I’m still around; I’ve been busy and I should get around to responding sometime this week.
Thanks, aptronym. We all have constraints on our time.
w.
Speaking of patience with others’ timing - I’m likely the worst offender in this thread. I didn’t take a trip this time - I’ve been catching up on DVDs of Flight of the Concords and sitting on my butt eating chips. 
But I do hope everyone has had at least as good a time away from this thread as I have.
Are these rhetorical questions?
I’ll pretend for a moment that they are not:
Overpeck, Hughen, Hardy, Bradley, Case, Douglas, Finney, Gajewski, Jacoby, Jennings, Lamoureux, Lasca, MacDonald, Moore, Retelle, Smith, Wolfe, and Zielinski here:
From: Overpeck et al. 1997. Arctic environmental changes of the last four centuries. Science, v. 282.
And Briffa, Osborn, Schweingruber, Harris, Jones, Shiyatov, and Vaganov here:
table not reproduced due to my fiascotacular encounters with the code function, but it may be found on page 2933 of the work cited below
From: Briffa et al. 2001. Low-frequency temperature variations from a northern tree ring density network. Journal of Geophysical Research, v. 106.
And Mann and Jones (the same Jones who was 5th co-author of the above paper) here:
From: Mann and Jones. 2003. Global surface temperatures over the past two millennia. Geophysical Research Letters, v. 30.
And Crowley here:
From: Crowley. 2000. Causes of climate change over the past 1000 years. Science, v. 289.
Now we have a list of 27 climatologists who are addressing your questions in their published work. Many of these papers – the Briffa, Mann, and Crowley citations above – have come up in the thread before since they are listed on the wikipedia site: File:1000 Year Temperature Comparison.png - Wikipedia that was referenced earlier in this thread (I believe on the first or second page of this thread.)
It looks to me like climatologists are concerned about whether their proxies can be validated through comparison with the instrumental record. Why do you appear to believe they are not answering that question?
I rarely agree with intention on anything, but:
This is certainly true - one of the first things that should happen in science education at the undergraduate and/or graduate level is learning to pick apart published papers with a critical eye.
That being said…
I haven’t read the paper in question yet, do you have a quote handy for where they say they can do this?
That’s not exactly the question I had mentioned. However, it does appear that some of these people have tried to answer my question - but not in a very satisfactory way.
For example, you cite Briffa 2001. Apparently, the proxy temperature measure in that study completely missed the recent increase in temperature. Apparently, when putting his graph in the IPCC report, Briffa simply truncated the data after 1960. And this was apparently the explanation offered for the truncation:
So yeah, it would appear that some “paleoclimatologists” are concerned about the divergence problem. Concerned enough to bury the divergent data.
And no rule against it either. You have chosen a value for which single-year changes effect large changes in slope - arguably a poor choice. I have chosen a value for which single-year changes do not effect large changes in slope - arguably the better choice.
This would be no different from picking October 28, 1929 and November 28, 1929 as “evidence” that the stock market wasn’t rising.
Ah, but I am not arguing that the hockey stick exists. That may be the point of the thread, but not the point for which you asked me to come into this thread.
I specifically stated that despite the hockey stick being false, that there was good evidence that the temperature increases in recent history were unnatural.
Well, at least your point is consistent - you seem to accept all the crap evidence at face value and reject all the good evidence.
Why would you accept 40-year-old non-satellite measurements of arctic ice area and not 40-year-old non-satellite measurements of temperature?
No, it’s entirely relevant. You’re just not seeing how your position is self-inconsistent.
If you accept the proxy records, then you can take the slope for any interval and see that current slopes are higher than historical slopes. You can also make the claim that historically, temperatures were once as high as they are currently.
If you don’t accept proxy records, then you can claim the current warming may be natural - but that you can’t claim there was a Medival Warm Period or a Little Ice Age because no temperatures prior to 1850 can be known.
To be clear, then, you are saying that you accept that other climatologists have published peer-review articles, but that you have enough expertise in the field to determine that the authors and the reviewers are wrong?
