Shock, awe. Untruncated and unspliced data used in a new paper from Briffa and Melvin at UEA restores the Medieval Warm Period while at the same time disappears Mann’s hockey stick. Here’s figure 5 that tells the story:
Look at graph 5c, and you’ll see 20th century warmth matches peaks either side of the year 1000, and that for the TRW chronology 20th century warmth is less than the spike around 1750. This puts 20th century (up to 2006 actually) warmth in the category of just another blip. There’s no obvious hockey stick, and the MWP returns, though approximately equal to 20th century warmth rather than being warmer.
Whoo boy, I suspect this paper will be called in the Mann -vs- Steyn trial (if it ever makes it that far; the judge may throw it out because the legal pleading makes a false claim by Mann). What is most curious here is that it was Briffa (in the Climategate emails) who was arguing that some claims about his post 1960 MXD series data as used in other papers might not be valid. It set the stage for “Mikes Nature trick” and “hide the decline“. Steve McIntyre wrote about it all the way back in 2005:
A Strange Truncation of the Briffa MXD Series
Post-1960 values of the Briffa MXD series are deleted from the IPCC TAR multiproxy spaghetti graph. These values trend downward in the original citation (Briffa [2000], see Figure 5), where post-1960 values are shown. The effect of deleting the post-1960 values of the Briffa MXD series is to make the reconstructions more “similar”. The truncation is not documented in IPCC TAR.
I have to wonder if this is some sort of attempt to “come clean” on the issue. Mann must be furious at the timing. There’s no hint of a hockey stick, and no need to splice on the instrumental surface temperature record or play “hide the decline” tricks with this data.
Bishop Hill writes:
Well, well, well.
In its previous incarnation, without a MWP, the series was used in:
- MBH98
- MBH99
- Rutherford et al 05
- Jones 98
- Crowley 00
- Briffa 00
- Esper 02
- Mann, Jones 03
- Moberg
- Osborn, Briffa 06
- D’Arrigo et al 06
It rather puts all that previous work in perspective, since this new paper has identified and corrected the biases. It should be noted though that tree ring paleoclimatology is an inexact science, and as we’ve seen, even a single tree can go a long way to distorting the output. On the plus side, it is good to see that this paper defines and corrects biases present in the MXD and TRW series of the Tornetraesk tree ring chronology dataset. This is a positive step forward. I suspect there will be a flurry of papers trying to counter this to save Mann’s Hockey Stick.
From the journal Holocene:
Potential bias in ‘updating’ tree-ring chronologies using regional curve standardisation: Re-processing 1500 years of Torneträsk density and ring-width data
Thomas M Melvin University of East Anglia, UK
Håkan Grudd Department of Physical Geography and Quaternary Geology, Stockholm University, Sweden
Keith R Briffa University of East Anglia, UK
Abstract
We describe the analysis of existing and new maximum-latewood-density (MXD) and tree-ring width (TRW) data from the Torneträsk region of northern Sweden and the construction of 1500 year chronologies. Some previous work found that MXD and TRW chronologies from Torneträsk were inconsistent over the most recent 200 years, even though they both reflect predominantly summer temperature influences on tree growth. We show that this was partly a result of systematic bias in MXD data measurements and partly a result of inhomogeneous sample selection from living trees (modern sample bias). We use refinements of the simple Regional Curve Standardisation (RCS) method of chronology construction to identify and mitigate these biases. The new MXD and TRW chronologies now present a largely consistent picture of long-timescale changes in past summer temperature in this region over their full length, indicating similar levels of summer warmth in the medieval period (MWP, c. CE 900–1100) and the latter half of the 20th century. Future work involving the updating of MXD chronologies using differently sourced measurements may require similar analysis and appropriate adjustment to that described here to make the data suitable for the production of un-biased RCS chronologies. The use of ‘growth-rate’ based multiple RCS curves is recommended to identify and mitigate the problem of ‘modern sample bias’.
