One of the commenters to my last post, an attempt to explain why the hacked climatology emails do not constitute a scientific scandal, came up with a darn fine idea:
If you think that global warming rests on a few temperature data sets and models, you are very wrong. If you don't understand this then you don't know enough to have an opinion on the subject, and you most likely will be treated just like any other ineducable troll.
Grab a climate textbook and do some reading...it will help if you have some physics background too. Yeah, science takes effort...
I just happen to have at hand a brand new textbook on the very subject at hand. It's called Paleoclimates: Understanding Climate Change Past and Present, by Thomas M. Cronin of Georgetown University, Columbia University Press, 2009. ( I have no idea why the CUP folks decided I would be an appropriate reviewer deserving a free copy of $95 textbook, but I haven't bought a book with my own money in more than four years thanks to this blogging gig and I'm happy to accept this one, too.)
As has been pointed out numerous times, nothing in the stolen emails and other documents that found their way onto the Internet last week in any way challenges the science behind anthropogenic global warming. But a lot of the material does deal with one particular subfield of climatology, dendrochronology, the science of which appears to confuse just about everyone who doesn't study the subject for a living.
I'm no expert, but Cronin is, and on page 312 he address the very issue that has so many amateurs puzzled. Specifically, what do climatologists mean when they write about "hiding the decline" in tree-ring proxies? It sounds bad, but it really isn't. The Real Climate gang explained it, and rather well I think. But many remain unconvinced. So let's turn to the text, specifically the section titled "Proxy limitations -- Divergence and Segment Length Curse," shall we?
... no tree ring-based reconstructions of northern hemisphere temperatures that includes the 1990s is able to capture the range of late 20th century warming seen in the instrumental records. This means that instrumental records show warming, but reconstructed temperatures from trees show cooling or no change.
That excerpt appears immediately above a graph that shows how temperatures inferred from tree-ring records since about 1850 (the "proxies") are a pretty good match for actual temperature records derived from thermometers right up until the 1980s. After that, the tree-ring data begin to show lower temperatures than were actually recorded.
Just why tree rings no longer provide useful proxy data for temperatures is not known. There are several theories, many of which suggest that climate change itself is the problem. Trees no longer grow as they once did before the climate started changing so rapidly. But the point is, there is no question that tree-ring growth rates of the past -- before we had thermometers -- can serve as useful proxies for historical temperature data. They are much less useful now, but that doesn't matter so much because we have actual temperature records. All of this was sorted out back in 1998. It's not new, nor even particularly interesting, to anyone familiar with the science.
This is why those working with tree-ring data want to "hide" the decline in recent decades; they know the data aren't useful. Perpetual thorn-in-the-side-of-actual-climatologists Steve McIntyre fails to grasp this simple issue when he questions the usefulness of dendrochronology data to support global warming models. And so, it would appear, do a large number of climate change pseudoskeptics who remain convinced the stolen emails paint a picture of scientists trying to obfuscate or distort climate records.
Incidentally, in case anyone wants to suggest that Cronin is somehow complicit in the alleged coverup, the author repeatedly takes great pains in his text not to come across as a climate change alarmist. I would say he actually goes too far in the opposite direction. In one section he even wastes a quarter of a page discussing the controversial 2003 paper in Climate Research by Soon and Baliunas that convinced half the journal's editorial board to resign in protest over a failure of the peer-review process. The very paper and journal that some of the stolen emails discussed in a manner that led many of the pseudoskeptics to conclude mistakenly that there was a coordinated attempts at scientific journal censorship.
No one takes Soon and Baliunas seriously in climatology circles, and Cronin does point out the serious flaws in their paper, which tried to argue that "the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millennium." But by including the paper, even as an example of flawed analysis, in a textbook, he's probably doing them a favor they don't deserve.
So, thanks, commenter Daniel J. Andrews. Turning to a textbook was a fine idea. For those don't have a recent climatology text handy, well, maybe it would be best if we let gave the benefit of the doubt to the scientists.
And if you made it this far, please turn to Carbon Fixation for what is the definitive commentary on the whole affair: "Global Warming and Climate Change: Phrases of the decade Newtongate: the final nail in the coffin of Renaissance and Enlightenment 'thinking'"
- Log in to post comments
More like this
Thanks for troubling to make the issue more plain, James. The whole hacking incident made me feel ill -- not because it uncovered Our Great Secret (oops, I've typed too much) but because it seemingly gave so much ammunition to those who would bludgeon us with their misunderstanding of the information in an effort to prove the Great Fraud of Science (which, thankfully, remains safely under wraps thanks to the trillions of dollars in bribes every scientifically-literate person on the planet accepts in order to stay mum).
Still, it's surprising the way God decided to confuse humanity with this tree ring fiasco. I'm pretty sure this means trees are in cohoots with evil forces. I never trusted that Lorax, you know. (I was one of the first to say he probably wasn't even born in the forest.)
Yours,
CBB
Tough isn't it. You're going to be tarred with the whole mess by the public. They will read the emails and see things like tricks being used to hide declines and will come to the conclusion they are being conned. That's the reality of it. It's not about the science at the end of the day.
Reading through them, they come across as being a really unpleasant bunch, and they have committed criminal offences in the UK. Would you want any of them as your PhD supervisor?
It's far more than tree rings. They were manupulating their entire temperature record. It's not just the emails, people have the code, and you sould take a look at it.
You say
But a lot of the material does deal with one particular subfield of climatology, dendrochronology,
However, the CRU does far more than just dendrochronology.
They are highly involved in the IPCC.
The emails relate to people outside the CRU too, and what they have been up to is just as contentious.
It really does question a lot of people, and hence their establishments too.
This is a small snapshot or a sample. If the sample is representative of all the establishments involved, then science is in deep trouble.
=============
The politics is different too from the science. If people believe that several establishments have been cooking the books on climate change, they will conclude that all of them are probably cooking the books. All done on the basis of the evidence put before them.
Nick
Nick@2
they have committed criminal offences in the UK
Really Nick? Have they?
Or have they just talked about doing something which may (or may not - law can be fuzzy) be illegal.
I'd like to expand on this - but I'm thirsty now and would love to kill a beer...
Word of the day: ACORN. As in,
"The Global Warming Scam just got ACORN'ed."
Whoa. My blockquotes are all wrong. My only defense is to point out that the Preview button doesn't. All it does is:
Hoping I got the end tags correct this time...
If you don't understand this then you don't know enough to have an opinion on the subject, and you most likely will be treated just like any other ineducable troll.
Anyone who can't identify at least one of the freshman-level blunders in Soon/Baliunas 2003 also falls into the category of ineducable troll.
"they have committed criminal offences in the UK."
That's libel unless you can prove it and libel is a criminal offence. Pot, kettle, idiot.
You have to prove a)malicious intent and b)the libeler knows what they say is false. Well, unless we're talking about an insane system like the UK has. Then you would be right.
Anyway, if the tree rings are indicating temperatures that aren't born out by observations, doesn't that throw the tree ring method of figuring out past temperatures into doubt? Or am I way behind the times, and that method isn't really used anymore?
That's the thing - the tree ring record overlaps the temperature record enough that we know that it's a good proxy before the 1960s-1980s (depending on your data set.)
No one in their right mind thinks the thermometer record is *less* accurate than the tree rings, the question is what regime change in tree growth was there that made in switch from being a good proxy to a poor proxy within the span of the temperature record.
where would the tree get the nutrients for growth in the altered conditions? Increased shrub growth is a likely outcome at first and them late fall decay of plant litter (hence the nutrients are freed to ground) that flow with the melting snow during the next spring likely feeds the ponds therein and this leads to an increased bacterial activity within the deoxygenated layer that takes their energy from releasing methane (that cannot be metabolized further) generated from the plant litter in the pond bottoms. Ecological feedback mechanism in action.
No, I'm sorry, but I'm not happy with this explanation.
I must say I'm not a flat-earth denialist. I accept that anthropologic climate change is a fact, and it's about time we moved on from that. However.........
If there are data sets out there that don't fit the theory, you do not and must not try to hide the data. They must be put on the record and then we have to explain them. Similarly, you cannot rely on information like tree ring data to provide temperature sets in the past, then say that they are unreliable to provide current information. They either can always be used, or never used. If you want to use them for one but not the other, you have to explain why (and not, "we now have thermometers").
Yes, one bad set of information does not mean the whole science should be thrown out. But I can understand why the denialists will seize on things like this to try and discredit the science. Unfortunately, when you hide data - for whatever reason - its not the denialists who are doing the discrediting, it's we ourselves.
A perfect analogy for this is Edwin Hubbles data sets on receding galaxies. When he made his observations, the data he obtained did not fit his theory, but he faithfully recorded what he saw, not what he wanted to see. And that was fortunate for both himself and the science of cosmology, because a later discover showed that his theory was correct after all, and his recorded observations perfected fitted his original model.
Climatologists should act with integrity and do the same.
