First here is Dr. Keith Briffa’s response in entirety direct from his CRU web page:
My attention has been drawn to a comment by Steve McIntyre on the Climate Audit website relating to the pattern of radial tree growth displayed in the ring-width chronology “Yamal” that I first published in Briffa (2000). The substantive implication of McIntyre’s comment (made explicitly in subsequent postings by others) is that the recent data that make up this chronology (i.e. the ring-width measurements from living trees) were purposely selected by me from among a larger available data set, specifically because they exhibited recent growth increases.
This is not the case. The Yamal tree-ring chronology (see also Briffa and Osborn 2002, Briffa et al. 2008) was based on the application of a tree-ring processing method applied to the same set of composite sub-fossil and living-tree ring-width measurements provided to me by Rashit Hantemirov and Stepan Shiyatov which forms the basis of a chronology they published (Hantemirov and Shiyatov 2002). In their work they traditionally applied a data processing method (corridor standardisation) that does not preserve evidence of long timescale growth changes. My application of the Regional Curve Standardisation method to these same data was intended to better represent the multi-decadal to centennial growth variations necessary to infer the longer-term variability in average summer temperatures in the Yamal region: to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.
These authors state that their data (derived mainly from measurements of relic wood dating back over more than 2,000 years) included 17 ring-width series derived from living trees that were between 200-400 years old. These recent data included measurements from at least 3 different locations in the Yamal region. In his piece, McIntyre replaces a number (12) of these original measurement series with more data (34 series) from a single location (not one of the above) within the Yamal region, at which the trees apparently do not show the same overall growth increase registered in our data.
The basis for McIntyre’s selection of which of our (i.e. Hantemirov and Shiyatov’s) data to exclude and which to use in replacement is not clear but his version of the chronology shows lower relative growth in recent decades than is displayed in my original chronology. He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights. I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation. Subsequent postings appear to pay no heed to these caveats. Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.
My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data. We do not select tree-core samples based on comparison with climate data. Chronologies are constructed independently and are subsequently compared with climate data to measure the association and quantify the reliability of using the tree-ring data as a proxy for temperature variations.
We have not yet had a chance to explore the details of McIntyre’s analysis or its implication for temperature reconstruction at Yamal but we have done considerably more analyses exploring chronology production and temperature calibration that have relevance to this issue but they are not yet published. I do not believe that McIntyre’s preliminary post provides sufficient evidence to doubt the reality of unusually high summer temperatures in the last decades of the 20th century.
We will expand on this initial comment on the McIntyre posting when we have had a chance to review the details of his work.
K.R. Briffa
30 Sept 2009
- Briffa, K. R. 2000. Annual climate variability in the Holocene: interpreting the message of ancient trees. Quaternary Science Reviews 19:87-105.
- Briffa, K. R., and T. J. Osborn. 2002. Paleoclimate – Blowing hot and cold. Science 295:2227-2228.
- Briffa, K. R., V. V. Shishov, T. M. Melvin, E. A. Vaganov, H. Grudd, R. M. Hantemirov, M. Eronen, and M. M. Naurzbaev. 2008. Trends in recent temperature and radial tree growth spanning 2000 years across northwest Eurasia. Philosophical Transactions of the Royal Society B-Biological Sciences 363:2271-2284.
- Hantemirov, R. M., and S. G. Shiyatov. 2002. A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia. Holocene 12:717-726.
Now a few points of my own:
1. Plotting the entire Hantemirov and Shiyatov data set, as I’ve done here, shows it to be almost flat not only in the late 20th century, but through much of its period.
How do you explain why your small set of 10 trees shows a late 20th century spike while the majority of Hantemirov and Shiyatov data does not? You write in your rebuttal:
“He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights.”
Justify your own method of selecting 10 trees out of a much larger data set. You’ve failed to do that. That’s the million dollar question.
Briffa Writes: “My application of the Regional Curve Standardisation method to these same data was intended to better represent the multi-decadal to centennial growth variations necessary to infer the longer-term variability in average summer temperatures in the Yamal region: to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.”
OK Fair enough, but why not do it for the entire data set, why only a small subset?
2. It appears that your results are heavily influenced by a single tree, as Steve McIntyre has just demonstrated here.
As McIntyre points out: “YAD061 reaches 8 sigma and is the most influential tree in the world.”
Seems like an outlier to me when you have one tree that can skew the entire climate record. Explain yourself on why you failed to catch this.
