In a previous post, I discussed, in general terms, the issue of the conflict of interest between being an IPCC reviewer and being an active protagonist in the field. Here I illustrate the problems with specific reference to MBH98, arguing that the running text of IPCC TAR made misleading claims about the MBH98 hockey stick and that the underlying conflict of interest appears to have contributed to the making of these misleading claims. This example is obviously highly relevant to the current controversy.
Here is exactly what the running text of IPCC TAR says about MBH98
Mann et al. (1998) reconstructed global patterns of annual surface temperature several centuries back in time. They calibrated a combined terrestrial (tree ring, ice core and historical documentary indicator) and marine (coral) multi-proxy climate network against dominant patterns of 20th century global surface temperature. Averaging the reconstructed temperature patterns over the far more data-rich Northern Hemisphere half of the global domain, they estimated the Northern Hemisphere mean temperature back to AD 1400, a reconstruction which had significant skill in independent cross-validation tests. Self-consistent estimates were also made of the uncertainties. This work has now been extended back to AD 1000 (Figure 2.20, based on Mann et al., 1999). The uncertainties (the shaded region in Figure 2.20) expand considerably in earlier centuries because of the sparse network of proxy data. Taking into account these substantial uncertainties, Mann et al. (1999) concluded that the 1990s were likely to have been the warmest decade, and 1998 the warmest year, of the past millennium for at least the Northern Hemisphere. [my bold]
I’ve bolded something different than the usual cut-phrases in the last sentence, which, of course, has ended up in press releases and has been endlessly repeated by the Canadian government; here my interest is a little different. One of the reasons for the widespread adoption of MBH98-99 was its claims of statistical “skill”‘?, “robustness”‘?, careful proxy selection and relatively even geographical and proxy balance, as well as its appearance of statistical sophistication to the statistically unsophisticated paleoclimate community (enhanced by rather inflated language to describe even simple statistical tasks).
Anyone who’s read Mann’s texts as closely as I have can hardly doubt that the paragraph comes directly from Mann himself. Some of the terms do not occur in exactly that form in the underlying article (e.g. the idiosyncratic term "self-consistent estimates" as applied to MBH98 uncertainty does not occur in MBH98 itself); an independent review author making a pr’cis of MBH98-99 would have been very unlikely to have written the above paragraph. In our GRL article, we reported that our emulation of MBH98 indicated that the cross-validation R2 for the 15th century proxy roster (as well as all other cross-validation statistics other than the RE statistic) was statistically insignificant (and argued that the high RE statistic was spurious). In fact, the R2 cross-validation failure was massive, with an R2 of ~0.0. We pointed out that the adverse R2 statistic was not reported in MBH98 and, in our EE article, we sharply criticized MBH for withholding this adverse information. Aside from our calculations, there is substantial circumstantial evidence in favor of a catastrophic failure of R2 cross-validation for 15th century proxies.
First, realclimate.org has not explicitly denied it. Instead, they’ve tried to argue that the RE statistic is the only one that should be looked at. Secondly, Wahl and Ammann, whose emulation of MBH98 is virtually identical to ours, have only reported an RE statistic. Although they purport to replicate MBH98 and refute us, they have notably withheld reporting of the R2 statistic in their website presentation. A logical question to Wahl and Ammann is:
Have you obtained highly significant R2 and other cross-validation statistics for the MBH98 15th century network as claimed in IPCC TAR?
So let’s assume that the MBH98 cross-validation R2 statistic for the 15th century proxy network is ~0.0 i.e. massively insignificant. How can this be reconciled with the following claim by the IPCC [not simply Mann et al.]?
The [MBH98] reconstruction “⤠had significant skill in independent cross-validation tests.
Personally, I don’t think that it is possible. To the limited extent that Mann et al. (or Wahl and Ammann) have faced up to the catatrophic failure of the cross-validation R2 statistic, they have tried to argue that the RE statistic is the cross-validation statistic "preferred" by paleoclimatologists and blustered that McKitrick and I were simply too stupid to know this. I don’t think that this argument holds any water in the context of publication in Nature, but it sure doesn’t work in the context of IPCC TAR. It is impossible to construe the sentence highlighted above as anything other than a misrepresentation of the failure of R2 cross-validation for the 15th century network. Did this claim "matter"?
All one needs to do is consider what happens if the IPCC review author charged with considering MBH98 had written the following sentence:
The MBH98 reconstruction failed the R2 and other cross-validation tests using the 15th century network.