Good job that didn't happen, then.
Nonsense. If you have data from other sources which shows that tree rings provide an accurate proxy for temperature over most of the period for which temperatures are known, but that some of them pick up spurious trends towards the end, why on earth would you throw out the whole lot?
"Unfortunately, when you hide data - for whatever reason - its not the denialists who are doing the discrediting, it's we ourselves."
Hide what data? This divergence problem is the subject of many papers,, it is well enoguh known and studied to have made it into teh textbooks, it was jst discussed in this blog post.
Your definition of "hide data" is.. well... unique..
I have to call bullshit on this. The fact that tree-rings in the last fifty years perform differently as a proxy was published openly in the literature years ago. Look at p. 752 in Briffa et al. 2002. Tree-ring width and density data around the Northern Hemisphere: Part 1, local and regional climate signals. The Holocene, v. 12, 6 pp. 737-757. Published many years before this email "controversy."
That you don't know that climatologists have openly been discussing this in the literature is not the fault of the climatologists. Stop accusing people of lying when you just don't know what they said. This is not hidden.
MartinM and Lee, did you actually read the original article? If so, go back and read it again. It says quite clearly...
... no tree ring-based reconstructions of northern hemisphere temperatures that includes the 1990s is able to capture the range of late 20th century warming seen in the instrumental records. This means that instrumental records show warming, but reconstructed temperatures from trees show cooling or no change.
That excerpt appears immediately above a graph that shows how temperatures inferred from tree-ring records since about 1850 (the "proxies") are a pretty good match for actual temperature records derived from thermometers right up until the 1980s. After that, the tree-ring data begin to show lower temperatures than were actually recorded.....
....This is why those working with tree-ring data want to "hide" the decline in recent decades; they know the data aren't useful.
As I said in my earlier post, IF the tree ring data does not agree with temperature recorded from other sources, it is not good enough to just not use it when it no longer agrees with the other sources or the theory and claim divergence. Divergence is just another name for 'this data doesn't fit the theory and we don't know why'. That reason - dare I say excuse - is only so useful. Because if we can claim divergence now, when the information does not agree with other data sets, it can also be reasonably claimed that it NEVER was a useful proxy for temperatures in the past. In other words, if there is no causation now, by what logic can you claim causation in the past? Causation then means causation now, and unless you can provide a justification for the breakdown in causation it is equally valid to state that it never existed in the first place, and all you had was a simple case of data correlation ie a coincidence.
I have read the 'Real Climate' blog (and the original paper)and am similarly not satisfied with their explanation.....
....Those authors have always recommend not using the post 1960 part of their reconstruction, and so while âhidingâ is probably a poor choice of words (since it is âhiddenâ in plain sight), not using the data in the plot is completely appropriate, as is further research to understand why this happens.
It is NOT appropriate NOT to use data, just because you are unable to explain it; never was and never will be. It MUST be used, and it should be discussed in the appropriate section of the paper. Failing to do that is a simple case of poor science, something that should be avoided. (so you might also see that my definition of 'hide' isn't unique after all, I just borrowed it from someone else)
Except of course that it was used and discussed in the appropriate section of the paper. Look at the example I gave in post #16. The constant claims of "Look th3y'r3 hiding something" ring false when I can simply say - really? If they're hiding it, why did they publish about it in 2002? And again in 2005 and 2007?
Not a denier, here. A PhD in Chemistry, and know approximately nothing about climatology.
But given that the divergence problem exists post 1960, are there lists of other times the climatalogical data doesn't all line up? Is this divergence unique?
I don't think that there is evidence so far of anything much in the emails. Scientists are just as catty as everyone else. No revelation there. If this were in the US, there is some case that FOIA laws were being thwarted, but I think the law is not as established in the UK.
Not my area. I assume these guys know what they are talking about, with some obvious error bars. But that's science.
You don't need a degree in climatology to know when your getting jerked around. Looks like Enron Redux! We need to get auditors and real scientists to get in their and find out what is legitemate and how much of this was just plain bunk. We know in private that the IPCC's top scientists admit the science is shaky and they finally admit that it has been getting cooler for the past 10 years. Coppenhagen is toast for sure now. Good thing I was getting used to living is a house with heat and lights. That mud hut would have been difficult to store all my valuables.
The evidence looks like a deathblow to global warming. Only time will tell I suppose but I certainly wouldn't buy a car off these goofs. Well maybe an H3 Straightpiped past the emission reducer.
@CamMacKay: please provide evidence of the IPCC's top scientists admitting the science is shaky, and admitting it is cooling. Name + reference, please.
If the evidence "looks like a deathblow", you're wrong.
@Nick: provide evidence they were altering their whole temperature data.
Let's see if I can finally get a 'skeptic' to provide hard answers to simple queries, rather than loads of handwaving or even outright silence.
Huuhhh? What am I missing here. We can believe dendrochronology records when they are extrapolated back into the distance past before thermometer records, even though you can't get dendrochronology to do the same thing today?
The comment that the "there are several theories, many of which suggest that climate change itself is the problem" is (ahem!) unconvincingly circular, to say the least.
As a trained geologist and statistician, I think that dendrochronology must be the most vivid example of the old saw that "if you torture any set of numbers for long enough they will confess to anything".
Deniers of all kinds are really the same. So, the fact that a bunch of scientists deleted (or wanted to delete) some e-mails they shouldn't delete ruins the whole idea of climate change? This is exactly how creationists reason. I suggest these people read a few books about science and epistemology, and learn how theories are refuted in the real world.
the hacked emails undermine the entire premise of global warming....discussions of changing HISTORICAL data that doesn't agree with the scam. not changing current data. the cat is out of the bag and the end of the scam is nigh
Stuart Love
:
What you're missing is that the dendrochonology overlaps the temperature records very well from ~1850 to ~1960/1980 (depending on data set.) After 1960 or so, late wood tree ring density changes in a manner unrelated to temperature in certain data sets, and in a manner not seen in the 1,000 years or go prior. This is mostly true for northern hemisphere data sets. New Zealand beech trees, for example, can still be used as a proxy through recent times.
So what do you do? Tree rings are not the only proxies. They can be checked against boreholes, glacial deposits, coral reef deposits, and other proxies to make sure they're in the same general area. Wikipedia has a good page on "Temperature change in the last 1000 years" showing comparisons of such proxies.
Some possible explanations that have been advanced in the literature include changes in accretion of snow and ice, exposure to UV light, and herbivory by insects, all of which could be related to changes in average temperatures, changes in trace atmospheric gases, or changes from globalization.
James, when even Monbiot throws Phil Jones under the bus it is time to admit that the CRU guys are at least suspect or lose all credibility.
To do otherwise identifies you as just another "useful idiot" for the "cause".
the hacked emails undermine the entire premise of global warming...
And what premise is that, exactly?
My apologies, I should have said "New Zealand cedar trees" instead of New Zealand beech trees in the above post.
If tree rings were a good proxy from 1850-1960, and a bad one from 1980-present, what is the justification for assuming that they are a good proxy before 1850 and that that regime change never happened before? Is there a good justification for why the current regime isn't the norm, and the century after 1850 was the exception?
Discussions regarding how to present scientific findings to the public are not scientific discussions. They're marketing discussions. Scientific discussions happen in the peer reviewed, published literature.
It's perfectly appropriate for scientists to edit, simplify, and even over-simplify everything that happens in the peer reviewed literature for the sake of educating the public. Any emails concerned with that mission are not evidence that climate science itself is being distorted or suppressed.
There are only so many hours in a day. A boiled down version of the facts is necessary if non-experts are to be included in concerns about global warming.
qbsmd
It's not an assumption. You check the tree ring proxy against other proxies for the local region you are in, over the same time period. For example, read "New Zealand climate over the last 500 years reconstructed from Libocedrus bidwil1ii Hook. f. tree-ring chronologies*" by Palmer and Xiong in The Holocene, volume 14, published in 2004 p. 282-289. There you will find that in constructing a proxy from New Zealand cedar, they use agreement with speleothem proxies from caves and Huon pine proxies from Tasmania. They conclude that while there are some differences (the 1800s is a time period when the Huon pines differ from the New Zealand cedars, but the speleothem proxy is in general agreement through the 17th, 18th and 19th centuries) the correlation between the three data sets is good.
A few years ago Mann, Bradley, and Hughes decided to see what would happen if the MBH 1998 reconstruction of paleoclimate had all tree ring data removed, in response to exactly this criticism (Mann, Bradley, and Hughes wrote another paper in PNAS in 2008 describing this.) The result was that the conclusion of MBH 1998 would have been the same with or without tree ring reconstructions, although tree rings allow the extension of those conclusions back 1700 years instead of 1300 years into the past without tree rings.
It's the same story with creationism - there are people out there who will repeat the same criticism ad infinitum even after that criticism is answered.