3. Why the hell did you wait 10 years to release the data? You did yourself no favors by deferring reasonable requests to archive data to enable replication. It was only when you became backed into a corner by The Royal Society that you made the data available. Your delays and roadblocks (such as providing an antique data format of the punched card era), plus refusing to provide metadata says more about your integrity than the data itself. Your actions make it appear that you did not want to release the data at all. Your actions are not consistent with the actions of the vast majority of scientists worldwide when asked for data for replication purposes. Making data available on paper publication for replication is the basis of proper science, which is why The Royal Society called you to task.
Read about it here
Yet while it takes years to produce your data despite repeated requests, you can mount a response to Steve McIntyre’s findings on that data in a couple of days, through illness even.
Do I believe Dr. Keith Briffa? No.
Sponsored IT training links:
Guaranteed success in NS0-154 exam with help of 650-177 practice test and up to date 642-515 exam dumps.
If you pay closer attention to the last 10 or so topics right here on WUWT there are quite a few who understand whats behind the controversy. For a start, although dendroecology and dendrobiology are valid braches or organic science, it is a leap of faith to turn that to climatological reproduction, and an even greater to limit to temperatures at any given stage in the life of a tree.
Scott A. Mandia (07:02:53)
you said
“BTW, Mann eta al.’s plot was essentially the same with or without tree rings. Shocker!!
However, when making a selection amongst facts, then of course any abberation or conclusion can be reproduced. If I was to take a sample of 1000 people from the streets of NYC and count colours and nationalities there would be quite a few. Then I narrow it down to 20 people to take a proxy and deliberately choose white people from that 1000, and on this basis say “everyone in NYC is white”
In reference to such faulty methodology of producing an preconceived result, I refer ou to:
http://wattsupwiththat.com/2009/04/11/making-holocene-spaghetti-sauce-by-proxy/
we see that some 50 non tree ring temperature proxies combined shows a MWP around 0,4 K warmer than today, lasting at least 500 years, and that most of the Holocene was warmer than today
@ur momisugly Richard S Courtney (13:50:21) :
One cannot use 40 years worth of data to calculate a 100 year trend. 🙂
My numbers were shown as degrees F per decade. Are you suggesting that the slope of temperature vs. decade is not increasing as one moves from 1850 toward present day? Surely you can see that the slope per decade is increasing.
19 of the warmest years have occurred in the past 25 years. The warmest years globally have been 1998 and 2005 with the years 2002, 2007, and 2003 close behind. The warmest decade has been the last ten years and the warming has been widespread globally. 2009 is likely to finish Top 10 or Top 5.
It is almost a certainty that 2001-2010 will be the warmest decade since 1850. Since 1980, each decade is getting warmer than the last.
Unfortunately, the greatest warming is predicted to be in the second half of this century even if we come to our senses and limit greenhouse gas emissions. We may look back at the record decades of today as being “the cool period of this century.” Sad.
Scott A Mandia – Ask yourself, “Why do I not know the WHOLE story?”
The answer is simple: Because Briffa will NOT explain it fully and answer questions about how he did his work.
There is a reason for that, and it is that the answer will look even worse than the silence.
There is NOTHING about this whole controversy that McIntyre is not willing to discuss publicly. If only Briffa were behaving in the same fashion.
Scott A Mandia:
There are degrees of twaddle, and this one of yours is off the measurement scale.
You say;
“My numbers were shown as degrees F per decade. Are you suggesting that the slope of temperature vs. decade is not increasing as one moves from 1850 toward present day? Surely you can see that the slope per decade is increasing.”
Rubbish! The last decade has shown no rise.
My point is valid. Your assertion of increasing global warming over recent decades is as valid as the MBH ‘hockey stick’ analysis because
(a) you are comparing different time periods
and
(b) you are using linear trends to assess fluctuating time series.
The various global temperature reconstructions (e.g. GISS, HadCRUT3) show two combined trends; viz, recovery from the Little Ice Age, and fluctuations of 60 year periodicity which coincide with the phases of the Pacific Decadal Oscillation (PDO).
The fluctuations provide cooling to ~1910, cooling from ~1940 to ~1970, and there has been cooling since about 2000. So, the reconstructions show similar length of time cooling as warming.
The most that can be said is that the rate of warming in the two warming periods is greater than the rate of cooling in the cooling periods and, therefore, the temperature was higher at the end of the twentieth century than at the start of the century. And the global temperature has fallen since then.
However, very importantly, the rate of warming in the two periods of warming was the same. One of those periods was prior to 1940 (i.e. 1910 to 1940) and the other was after 1940 (i.e. 1970 to 1998). But about 85% of all the emissions of greenhouse gases from human activity was after 1940.
Clearly, there is no reason to suppose that the period of warming from 1970 to 1998 was induced by the emissions from human activity when the earlier – and similar – period of warming could not have been. And that warming is part of the recovery from the Little Ice Age that began three centuries ago (i.e. prior to the industrial revolution).