Here’s the money quote from the paper:
If the good fit between these tree-growth and temperature data is reflected at the longer timescales indicated by the smoothed chronologies (Figures 5c and S20d, available online), we can infer the existence of generally warm summers in the 10th and 11th centuries, similar to the level of those in the 20th century.
Conclusions
• The RCS method generates long-timescale variance from
the absolute values of measurements but it is important to
test that data from different sources are compatible in
order to avoid systematic bias in chronologies.
• It was found in the Torneträsk region of Sweden that there were systematic differences in the density measurements from different analytical procedures and laboratory conditions and that an RCS chronology created from a simple combination of these MXD data contained systematic bias.
• Both the known systematic variation of measurement values (both TRW and MXD) by ring age and the varying effect of common forcing on tree growth over time must
be taken into account when assessing the need to adjust subpopulations of tree-growth measurements for use with RCS.
• It was necessary to rescale the ‘update’ density measurements from Torneträsk to match the earlier measurements over their common period, after accounting for ring-age decay, in order to remove this systematic bias.
• The use of two RCS curves, separately processing fastand slow-growing trees, has reduced the effect of modern sample bias which appears to have produced some artificial inflation of chronology values in the late 20th century in previously published Torneträsk TRW chronologies.
• A ‘signal-free’ implementation of a multiple RCS approach to remove the tree age-related trends, while retaining trends associated with climate, has produced
new 1500-year long MXD and TRW chronologies which show similar evidence of long-timescale changes over
their full length.
• The new chronologies presented here provide mutually consistent evidence, contradicting a previously published conclusion (Grudd, 2008), that medieval summers (between 900 and 1100 ce) were much warmer than those
in the 20th century.
• The method described here to test for and remove systematic bias from RCS chronologies is recommended for further studies where it is necessary to identify and mitigate systematic bias in RCS chronologies composed of nonhomogeneous samples.
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From joeldshore on November 1, 2012 at 9:59 am:
Exactly. The Climatic Optimums have been reaching subsequently smaller maximum temperatures. Through Holocene to Minoran to Roman to Medieval, this interglacial has been cooling off. The modern warm period is now about the maximum to be expected from the long-term trends. The cooling may well be started.
As shown by Willis Eschenbach in multiple posts, the forcing effects of volcanoes are poorly understood. Start here:
http://wattsupwiththat.com/2012/09/10/volcanic-corroboration/
He references a paper in press, draft copy found here:
http://www.uib.no/People/ngfhd/EarthClim/Publications/Papers/Driscoll_etal_2012.pdf
From the in-press listing:
At the end of that post is a list of his previous posts. Volcanoes may cause cooling or warming, going by the temperature records. BEST tried to tie eruptions to cooling episodes, except the cooling they were noting actually occurred before or after the eruption, etc.
To summarize, volcanoes are noise, with negligible effects more than a few years out, with negligible to no influence on long-term trends. At least in “modern” geological times with relatively limited vulcanism, of course.
As to solar forcings, the common perception was there has been a modern Grand Maximum, and TSI has had a marked increase since the early 20th century, which would not yield cooling. But if you’ve been following the work of Dr. Leif Svalgaard, you would know that Grand Maximum has gone away, and TSI may have rose slightly at the beginning of the 20th but was pretty much level for the rest of the century, which wouldn’t be yielding cooling.
We are due for cooling, but I do not see how cooling of the second half of the 20th century would have followed from the volcanic and solar forcings.
Exactly. We see an apparent charge and discharge/hold pattern, summing to a rising trend. We have entered discharge/hold.
But there are known patterns like the PDO that do match the temperature record, thus we know there are patterns in there.
From joeldshore on November 1, 2012 at 10:49 am:
That data is created on a computer, and as many common “random” number generators will repeat when starting with the same seed, and with simple biases like the method of rounding numbers and the specific programming of math routines, patterns may be generated that do exist. To simply say they cannot possibly be in there without verification is embracing ignorance.