To be crystal clear, you have at least a M.S. and first-author or last-author peer-reviewed publications of your own in a climatology-related field?
Okay, so which ones don’t show divergence in the 20th century?
List out data sets you think are acceptable or interpretations you think are acceptable; we’ll argue based on those data. This then avoids the whole problem of me (a non-expert) randomly picking data sets and you shooting them down.
If you have expertise in the field (as I have defined above), then I concede that I no longer can argue with you about the data sets - your expertise will trump anything I say as far as forming your opinion is concerned. However, you will understand that even in that case, unless you are willing to give me personal information to identify you, that my opinion will be based on what I can find in peer review.
If you do not have expertise in the field (as defined above), then I seriously question what information goes into your decision-making. We deal with peer review not because it’s perfect, but because it’s better than non-reviewed sources.
I think I’ve explained this above, but let me be crystal clear: I believe that we should use the most reliable information possible. If we are all non-climatologists, I will argue for using peer-reviewed literature. If you are a climatologist, I agree you are free to make judgements for yourself.
Let me make an analogy in my field of expertise (organic chemistry).
The mechanism of ozonolysis, for many years, was disputed. Many papers argued that [3+2] cycloaddition of ozone across an alkene formed a molozonide which underwent a retroaddition to give a carbonyl oxide, and then a final [3+2] cycloaddition gave the trioxolane which could be reductively cleaved. A small minority of papers argued against concerted disassociation and diradical formation.
Now I, as a trained organic chemist, contend that this debate is settled in favor of the Crigee mechanism, and that definitive experiments have been done which have settled this debate. I can cite you peer-reviewed papers, 90% of which support the current “consensus” on ozonolysis mechanism.
Do you, as (presumably) a non-organic chemist, wish to contest any of this? Is there anything in either mechanism which you, as a non-expert, can pick out as unreasonable?
Assuming the answer to both questions is no, then I simply make the analogy that I accept what the experts in the field of climatology say. Unlike the example I gave, climatologists use words that are comprehensible to non-experts (“atmosphere” and “glaciers” instead of “molozonide” and “trioxolane”), and I believe that gives people a false sense of understanding - “I know what a glacier is, and therefore I am qualified to interpret glacier data.”
Limiting the answers to yes or no is the actual obfuscation here (is that the word of the week?).
Global data is simply a collection of local data - you cannot single each local data set, exclude it on an individual basis, and then claim we can know nothing about global temperature. If glacier records and tree rings and ocean sediments all give the same answer, then it is a global picture even if none of the data sets are individually global.
That’s the real question - whether there’s enough data which independently confirms the glacier data.
I’m not sure the answer to this question will help your case. I believe that their results corroborate independent measurements of historical temperature - thus, their glacier study both shows accurate global temperatures (as measured against an independent set or sets of data) and proves global temperatures.
Yes, but given that non-reviewed information (including posts on the SDMB) have not gone through that process, peer reviewed journal articles are superior to what an anonymous individual has posted on a blog, website, or forum.
That it does not. But given that your post (non-peer reviewed) and the author’s paper (peer reviewed) disagree, which should be given precedence? If the public needs to make a policy decision, which conclusions should the public accept?
You yourself just said that peer review finds the obvious errors. If you believe than an untrained eye can pick up something that peer review doesn’t, either you are claiming that peer review is worthless, or that climatology is a field in which people can train themselves on the fly.
What is more probable, that an apparent contradiction/error which at least two skilled individuals have OK’d is an actual contradiction/error, or that an apparent contradiction/error as seen by an unskilled individual is not an actual contradiction/error?
Peer review isn’t perfect, but it beats no review.
Well, it depends what your claim is. If your claim is that the rate of recent warming is unprecedented if (1) one uses the Esper proxy study; AND (2) one looks at the reconstruction in 150 year intervals; AND (3) one ignores any uncertainties in the reconstruction, then yeah . . you are free to look at 150 year chunks.