Richard
Richard,
Be so kind as to explain how the PDO causes stratospheric cooling. Actually, I would love to hear how ANY natural forcing mechanism can warm the troposphere while at the same time cool the stratosphere.
BTW, greenhouse gases do precisely this.
Scott A. Mandia (16:56:05) :
19 of the warmest years have occurred in the past 25 years. The warmest years globally have been 1998 and 2005 with the years 2002, 2007, and 2003 close behind. The warmest decade has been the last ten years and the warming has been widespread globally. 2009 is likely to finish Top 10 or Top 5.
It is almost a certainty that 2001-2010 will be the warmest decade since 1850. Since 1980, each decade is getting warmer than the last.
Unfortunately, the greatest warming is predicted to be in the second half of this century even if we come to our senses and limit greenhouse gas emissions. We may look back at the record decades of today as being “the cool period of this century.” Sad.
What is sad is that you have not understood my example about rates of change: the derivative of sin(at) is cos(at), which means that the rate of change can be as big as the change as time progresses in oscillating functions.
Go to http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png to see that oscillation is the description of data since the Holocene started.
All your statements would hold if you go and sit at 1500 years ago on the rise of one of the curves. It is inevitable that rates increase, either sign, when there is oscillating behavior.
Maybe your math skills are not up to understanding this? It would explain why you keep harping on the rate of change.
Look at this record of the holocene that shows oscillating temperatures:
anna v (22:06:25) : “If the methods of the IPCC and GCM projections were used to build a plane, of course you should never enter it. ”
BRAVA! Logic at its zenith.
Chris
Norfolk, VA, USA
P Wilson (15:30:51) :
“Scott Mandia. I don’t know what faith this hockey stick brings. Its as though you’re more interested in it being reproduced than the means by which it is contrived.”
Ouch!
Chris
Norfolk, VA, USA
Scott A. Mandia (18:34:43) :
Richard,
Be so kind as to explain how the PDO causes stratospheric cooling. Actually, I would love to hear how ANY natural forcing mechanism can warm the troposphere while at the same time cool the stratosphere.
BTW, greenhouse gases do precisely this.
I suppose in your books H2O is not a natural forcing mechanism, nor all the other naturally occuring green house gases ( including the trace CO2 of course).
And while we are at it, can you give the forcing agents that created in our past a plot like http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png
?
I thought not.
Scott A. Mandia (16:56:05) :
“19 of the warmest years have occurred in the past 25 years. The warmest years globally have been 1998 and 2005 with the years 2002, 2007, and 2003 close behind. The warmest decade has been the last ten years and the warming has been widespread globally. 2009 is likely to finish Top 10 or Top 5.”
Wow…this is so bad I am almost starting to feel sorry for you, Scott.
On what scale??
Since records have been kept?
150 years? 250? 1000? 10,000? 100,000?
Even 100,000 and you only scratch the surface, and provide the marker where homo sapiens first appeared.
4.6 Billion years of Earth Cycles, Scott.
And you want to get your panties in a wad over a few decades, scores or centuries.
Don’t worry…there is still time to escape from the religious sect of AGW.
Just open your mind…(and swallow your ego).
Meanwhile….I run regularly in the “hills” of my coastal Virginia home, in a state park that, with mixed subtropical stands of tupelo and cypress, also features beech and other northern hardwoods…indicators of the ebb and flow of multidecadal climate cycles.
But on a larger scale (and longer period of cycles, some yet undiscovered) the “hills” I run on, are actually ancient dune boundaries with the Ocean from the early Holocene many thousands of years ago.
Face the truth, Scott. You have been duped into “group-think” aka “consensus”. Don’t take it personally…it happens to the best of us.
And it has happened on a global scale, many times before in human history.
Even perhaps when those Early Holocene humans were skipping about enjoying their warm, balmy Optimum.
CHRIS
Norfolk, VA, USa
Thank you psi for reminding us of the subject. You have nailed it.
Scott, you are clearly trying to divert attention with your unending reference to unrelated and doubtful “facts” please give it a rest.
So is the Briffa v McIntyre Battle done?
Is there a winner?
What is the outcome of this debate?
Is one tree “YAD061” really the sole driver of all of Briffa’s ‘significant’ data? (that would be so hard to believe.)
Just reading thru the first 20 posts and recent events explain everything.
1 Abuse of tree ring data
2 cherry picking data
3 Over weighting of proxies by placing weights in the /Fortran code
4 Blocking release of data
5 Playing the I am sick excuse
Shed a little November heat on this and Briffa is exposed.