Gunga Din says:
I’ve already given my opinion on this up-thread, which in a nutshell is this: Nobody that I know of is really disputing whether the MWP happened…That is a “red herring”. There is general agreement that lots of temperature proxies from different locations show a warm period sometime during the period from 900 AD to 1400 AD and even that this warmth is, in some places, as pronounced as the modern warmth. The issue, however, is that the exact period of warmth seems to vary from one location to the next, that is, they are not synchronous: some show warmth right around 1000 AD, some around 1200 AD and so forth. As a result of this, when a global or hemispheric temperature reconstruction is performed, this lack of synchronicity leads to a broad, diffuse warm bump that is not as pronounced as the current warming when the warming is happening with greater synchronicity from place to the next.
joelshore says:
“…lack of synchronicity leads to a broad, diffuse warm bump that is not as pronounced as the current warming when the warming is happening with greater synchronicity from place to the next.”
Wrong. Exactly the same thing is happening in the modern [naturally] warm period:
http://c3headlines.typepad.com/.a/6a010536b58035970c013486e5c5e6970c-pi
http://icecap.us/images/uploads/GT14.jpg
There were also several episodes of even warmer temperatures throughout the Holocene. But joelshore ignores those, because they deconstruct his alarmist narrative.
Nothing happening now is unprecedented or unusual. It is normal and natural. It has all happened repeatedly before, and the Null Hypothesis has never been falsified.
joeldshore says:
November 1, 2012 at 12:33 pm
He’s doing you a favor, Joel. Every time you reference that hack, your credibility declines here.
joeldshore:
At November 1, 2012 at 12:30 pm you say to me
As usual, you completely miss the point.
Nobody claims the long term global temperature trend is a purely random effect.
It is mostly recovery from the LIA. And we do not know the cause(s) and/or mechanism(s) which created the LIA or recovery from it.
We observe recovery from the LIA.
We also observe various cycles some of which we can describe but do not understand (e.g. PDO, ENSO, AMO, etc.) imposed on that recovery.
We observe a fluctuation in the temperature time series of recovery from the LIA.
Is that fluctuation an indication of one of the cycles? Probably.
Is that fluctuation a random effect? Possibly.
Is that fluctuation a result of AGW? No, it is in the wrong direction.
Indeed, that fluctuation indicates that AGW is insignificant as a contribution to the fluctuations in recovery from the LIA.
It is NOT science to adopt a chosen one among all possibilities then to ignore the other possibilities. Indeed, that is the error of warmunists: scientists don’t do it.
Richard
“Mann’s hockey stick disappears – and CRU’s Briffa helps make the MWP live again by pointing out bias in the data”
joeldshore says:
November 1, 2012 at 12:41 pm
Gunga Din says:
Did the Medivial Warm Period happen or not?
I’ve already given my opinion on this up-thread, which in a nutshell is this: Nobody that I know of is really disputing whether the MWP happened…That is a “red herring”.
===========================================================
So even Mann admits his Hockey Stick has disappeared? Does he now also admit to the Little Ice Age?
Does he admit he lost the Hockey Stick War?
(I’ll give you the benefit of the doubt. Maybe you just don’t know him.)
Gunga Din:
No.
You’ve really bought into a lot of myths that are circulating around here. The people who have told you that Mann says there was no MWP or LIA are creating a “strawman” that they can then proceed to knock down. Here is what Mann et al. said in their 1999 paper (which was the first of their work to reconstruct back 1000 years, i.e., far enough to get to the MWP):
( http://www.ltrr.arizona.edu/webhome/aprilc/data/my%20stuff/MBH1999.pdf )
Before you can criticize something intelligently, you have to understand it. However, if, for ideological reasons, you want to tear it down by using false arguments against it, the first thing that you have to do is mischaracterize. This helps explain why you have apparently been told a lot of falsehoods about exactly what it is that Mann et al. say.
