It’s useful, but not essential. Happy now?
You say that as if claims 2-9 relied on claim 1. That’s not so, they are all independent. There is a great many types of evidence, all independent and consistent with the same conclusion. Disproving one (or several) doesn’t really undermine the overall conclusion, no more than an ill-fitting glove should have undermined OJ’s guilt.
Whatever. You’re just answering your own question.
Not really. I certainly didn’t mean that. Anyway, let me restate things:
Anyway, if somebody argues that Claim X is established by the preponderance of (independent) facts 1 through 10; and it turns out that fact 1 is wrong, then it tends to undermine Claim X.
My point stands.
Let’s see if I have this straight:
If current temperatures are unprecedentedly high, then it strengthens the catastrophic AGW theory. However, if current temperatures are NOT unprecedentedly high, it DOESN"T weaken the catastrophic AGW theory.
Do I have you right?
deleted
There’s a difference between discrediting the evidence and disproving it.
If the proxy data were merely discredited - and I think that’s what you’re trying to do - that means we don’t really know what the temperature record of the past 1000 years looks like. I don’t think this weakens the case for AGW.
The only way the data can disproved is if we have more reliable data that replaces it. If that happens, it will bring us closer to the truth behind global warming. It’s possible that the new data shows previous periods that were even warmer than today, and still be consistent with AGW. For example, it may indicate that the previous warming periods are precisely correlated with some known natural forcings which did not occur in the 20th century.
The above is just my opinion based on my understandings. Others may well disagree.
Well, let me ask you this:
If somebody publishes a picture of the Loch Ness Monster, does that strengthen the hypothesis that there is a Loch Ness Monster?
If that same picture is later shown to be fake, does that weaken the hypothesis that there is a Loch Ness Monster?
If there are 5 pieces of evidence that (independently) support a hypothesis and two of them are discredited, does that weaken the hypothesis?
brazil:
I’ve read through this thread and like to contribute my 2 cents.
As a layman with some basic knowledge of the scientific method, but no proffesional expertise in these subjects discussed whatsoever (a situation somewhat resembling yours i gather) I tend to see things this way:
The picture i get from my (limited) understanding of the aggregated body of research done on historical temperature records - instumental or through proxy - is that they seem to indicate that we are experiencing a rapid increase in global mean temperature in the last couple of centuries.
It would seem that stating anything with 100% confidence about global mean temperature before the instrumental record began is hard, since:
a) you are left with no option but trying to measure the historical record through proxies, and measurement through proxies may be subject to some varying degree of error, systematic or random.
b) the subject of interest is global mean temperature which complicates the task even further since you may find that the global mean does not necessarily always corresponding to local variations. Furthermore, proxy records may be geographicly isolated to parts of the globe and so on.
Now, how accurately we can measure historical mean temperatures over say the last 1000 years are given by the current state of scientific tools available. We can only make as good a measurement as permitted by the tools available to us at this point in time.
What we are discussing here is the scientific community collectively trying to come to a consensus about how to interpret the aggregated measurements made with the best tools available to us at this point in time.
What can we say about the historical record and with what confidence can we say it, given that we know that tools available to us for measuring is imperfect?
As I understand it, in the scope of IPCC panels report is surveying the scientific communitys collected body of work on historical global means and - aggregating the collective knowledge of proxy records and their strength and weaknesses, random and systematic error - assessing what can be said about global means.
In addition a number of other reports have been issued by councils, commitees etc that have - using the scientific method - tried to aggregate the collected body of research and quantify what we can say about historical global mean temperatures and with what degree of confidence we can say it.
Concencus seem to be that we can with a high degree of confidence say that we have seen a rapidly increasing global mean temperature in the last 400 years.
In the preceding 600 years the level of confidence with which we can make statements is lower since the tools of measurements available to us are less perfect.
A lot of the proxy studies made indicate that global mean temperature is indeed at it’s highest point the last 100 years for the millenium. Some other proxy studies indicate that another local high roughly 1000 years ago was warmer than today. We cannot presently say with one was the warmest with hundred percent certainty, since that far back in time the tools of measurement available to us constitute a much higher level of uncertainty than for the last 400 years.