I am not a dendrochronologist - my current field of research is related to adaptive responses in animals as a result of feral invasions. And in that field I am well aware of the effects of climate change. So I will confess that I don't know enough about the field to make an informed comment.
But I must say I, like a few others here, am very dissatisfied with the explanation for divergence in the tree ring data. If I may use an analogy:
A favourite of the denialists is to cherry pick data to support their claims, and they often use a graph of solar activity vs global temperature (see the discredited 'documentary' by Martin Durkin, "The Great Global Warming Swindle" to see what I mean). Whenever you look at the graph, there is a strong correlation between solar activity and global temperature up until the mid 1970s, and denialists love to put forward this graph, and conveniently ommit all the data after that date. The reason is obvious - after the mid 70s the relationship breaks down completely, and temperature continues to climb while solar activity decreases. I love to debate denialists who use this data to support their case, because it is so easy to dismantle their arguments and credibility. Cherry picking data like that is unethical, and it is poor science.
Now, once again, I will confess I don't know the intimate details of what has gone on in this situation, but it would appear from what has been said here and elsewhere is that exactly the same cherry picking of data has been going on with regard to tree rings. If true, I would be extremely concerned by the exclusion of any data based on 'divergence' from the expected trend, on the sole premise that it wasn't understood. Several other posters here have expressed similar views, and I am yet to see a satifactory explanation of how data that clearly diverges from other observations can be considered relevant when it suits, and not acceptable when it doesn't. Any statistician, and hopefully every scientist, understands the difference between correlation and causation, and unless there is a causative response between temperature and tree ring data, the latter would not be a valid indicator of the former. A correlation may have existed in the past, just like between solar activity and temperature, but all that means is there was a coincidence in the data.
What am I missing?
But speleothem proxies are influenced by rainfall just like tree proxies. Plus neither proxies match local temperatures. Somehow it teleconnects to global temperature. So it all magic, not science.
Also Mann is such a poor statitician (actually not one at all) that the loose cannon methods he uses show hockey sticks no matter what data he plugs in. Mann's procedures mine for hockey sticks even in red noise data. In the case you cite it mined up some upside down lake sediment proxy and made that the heavily weighted proxy that generated his hockey stick.
Idiot doesn't realize that if he adds a bunch of horse apples, and cow pies to his milkshake that only removing the cow pies isn't going to make it taste better. Especially since the recipes says "Taste the mixture often and if adding an ingredient has an adverse effect the add a whole bunch more".
It's like you idiots don't understand the underlying science. Feynman's complain about south of the border science education seems to apply to climatologists, and you. You never understood the underlying principles at work nor the criticism and therefore you get confused by the numbers. You do science by rote.
@Brian Macker: "It's like you idiots don't understand the underlying science."
How wonderful for us that you're here to explain it to us. Perhaps you could explain how the IR-absorption in CO2 DOESN'T trap heat reflected and re-emitted from the surface of the planet, because I must admit, the whole thing has me confused!
I think you should be more concerned about the feedbacks in climate system. Without those, there are no catastrophic changes.
I'm not certain, but I would guess that it's the post immediately preceding yours.
I want to highlight this because I see it so often and I think that it's important. And untrue. And totally insulting to all those people who actually have a clue. Denialists spew the phrase "height of arrogance" a lot, but this is it. To think that you can start off with "I am not a dendrochronologist" and end off with, essentially, "dendrochonologists have no clue about dendrochronology but I do" is, indeed, the height of arrogance.
If you don't know how it works, ask questions. Don't start off by assuming fraud and/or incompetence.
Can't exactly read anywhere in my post where I said dendrochronologists have no clue about dendrochronology. And I have read the post before mine over and over again, and it doesn't answer my question.
I will state it again in really simple terms because you don't seem to have actually read my post properly. Maybe that was my fault for communicating it incorrectly, so I will try again.
If there has been a breakdown in correlation between the data from tree rings and the data from other sources, that needs to be explained better than simply saying 'divergence' (I have done a literature search and found no answers there either). There may well have been excellent correlation between tree ring data and other data sets in the past, but so what? Correlation is NOT causation, and unless there was a causative relationship between the figures you can't use one to infer the other. I assume you know enough about statistics to understand that.
It is simply not good enough to state that there USED to be correlation, but now that has broken down so we won't use the data. That's something that denialists do, and we rightly call them on that.
I do not believe that this whole affair (for want of a better word) damages the case for anthropologic climate change in any way. To claim that based on a couple of statements in less than a handful of emails over 12 years of hacked data is patent nonsense. But it does raise questions re how some people (not all scientists are saints you know) use data. I am also not assuming fraud or incompetence, just asking for an explanation re the causative relationship between tree rings and temperature, and why it has broken down. Maybe if we actually had a dendrochronologist provde some information here we might get a better outcome than some of the vitriol being espoused
So pough, you will note that I do have a clue about the effects of climate change and I am asking questions. Just haven't received any answers yet. How about you attempt it.
IANAD (I am not a dendrochronologist)
In the interests of better communication, let me see if I get your points.
1. You haven't found, to your satisfaction, a description of why included datasets should be included, ie. what reasons (apart from a match to known temperatures and other datasets) dendros (long word bad!) believe that temperature is the limiting factor for those trees.
2. If a dataset matches temperature for a certain period and then changes, it should be concluded that all information in that dataset is suspect and should be viewed as inconclusive.
3. The solution to the as-yet unresolved divergence problem has not been expressed clearly.
Is that at least close?
BTW, the book that this post is about may have some answers for you, or else the author of it would. Also, I think blogger delayed.oscillator might be a dendro.
I would trust the tree rings over people reading and recording temp. too much room for error or manipulations
and it cannot even be explained why the tree rings have stopped representing climate, do you hear what your saying?!
So, Wendy prefers proxies over thermometers. Well, Wendy, how about this proxy: http://whyfiles.org/006migration/index.php?g=3.txt
(altered bird migrations and nesting patterns)
Ask your parents (I'm guessing you're a young woman) how many days with extreme frost they experienced in their youth, and how that compares to now. Ask many people all over the world the same question, and note the pattern.
Ask farmers when how the timing of seeding and harvesting has changed over the last decades, and ask them why there is such a shift.
There are more such examples on just about every aspect of our lives. However, you're probably like the frog being slowly boiled (that'll be a metaphor).
such anger, this is why so many people stay out of the argument. Can you discuss things in a normal tone without all the emotion? I remember lots of snow, I see more tropical looking birds now, etc... So my question is lets go back further then that, have there been other times in our recorded history where people noticed a different climate/weather pattern then when they were young? I believe the answer is yes.History shows us that our planet experiences climate fluctuations. On average yes our planet is getting warmer currently,mostly in winter and mostly at the north pole. The southern hemisphere is stable. We have also just come out of a colder period(the little ice age)but we have been warmer as well in the past...The medieval warm period. So people and trees and history shows change, tell me why the trees no longer get included in climate study, tell me why current slight climate change is so unusual, and why is it a problem.
Nice try. People just get the emails for yourself and start with the most recent. GW conclusions are not the issue. It's the insane unscientific arrogant issue advocacy. They bully, threaten, lie. They deny information to those who seek it, lie about destroyed stats. threaten to have people fired, threaten journals that disagree, threaten to change peer review status to discourage other opinions. This is not the scientific method I learned about. Also they themselves are concerned their models are all wrong, they question their own ability to predict anything. They aren't even honest about their own views. Why would they seem so devastated the Earth is cooling. "Travesty" is their word. Isn't that good news? They all do agree they want global governance though! Read these yourself people!
If you can't stand the heat...
Yes, the climate of planet earth knows fluctuations. We have consistent explanations for most of them (orbital forcing, followed by GHG feedback), but NOT for the recent increase in temperature. In fact, it should be cooling due to the orbital forcing.
Well, we actually DO have an explanation, but that (GHGs) leads automatically to an expectation of at least 2 more degrees of warming even when we start reducing our emissions NOW. With 2 more degrees, we're talking about a considerable rise in sea levels, we're also talking about many places on earth where current living conditions simply cannot be maintained. In the past, climate changes have led to plenty of "völkerwanderungen". Just imagine Mexicans having no other choice but to move north, since their country cannot sustain even its current population due to climate change. Americans are already complaining about all those Mexican immigrants (illegal or not)! You will hopefully know how desperate people react. And that's just one of many aspects. You can read the IPCC report on possible consequences yourself.
Please tell Australians their climate is stable. The climate researchers there might show you a graph or two that completely negates that claim. Actually, you can do it yourself here:
http://reg.bom.gov.au/silo/products/cli_chg/
Go to the "timeseries" and play around a bit (select e.g. "mean temperature"). The warming in Australia is actually faster than the global average.
Finally, SOME tree chronologies show a very clear divergence problem. Some in the 1960s, some in the 1980s, some hardly at all. The RAPID climate change of the last few decades (it most certainly is not slight) may have played a role, but also pollution.