What happens to the hockey stick graph? Does it get inhaled into the Summary for Policymakers as a key promotional graphic? Would anyone rely on its ability to make confident assertions about whether the 1990s were the warmest decade or 1998 the warmest year? Does the hockey stick get used in Kyoto promotions all over the world? Even to pose the question is to answer it. If the failure of the 15th century cross-validation R2 statistic had been disclosed in IPCC TAR, the hockey stick simply would not exist as an icon.
Some people might argue that even an arms-length IPCC review author might not have been able to pierce the prior misrepresentations in Nature. In legal proceedings involving conflict of interest (as I understand it), courts seldom engage in speculation about what a non-conflicted party would or would not do – they generally assume near-perfect behavior by a non-conflicted party. Thus, in my opinion, given the conflict of interest, it is irrelevant to speculate whether an independent review author might or might not have identified the withholding of cross-validation statistics in MBH98 and pierced through to the underlying problem in the Nature article. We are entitled to assume that a competent and independent IPCC review author would have noticed the withholding by MBH98 of the cross-validation R2 statistic, would have sought this information directly from Mann et al. and reported the massive failure of the cross-validation R2 statistic with a completely different outcome for the use of the hockey stick in IPCC promotions.
So here is a very specific example of why it is a good idea to avoid conflicts of interest (as acknowledged by Vranes, Pielke and von Storch), specifically showing how the conflict of interest inherent in an IPCC lead author reviewing his own material ended up having a material effect on IPCC TAR.
Climate Audit 
38 Comments
Very interesting article and website. I was exploring the Internet to see if there are any intelligent people capable of thinking for themselves in regards to “Global Warming” Thankfully I see there are.
A very supercilious post Stuart I must say.
Why don’t you do some checking and see is the globe is warming? If you do you’ll find EVERY measure of the temperature of the globe’s surface and lower atmosphere now shows definite warming. So, do come back and try and show otherwise…
What about the balloon based measurements? Or is that next on the hit list for “adjustments”.
The world warms up, the world cools down. That is what it does. For all the nonsense spouted about how the IPCC etc. are researching “climate” as opposed to “weather”, all their evidence is of an extremely short-term nature. A couple of decades of apparent increase in average surface temperatures, enhanced by positie statistical adjustment in lower troposheric satellite temperature measures.
Paul, it’s good to kow you are such an expert climatologist/meteorologist.
You will thus know that Spencer, at least, of Spencer and Christy is an agw sceptic, if not just read what he has had to say on TCS. So, I find it odd (amazing actually give then time invested over the years in promoting S&C as the only temperature record worth following by those of AGW sceptical nature like you) that you don’t accept what they now say, or to be fair, perhaps seem they will be saying since it’s not yet confirmed by peer reviewed paper. Perhaps it’s becuase it looks like they now don’t say what you want to hear? That’s probably it…
Fact is the only thing left for sceptics does seem to be the M&M dispute of MBH, hence all the bruhaha here. Or can you think of something else ‘disproving’ AGW? I can’t, it’s certainly not the ballons (ooppss, that might put ideas into people heads, ‘lets rubbish the ballon data’).
Question. Why is the surface temperature record open to such scrutiny, analysis and “adjustment” as satlelite records?
Of course that should read “not” open
What in the world are you talking about , Peter? What is it that Spenser has said which makes you think he’s now promoting AGW?
Dave, do try to read what I said, not what you want me to have said. ‘You will thus know that Spencer, at least, of Spencer and Christy is an agw sceptic’ and ‘what they now say’ being that their record is in line, now says, much closer to what the others do. Not, to be clear for you, that Spencer has changed his tune about what we should do. Again, let me emphasise that any peer reviewed paper is yet to appear, so I could be wrong. Just going by what I read on their website.
Paul, so you’re saying the surface record isn’t open to the same scrutiny as the satellite one? OK, back up your allegation with evidence. Btw, you are, I think, ‘begging the question’ and that is a logical fallacy 🙂
Steve Jones has refused to make his raw station data available. See Top 15 Reasons for Withholding Data.
“Or can you think of something else “disproving’ AGW?”
Well, there IS a 7-year cooling trend of late in the MSU satellite data.
“Or can you think of something else “disproving’ AGW”
Peter, you are missing the point. It is not up to the skeptics to disprove AGW, rather, it is up to you and your co-religionists to prove it.
Talking about temperature trends does not cut it – it may show GW but it does not show AGW.