So: the hockey stick defined as the global mean temperature the last hundred years being the warmest we had for the last millenium seems - in my eyes - quite likely given what we can say with any level of confidence. It would seem that either the warmest point in time is now (and therefore hockey stick is true) or with some level of probability it was roughly 1000 years ago when another local maximum occured.
In either case those two seem to be the two maximums it is standing between. So it seems strange to say that hockey stick is “unreasonable”, “discredited” or whatever. It seems to me that - given what we can say with our imperfect tools - today is still the most likely maximum - given that the instrumental record black line in the Rohde graph on wikipedia is for 2004 is ~.4 degrees above all proxy records for the local max around year 1000 and rising rapidly. (putting all discussion about “splicing” aside)
Indeed that last fact may indeed render all your talking points moot in a very short period of time should the current trend - for which we have very good tools to measure - continue. Something i believe you may be well adviced to ponder on somewhat 
– Cheers Sherwood
I think it’s a little misleading to speak about “100% confidence.” I’m certainly not demanding 100% confidence.
Not really. Personally, I’m not all that interested in alleged “consensus.” I’m interested in the underlying arguments and evidence.
I dispute this. The ultimate reason for confidence about precedent for temperatures over the last 400 years is the fact that we are coming out of the “Little Ice Age”
Do you accept my earlier definition of hockey stick? It’s more than just “current temps are the highest in 1000 years”
It depends how you define “current” Since the 1998 el nino, temps are essentially flat. If that trend continues, it’s gonna be a big problem for Hansen et al.
I was certainly not implying you were, I was trying to the best of my knowledge to describe my understanding of the what we can presently know and with what certainty.
Well, the “alleged” consensus represent the collective judgement of the scientific community of the underlying arguments and evidence. Or maybe i should rather say that the report of the IPCC f. e. represent their collective judgement of the - arguments and evidence.
Should I then understand your position as being that you are only interested in what judgement you can personally draw from arguments and evidence (in this case the original research that the IPCC was surveying) with your level of understanding of them? I respect that position, but i would imagine it kind of puts the burden on you to basically repeat f. e. the work of the IPCC and then report what conclusions you came to?
Please allow me to try to interpret your position here as i understand it (because i do not think you have stated it as clearly as you could have). I will also add my response to your argument as i understand it.
(However once again your argument is not perfectly clear to me so if i misinterpreted it please elaborate so we understand eachother correctly!)
Am i correct in understanding that you believe:
a) It is not the case that the scientific tools available to us (proxy measurements etc) can say something about the last 400 years with a higher degree of certainty than the preceding 600 years.
b) It is a fact that the increase in temperature in the last 400 years is wholly explained by there being a small ice age 400 years ago.
Would you mind pointing me to the post where you made the definition originally, or ideally restating it in the context of / in reply to my argument above, stating why you believe that definition is more relevant than the one i made?
The latter would help most in making your position clear and advancing our discussion.
Then your description isn’t very meaningful.
Maybe you should say that . . . but you might be interested to know that the IPCC’s temperature record of the past 1000 years has changed considerably over the years.
No. I won’t completely disregard arguments along the lines of “most scientists say X.” I just don’t find them compelling without more.
No, that’s not correct. As far as confidence goes, the distinction lies in what is being measured. Let’s suppose that somebody has a lousy measuring stick, and he claims that according to his measuring stick (1) brazil84 is shorter than the Empire State Building; and (2) brazil84 is shorter than Woody Allen.
Even though the measuring stick is lousy, we can still be pretty confident of claim (1).
Actually, I would mind. Because I think you should read this thread before posting in it.
See here for a discussion about trying to determine trends over short time periods…which holds even more strongly when you cherry-pick the start date of the time period to have the start year be the one that just happened to be head-and-shoulders above any previous year! And, note that the last 7 years are all in the top 8 warmest years. The only year in the top 8 from outside of the last 7 years is 1998.