Brian Macker
Let me let you in on a secret: speleothem proxies are based on the ratio of oxygen 16 to oxygen 18. If the ratio for a wet year is 80/40 and the ratio for a dry year is 36/18, it works out the same because it's a ratio. Your assertion that the amount of rainfall matters is irrelevant unless the amount of rainfall is zero or below the limit of detection.
It being New Zealand, there are no deserts, so zero rainfall years are pretty much non-existent.
You are simply lying:
From p. 286-287 of the Palmer and Xiong paper I referenced above.
Bisky: "ill doers are ill deemers". Think about how that applies to you.
Also to reply to a few of these, CO2 absorbs a few very narrow bandwidths of IR. Some think it already absorbs all that is available to it, more wouldn't matter. Co2 by itself is less than 0.1% of the greenhouse effect. The explanations get convoluted from there. Climate models have all been wrong. Measurements in the upper atmosphere were expected to decrees relative to the whole as increased greenhouse effect traps heat lower. Models have been the inverse of reality. A question was asked where in the emails is their official stance discredited. Answer-everywhere. I've just read the 25 most recent email. You can start there. They really emphasize peer review. I found the paper peer reviewed by 31000+ scientists very interesting. All I know, the debate isn't over because there never was a debate to begin with. Except for a few secret debates they've hacked into. There are some prominent scientists who question assumptions like all good scientists do and I would like to see public debate, before we issue a global tax and global government while the Earth is actually cooling. These emails reveal these clowns are anything but scientific. They run science like a political war room. It's shameful! AGW theory is way too new to have people called deniers and contrarians who raise valid points, and fired and careers ruined. No other science behaves this way. Shame Shame Shame. Maybe the warmers were the deniers in the 70's when CO2 was causing cooling. They are getting their revenge.
These hacked emails beg an obvious question. Why has scientific discourse been reduced to this over a very new science and the very new theory of AGW, which replaces the recent AGC theory? "Contrarians, skeptics, and deniers" are the terrorists because they work so hard to discredit the theory and are biased, so the IPCC must be equally terrorists in the other direction to counter the enemy and bully and fire and spin. I was told a few years ago our 3% contribution to Earths CO2 emissions has started a warming feedback loop that is and will continue to override natural Earth cycle and even the Ice Age cycle. Now that that isn't true and the Earth is cooling, to the obvious bemusement of the scientists in the emails, who secretly question their own models, why not slow down and tone it down and allow all debate and stop the name calling of people with varying opinions. Why do they hope warming is true? I know the answer. The prize is tremendous. Centralized global control and taxation of CO2 is global control of everything. Since real debate is beginning and the Earth is cooling, it's now or never. They are like Bush who had to invade quick before
the WMD's were disproven by investigators. This is war for them. The prize is right in front of them but it's really too late. This is the beginning of the end. People are tired of panic politics. Gore is going to be very depressed, poor guy.
Yes pough, what you have said in reply to my last post is essentially what I am saying. It is important for everyone to realise - and anyone who has studied science at at least the undergraduate level already knows this - that in order to use one set of data to draw conclusions about another (ie tree rings and temperature) there must be a causal relationship betwen the two ie changes in temperature equate to changes in certain tree ring characteristics, and that these changes are both consistent, and can be confirmed by experimentation or from other data sources.
In my literature search on this subject I have come across two papers which discuss the 'divergence problem' (why tree ring data suggests temperature declines over the last 50 years while other measurements show it is increasing), and while they suggest possibilities, they do not have the answers. I believe this is the crux of the issue, and it is what I have been attempting to say all along (perhaps poorly??).
It is apparent that there has been a correlation between tree ring data and temperatures over much of the historical record, with a few notable deviations. However, if that correlation has broken down for whatever reason, the reason it has broken down has always existed and has always had the potential to influence the data. The reason could be anything from global dimming effecting photosynthesis, to changes in soil nutrients, loss of understory, acid rain affecting leaf volume, or .... who knows. Obviously, the larger and more diverse the sample size for the data set, the less likely that local factors will have skewed the outcomes.
But I suggest that until there is a satisfactory explanation as to the causal relationship between tree rings, temperature and whatever confounding factors are causing 'divergence', the use of the tree ring data set to draw definitive conclusions has to be questionable.
There are a miriad of proxy data sets for climate change - I am working with one myself regarding the change in range of certain invasive species - but I would not dream of attempting to draw conclusions or even use it for fine measurements of temperature; there are just too many variables. Dendrochronology is a relatively new science (at least to this level anyway), and it may well be that its advocates are making claims beyond its capability to definitively support. From the admitted lack of information (from peer reviewed literature on the subject) regarding important influences, it would appear that this is a reasonable charge to level.
But there are series that don't show the divergence problem, for instance Yamal, which of course is why McI has focused his attention on trying to destroy Briffa's credibility and that of his work on Yamal.
Multiple errors in a single sentence. Congratulations are in order.
Sorry dhogaza, it doesn't matter if there are datasets that don't show the divergence problem. The fact that there are sets that show divergence indicates that there is some underlying confounding factor which results in there being no direct causal relationship (unless the factor is considered and either discarded as being irrelevant in a particular case, or the datasets adjusted to take it into account). If the data is to be useful in order to draw valid conclusions, we need to understand why divergence occurs, and whether or not it was a relevant factor for the event or period we wish to analyse.
Having some datasets showing divergence and some not is actually very helpful, because the different cases can be analysed to determine what is different between them, which can then lead to a testable hypothesis as to what is causing the problem.
I don't know how far down track dendrochronologists are in this area, but the papers I have read all recognise the problem and recommend further research. That is as it should be, and I would expect nothing different from a good scientist. But I would suggest that it also means that until the problem is better understood, it is not possible to draw definitive conclusions on temperatures from tree ring data; however, but it may be a useful guide to further research.
mandas, looks like you're all set to revolutionize dendrochronology. The only question I have is, why not talk to dendrochronologists?
Sorry pough, I don't know any. That's why I read their papers. This is from:
Esper J & Frank D, (2009), Divergence pitfalls in tree-ring research, Climatic Change, 94:261â266 DOI 10.1007/s10584-009-9594-2.
In this paper DP = divergence phenomenon
....DP was first described over a decade ago by Jacoby and DâArrigo (1995) and since then has been reported from a variety of sites mainly concentrated towards the Northern Hemisphere boreal forest zone (see DâArrigo et al. 2008 for a review). DP effectively describes a disassociation of late twentieth century (typically post-1960) tree growth parameters, such as ring width or maximum latewood density,
from regional temperature trends. This disassociation does not necessarily comprise a weakening of the high-frequency climate signal. That is, inter-annual tree-ring variation may be predominantly controlled by temperatures, but the long-term warming trend is not (fully) retained in the tree-ring time series. Such a situation is of importance, as it limits the suitability of tree-ring data to reconstruct long-term climate fluctuations, particularly during periods that might have been as warm or even warmer than the late twentieth century.....
Seems they agree with me.
There is a lot more, including where the authors discuss data collection methodolgies and even artifical DP, including divergence in more historical times.
.....And finally, we also note cases where attention was paid to âdivergenceâ in recent years and offset of similar magnitude at different periods neglected (Fig. 1i, e.g.,
Wilmking and Singh 2008). Similarly, it is not unexpected that a fraction of data selected on the basis of recent low-frequency trends or fit with instrumental records (i.e., ârespondersâ) will agree more closely with the instrumental target or warming trends than the remaining fraction of data (ânon-respondersâ; e.g., Pisaric et al.
2007). Application of such splitting procedures might be prone to circular reasoning and just emphasize the variance of measurement series around a mean chronology (Fig. 1j) in recent times.
Finally I would like to suggest that if people here actually read the source documents before putting fingers to keyboard we might actually have a more sensible discussion (yeah, I know, fancy doing something as difficult as getting the facts before forming an opinion). And note - read the SOURCE documents, not the opinion of a blogger or someone else who probably also has not read the source documents.
So email 'em. Can't hurt to try. I'd be very interested to hear what they have to say on the matter.
These would be the same "scientists" that supported the Caloric Theory of heat for two hundred years, or the equally preposterous theory of Aristotle's for over two thousand years. They would be the same "scientists" that supported Ptolomy over Copernicus, that drove Simmelweiss out of medicine and eventually drove him to commit suicide. These would be the same "scientists" that drove Michael Gold from academia for exposing the cancer research fraud and trashed your colleague Edward Hooper for drawing a link between AIDS and the development of the polio vaccine in the Congo. These are the "scientists" that you advocate that we trust?? You'll forgive all those of us who would rather trust reason than authority, but that IS how science has advanced. Whatever the true nature of the current scientific debate on climate change, you do science no favours by coming down on the side of compliant acquiescence.
...So email 'em. Can't hurt to try. I'd be very interested to hear what they have to say on the matter.
So call me naive - I tend to think that what they have to say on the matter is in their papers.
But I will say one thing pough, at least your comments are a cut above some of the morons who think they are wiser than most.