However, if you are claiming that the recent rate of warming is unprecedented without regard to any particular interval length, then it’s my privilege to choose any reasonable interval length to test your claim.
Do you agree that 40 year chunks are reasonable? 100 year chunks? 200 year chunks?
I don’t think so . . . the graph appears to have been 40-year smoothed.
Again, it depends what your specific claim is about the market.
Where exactly do I say that I do these things?
If it’s entirely relevant, then why did you state the following:
bolding mine
Your position is flip-flopping so quickly, I’m getting whiplash.
ANY interval?
That’s nonsense. One can be skeptical that reconstructions such as Esper’s are as accurate as the are offered to be while still agreeing that certain periods were likely warmer (or colder) than now, but without knowing the exact amount of the difference.
Peer review finds trivial errors, serious errors, procedural variances which did not produce errors, and, fairly often, significant errors in methodology which bear on more than the paper being reviewed. The review doesn’t come just from the publishing concern; it comes from the many hundreds of interested parties who read the articles.
So, if you are saying that the data of any particular research paper do not support the conclusions, you can write to the publisher, and state your case. Of course, you need to have your own observations fairly clearly laid out, and your objections referenced to fairly well known principles, or reliable, reproducible data. Letters between researchers continue to be exchanged for years after particularly important studies are published.
Internet blog review, on the other hand requires no particular expertise, education, or preparation. You just say, “That’s bullshit.” If the person who spent a year and a half working on an analysis of three years work in the field doesn’t respond to you, then you go else where and reference where “That study was debunked!”
The famous “hockey stick” graph is not the sole piece of evidence upon which the theory of anthropogenic influence on global temperature rests. Repeated measurements of world wide temperatures have been made by many institutions. Yes, most of them are in the northern hemisphere. Yes, it turns out that the climate of the southern hemisphere is responding significantly differently to the world climate shifts of the last hundred years, and also responded differently to the climate shifts of other historic periods, of all lengths. Not that surprising, really, given that most of the worlds land is in the north, and most of the worlds Ice is in the south.
I am unsatisfied with the current reliance on both paleoclimate proxy records, and computer modeled projections of trends based on them. Projections based on proxies seem a bit too far from reality to me. But that in itself is not sufficient to “debunk” the particular significance of the issue highlighted by the hockey stick graph. Even if that graph is simply art work, the data from instrumentation show increases entirely consistent with the prediction the hockey stick makes. Climate is warming, and the rate of warming is significant in magnitude, and effects are greater in areas inhabited by humans. There are well maintained records, openly peer reviewed, and responsively maintained by NOAA, NASA, and various other institutions staffed by people who have studied the phenomenon for literally lifetimes. There are similar agencies in other countries doing the same thing.
Popularity is not proof of a theory. However, reliably reproducible results are evidence. Proxies have been being studied in greater detail in the last decade than ever before. Some have proven less reliable than expected; some remain untestable because no standard exists. But, when multiple methodologies provide similar results, it is not unreasonable to use those results in examining world wide historic trends. Unfortunately, climate is sufficiently chaotic in nature that every prediction, foreword or backward in time is greatly compromised in confidence over the very long periods under discussion.
Right now we have just passed the low point in the eleven year solar cycle. Reasonable estimates give that as a -0.2 degree C variance in expected temperature averages, worldwide in comparison to the high point. The North American temperatures are further moderated in increase by an active La Nina during the last year. Increases in wind shear in the North Atlantic have altered the formation and movement of hurricanes from those of previous years. Movement of dust clouds from Africa, a phenomenon not studied before this century (decade) show an unexpectedly high level of influence on cloud formation over the South Atlantic, and the Gulf of Mexico. These factors complicate prediction enormously, and they are far from the only ones to be considered.
But given all that, still, it is not a theory that global temperatures have increased. It is not a theory that areas where human influence is higher have greater warming. It is not a theory that green house gases increase temperatures, and that one of these is Carbon Dioxide, which is increasing in concentration over all instrumental recording periods, and that temperatures also show increases over all warming periods.