The interesting question is whether those who have jumped on this “temperature flattening out” meme (which even includes the few real publishing climate scientists who are skeptics, like Richard Lindzen) are going to actually concede that there is any big problem with their point-of-view if, a few years from now, we get to the point where the 1998 temperature is being exceeded quite regularly and it becomes clear that the global temperature has not in fact flattened out. My guess is that they won’t.
I would rather say that originally my description was quite meaningful, being part of a coherent argument stretching over several sentences and all. Now having been boiled down to the simple blatant assertion you make above it seem to me suddenly somehow stripped of it’s original meaning.
Whole argument reprinted, as I think it would be more constructive for us to discuss it as the whole coherent argument it originally were rather than you responding to some small pieces of it and both of us forgetting the context those small pieces were originally in:
Yes I am very interested. Could you please outline how it has changed over the years?
Fair enough. But is that your position then visavi f. e. the IPCC, you don’t find it compelling “without more”? More of what? It seems like i try to advance my view of things here in good faith and i don’t really in all honesty see you responding to the arguments i make. It feels more like you are “dodging”, and changing the subject.
Fair enough, but how exactly did this relate to what i originally wrote i.e. that the my understanding of current knowledge is that we have a fairly good picture of the last 400 years and a somewhat murkier of the preceding 600 years. Please try to make your argument a little more clearly and in response to the actual argument you are responding to. Otherwise it seems (to me at least) like your obfuscating.
There are 5 pages of this thread which i actual have read over the past couple of days on and off. My memory is not perfect however. I am quite dissapointed that you will not point out your definition or restate it. This in my view at least points to the conclusion that you are not - in contrast to the claim you so boldly made in your OP - having this discussion in good faith, but rather selectively chosing from other viewpoints small parts, out of context to respond to.
To bad, i’m feeling further participation here will lead to no good 
However if you actually are interested in meaningful, constructive exchange of perhaps conflicting ideas and viewpoints i am happy to reconsider. Please let me know in that case.
Hey, and guess what happens when you cherry pick the start date to take advantage of the fact that we’re coming out of the Little Ice Age? That’s right, you get a nice warming trend.
And here’s a question that’s just as interesting: What happens if temps continue to stay flat or even decline over the next 10 years? Will Hansen admit that his predictions were dead wrong? Will his point of view change? My guess is that it won’t.
And since you’re back in the thread, would you mind trying to answer the questions I asked in Post #102? I couldn’t find your answer anywhere.
Let’s put it this way: The aspect of your statement in question doesn’t have much meaning.
Look at this – http://www.climate-skeptic.com/2007/09/chapter-4-skept.html – under “The Medium View.”
More arguments (and evidence) beyond a simple appeal to authority.
Exactly what argument do you make that you feel I am dodging? Please just spell it out.
You suggested that the reason for the distinction was that the tools don’t work as well. The real reason for the distinction is the ease of measuring what we are trying to measure.
And by the way, I don’t necessarily accept that we have that great a picture of temperature changes between 1600 and 1850. Because of the Little Ice Age, it is possible to be reasonably confident that current temperatures are unprecedentedly high over the last 400 years. But as to further details of the Little Ice Age? I’m skeptical.
As intention pointed out, it doesn’t make sense that we need thousands of thermometers to measure temperature today, but 400 years ago it could be done by measuring a few glaciers.
You can conclude whatever you like, but the fact is that my definition is not hidden in this thread and you can find it just as well as me. I think that anyone who reads the thread in good faith will see it pretty quickly.
I am happy to have a meaningful exchange. But in fairness, you should read the thread in good faith before you contribute.
Excuse me but what does that even mean? What aspect of my statement? Ah, “the” aspect, the one “in question”. I see…
Actually it’s quite plain to see for anyone taking the time to read my original post that my statements had a perfectly and easily understandable meaning i.e.
I am simply stating some very well known facts about the limits of what we can empirically say using the scientific method as applied to historical global mean temperatures. Nothing very hard to understand at all and everything entirely meaningful. You may agree or disagree but your rambling about it lacking meaning seems to me quite the non sequiteur.