Naive. To be honest, I think that if you have some specific questions it's better to ask them than to comb through what's written in the hope that they have written the answer already.
Mandas is ignoring the fact that the divergence problem is defined as impacting series which previously were temperature limited and no longer appear to be.
This is based on physiology, not just comparing with the modern temperature record:
"Divergence-related studies have investigated what appears to be a widespread shift in the ecophysiology of tree growth response to climate" ... they look at the tissue characteristics within the tree rings, this isn't based simply on comparing tree ring width with modern thermometers. The physiological characteristics found when growth is temp largely disappear in recent years in those series showing the problem.
So unless our understanding of tree physiology is seriously out of whack, it doesn't necessarily have any bearing on the accuracy of past reconstructions.
A good review paper, accepted for publication two years ago (the link is to the accepted prepublication PDF).
The divergence problem also occurs mostly where the instrumental record is weak, and is confounded by siting issues (thermometers being at different elevations and otherwise differing microclimates than the tree sites, etc) ...
Anyway, the review paper is interesting (and more comprehensive than Mandas' skimming of papers). The conclusions aren't nearly so fatal for tree ring reconstructions as Mandas appears to believe to be the case.
Interesting gems are buried in the review paper for those wanting to understand the problem and implications better ...
Of course Eric Raymond's "smoking red hot cannon" evidence of scientific fraud stems from the reading of code in which Briffa or a member of his team apparently play with plotting a reconstruction with and without the bias corrections mentioned above.
And, of course, Eric Raymond declares the bias adjustments to be "pulled out of their ass to make the hockey stick look better to ensure more funding" (paraphrasing but reasonably accurately, I think, I'm not about to go back to that cesspool to get a direct quote).
Every time you look at a denialist claim of this sort, and go back to see what researchers are doing, it's clear that the denialist claims are based on ignorance. Of the willful variety.
A lot of interesting stuff in this recent review paper ...
I hosed my link to the review paper. Try this:
http://www.ldeo.columbia.edu/~liepert/pdf/DArrigo_GPC2007.pdf
Not sure what evidence you are basing my 'skimming' on there dhogaza. Have you been looking over my shoulder again, or are you just trying to suggest that since you and I don't agree 100% on the issue there must be some problem with my research methodology? Not exactly a robust argument, but if that's what you want to go with ......
And your view that tree ring reconstruction is far more robust that I have suggested (not sure where you got the idea that I think it is fatally flawed), is actually contradicted by the very quote from the paper you used, ie
...The principal difficulty is that the divergence disallows the direct calibration of tree growth indices with instrumental temperature data over recent decades (the period of greatest warmth over the last 150 years), impeding the use of such data in climatic reconstructions.... Residuals from such regression analyses should thus be assessed for biases related to divergence, as this bias can result in an overestimation of past temperatures and an underestimation of the relative magnitude of recent warming (Briffa et al. 1998a and b)....
This paper is saying EXACTLY what I have been suggesting; that we need to understand DP better if we are to use tree ring data as an accurate proxy for temperature reconstructions.
Perhaps you don't understand the concept of proxy reconstructions too well, so I will give a very basic summary here. And I apologise if you are an expert, it isn't solely directed at you, but at others who may also not understand.
Proxies are used when direct measurements of something, in this case temperature, cannot be conducted for some reason. Obviously, we can't directly measure temperatures in the past, so we need to use a proxy to 'measure' them indirectly. In this case tree ring information is being used. However, you first have to calibrate your proxy against known information - a standard. So, you look at the proxy and determine some characteristic that can be determined or measured, then plot or record the proxy information against the standard (ie direct temperature measurements). You do that over a LOT of data points, until you can determine whether there is any correlation between the proxy and the standard. Once you do that, you then have to be able to 'predict' the measure you want (ie temperature) based on the proxy data. If you can do that successfully and repeatedly, then you can say with some degree of certainty (NOT 100%) that your proxy is a useful means of determining what the measure you want should be. In this case, calibration of tree ring data against known temperatures allows a proxy determination of the historical temperature record. See, its all simple really.
The problem with using proxy information is that it can NEVER be 100% accurate, because unless there are no other factors influencing the outcome (which is never the case in environmental sciences, there are just too many variables), your results may not be a true reflection of the actual situation.
Dendrochronologists are running into exactly this problem with DP - tree ring data has been a useful proxy for determining the historical record, but the correlation has broken down for some reason - noone is sure why - and tree ring proxy information has been diverging from direct measurements for the past 50 years (according to what I have read - or skimmed depending on your views). And this is not only occuring now; there have also been deviations in the past when tree ring data has differed from other data sets.
This raises exactly the question I have been raising here - and it would appear is being raised in dendrochronology papers. If there are divergences between the proxy information and the actual information, it needs to be explained, otherwise it raises questions about the veracity of the proxy. However, if you can explain what factor is causing the deviation, you actually strengthen both your case, and the accuracy of the whole measurement process.
This isn't rocket science people (yes, it's tree science (joke)). If an undergraduate had come to me with a data set that he/she was proposing to use as a proxy, but it continually deviated from the known standard, I would tell him/her to either explain the deviation or advise him/her that it probably wasn't a very useful proxy. At the very least, any suspected deviations would need to be very clearly highlighted and discussed.
I am NOT accusing dendrochronologists of not doing that - they quite clearly are as a whole. But this issue (it seems to be dying down now) raises the important issue of how data is used and presented, and what we can and cannot say with any degree of certainty. And based on what I have read to date, I would be uncomfortable using the tree ring data sets as an accurate measurement and predictor of temperature information without either the DP being explained, or without some correlating data (which should be used anyway).
This has to be an open and transparent process. There are flat-earthers out there who will seize on the SLIGHTEST hint of a conspiracy to 'hide' data, and some of those people have a lot of political power. Let's not give them any ammunition.
You mention a few papers. I would expect a comprehensive, professional literature review to be well, more comprehensive and more professional. In comparison, what you've done is to skim the literature.
Don't take it personally. People write comprehensive review papers for a reason, to get a snapshot of the major issues within a field organized in one place.
Once again, not sure what you are basing your assertion on that all I have done is skim the literature. My mistake I guess - next time I will write a literature review. I just didn't think it was appropriate to write and insert one here.
But I actually think I'm pretty good at writing them. You might even say professional. Of course, you shouldn't take my word for that, you don't have any evidence.
But apart from that, what do you disagree with me about?
This. Either you, or the professionals in the field, are wrong.
Do as pough suggests, write briffa yourself.
Not sure why you would disagree with a fundamental tenet of statistics that is in every textbook on the subject and which the professionals in the field - yes, even this one - have openly stated as true over and over again.
But you are free to hold whatever view you wish.
Maybe you could explain why it isn't correct.
Determing the physiological response of a tree to environmental factors isn't a matter of statistics.
Just because one can't pin down the confounding factor causing divergence at one point in time doesn't mean that one can't exclude that confounding factor at other times or in other series at other locations.
The dendro people focus as much or more on physiological factors than statistics.
More accurate would be to state that temperature no longer becomes the limiting factor of growth (look up liebig's law of the minimum).
The two most likely natural explanations would be precip or snowmelt timing changes. If the cause is natural, there appears to be a temperature threshold phenomena - below a certain temperature, divergence doesn't occur. So you don't need to throw out the entire proxy reconstruction.
Also, I let you off the hook on this:
Followed by a quote including this:
Briffa's saying something very different than you've said ...
Anyway, enough, go e-mail Briffa or something and start writing your papers overturning a lot of existing work.
Would anyone care to explain to what extent climate science or dendrochronology are experimental science? Are hypothesis formed and tested, or are these endeavors a primarily a search for correlations that justify causal claims? To what extent might the latter be considered science? I suspect that the latter is the case but admit my nescience, and I do not understand how the production of a model proves the accuracy of the model. Finally- I hope this is taken as a healthy skepticism- If scientists cannot determine the cause for a change in tree behavior as it relates to temperature, why should the electorate believe that the cause for global climate fluctuations has been determined. Even granting that climate is changing, how do we know that we are the cause? I don't mean to be abrasive, and I would like to know these things, since a history of science pretty clearly shows that most theories are eventually shown to be incomplete if not entirely wrong headed. This is too important to screw up. Thank you.
Is it not the nature of Science to go out of its way to prove itself wrong in order to get to the truth?
Why then are skeptics treated with such disdain by the Scientists who are studying the climate?
From my perspective, the AGW proponents are nothing but a herd of bleating nanny goats who have lost their way in the fog of the miasmic green ooze called, 'Global Warming'.