Other than the hockey stick, what else do you regard as proof that current GW – if it is real – is anthropogenic ?
“If you do you’ll find EVERY measure of the temperature of the globe’s surface and lower atmosphere now shows definite warming.”
It’s NEVER been that big of a deal that the satellites showed cooling vs warming (although it was interesting how some so adamantly dismissed the MSU readings when they showed a net cooling, then readily used them as proof of AGW once they showed a net warming). The important part is that the satellite readings should be warming – according to greenhouse theory – at least as fast as the surface readings, which hasn’t the case (unless maybe you believe Fu’s two pubs, which Spencer, Christy, and others have ripped to shreds). Regardless of whether or not the MSU show warmings or cooling, the end result is that something is strongly amiss – either in greenhouse theory, surface readings, or both.
fFreddy. Jese so many fallacies I dunno where to start. I’m not religious (nor am I going to sling that ad hommish mud back), it’s not about proof and it’s not about showing all the warming has been due to us. It is about some pretty basic atmosphere physics, about what’s going to happen if we sit back and do nothing and about the increasingly obvious.
LOL Michael, for years *it was* about the S&C sats. Where have you been? Are you late to this party? Or are you practiced in the art of volte-face?
Peter,
Re-read my message. I AM referring to the “S&C sats.” As I said, the importance of the MSU readings is NOT (and has never been) a warming signal vs cooling, the importance is the discrepancy between the satellites (& radiosondes) vs the surface. Greenhouse theory and GCMs say the S&C’s measurements should be warming at least as fast at the surface, yet they aren’t, and that’s an indication of a major problem. Certainly it was more dramatic when the satellite measurements had an overall net cooling, but that has NEVER been the issue of warming vs cooling. The fact that both satellites and surface readings shows warming is in itself irrelevant. It sounds like you were one of those who claimed victory the day the sats showed a net warming >0.00 deg C and never understood the real issue in the first place.
You can find this at the “MSU Science Homepage” written by Dr. Spencer himself:
“…Surface thermometer measurements indicate that the temperature of the Earth is warming at an average rate close to +0.20 deg. C/decade since 1979, while the satellite data shows a warming trend of about half of this. These differences are the basis for discussions over whether our knowledge of how the atmosphere works might be in error, since the warming aloft in the troposphere should be at least as strong as that observed at the surface…”
It’s not obvious to me. Prove it.
And if you don’t think your beliefs need proof … we’re back to religion.
fFreddy, Ok, if the evidence as is isn’t good enough for you it will take more time, lets review things in five years.
Nice try btw, but I’m not one for beliefs, beliefs are for the religious.
Spencer & Christy aren’t fools. That’s why they use the word ‘might’, it’s bet hedging.
Michael, again, see you in five years, or ten, or fifteen. It wont be all that long either way.
To repeat the question :
Other than the hockey stick, what else do you regard as proof that current GW – if it is real – is anthropogenic ?
You have not answered this question. Unless you do so, I will have to assume you have no answer.
They use ‘might” because there is another possible explanation as to the disagreement: problems with the surface record.
Freddy, what is proof? What do you mean by it?
I’ve seen what some people call ‘proof’, otoh others, many here for example (even youself I’d bet) probably wont accept agw *ever*, period, whatever ‘proof’ is shown them – am I right?
So, what makes me think the evidence is good, the models reasonable? The global average surface temperature record(s), the way the oceans are now behaving, the loss of land ice worldwide, changes to fish stocks, the basic atmosphere physics, the evidence that it’s not the sun that’s causing all the warming, that I trust all those involved to be good scientists will do for starters.
And what would make me think the evidence is the other way? For a start a sustained decline in global averaged temperatures to normal levels, a reversal in ocean temperatures, and cessation in the decline in ice loss worldwide.
OK, I have answered you. Now, again for emphasis, tell me, what might change your mind? I suspect it’s closed to the possibility of large magnitude agw. Am I right?
Oh Peter, I do read what you say. But normally when I use ‘they’ as in ‘they say’ I mean that they actually say something, not that YOU think the data they post now says something different. And since you specifically mentioned Spencer, I’d assumed you meant Spencer had actually SAID something to the effect that their results were now in line with what the warmers say. But, of course, I should have known better than to actually try understanding what you actually said since you use ‘say’ in such a non-intuitive way.
Humm, the confusion that can happen with written speech dashed off sitting at a PC I think – plus, I admit, my perhaps dodgy English.