Assuming that human activity is not a part of global warming is stupid. In every other interaction where humans affect the environment the actions of humans overwhelm all other factors. Forest growth, fish populations, erosion, extinctions, background radioactivity, metallic elements in the biosphere, all show more change from human activities than any other source. We move mountains, and we do it in decades, not epochs.
Arguing about a single graph is equally stupid. OK, the graph is absolutely wrong. Art. Just made up stuff. The temperature is still rising, and the point of the graph is still true.
Tris
So you’re saying that you believe in some sort of conspiracy theory in which scientists conspire to suppress The Truth?
I’m trying to figure out why you’ve decided to go with an unattributed quote. I can see it being useful in a debate where one doesn’t want one’s opponent to look deeper into the context of the provided quote, or I can see it being an accident.
A google search on “we make the assumption that it is likely to be a response to some kind of recent anthropogenic forcing” leads to a climateaudit presentation, not surprisingly:
Regardless, Briffa and his co-authors are on record providing more information on this issue. Here’s a similar quote:
From: Briffa et al. 1998. Reduced sensitivity of recent tree-growth to temperature at high northern latitudes. Nature v. 391
You used the term “bury” to describe what you thought Briffa was doing with the data. What an insightful way for Briffa to bury the data – by writing an article about it and submitting it to one of the most widely read scientific journals in the English-speaking world, kept on hand by tens of thousands of academic and public libraries!
Reading the article reveals that Briffa et al. suggest some hypotheses to explain the recent changes in wood density:
[ul]Stress from lower soil moisture may change the linear thermal response observed at lower temperatures. (The authors don’t like this explanation because of the lack of evidence for lowered soil moisture in these high northern latitutdes recently.)[/ul]
[ul]Changes in the warmth of spring or snow melt time may influence wood density.[/ul]
[ul]Opal did it. :)[/ul]
[ul]Changes in competition with other types of plants.[/ul]
[ul]Increased insect herbivory.[/ul]
[ul]More ultraviolet light or “decreased solar radiation receipts.”[/ul]
[ul]Increasing acidic deposition.[/ul]
The authors don’t mention it, but I would add changes in micronutrient isotope ratios – the 1960s make me think of nuclear tests and other release of radioactive isotopes in the northern hemisphere. However, I would think insect herbivory increasing with increasing temperature makes more sense than my hypothesis.
It turns out that the divergence does not occur due to the failure of a mathematical algorithm, but instead because of a recent (not ancient) change in the density of the wood. You’d have a case for failure of the reconstruction algorithm if you could show that this change in the physical factors of the wood density happened before in the record, but Briffa et al. maintains that it is recent.
Briffa et al. also mention when the proxy can be good:
From: Briffa et al. 1998. Reduced sensitivity of recent tree-growth to temperature at high northern latitudes. Nature v. 391
The same article as above. Table 1 shows the correlations, which look pretty good for decadal tree growth vs. temperature but pretty bad for interannual tree growth vs. temperature.
Wouldn’t it be a good idea to use the tree record only where it can be shown to be valid and use other proxies for other time periods?
But you’ve mentioned a lot about not splicing records. Not sure why you don’t want us to do that.
If I were drowning and rescued by paramedics, they would measure my heart rate by pulse first. When they got to the hospital, they would switch to a heart monitor. If they chart my heart rate over time, they will splice data from two different methodologies. I don’t have a problem with that, I want them to do that. I’m still not sure what your problem with it is.
It is unrealistic to expect every method to measurement to provide the best proxy for temperature over all time periods. (For example, in radiometric dating, radiocarbon dating is effective over some time periods while potassium-argon is better over other time periods, and rubidium-strontium dating over yet other time periods. Use potassium-argon dating on something only 1,000 years old, and it will fail miserably. Creationists love that trick.) Demanding that scientists do something unrealistic doesn’t prove them wrong when they don’t do it.