James,
I found it humorous that you used a quote from a post attacking me, for the lead-in to this article. As I said in reply to that post, the gentleman attacked me for a lack of knowledge on climate science, even though I've never discussed that topic on this blog. I also find that to be quite humorous, plus the condescending "science take effort" quote when I had already said I was a geologist. Maybe that doesn't count as a science to some hahahah hahah :-P
But on the serious side, since I have the chance to ask, would you or some of the other posters please give me a list of what you consider to be the seminal articles in the field of climate science and the AGW hypothesis? I'd prefer the articles, rather than the textbook, since I've already member of most of the societies (like AAAS, GSA, etc.) and can renew or can become one quite easily. I don't get free $100 textbooks and I prefer to read online. I'll certainly read and study every one of them, I'm becoming very curious about the whole field after the CRU incident.
Also I was talking to marco about the need for the models to be open source. Looks like I have found at least some open source code to some of the models, and I've found some models I can run on my own servers, PC's, etc., I'll be having some fun playing around with that stuff, if I can get all the data I need cheaply. If you guys have any suggestions for where to get models, code, and data, I'd love to hear about that also.
I'm a hands-on type guy, I'm not afraid of any computer or science work, and I don't like all this tribalism and visceral, emotional approach. Scientists can disagree but it doesn't have to be full of venom and spite. Just my two cents on that. You can email me at chris@cst.net if it's easier to send me what you think I need to study that way, rather than as a post. I'd definitely like to learn more of all sides of the discussion and experiment with the models myself.
sorry, should be "I've already *been* a member" of most of the scientific societies ... typo there. I'm qualified to get into any I need to get into to read pubs.
@Chris Salmon,
check Realclimate:
http://www.realclimate.org/index.php/archives/2009/11/wheres-the-data/
And denialists wonder why we find them so tiresome.
Hypothesis formed and tested? The entire notion that burning fossil fuels, therefore increasing atmospheric CO2, would lead to global warming is about a century old. The detailed physics as to how CO2 forcing itself would work was nailed down in the 1950s.
Observed warming, successful models built upon that hypothesis, etc - are all confirmation of that hypothesis.
Yes, it's experimental - hypothesis proposed, the experiment run for further decades by humans on the entire planet we call "home", hypothesis confirmed.
I suspect you suspected "the latter to be the case" because you want to believe that all of climate science is somehow "unscientific" ...
Oh, the dendro bit ... look up Liebig's law of the minimum and ponder that selection of locations where trees are temperature limited are informed by plant physiology, and that much of plant physiology has been experimentally determined. In contexts that have absolutely nothing to do with dendro, climate science, AGW, or right-wing politics.
Yes, Real Climate's list is going to be very useful. I hope Chris Salmon understands that this list of data, code, etc points to stuff that researchers have been putting up on line for many years now.
In fact, one stunning denialist complaint has already cropped up - "you're only PRETENDING to free the data and the code, because you're pointing to stuff that was released years ago!"
Bizarre.
All this discussion of dendrochronology is very interesting (thanks all) but it misses an essential point.
This stuff is all extremely well known and has been discussed in the scientific literature for more than 10 years. Had there been a problem with the issue of leaving out data, anyone reading various papers by Briffa et al, that used this "trick" openly and without obfuscation could have objected (e.g. this 2001 paper: see end of fourth page of PDF). Yet the first objection we see arises out of quote mining a trove of stolen emails, followed by a frantic campaign to justify the unsupportable conclusions arising out of that.
Why does it take a stolen email for it to become a hot topic and a problem with dendrochronology? The real issue is that the denial camp is clutching at straws to show that the mainstream science is dishonest. Having been exposed in their attempt at using this "hide the decline" quote mine as a pointer at dishonesty, you'd think they would apologise and move on. But no. Painting the other side as dishonest doesn't apparently require that you be honest yourself.
BTW preview appears to be broken. I get an error message when try to preview.
Very good point. Unfortunately some in the denialsphere have been vocally and dishonestly using the "hide the decline" quote to claim that his somehow applies to all the dendro work done by a variety of people over the last couple of decades.
You can find some textbooks online. Raymond T. Pierrehumbert's textbook Principles of Planetary Climate (.pdf) was helpful for me. His website also has a workbook and tutorials.
Education is a marvelous thing!
Hey thanks guys, I appreciate the info. I'll study it, I enjoy studying science, obviously. Keep 'em coming. Maybe I'll start a climate study blog for people who want to come up to expert level on the topics at hand.
I'll have to say, I still think the CRU guys are crooks and the episode has given science a black eye. That's regardless of any conclusions regarding AGW. I also will likely not use the term "deniers" or "denialists" or "warmers" or "warmists," etc., because I don't feel those are useful terms, and I'd like to see the discussion become less polarized and tribal.
I will however use the term "true believers" which I use for anyone that's given over totally to any faith or ideology.
Although my concentration in Geology was paleontology and stratigraphy, I don't even like to say "I believe" in evolution, because I don't think it's something to "believe" in, just the best current theory that's most consistent with the evidence. Not a "belief" if you see the difference. Science, in my opinion, is based on logical induction, not logical deduction, so I think things are never "proven" in the logical sense. Nothing is ever "proven" in science in this view, yet that, itself is the great power of science, because it allows for progress. To assert something is "proven" (again in my view) is to assert that you can see the future, and no one can. All observations take place in the past - even a minute ago is the past. So we have to be careful about this tribalism, this totally self-assured - cocky, even - attitude, this adoption of a belief system that excludes all other thought, when it comes to science. Again it's all my opinion, but might engender some thought in some folks.
While I'm waxing philosophical, let me quote one of my favorite philosophers:
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense."
- Buddha
I guess that makes me a permanent skeptic. I'm even skeptical about skepticism!
Really dhogaza.....???!!!
.....Determing the physiological response of a tree to environmental factors isn't a matter of statistics.
......Just because one can't pin down the confounding factor causing divergence at one point in time doesn't mean that one can't exclude that confounding factor at other times or in other series at other locations.
If you are serious about those two statements, then I must apologise. I took you for someone who had at least some element of science education. Seems I was sadly mistaken.
I would like to give you a lesson on how every scientist has to understand statistics, and how the analysis of data is absolutely critical to the understanding of how to apply that data and draw inferences. But, if you are going to make - not to put to fine a point on it - really stupid statements like those, then there isn't a lot more I can say.
Chris Salmon, did you really say that you don't 'believe in evolution, but that its the best theory to fit the facts'??
If you truly meant that, then your science education must have been extemely poor.
Evolution is a fact. We can see it occuring around us all the time. There is absolutely no doubt that living things evolve. It is - I'm sorry to inform you - proven. We have witnessed it.
There are theories OF evolution, ie to explain how and why it occurs, but it is a verifiable, undeniable fact. It is also a theory - but it is a theory in the same way that gravity is a theory. Once again, there are theories OF gravity, but gravity itself (ie the concept that massive objects are 'attracted' to each other), has been pretty well proven I would like to suggest.
And I'm sorry once again - that 'philosophical' statement you attributed to Buddha highlights what is wrong with this whole debate on climate change and is probably one of the worst pieces of advice you can give to any scientist.
...'Believe nothing ... unless it agrees with your own reason..'....
That's why deniers believe the way they do - because they won't accept anything that doesn't agree with their own world view, even when the evidence is overwhelming and when they are being told by people who know what they are talking about.
If you want to be REALLY sceptical, how about you DON'T believe things that agree with your own sense of reason. Question them, but be prepared to accept the answers when they come - especially when they challenge what you already think. That's the mark of a true scientist.
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense." - Buddha
"There are many aspects of modern physics which seem to violate our intuition. The classical theory of physics which was held from the time of Newton until this century provided an orderly model of a world made of objects moving around and pushing each other around in predictable ways. The mathematics could be difficult, but the basic ideas meshed with our common sense notions of how the world works. Starting at the beginning of this century, our physical theories began to include aspects which ran counter to that common sense, and yet the theories consistently made accurate predictions of experiments which could not be explained with Newtonian physics. Gradually, and despite much resistance, physicists have been forced to accept these new results...."
-- Gary Felder
http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/b…
"But the point is, there is no question that tree-ring growth rates of the past -- before we had thermometers -- can serve as useful proxies for historical temperature data."
If we don't know why sometimes tree ring growth doesn't match instrumental records, and we do know that rings can even indicate temperature changes in the opposite direction to instrumental ones, how can there be 'no question' that pre-instrumental tree ring data is an accurate reflection of temperature? (or do you mean something else by 'useful' in this context?).
Those that diverge actually correlate with about 2/3 of the instrument record, and also with *other* proxy reconstructions used to calibrate them. That indicates that there's really something unique about recent decades causing the divergence.
The major risk is that the modern divergence could mean there's some sort of temperature threshold effect, most likely effecting precip or snowmelt timing, which flips the tree into a mode where the limiting growth factor is water rather than temperature.
That means that in those limited areas exhibiting the divergence, the MWP in those locations may've been warmer than the reconstructions show.
Why anyone would think that the fact that some regions (not all or even most) might have had a warmer MWP than current science suggests this implies that current warming isn't a problem, or that *future* warming isn't a problem, is beyond me.
