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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joeldshore says:
October 30, 2012 at 5:07 pm
‘It often sees patterns in random data when the patterns aren’t really there.’
We’re not talking Escher prints here. It’s a very basic trend, followed by not-a-trend. You are flailing.
In the “picture is worth a thousand words” department, here is a graph that shows in blue the data and trend for 1975-mid 1997 http://tamino.files.wordpress.com/2012/10/crumod2.jpg . Then in red is the data from mid-1997 to the present with the red line just being the blue trend line extrapolated to the present. As you can see, the post mid-1997 data does not deviate in any marked way from the trend line one draws based on the data up until mid-1997. [And, if you wonder if mid-1997 is some sort of cherry-pick, the answer is that it was, but it was the cherry-pick that was made by David Rose in his recent claim about global warming having stopped.]
vukcevic says:
October 30, 2012 at 2:59 pm
You might like to do some calculations using geomagnetic storms induction as a trigger
http://igppweb.ucsd.edu/~cathy/Classes/SIO229/geomag_2012_64-71.pdf
Table of Skin Depths
material , S/m 1 year 1 month 1 day 1 hour 1 sec 1 ms
core 3 10^5 4 km 770 m 200 m 40 m 71 cm 23 mm
L. mantle 10 900 km 170 km 46 km 9 km 160 m 5 m
…
The table shows skin depths for a variety of typical Earth environments and a large range of frequencies. The first line shows that for practical sounding the core is effectively a perfect conductor into which the external magnetic field does not penetrate.
Let this be the final word on the subject.
Bart says:
So, when the same thing occurs in synthetic data sets of a linear trend plus noise, does that mean that the computer disobeyed the commands of the programmer and just decided to make the underlying trend stop even though it was programmed to keep going?
Bart, I think you are intelligent enough to know better than this.
joeldshore said on October 30, 2012 at 6:10 pm:
It shows Tami welcomes manipulating the presentation to provide a false fact.
You’re *ahem* mistaken about “mid-1997”. As clearly reported in the original WUWT report (bold added):
From start of 1975 to start of 1997 (end of 1996) to present looks somewhat different:
http://www.woodfortrees.org/plot/hadcrut4gl/from:1975/to:1997/plot/hadcrut4gl/from:1975/to:1997/trend/plot/hadcrut4gl/from:1997/plot/hadcrut4gl/from:1997/trend/plot/hadcrut4gl/from:1975/trend
There is no single straight line, 1975 to start of 1997 is not perfectly overlain on 1975 to the present, last month currently being August 2012. Your “proof” is a lie.
And if it was “mid-1997”? The mistake would logically be to choose August, as that month was mentioned.
http://www.woodfortrees.org/plot/hadcrut4gl/from:1975/to:1997.75/plot/hadcrut4gl/from:1975/to:1997.75/trend/plot/hadcrut4gl/from:1997.67/plot/hadcrut4gl/from:1997.67/trend/plot/hadcrut4gl/from:1975/trend
Closer, but still not the single line of the Tami site graph. Your “proof” doesn’t exist.
BTW, HadCRUT3 is also fun to look at.
Start of 1997
“Mid-1997”
No “proof” there either.
What’s the matter, Joel? Aren’t people thinking critically and scientifically supposed to verify facts for themselves, rather than trust something that popped up on some internet blog?
Leif Svalgaard says:
October 30, 2012 at 6:11 pm
Let this be the final word on the subject.
If you mean that :
The first proposition, that the sun affects magnetic field of the earth, is foolish, absurd, false and deviating because it is expressly contrary to rule of science … and the second proposition, that the earth climate change is caused by the sun, is absurd, false in philosophy, and, from a our point of view at least, opposed to the true science.
In the name of established consensus you are to relinquish altogether the opinion that the sun is cause of any changes on the earth, nor henceforth to hold, blog comment, or defend it in any way whatsoever, verbally or in writing.