Ok, now I see that I am actually not having an open discussion in good faith with the poster brazil84. I am in reality having a bad-faith debate-by-proxy with AGW sceptic Warren Meyer where I am supposed to read ~7 pages of chapter four of his book A Sceptical Layman’s Guide to Anthropogenic Global Warming.
How about this instead: You brazil are the one who made the assertion that IPCCs “temperature record of the past 1000 years has changed considerably over the years” and hinted that you were about reveal in what way. How about you summarize the parts of those ~7 pages that relate to the IPCC temperature record of the past 1000 years changing considerably over the years, and feel free to make it a coherent argument of your own design.
Ah, yes simply buying the statements of some authority is a bad thing I am the first to agree as I am sure Warren Meyer would as well.
I will try to make my original argument once again and offer you one more oportunity to have a good faith disscussion with me with this as a starting point.
(I will label my understanding of the facts as P1- calling them informally my premisses and then s:
Our tools of measurement to make statements about historical global mean temperature (hereafter HGMT) is:
P1) very good for the last 150 years or so.
P2) quite good for the last 400 years.
P3) somewhat murkier for the 600 years preceding.
The above represents MY understanding of the state of research as communicated by f.e. the IPCC
P4) The aggregated HGMT measurements for the last 150 years shows rapid increase in GMT.
P5) The aggregated research of proxy records for HGMT for the last 400 years show rapid increase in GMT for the last 150 years or so, the last couple of decades being the warmest during the period.
P6) The aggregated research of proxy records for HGMT for the last 1000 years show with some certainty:
a) there are two potential maximums during this time period, one now, and one 1000 years ago.
b) there is a probable local minimum somewhere around yr 16-1700.
c) a plurality of proxy data indicate the present maximum is warmer than the one 1000 years ago, but it is hard to say with absolute authority.
So my argument then: given premises (again meant informally) 1-6 in my view it is quite likely that the time we are living in is the warmest in the last 1000 years, although it is hard to say with absolutely certain. It may also be that the warmest time was 1000 yrs ago and now is the second warmest.
Given that this is what we know it is then unreasonable to say that the hockey stick is somehow discredited or unreasonable.
The argument that i’d like for us is spelled out above for your convienience, once more.
How is this not one and the same? The tools not working as well further back in time or the ease with which we measure further back in time - is that not the same thing? What do you mean?
Well I think I will make the following appeal to authority here. The reason for ME having come to the understanding that we have somewhat better measurements for the last 400 years is my understanding that this is something that is stated in the IPCC. That is they have evaluated the aggregated body of research and tried to verify the level of certainty.
You are free to accept or not accept but like you said - until you start wrestling with the actual arguments and facts its just your opinion on the one hand and the authority of the IPCC on the other.
Yeah thanks and hidden or not theres still 228 posts in one of which it resides. You obviously know where and hopefully you know what it was but still you’d rather send me searching than make yourself properly understood.
Which I have, setting aside that there is no such requirement to participate. You are of course free to set whatever rules you like for whom you feel dignifies spending your precious time on. If you truly want a meaningful exchange however it would be in your best interest to extend me that curtesy.
Errata:
I will label my understanding of the facts as P1-P6 calling them informally my premisses and then stating the conclusion i draw from them in regards to “hockey stick”.
it should have read
errata 2:
The argument that i’d like for us to discuss is spelled out above for your convienience, once more.
Sheesh. The part about 100%. Duh.
He lays it out very well. If you are too lazy to take 5 minutes to read what he says, you could just look at the pictures – there’s one from each of 3 IPCC reports, plus a couple details and extras.
If you were arguing in good faith, you would perhaps take 5 minutes to read the argument presented, and then respond to it.
Clearly the IPCC’s version of temperature over the past 1000 years has changed significantly.
Lol. Whatever. Just look at the pictures:
(From the 1990 report)
(from the 2001 report)
(from the 2007 report)
And my response is that the “hockey stick” is more than just the assertion that recent temperatures are unprecedentedly warm over the past 1000 years.
Because the problem is with what we are trying to measure – not how well the tools work. It’s possible that the tools don’t work very well at all even looking back just 400 years. For example, the Little Ice Age may have been significantly cooler than Mann claimed.