But that's the denialist argument and that's why they huff and puff against the science that shows that the MWP was most likely a regional rather than global event, and not necessarily even synchronized.
And, of course, the modern divergence might be due to entirely anthropogenic causes - air pollution, for instance - which wouldn't impact past reconstructions in the first place.
What a debate! Thank you all, I'm fascinated!
I'm no expert so please correct me if I'm wrong.
Besides the whole divergence problem, the only answer in the question "If we trash the tree-ring data altogether, do the climate models still work?" is Moderately Unbalanced Squid's one in comment Nr 31:
The result was that the conclusion of MBH 1998 would have been the same with or without tree ring reconstructions, although tree rings allow the extension of those conclusions back 1700 years instead of 1300 years into the past without tree rings.
What other papers are contributing to this statement? Because, as I see it from various comments in Climate Audit, the whole reasoning of 'skeptics' is
Because this decline in the tree ring data calls the entire tree ring record as a temperature proxy into question, meaning that the nice, stable, flat handle of the hockey stick graph â the portion that makes it appear that temperatures were nice and stable prior to the evil influence of man on the climate â is potentially meaningless. If tree rings fail to respond to the modern warming, they may have failed to respond to similar warming in the past.
and so, to them, the whole theory of AGW is wrong.
So, once more, beside the whole divergence problem, could you please, please point me to recent papers and/or publications that don't need tree-ring data to draw the conclusion that AGW is indeed the cause of the planet's temperature rising.
AGW theory is based on physics, not proxy reconstructions of past temperatures, whether tree rings or anything else. Always has been, always will be. The GCMs (models) are physics-based, the proxy data isn't used in their construction.
The proxy reconstructions of past temperatures simply serve to put AGW warming in *context*. How much warming are we seeing compared to the past? That's the *only* question the proxy reconstructions answer.
One problem with this reasoning is that they correlate well with other proxies back to 1300 years ago or so, i.e. the MWP.
Even so, imagine the MWP was about as warm as now (i.e. the other proxies are wrong, including tree ring reconstructions that don't show the divergence problem, such as the bristlecone pines of the western US).
While interesting, it has no bearing on the implications for the next century. The changes we're seeing are already having an economic impact, and it's only going to get worse as the planet warms. So what if it was nice in Greenland during the MWP? How does that help people trying to farm in the "breadbasket" of the US in the face of increased warming and likely increases in the frequency of drought?
Except for the troubling fact that non-tree ring proxies are telling us the same thing ... they just don't go back as far in time. But they go far enough back in time to contain the MWP ...
@dhogaza. You state thar AGW theory is primarily based on computer models.
As yet though, current GCM models are primitive, and climate modeling is in it's infancy as a field. Computer models aren't currently capable of simulating clouds, which are of crucial importance in regard to temperature. Models are nowhere near reliable enough to underwrite the massive and costly changes being advocated by the IPCC.
wikipedia: "Problems in the simulation of clouds and upper tropospheric humidity, remain worrisome because the associated processes account for most of the uncertainty in climate model simulations of anthropogenic change."
I did not. I said this:
Not computer models.
Fail.
From the documentation for NASA GISS Model E:
bitbutter fails again.
And, yet, primitive as they are they have a string of confirmed predictions to their credit, they generate ENSO-like and other large scale phenomena, etc etc etc.
Oh dear. I just started to pay attention to all this tree ring stuff. And I'm no expert. But I've been saying for some time the trees have gone into irreversible decline thanks to atmospheric pollution from fossil and biofuel emissions.
check out the pictures. The trees on the East Coast dropped leaves over a month early this autumn. The conifers are rapidly losing needles and becoming bare.
Just like a starving person gets thinner, the biomass of tree trunks shrink because they can't photosynthesize and produce chlorophyll. Their stomata are damaged by invisible toxins in the air, like ozone, and nitrous oxide. The cumulative foliar damage is lethal to vegetation.
Before you know it - and vast numbers of states are declaring agricultural states of emergency with the FDA because of widespread crop failure - these poisonous gases in the atmosphere are going to kill us - people - too!
Air pollution is one possibility under investigation, yes. Too early to pin it on anthropogenic causes but it's suspicious that the divergence happens in the 1950-1960 timeframe.
But precip and snowmelt timing changes as temperature passes a threshold is another possibility being investigated.
Gotta look into all possible causes, you know (there are other things being researched, too).
@dhogaza re clouds. I accept that the information I had may have overstated the cloud problem in climate models. Though i think it's agreed that they are an important source of uncertainty in those models.
"And, yet, primitive as they are they have a string of confirmed predictions to their credit, they generate ENSO-like and other large scale phenomena, etc etc etc."
Although I don't understand the article fully, the following seems to indicate that ENSO itself is not captured by GISS model
http://wattsupwiththat.com/2009/10/24/why-does-ocean-heat-content-diver…
"âWe note the absence of ENSO variability in our coarse resolution ocean model and Willis et al. note that a 10-year change in the tropics is badly aliased by ENSO variability.â"
Perhaps you read it differently.
It's Wednesday morning. I don't see his corporate backers fleeing him just yet, but the people who voted for him are turning away in disappointment.
@dhogaza
I completely agree with you. Unfortunately I'm not a specialist on the subject. All I need is more references, e.g. papers, books etc like the one Moderately Unbalanced Squid mentioned earlier.
In the mean time, a good read is The Copenhagen Diagnosis: http://www.copenhagendiagnosis.org/
Yes, as I understand it it's the primary reason why climate sensitivity is thought to lie within a relatively large range of ~2.5-4C. As cloud feedbacks are better understood, that range will be better constrained. Climate scientists are quite confident in that range, large as it is, due to other physical (physics-derived) constraints.
Individual models runs show the kind of variability associated with ENSO. My understanding is that while the gross-scale picture's pretty good, with the expected areas of the planet cooling and warming during such cycles, etc, they're not perfect. That's why I said "ENSO-like" phenomena.
Maybe someday when I'm bored I'll read up on it.
However, I won't read Watts. Watts has a high-school education, no more, and isn't going to teach anyone anything about science. He's an ideologue uninterested in truth, and lacking the education to differentiate between truth and fiction. CO2 snow in antarctica, anyone?
The Google and I found a really good review piece on the use of tree ring proxies about a month ago, but unfortunately I didn't bookmark it and I've been unable to ferret out of my browser history. And The Google hasn't led be back down that particular search path when I've tried searching for it again :(
I'm really annoyed, it was a great primer and I learned a lot from it, and I'm sure many others would find it useful if I could just bleeping find it again.
@orion
I think you just misunderstood what I was saying. I don't like to say I "believe" in anything, not just evolution. Evolution is both a fact and a theory. I don't like to claim that I "believe" in a theory, because theories are never proven. Also it misleads lay people because it sounds like you're a "believer" in whatever your espousing. But still I find evolution to be practical and useful.
You can disagree with what I'm saying, that's fine, but make sure you haven't jumped the gun here. I have no doubt that evolution is consistent with what I've personally seen in the rocks. I just don't like to use the word "believe." We aren't opponents in any way regarding evolution.
Anyway I've been away from this discussion for several days, I see it turned into a pretty cool thing for everyone. I'm going to start a climate study group on facebook and collect all this recommended data there, with discussion for each piece of the literature. It's called GeoClimate, in fact I'm going to go work on it right now. Personally, I'm going to discourage the use of pejorative, cliched categories like "warmist," "denier," etc. But we'll see if the division into extremes and whole belief systems can be controlled. It's possible users would prefer to argue and call names, than study. Anyone's welcome to contribute. I'm going to go through all the literature that's been mentioned here, and other sources, and open a discussion about each one, to try and develop understanding. That should make a nice reference for the future as well.
I also hope Jadehawk knows her place. If she can't figure out that she's in front of a computer or in her home, how will she ever survive a hiking expedition?
I'm just curious.
Tree rings show one thing after 1960s and thermometers show another. Can it not be that the area around the thermometers used have changed? That is the "city" has grown around them with more cars driving around and such. So the readings are no longer valid because the area as changed and thereby affected the recorded temperature?
Are there any sources on where the thermometers are placed in relation to nearby civilization? And if the thermometers distance to civilization has remained the same during all their recorded temperatures.
I just find it odd that the error must be with the trees since they were used before without any problem.
Its feels more likely that everything is wrong both the thermometers and the trees and people just don't have any clue. Still wondering how warm the next summer will be. That data is never right ;).
@Andreas:
While your comment makes sense, it is essentially based on insufficient knowledge of the divergence problem. Note that I do not blame you for this insufficient knowledge.
The fact is that there are *some* treeringchronologies that deviate from the temperature record: those in the northern part of the world. If I remember correctly the divider lies around the 52nd degree latitude. Further south, and the treerings follow the thermometer-readings just fine. Above that, and divergence pops up in several (but again, not all) chronologies.
However, one of the things that's been pointed out is that the nearest thermometer record tends to be a long distance from the site of the trees, and frequently at lower elevations.