S&C are, I think (again, only what I’ve read), and after the latest correction, now producing satellite temperature records more in line with all the others. As such they are also more in line with what those you describe as ‘warmers’ say (as in write, speak). That is not to say they have undergone a change of their broader views re you know what.
Actually, you are wrong, I am not closed to anything.
What would I regard as proof ? Very good question, which, fortunately, I don’t have to answer. It’s your hypothesis, you prove it.
One thing I would say is that the whole issue is so polluted by politics that any proof is going to need fully open and independent confirmation by people outside the climatology community.
I’m still looking for your answer to my question – if there is GW, how do you know it is AGW, rather than natural variability.
The items you have listed there all appear to be indications of GW, except for the last – trusting the scientists – which is an article of faith. Given the way these climatologists seem to be playing games with what I regard as the basic components of science, I cannot share your trust.
Once again, you have not answered my question. So I’ll ask it again:
Assume for the moment that the arguments subside and that there is definitely global warming at present – how do you know it is anthropogenic ?
What are you referring to as ‘the latest correction’? The last interpretation I saw of the satellite measurements was by someone who basically adjusted the readings and used model results to justify uping the temperatures. But that’s been quite a while now and I wasn’t much impressed by that fellow’s reasoning. Has there been more recent adjustments, in particular by S&C? At any rate, the decadal rate of warming is still only .086 according to the data which can be reached via Daly’s old site. And it wouldn’t take much of a large volcanic eruption to wipe that out. We haven’t had one for quite a while you know. But even at that rate you’d have to get quite a bit of acceleration of heating rate to reach the lowest projections of the IPCC for the coming century. And given that most everyone, warmers and skeptics alike believe the fossil emissions will peak at or before mid-century, it’s real hard to believe the mid and high projections.
Dave,
http://climate.uah.edu/may2005.htm
***Notes on data released June 10, 2005:
UAH is reprocessing the complete global temperature dataset to include a new
correction, according to Dr. John Christy, director of the Earth System
Science Center (ESSC) at The University of Alabama in Huntsville.
“The April and May 2005 results include that new correction,” Christy said.
“We expect to have the complete dataset available in time for the June
Global Temperature Report.”***
The website also states: “Global temperature trend since Nov. 16, 1978: +0.12 C per decade.” (trend was previously calculated to be +0.09 C per decade through April)
Land based trend from http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt : +.07 (Nov ’78) to +.59 (May ’05) over 26.5 yrs = +0.20 deg C/decade. Going from Dec ’78 instead (+.04) as I think S&C actually do in their calcs gives +0.21 deg C/decade.
From NCDC here ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/land_o_C.all (Dec ’78-May ’05), trend of +0.17 deg C/decade.
From CRU here http://www.cru.uea.ac.uk/ftpdata/tavegl2v.dat, trend of +0.20 deg C/decade.
+0.12 vs +0.21, +0.17, and +0.20…still doesn’t even look close.
Freddy,
I could take your post, substitute reference to me with you, and reply to you with it. Because, from my pov, I see a lot of what people like you say here as faith and trust in Steve and his ilk. I could also say prove to me Steve (or you) are right, and when you (to your undoubted satisfaction would), I could (like you would if I showed/proved AGW to my satifaction), again say ‘not good enough prove it’. So, that’s not very constructive and we’re unlikely to make progress.
Like many others who support places like this the evidence is not strong enough for you to accept the role of humans in climate change. OK, then there is little I can do but say time and further evidence will tell. Right?
Wrong. You are asserting a symmetry in our positions that does not exist.
Most propositions can be classified as ‘proven true’, ‘proven false’ or ‘not proven’. Most new science starts off in the ‘not proven’ category, and eventually moves into one of the other two.
You believe that the proposition that “current GW is anthropogenic” should be categorised as ‘proven true’. By contrast, I am *not* asserting that AGW is ‘proven false’. Even if M&M are proven correct in all respects and MBH are proven to be completely bogus, I am asserting that AGW remains in the category of ‘not proven’.
With regard to what is sufficient proof for you may not be sufficient proof for me – yes, that is certainly possible, in which case we agree to disagree and await new evidence in either direction.
The question I keep asking you is what is it that causes you to move the AGW proposition from ‘not proven’ to ‘proved true’. Your answers a few posts back seem to have been that a) GW is happening, and b) “the scientists” say it is anthropogenic. Note that I am categorising any reference to a black box computer model under b).
Please note that this is an entirely genuine question on my part. Clearly, something has persuaded you that GW is anthropogenic; I’m just trying to understand what.