I think it makes more sense to use the tree ring chronologies for ranges within which it can be shown to have a correlation for temperature, and not use tree ring chronologies when the density of the wood moves outside that range. Then you can cross-check with other methodologies for the range in which you’ve used them, and depend completely on the other methodologies for the range in which tree rings cannot be used. That’s a multiproxy approach.
I don’t know that this is really the best criterion - I think we’ll have to see what ideas come out of various posters and accept that they may or may not know what they’re talking about. Take all internet debates with a grain of salt.
For example, I’m not a climatologist, but I’m not really going to discuss my qualifications or lack thereof beside that simple statement.
Lol, it depends what you mean by “conspiracy.” It would appear that the IPCC truncated a little inconvenient data. If that’s included in your definition of conspiray, then yeah, there’s a conspiracy.
Which article are you talking about? It seems a little odd that he would write, in 1998, about truncation of data done in 2001.
In any event, it does appear that the IPCC left out some inconvenient data from its report. If the word “bury” is too strong for you, feel free to use “omit” instead.
I don’t know what relevance the 1998 article has to the 2001 truncation, but anyway, how could one test these seemingly ad hoc explanations? How do you know that there wasn’t some temperature extreme 800 years ago that was masked by one of these factors?
Well, it’s good that you have a sense of humor around conspiracy theories. Laughter helps to keep paranoia at bay. 
It would seem odd if the truncation occurred in 2001.
Let me pose the following scenario:
1990s – Briffa et al. measure tree-ring densities, discovering that the densities of many trees after 1960 are outside the range they can reliably associate with atmospheric temperatures.
1998 – Nature publishes an article by Briffa et al., letting the scientific community know how decadal tree growth can be related to temperature pre-1960, but that after 1960 the densities decrease so much that they are in a range not seen before, so it cannot be associated accurately with temperatures.
2001 – The IPCC publishes a report in which Briffa decides to include the information on tree ring density in the IPCC report (I’m assuming the quote you posted earlier was from an IPCC report.) Since the IPCC reports are compilations of work done by climatologists and other scientists over the time before the report is published, it wouldn’t be surprising for the report to include information also published in the Nature article three years before.
What is there about that scenario that doesn’t make sense?
I thought it was obvious: Briffa et al. 1998. Reduced sensitivity of recent tree-growth to temperature at high northern latitudes. I quoted it twice in my post, and the title gives you a handy idea of what the article is about.
I would recommend that you read the article. I think you have misunderstood the implications of what Briffa et al. wrote.
Here’s a more explanatory quote:
From: Hughes, M. 2002. Dendrochronology in climatology – the state of the art. Dendrochonologia v. 20. (Emphasis mine, not in original.)
I am a little disturbed that you criticize the accuracy of current proxies, but complain of a “conspiracy” when proxies known to be of lower accuracy are excluded. Do you see any cognitive dissonance in this?
For one thing, the unusually low density of the wood has not been found anywhere else in the record (as of 2002 – see the quote below.)
From: Hughes, M. 2002. Dendrochronology in climatology – the state of the art. Dendrochonologia v. 20. (Emphasis mine, not in original.)
So there is at least some evidence to suggest that changing snow patterns and snowmelt time are indeed responsible. But it is a good question. First, since you don’t see that wood density anywhere else in the record – which appears to be the case - you know that it must be something about the 1960s and afterward that has not occurred during the earlier time periods you have tree ring cores for.
Second, you cross-check tree ring core density with other measures of past temperature to see if it disagrees. Those areas of disagreement become areas of interesting research. If any of them had that unusually low wood density, then that would be a red flag.
Third, you can examine tree ring cores from elsewhere in the world and compare them to your data set – if, as I suggested, radioisotopes were responsible, then northern hemisphere tree ring cores should show the effect on density more dramatically and earlier in the record than southern hemisphere tree ring cores because most of the radioisotopes released in nuclear testing and reactors were in the northern hemisphere. Since increased insect herbivory is expected with increasing warmth, you could expect southern hemisphere tree ring cores to show increased density later since the warming in the southern hemisphere has been slower than warming in the northern hemisphere.