So temperature trends in the areas the trees are on might not match trends at the thermometer sites.
My reading of D'Arrigo et la 2007 leads me to believe that scientists looking into the divergence problem think this probably isn't the problem, though. They think the divergence is real, not an artifact.
The main problem with Andreas's question though is that AFAIK the divergence problem (for those sites that display it) is large enough that any adjustment for UHI effects wouldn't explain it.
As I commented in the thread these alarmist climatologists do not consider the entire process before making their claims and assumptions.
Are you so ignorant as to think the rate of groundwater flow is not going to be effected by rainfall? Of course it will be. So the rate of disposition will be. So will the plant growth at ground level. As will the rates of decay in the soil. Some of that oxygen is coming from the plants, not just the atmosphere.
If oxygen isotope levels measure yearly temperature then why donât they use those instead of wood density, or ring width when doing studies with trees. We can measure isotope ratios in wood too. Could it be that plants preferentially take up certain isotopes? Could it be that atmospheric ratios of isotopes donât fluctuate the way you assume?
âLet me let you in on a secret: speleothem proxies are based on the ratio of oxygen 16 to oxygen 18. If the ratio for a wet year is 80/40 and the ratio for a dry year is 36/18, it works out the same because it's a ratio.â
So let me let you in on a secret. I know how radio dating is done. I wasnât claiming that the ratios of atmospheric oxygen would change for wet verses dry years. Itâs the micro conditions Iâm concerned about, the ones in the living soil, in the caves, and in the atmosphere around the plants, in the subsoil, and ground water. Donât you realize how speleothems are created? They are created by acids in the water (CO2, humic, etc.) dissolving existing rock, which has itâs own oxygen ratios. The acidity of the water matters and that is effected by plant growth, how long the water pools in the soil, quantity of water flushed, etc. The assumption is made that none of these processes matter and none are affected by rainfall levels, a poor assumption.
In fact these proxies do not agree with each other over large spans should be a big clue that there is a problem. Instead of dealing with that problem it is swept under the rug. You ignore it. There is good correlation between proxies for some periods but not others. Guess what, there is something called spurious correlation. If you understand math, which obviously you donât, you would realize that you can tweak data till you get a high correlation on some segments of a graph while losing it on others. So a 70% correlation on only a portion of data is unimpressive. The cross proxy correlations they get prove nothing other than their ability to delude themselves. Not effected by rainfall, bullshit.
Furthermore, the speleothem record has a completely different granularity than our yearly temperature record. Do you think atmospheric oxygen isotope ratios fluctuate with local temperatures? To believe that youâd have to be totally ignorant of the entire weather/climate/atmosphere system. What is the proposed mechanism that ties local oxygen isotope ratios to local temperatures? Can you understand what you are saying man? You are saying that if I go to New York City the isotope ratios are going to be different there than if I go to Detroit, Moscow, or Rio. That each will diverge following local temperature. Havenât you ever heard of something called, the wind?
Donât you realize that the temperature records for New Zealand are very short? Oxygen isotope ratios throughout overlying shifting atmosphere couldnât possibly fluctuate in the way you claim to match local temperatures. We donât have long enough temperature record to do ANY good correlation of temps to isotope levels. Rising slopes will always correlate.
Iâve heard no claims that some unknown mechanism of diffusion of oxygen bearing compounds is affected by temperature of raindrops. If so then one would expect not correlation to temperatures as taken, highs and lows for the day, or at certain periods, but a correlation to temperature during rainstorms. That would need to be tested and no one has.
Thus there is absolutely no mechanism by which one would expect the isotope ratios to non-spuriously correlate with local temperatures. Itâs like expecting a non-spurious correlation between my hat size over my lifetime and the Nikki index. Just because they might correlate when smoothed doesnât mean there is cause and effect, or any connection whatsoever.
So what do they have? They have speleothems that donât correlate to local temperatures. They have tree ring data that is affected by rainfall, and spelothems that correlate to that. They have tree ring data that doesnât correlate to local temperature much of the time. They can only get correlation if they ignore broad swaths of the data. That is what âhide the declineâ was all about.
They also adjust the actual temperature data to till they get the kinds of correlations they want. There have been several situations where temperature adjustments make no sense with regard to changes in location and method. When you put up a shelter over a thermometer on a particular day then that does not require you to adjust temperature up and down by steps over the period of decades. Such adjustments are required to get correlation to proxies. I wonder why they are doing them. This has happened specifically in New Zealand, Australia, and Siberia.
Itâs tenuous garbage. They might as well be throwing bones.
They also do the same crap as bone throwers. They make predictions based on those bones and when the predictions donât pan out they make excuses, or change their interpretations ad hoc, but continue to believe in the bones. Thatâs what I see them doing.
Another lie is to claim that âtree ring data were removedâ. Baloney, only piecemeal removal was done. What is needed is total removal, but then you cannot correlate against local temps. Nor was the removal done in a way to address the criticisms.
Plus they make claims that MWP was only local but then assume that local New Zealand conditions should be a proxy for global climate. So what if there happens to be some local temporary correlation to global averages at a decadal level in one locale. Locale temperatures that are smoothed need to track global ones in every locale in order for their methods to be based on good assumptions. If this doesnât work in most of the world then all they have done is found a method to mine for spurious correlations.
#45: Brian Macker has responded to this after I goaded him about it at my blog. Unfortunately, he responded there rather than here.
Whoops, didn't notice he also posted it here... never mind (and feel free to delete my prior comment and this one).
You can go to Jim Lippards blog to see an additional response when he approves it. I posted there because he copied over text where Squidy called me a liar.
In the new comment. I link to a NASA article where they specifically state that they use speleothem oxygen isotope ratios to ESTIMATE RAINFALL!!!
NASA, home of crazy "killer coal car" "lock deniers up" "vandalize the power plants" "the sky is falling" Hansen, says the ratio varies based on rainfall!
NASA, admits heavy rainfall results in more light oxygen!
Who's the liar?
Squidy is also wrong about local temperature comparisons. The papers that did away with MWP rested on non-local temp correlation, for which the justification called teleconnect was invented. The "denialists" certainly didn't make up that ridiculous concept and term for tree ring data.
Some dendrochronologists have done local temperature correlations and have deemed the proxies unsuitable for such use, precisely because they don't track local temperature properly. The experts who know the most about it say that it's garbage science to do this.
Yeah there is one dendrochronologist Briffa who seems to think there is value in this teleconnect idea, but he based his study on a non-statistically significant handful of trees of which the data was skewed by a single freak tree.
This is NOT good science.
Oh, I get it. It was ok to not use them now when they show cooling but it's definitely ok to use them when we have no accurate or existent temp data going back more than 50 years (and don't give me that crap about those voluntary sparse sea temp samplings in the mid 19th being accurate. I know you can't factor out an entire globe of temperature variations, not to mention the bias of the improper sample by people ill equipped to carry out any precise measurement, by adding 1 degree to it)
Scientists: "You're a fool if you don't see all the evidence."
People: "what evidence?"
Scientists: "The evidence that we hypothesized, tested, confirmed and reviewed... don't be ignorant"
It's like chicken little grabbing some snow and saying "How can you deny that the sky is falling?"
This is a lie.
Why does Brian Macker lie? Why does Brian Macker believe that lying about something that can easily be looked up in Google will convince anyone of anything other than the fact that his moral compass needs recalibration?
Thank you for all posts.
If the tree ring proxy cannot deal with the warming right now. Then what is stopping it from diverging from warming in the past.
It is ridiculous science to count one batch of results as valid up until there is divergence from what you would like to see and then superimpose the results from something else.
As I said before if the tree ring measurements are invalid now what is stopping them being invalid for 200 years ago, or 400 years ago.
Only someone who is naively accepting everything that they are told would not see this.
To be honest this just shows that the proxy is invalid. There may be global warming happening, but the tree ring proxy is partly there to show that its not cyclical (eg they don't show the medieval warm period). Now if the tree ring measurements aren't valid (which is apparent because they diverge from the temperature whenever it goes up) then there is no proof that global warming isn't a cyclical thing.
@Scott Bevan:
First of all, please remember that not all tree ring chronologies show a divergence problem. In fact, the vast majority do not. The closer you get to the poles, however, the more likely you find tree ring chronologies that 'suddenly' show divergence. That mostly happens around the 1960s-1980s.
Second, the 'naive' people, like dendrochronologists (who actually study this stuff), have discussed this issue at length. That you are no aware of that is no shame. That you think you know better than they do is.
Along with what Marco said, there's also good correlation with other proxies over lengthy stretches of time, so that gives good confidence that they're not diverging always or randomly.
But it is a mystery, which is why it's called the divergence problem. It's the scientists themselves, of course, who gave it its name, discovered the problem, have done all the publishing of the science.
If it weren't for the scientists, denialists wouldn't even know of the problem's existence.
Great report. Opened up my eyes a little! some heated discussion going on here in the comments.