So. I assert that “current GW is anthropogenic” is ‘not proven’. You assert that it is ‘proven true’. Other than “trust the scientists”, what causes you to make this assertion ?
Bother.
Peter Hearnden, the above post responds to your post at 14 Jul 2005, 3:26 am.
John A – is your threader taking its revenge ?
No Peter, there’s not ‘faith’ involved. M&M have presented specific, detailed complaints about MBH98, etc. Despite having RealClimate to counter on, Mann et. al. have not refuted any of the points. Instead they’ve used misdirection and outright lies to avoid having to face the truth. What’s happened is clearly chronicled here. If you actually think Mann has presented valid rebuttals of anything M&M have done, go ahead and present it, but you’ll find that all of the Mann ‘disproofs’ have been objectively countered here already.
Peter – no, wrong. You assume a symmetry in our positions that does not exist.
To clarify : most propositions can be classified as either ‘proven true’, ‘proven false’ or ‘not proven’. Most new science will start in the ‘not proven’ category, and move to one of the other two categories as the evidence develops.
With regard to the proposition “current global warming is anthropogenic”: you clearly believe this, i.e., you categorise it as ‘proven true’. However, I do *not* categorise it as ‘proven false’. Even if M&M are proved correct in all respects, and MBH are proven to be completely bogus, the effect will be to leave the proposition in the category ‘not proven’, where I think it belongs.
Clearly, something has caused you to put the proposition in the category ‘proven true’. You say that what you regard as proof may not be sufficient proof for me: this is quite correct, and if it turns out to be the case, then we will agree to disagree, and await new evidence in either direction.
But my question remains, what is it that has caused you to categorise “current global warming is anthropogenic” as ‘proven true’ ? All the items you cite a few posts back could be categorised as either a) global warming is happening or b) “trust the scientists”. (Note that I am categorising any argument based on a black box climate model under b) . )
Please note that this is a perfectly serious question from my point of view. Something is making you believe in AGW, I am trying to understand what.
So. I categorise the proposition “current global warming is anthropogenic” as ‘not proven’. You categorise it as ‘proven true’. Why ?
More accusations of lies I see, second time today…
All hell would break loose if I made such an accusation of this place (yes, yes, I know this place is above such things but that naughty X, Y or Z climatologists aren’t).
Various Hockey Team members have claimed that M&M produced a ‘reconstruction’ of their own which failed statistical tests and this shows a flaw in their (M&M’s) science. In point of fact, as Steve has pointed out many times here, and in particular before the most recent cases of such claims, they were not producing a reconstruction of their own but simply showing that Mann’s methods in MBH98 either yielded insignificant results or were not robust. Pretending that this was M&M’s own reconstruction and then pushing the statistical failure onto M&M, despite knowing that this is not the case, is a lie.
You’re welcome to present something Steve has published or stated concerning his published work which you think is a lie, but I think he would disprove it quite easily.
fFreddy,
firstly, remember I’m someone who thinks the warming will be 1-4C, that one degree – OK? Also, I don’t think I’ve claim ‘the warming’ in proven anthropogenic have I? Whatever, I see a world that has warmed. I think UHI’s are allowed for and I think the surface record is accurate to it’s specified limits. I think it’s clear humanity is responsible for the rise in CO2 concentration. It’s also clear we are ading other ghg’s to the atmosphere, and that there is a lag between emission and warming. I’m also of the view that the RSS satellite record better represents reality that the S&C one (but I also think the sat’s dodgy since the sensors are only supposed to be accurate to +- .2C (of the top of my head that is)). SO, for me, it’s clear the planet is warming, pretty fast too (and look at this year, on a par with ’98 but no El Nino…).
Now, I’m not a qualifed atmosphere scientist/physicist/meteorologist – nor have I ever pretended to be. I’m an interested underemployed amateur. I do, however, respect them as a body. As a body they seem to me to accept the predictions I do.
Models. Given the above I either have to say ‘I’m not an expert so I’m not going to try and refute them’ or I say ‘I’m not an expert but I know better than you do’. I go for the former. I do think that if you do a Stefan Boltzmann (I think he’s the one) you will get warming due to the extra CO2 (indeed, when you look carefully hardly anyone now claims there wont be some warming), I find it hard to accept there wont be feedback warming and I cant thing of counteracting feedback coolings. So, I’m happy with the model prediction, and, since I dislike extremes, I go for the middle view – back to 1-4C – push me and I’d say 2-3C. 1C, not much problem, 2C plus, things are getting dodgy.
