to correlate with temperature rise after all, so a search has had to be made for convenient straws to clutch (like aerosols) in the hope of rescuing dogmatic theory.

Adequately understanding climate will gradually be accepted as a necessarily Sisyphean task. As the descent into the next ice age begins, AGW will be seen for what it is: an inexplicably hubristic footnote to history.

Jul 12, 2012 at 9:24 AM | Unregistered Commentersimon abingdon

simon abingdon

Your argument is simplistic as it assumes "other things being equal" on historical timescales and that variables can always be considered in isolation. The ramifications of the multifarious interplays among competing climate effects will continue to defy any attempt at formulating coherent theory.

I'm baffled here. The reasoning I used doesn't have any of the faults you outline. In fact it is distinguished by avoiding them.

If clouds were a negative or neutral feedback, the climate system could not warm under modestly increased forcings (eg Milankovitch; MWP; 1910 - 1940). Climate variability would be smoothed out.

The same holds for the net of all feedbacks, known and unknown. Unless feedbacks net positive, the climate system cannot respond to minor changes in forcing. Everything known about climate behaviour on all time-scales demonstrates that it is sensitive to minor changes in forcing. Therefore feedbacks must net positive.

That's why increased forcing from CO2 will gradually engage positive feedbacks and slowly, discontinuously at first, warm the climate system.

The recent flattening of the warming trend is interesting but beside the point. Consider it a demonstration that the climate system is sensitive enough to be influenced by Increased stratospheric sulphate aerosol loading from Chinese coal and equatorial volcanism, predominantly La Niña conditions, the historically quiet solar cycle 24, heat mixing into the deep oceans and more besides. But if CO2 forcing is maintained, never mind increased, the warming will resume in due course. How can it not?

Jul 12, 2012 at 10:29 AM | Unregistered CommenterBBD

If it were positive, why would it not run away to the upper stop? Maybe it is doing so now, but why never before? Also, does forcing actually get positive feedback if at the same time (as now) the temps are held down by 'natural variation'? The fact is you can't explain what is going on and your arguments amount to handwaving. and epicycles.

However, where is the answer to my question about Harries (posed on the communicator thread, I think)? He got so near to revealing the smoking gun, but did not go all the way. Why not? Is CO2 saturated in one band? What is the effect of that on the 3.7 watts per doubling? What is the watts/sqm equivalent of the extra heat absorbed by CO2?

Jul 12, 2012 at 10:45 AM | Registered Commenterrhoda

@BBD Jul 12, 2012 at 10:29 AM You say "How can it not?" I say because the forcing may itself provoke an unanticipated feedback of greater value. There is no law of nature that says this cannot happen. Your final paragraph includes the phrase "and more besides". Indeed so. Who knows what unsuspected cans of worms remain to be opened?

Jul 12, 2012 at 10:59 AM | Unregistered Commentersimon abingdon

simon abingdon

You say "How can it not?" I say because the forcing may itself provoke an unanticipated feedback of greater value. There is no law of nature that says this cannot happen.

The entire history of known climate behaviour says you are mistaken...

I don't think you have really understood the point I was making above. The entire history of climate behaviour makes a mockery of your position.

Jul 12, 2012 at 1:10 PM | Unregistered CommenterBBD

Handwaving nonsense, BBD. You do not know the entire history of climate behaviour, nor do you have the merest chance of explaining it if you did. Nobody in the climate community could make such a claim. Not even UEA.

Jul 12, 2012 at 1:17 PM | Registered Commenterrhoda

Jul 11, 2012 at 8:56 PM | rhoda (On "Climate Communication" - What Do You Think?)

So, if Harries is to be believed (and I see no reason why not) one of the CO2 bands is now saturated.

Glad you see no reason not to believe Harries et al! :-)

The reason there is only a small response in the 970-980 cm-1 part of the spectrum is that the absorption by CO2 is only weak at these wavenumbers anyway. You can see this in the absoroption spectra posted by Jeff ID - see the green line in Figure 4. You do have to convert wavelengths (in the absorption spectra) to wavenumbers (in the Harries et al paper) - one is the inverse of the other, ie: wavenumber = 1 / wavelength

The upshot is that the small peaks in the CO2 absorption spectrum (green line) at wavelenths of about 8-12 microns (millionths of a metre) correspond to wavenumbers 83,300 - 125,000 m-1 or 833-125 cm-1 (so including the 970-980 cm-1 area I mentioned above). Absorption in those parts of the spectrum are weak so any changes in CO2 only have small effects. In contrast, you can see strong absorption at longer wavelengths (the big peak in the green line between about 12 and 20 microns) which corresponds the to smaller wavenumbers including 710 and 740 cm-1 which I again I mentioned above as showing the large change.

So Harries et al see larger changes in parts of the absorption spectrum where absorption by CO2 is strong, and the see smaller changes in parts where absorption is weak - exactly as one would expect.

Hope this helps!

BTW I agree it would be useful to express this in terms equivalent to radiative forcing rather than just changes in brightness temperature. I'll ask them about that. Please don't expect a quick reply, as it may take a while, but I promise you I'll look into it.



Jul 12, 2012 at 1:25 PM | Registered CommenterRichard Betts