D Boehm says:
As usual, the only links you provide are to pictures created by ideologues who have an agenda…And, you don’t even provide enough information so that one can even research how the data was created! Hence, you are only illustrating the fact that you are a “fake skeptic” who will believe anything that they see if it supports their point of view.
In terms of specifics: The first link may have been created using data that was not corrected for known biases such as time-of-measurment bias. The second link is completely irrelevant as it is looking at trends over small regions over short timescales, so the noise is going to be huge.
At any rate, the current warming has certainly not been completely uniform but it has been much more synchronous than the warm periods experienced seen in proxies from different places during the loosely-defined “Medieval warm period” that spans about 500 years!
So, are you going to provide us with the first hemispherical or global temperature reconstruction going back more than 2000 years? That would certainly be impressive! (Also, as one goes back further in the Holocene, there are known reasons why, for example, summers would be warmer at high Northern latitudes due to the Milankovitch oscillations, so your point becomes increasingly irrelevant. Yes, there are other forcings that can produce increases in temperature on such timescales.)
richardscourtney says:
That is exactly what science is. It allows us to choose among the infinite explanatory possibilities on the basis of sound scientific exploration.
And, it is the method of those on the losing side of the scientific debate (particularly when the debate involves strongly-held ideological positions) to claim that the scientists have colluded against their point-of-view and unfairly excluded it. The same arguments are made by all those fighting against science, whether they be those who fight against the theory of evolution or what have you.
joelshore says:
“…it is the method of those on the losing side of the scientific debate (particularly when the debate involves strongly-held ideological positions) to claim that the scientists have colluded against their point-of-view and unfairly excluded it.”
As the resident expert on losing the debate, and the most ideological commenter here by far, I should remind joelshore that the only reason alarmist scientists are colluding to exclude skeptics [and they certainly are, as shown in the Climategate emails], is due to the immense amounts of taxpayer loot handed out. They know if they enter into real debates they will lose, and thus their gravy train will be derailed.
The fact that the alarmist side refuses to engage in open and fair debate also shows that they do not have the courage of their convictions. They are simply running a scam on the public, and joelshore is their enabler. If joelshore doesn’t see that, it is because he is blinded by his anti-science ideology. Science is about openness and transparency — qualities that are anathema to shore and his ilk.
And as usual, joelshore finds fault with every chart I have ever posted. They are all wrong, every one of them… according to joelshore. What are the odds, eh? Out of more than a thousand charts I’ve posted, from hundreds of different sources, joelshore cannot bring himself to agree with a single one of them. That’s ideology for you. And that is why those on joelshore’s side are losing the debate.
joeldshore:
At November 1, 2012 at 3:30 pm you write
Thus you condemn yourself by your own words as being a pseudoscientist.
Science
consists of seeking the closest approximation to ‘truth’ by attempting to find evidence which refutes an existing understanding and amending the understanding in the light of the evidence.
Pseudoscience
consists of adopting an understanding as ‘truth’ and attempting to find evidence which supports it while ignoring information which refutes it.
Hence,
science NEVER ignores any possibility
while
pseudoscience adopts one possibility and ignores others.
Richard
PS I will not be able to answer any reply because in a few hours I am to leave for one of my regular absences for one to two weeks. Sorry.
Joel, sensu lato means “in a broad sense”. Thus the statement is actually ‘…while cooling following the 14th century could be viewed as the initial onset of the Little Ice Age in a broad sense.’
This is practically legalistic language, used when a possibility cannot be explicitly rejected but the remoteness of the possibility is being noted. Like if a lawyer said in court “Yes, my client’s blowing of his nose could be viewed as the initial cause of the traffic accident in a broad sense…”
Meanwhile we can look at the hockey stick graph from Mann 1999:
http://www.ncdc.noaa.gov/paleo/ctl/images/mann2.jpg
Found here: http://www.ncdc.noaa.gov/paleo/ctl/clisci1000.html
After 1400 is a little dip around 1450. Temperatures recover to basically a flat line from 1500 onward, until the “unprecedented” 20th century warming.