There are other comparisons you can make – if you want to test the idea of increased competition from other plants with the notion that introduced species may be playing a role, then you examine the areas from which your tree ring cores were taken, and compare cores from forests that have a lot of introduced species with cores from forests that have fewer introduced species. If you compare samples from forests where snow melt occurs at different times, you should observe differences in the density of the wood if snow melt timing is responsible.
There are a lot of ways to test the hypotheses proposed.
And I’m not sure how to make it any clearer. But to take your analogy, let’s suppose that one graphs your heart rate, and there is a marked change right around the time that the paramedics switch from pulse to heart monitor. A reasonable person would strongly consider the possibility that the “marked change” is an artifact of the switch, and doesn’t necessarily correspond to any change in the reality of your heartbeat.
Well, I was laughing at your insinuation. Take that for what it’s worth.
As I understand things, the IPCC report was based on Briffa 2001.
For starters, I see a straw man, since “conspiracy” is your word - not mine. But anyway, it’s a bit of a mischaracterization to state that “proxies known to be of lower accuracy are excluded.” Because 20th century divergence casts doubt on the entire proxy. And yet only the inconvenient part has been excluded.
Where in the quote does it say that?
And is there any evidence that the 20th century was unique with respect to the factors you list – for example insect herbivory?
Except that in this case:
-
The temperature record overlaps the proxies for a considerable amount of time – 1856 to the present for the instrumental record.
-
The recent warming period appears after the instrumental record has already started – it does not appear when the proxy meets the instrumental record.
See this graph to follow the timing: http://en.wikipedia.org/wiki/Image:HadCRUT3-temp-record-alternate.svg
It looks to me like the temperature anomaly only rises above -0.3°C in the 1870s-1900 and again 1920-present. Where is your “marked change” and where is the “switch?”
- The whole idea of a “switch” is a fallacy in this case - no one stopped measuring proxies when the temperature record starts in 1856. The proxies continue to be measured in the modern era and the overlap is used to measure how well the proxies perform vis-a-vis instrumental measurements.
For example, have a look at these correlations:
_______________Decadal maximum latewood density________Decadal tree ring widths
with
1881-1981
instrumental________0.64_________________________________0.43
record
with
1881-1960
instrumental________0.89_________________________________0.74
record
See Table 1 in Briffa et al. 1998. Reduced sensitivity of recent tree-growth to temperature at high northern latitudes.
Briffa then discards methods of using tree density and rings that don’t correlate well because they don’t work. However, you criticize him for not using the methods that he discovered don’t work! How then are we supposed to find methods that do work if you criticize us for not using methods that don’t work?
I take it for exactly what it’s worth – a rhetorical device to make readers think you’re laughing at me, a kind of ad hominem in acronym form which does not address the substance of my posts. I don’t think anyone believes you’re actually laughing out loud. 
How do you understand things? You haven’t even provided a citation for your quote in post #185 yet.
You were free to answer the question in any way you wanted. You could have said “No, I don’t believe it’s a conspiracy, I just believe Briffa has fraudulently altered his data on his own.” Or “perhaps this is an error that slipped through peer review.” It’s a little late to say a conspiracy is a straw man when you have agreed that there is a conspiracy:
Tree rings and density do not care about human designation of a century as the 20th, 21st, or 19th. They do respond to environmental factors - temperature, light, and snow melt time, for example.
From: Hughes, M. 2002. Dendrochronology in climatology – the state of the art. Dendrochonologia v. 20.
I posted this exact same quote above in post #195.
Let me spell it out for you in words: Your claim that I’m accusing anyone of a “conspiracy” is laughably absurd. Essentially a refuge for an argument that is failing on the merits. Clear enough?
So ask me for one.
Nonsense. I haven’t agreed that there is a conspiracy. To me, what matters is the underlying reality of what the IPCC did. Not semantic games over how to characterize that conduct.
And as far as I can tell, it’s non-responsive to my question.