How’s that? Religious probably 😦
fFreddy,
I agree with you. At present I believe there is no “objective” proof for AGW. The earth has been warming and cooling for millions of years, glaciers have grown and receeded all without any intervention from man. From what I have seen the only thing which some people have claimed as proof is based on climate models which can never be accurate. To my knowledge they have not been tested simulating past climate. Science requires theories to be tested and reproduced by others objectively. I would also put AGW in the category of “Not proven”. On top of that I bristle when others want to spent perhaps trillions of dollars on a problem which has not been “proven true”
Well darn me! I send a perfectly reasonable (and long 😦 ) reply to this, listing my views, it appears here, yet now it seems to have gone?
“…I’m also of the view that the RSS satellite record better represents reality that the S&C one…”
And why exactly is that?
Attn : Peter Hearnden
Peter, my apologies for taking so long to respond, real world was interfering.
OK, I think I am getting a clearer idea of where you are coming from. Let me see if I can narrow it down a bit further. As I said previously, this is probably going to end up as agreeing to disagree; and as you said, we will have wait five to ten years for better data. But that’s fine, it is the nature of science.
To extend the idea of the categories ‘proven true’, ‘proven false’, and ‘not proven’ : the ‘not proven’ category is a fairly broad one, and it represents the battleground where science happens. It is normal for there to be champions of a particular theory who could be characterised as being out at the end of the ‘not proven’ category, trying to move their theory into ‘proven true’, preferably by means of experiment.
Although the second sentence of your post #33 does not explicitly say so, I interpret it as saying that your position is over at the ‘true’ end of ‘not proven’.
(Call this Point A.)
For the rest, you are saying :
1) there exists current anthropogenic CO2 growth,
2) there exists current global warming
3) there exists a known mechanism – the greenhouse effect – whereby 1) causes 2)
4) we don’t know of any effect that will be the opposite of 3)
Therefore, current GW is AGW.
(Call this Point B.)
Regarding models, you seem to be saying that you accept them, rather than that you are persuaded by them, by which I mean that your acceptance of AGW pre-dates these model results. If the model results had come out against your pre-existing position, you might have looked into them more closely, but since they supported your view, you have not done so. (Again, fair enough.) You don’t go for the extreme options but are happy with the moderate ones. The same goes for your view of climatologists en masse.
(Call this Point C.)
Finally, I remember seeing a post somewhere which seemed to fit your view of what we should be doing about emissions reductions, even if AGW is not proven. (It might actually have been from you, though I don’t recall exactly.) It compared the human race’s current position with an individual whose doctor says that there was a 50% chance that he has cancer. The post suggested that you should take treatment now, and not faff around looking for a second opinion, or hoping ti will go away by itself.
(Call this Point D.)
I’m a bit uncomfortable here because I am doing too much interpreting, which runs the risk of putting words in your mouth with which you do not agree (particularly with reference to Point D).
So could you tell me, do you feel that Points A to D above fairly summarise your position ?
FFreddy, Yes, I think you do summarise my position. One or two points though.
Re point B I don’t say (as in I understand it to be so) all the warming is due to us, (never have!) clearly you can’t say that because there is both a natural variability that might cause warming to a level that we see at present (except, atm , what??? the suns output has steadied) and there was warming early this century when ghg’s were less (but the sun warmed?). So I say I think the human compontent to warming is becoming clearer, not that it’s all due to us. I do think our effect should become more and more obvious, probably dominant. Otoh, say the sun cools a little for 50 years (it could, we don’t know) and the temperature falls .5C due to that but warms 1.5C due to us, would our effect be obvious in the 1C net warming? Perhaps not. So we might (gasp) still be debating this in 2050, but, imo, I doubt it.
Re D. To me it’s more a case of the doctor saying ‘Look, your still in fair shape, but there is, in my medical opinion, strong evidence if you carry on this way you might harm your health. I lack the ability to prove it, but: you keep adding to the things you do to your body that risk harm, the evidence that these things you do risks harm isn’t going away, indeed new evidence keeps appearing. I advise you to change your diet.’. Friends might say ‘enjoy life, do as you want, I know someone who say’s it’s not a problem’, others friends might say ‘think of you your friends and family and your other responsibilities. Listen to the doctor.’ – it’s a choice. Clearly I know what I’d do.
I don’t have strong objections to A and C – close to what I think.
Now, is it your coup de grace time 😉 or are we closer to agreeing to disagree?