Where is the LIA? There are small variations of tenths of a degree at most, usually hundredths, essentially a straight line from beginning until the “unprecedented” warming. What “could be viewed” sensu lato as the LIA is a small brief dip.
We know what we see. That we understand. And we know what that statement really said.
joeldshore says:
November 1, 2012 at 3:30 pm
“That is exactly what science is.”
No, that is exactly what primitive superstition is. That is the sort of rush to judgment which resulted in leeches, burning “witches” at the stake, and ritual human sacrifice. You are advocating a return to the Dark Ages.
In Science, you need to have both a mechanism, and data which confirm the mechanism. Right now, you have a mechanism, and you have data, but the data do not confirm the mechanism. Failing to dis-confirm it is not enough.
It is not enough that you have a possibility. There are all kinds of possibilities for dire things to happen. We can’t live our lives in fear, especially when the proffered cure is worse than the disease.
kadaka says:
“Where is the LIA?”
Exactly. The LIA was the second coldest event of the Holocene. Mann tried to erase most of it, just like he tried to erase most of the MWP. He did that by excluding a large data set from his proxy [“censored“]. The Mann is simply dishonest.
Bart says:
November 1, 2012 at 11:56 am
I was going to mention with regard to the above post, using such a statistical model to determine significance is akin using a herring to cut down the mightiest tree in the forest. It’s the wrong tool, and it’s not going to do the job.
This is really what aggravates me the most about the whole debate – that those who are quickest to claim that they have “science” on their side typically have no actual idea about what they are doing or why. It isn’t science. It is a mockery of science. It is cargo cult science.
Most of the time the planet is in an ice house phase. In this chart we see the short interstadials, which are most beneficial to the biosphere. We are currently in a warm period, but as you can see it is not as warm as past interstadials.
We could use a couple more degrees of global warming. But according to the alarmist crowd, every change is bad.
D Böehm says: “Where is the LIA?” Exactly. The LIA was the second coldest event of the Holocene. Mann tried to erase most of it, just like he tried to erase most of the MWP.’
I never thought that I will be defending Mann – but I have to; so hopefully you can see how ignorant the Fake Skeptics are: LIA was colder in Europe, North America – at that same time – S/H had much ”HOTTER” days = LAWS OF PHYSICS say so; Your pagan believes are giving oxygen to Mann. Hansen. b] during the MWP was ”MILDER” climate in Europe / North Africa, Middle East, NOT GLOBAL warming! It was milder, because Sahara still had some vegetation / lakes with permanent water -> it was producing LESS dry heat – less dry heat, was destroying LESS humidity created in the Mediterranean = humid = milder, not hotter. Milder means: cooler days / warmer nights.
You are using IGNORANT lies, accumulated for the previous 150y, by swindlers, Mann WAS one of them; he knows the reliability of the ”pagan beliefs” + he knows that he is smarter liars, than the Fakes like you – therefore, he can entertain and change any lie; having bigots for opponents like you. Apart of me, nobody takes in consideration: what human did to the climate, by inventing ARTIFICIAL CREATION of fire. Man erasing LIA + MWP, was the only honest thing that he ever did. Which proves that: people like you are bigger prolific liars, with a smaller common sense. You have to get read of the pagan beliefs, if you want Warmist to take you seriously. Warmings / coolings are NEVER GLOBAL – universe is NOT spinning around the earth. ,
stefan,
What’s with all the flaming hatred?? I doubt you have many friends.
Note that MBH98/99 proxies were in Siberia, not in the Southern Hemisphere. Sheesh, you go off the deep end over things you don’t even understand. Chill out.
richardscourtney says: ” And we do not know the cause(s) and/or mechanism(s) which created the LIA or recovery from it”
Yes, we do! Your pagan beliefs don’t permit you to know. LIA wasn’t GLOBAL cooling; but colder in Europe, north America – because Arctic ocean had less ice cover -> was releasing more heat / was accumulating -> radiating + spreading more coldness – currents were taking that extra coldness to Mexican gulf – then to the Mediterranean – because Sahara was increasing creation of dry heat and evaporating extra water in the Mediterranean – to top up the deficit – gulf stream was faster / that was melting more ice on arctic also as chain reaction – Because Mediterranean doesn’t have enough tributaries, to compensate for the evaporation deficit.