Because I would prefer that you read the entire thread before you post. If you were attempting to argue in good faith, you would read the whole thread before you posted in it. Just my opinion.
And I would ask that you extend me the courtesy of actually reading my posts in this thread before you respond. It’s your decision.
First of all, the problem of cherrypicking is much more relevant when you are looking at trends over so short a time that the noise is large compared to the signal, as the article that I linked to discusses. Second of all, it seems that this claim of recovery from the Little Ice Age is more of an excuse than anything else. Much of whatever such recovery has occurred had occurred even before the start of the instrumental record or in the early part of it. There is no evidence based on an understanding of natural forcings to suggest that we should be continuing to come out of the Little Ice Age and that, in fact, any of the warming since 1950 can be attributed to that.
Well certainly, if that occurs (and ignoring the quibble that I have with the word “continue”), then it will be necessary to understand why that is occurring and how it modifies our understanding of the climate system and the strength of the various forcings. Historically, the bulk of the scientific community has been willing to modify their views in light of the evidence…For the so-called “skeptics”, this for the most part doesn’t seem to be the case.
Your Valley Girl impression is amusing, but:
I reprinted the full paragraph the 100% percent statement was in, mind explaining again how it is meaningless?
Actually this is a quite good example of you dodging and being unresponsive wouldnt you say? I asked you what like totally like 4 times now, duh.
I’ll reprint it again:
Ok so let me tell you what i see.
I see two graphs i have seen before and which i know what they show.
I see the original hockey stick graph by Mann (the picture from the 2001 report). It is to my understanding a graph of one set of proxy data i.e. the set explored by Mann in his research.
Furthermore I see a graph (2007 report) aggregating different sets of proxy data (9 or so), one of which being the Mann data.
I would be hard pressed to say that the 2007 graph “contradicts” the 2001 graph or anything like that. One shows 1 set of proxy data the other shows 9.
Then in addition i see a graph that i have no idea what it is showing. Since you have read your pal Warren laying it out so nicely do you mind explaining which proxy data it is showing? Is it even global mean temperature?
Yeah, and you can’t be bothered to explain again what it actually is, i have to search the thread, got it. I’ll get back to that.
How have you been able to show how “how well the tools work” to be in contradiction to “there is a problem with what we are trying to measure” and “the little ice age may have been significantly cooler than Mann claimed”?
Your argument is incoherent and basicly a non seqiteur and as such impossible to respond to.
I have done both, which i have also stated previously. That does not necessarily entail that i remember all of the thread right off the top of my head. Seems like quite the silly thing to require from people if you are actually interested in an honest exchange of ideas.
However, to be able to move forward i read through the thread yet again and found this:
Now this seems totally disingenious definition if you want to argue that the “hockey stick” has been “discredited”…
The “hockey stick” is a particular graph showing a particular survey done using a particular set of proxy data. It was so named the “hockey stick” since the graph resembled a hockey stick.
Are you actually saying that the real life historical mean temperature for the last 1000 years must be proven to resemble a hockey stick when printed in graph form or else Manns research is “discredited”?
My argument above then i would rephrase in compact form as this: It is not unreasonable given what we know that the actual historical GMT resembles a hockey stick to a fair degree for the last 1000 yrs, albeit with a somewhat bent hilt. it may also be that it resembles the bottom half of a circle or some related shape. We dont know for sure. We know pretty well it does not resemble a snail or a beetle car.
We know with resonable certainty that the the last 400 yrs resemble a somewhat irregular hockey stick with some of the handle chopped off. We cant say for sure whether the shape for the last million years is a couple trying nr 34 from the karma sutra. But we have a number of strong and discomforting indications that it is going to resemble a downhill slope ascending to our right in the near future.
How is this useful again?
What time period would you consider too short?
Given that we don’t know with certainty what temperatures were like before the Little Ice Age, it seems somewhat hubristic to make such an assertion.
My prediction is that the catastrohpic AGW theory will be tweaked a little bit, but not abandoned. Not by the die-hards, anyway.
Can you give me some cites?
Oh, and do you have any response to the questions I asked in Post #102?