Then ”working people dug Suez Canal – some water started coming into Mediterranean from red sea – small, but accumulative effect!!! Human can change the climate, but cannot produce GLOBAL warming! The moon is spinning around the earth, but the universe is not!!! Bigots like you, that use outdated pagan beliefs are giving oxygen to Mann, Hansen, For every change, there is a real reason and there is the outdated pagan crap – apart from me, nobody takes in consideration what human invention of artificial fire did to ”LOCALIZED climates” instead, is used as phony GLOBAL warmings / coolings, shame shame Richard & Co:: http://globalwarmingdenier.wordpress.com/midi-ice-age-can-be-avoided/
[Dial back the name calling. — mod.]
D Böehm says: ”stefan, Note that MBH98/99 proxies were in Siberia, not in the Southern Hemisphere.
Mate, ”proxy” is accumulation of the biggest crap ever!!! They were more cherry-picking, by shonky climatologist; than now – because was no scrutiny.
2] in Siberia they still find woolly mammoth flash that is good enough the dogs to eat it – if there was any phony GLOBAL warming for few weeks, for real ; wouldn’t be the case. If you can comprehend the damages you guys are doing to the truth; by your GLOBAL temp going up and down as a yo-yo -> you wouldn’t be going outside without brown paper bag over your heads! reason you are scared to read my posts.
stefan says:
“reason you are scared to read my posts.”
I am not scared to read your posts, as you can see. I look at them with the same fascination I would have looking at a train wreck.
joeldshore says:
October 30, 2012 at 5:07 pm
Bart says:
” The human brain is an amazing pattern recognition device which can generally, sometimes with the aid of some basic filtering/smoothing, cut through the clutter and identify what is truly happening.”
…The problem in this case is that the human brain is too good a pattern recognition device. It often sees patterns in random data when the patterns aren’t really there. ‘
_ _ _ _ _ _ _ _ _ _ _
What the man who thinks there’s no way mankind can check for elevating infrared spectra in the atmosphere described for us is called Anthropogenic Climate Change.
Claim to see warmth when entire countries meteorological organizations are saying, “that’s not the data we sent those government employees, ours is posted raw, online.”
I’m starting to think certain “skeptics” are dispatched to reinforce the “crazy denier” meme whenever real skeptics are talking calm and logically and decisively making their points. Gotta prove those angry anti-science raving loonies are the real “normal” on those skeptic sites, eh?
[it’s a fine line, sometimes, between ignorance and false flag postings but we do try to make the distinction . . mod]
kadaka says:
Give me a break! You will go to any lengths to deny things that are inconvenient. We are in the 21st century…Pseudorandom number generators have gotten pretty damn good! And, a lot of people have seen basically the same sort of things in a lot of different contexts using a lot of different random number generators. I imagine there has probably even been some theoretical analysis on this sort of stuff too.
You are spinning your own interpretation on it.
As I have explained, the point of Mann’s work was that when you average things together from around the hemisphere, the lack of synchronicity in the MWP (and presumably the LIA too) leads to a broad diffuse MWP and a broad and diffuse LIA. They don’t disappear altogether.
Hence, just collecting a bunch of graphs from different places that show some warmth somewhere between 900 and 1400 AD (as CO2science has done) and/or some coolness somewhere between ~1400 AD and 1850 AD does not demonstrate that Mann is wrong. Some other reconstructions since Mann’s 1999 work have found a more distinct and cooler LIA…although not generally a warmer MWP…and hence a somewhat bumpier “blade” than that of Mann et al.