Yes your holiness.
kadaka (KD Knoebel) wrote in
http://wattsupwiththat.com/2012/10/28/manns-hockey-stick-disappears-and-crus-briffa-helps-make-the-mwp-live-again-by-pointing-out-bias-in-ther-data/#comment-1130165
You’re *ahem* mistaken about “mid-1997″. As clearly reported in the original WUWT report (bold added):
No, he is not mistaken. You only have been gullible enough to take at face value what the “original WUWT report” reported. The temperature curve shown in this WUWT article,
http://wattsupwiththat.com/2012/10/13/report-global-warming-stopped-16-years-ago/
is a forged temperature curve that was taken from the David Rose article,
http://www.dailymail.co.uk/sciencetech/article-2217286/Global-warming-stopped-16-years-ago-reveals-Met-Office-report-quietly-released–chart-prove-it.html#ixzz29E78OR9H
in the Daily Mail
That this temperature record in the Daily Mail article is forged can easily be shown.
Go to woodfortrees.org and compare the curve in the Daily Mail article with the curve from August 1997 in green, and the additional part of the curve in red, how it would have looked like, if it really had started at the beginning of 1997:
http://woodfortrees.org/plot/hadcrut4gl/from:1997.1/plot/hadcrut4gl/from:1997.8
David Rose of the Daily Mail didn’t set a good example for honesty at the side of the “skeptics” there.
Does anyone of the “skeptic” WUWT followers do ever any fact checking, when they believe something was in support of their preconceived views?
Correction to my previous comment:
The starting points in the woodfortrees.org graph must be 1997 and 1997.58 or 1997.67 (I can’t exactly pinpoint it). Somehow, I don’t know how, I got into my head the number after the decimal point was the month number. Sorry about that.
Here is the graph with the corrected starting points:
http://woodfortrees.org/plot/hadcrut4gl/from:1997/plot/hadcrut4gl/from:1997.58
http://woodfortrees.org/plot/hadcrut4gl/from:1997/plot/hadcrut4gl/from:1997.67
It doesn’t change anything else what I said about the forged graph in David Rose’s Daily Mail article, though.
joeldshore:
I remind that in answer to you at October 30, 2012 at 12:28 pm I wrote
Subsequently, October 30, 2012 at 5:07 pm, you say to Bart:
And you emphasise your point when, at October 30, 2012 at 6:16 pm, you say to Bart:
OK. I understand that to be a clear discussion of “possible reasons for that cessation” which fulfills my request. Thankyou.
I am writing to address the issue you raise and which I have quoted. As I understand it, your point is this:
There is a long term linear trend in the data since 1970 and the recent cessation of a trend is merely random fluctuation around the long term trend.
OK. For the sake of argument I will accept your point as being true and consider its implications.
The total data set does not run from 1970 to present: it runs from ~1880 to present.
The trend runs throughout all that data set which has periods of ‘stasis’ prior to 1910, from ~1940 to ~1970, and since ~2000 (+/- 5 years in each case).
(Also, there are good reasons to think the trend originates centuries before the start of the data set and at the initiation of the LIA but here I am considering the data set).
Importantly, there was negligible AGW prior to 1970.
The period from 1910 to 1940 has the same trend as the period from 1970 to 2000.
And
The period from 1910 to 1970 has the same trend as the period from 1970 to the present.
Therefore,
if your claim is true that the recent cessation of a trend is merely random fluctuation around the long term trend, then the lack of change after 1970 to the long term trend is strong evidence that AGW has had no discernible effect.
Please note that I have only addressed one of your claims. Your other claim was refuted by kadaka (KD Knoebel) at October 30, 2012 at 9:40 pm.
Richard
kadaka says:
No…What I do is actually read and understand peoples’ arguments. What you do is attack bizarre “strawman” versions of their arguments. There was no claim made that if you fit a trend line from 1975 to the start (or middle) of 1997 and one from 1975 to the present that they lie exactly on top of each other. Why would that even be the argument?!?
The argument is that if you fit a trend line from 1975 to the start of 1997 (or the middle of 1997, the exact time not making much difference) then an extension of that trendline to the present shows that the data since then has not deviated in any significant way from that trendline.
It is also strange that you are so interested in the fact that your trendlines from 1975 to the start of 1997 and those from 1995 to the present don’t lie EXACTLY on top of each other. Why would you expect them to? They are in fact quite close…and, furthermore, your trendline from 1975 to present is actually STEEPER than the one from 1975 to 1997. Do you think that is compatible with the claim that global warming stopped in 1997?
richardscourtney says:
So, you think that in the absence of AGW, there was just going to be this indefinite trend of temperatures rising at a rate of 1.5-2 C per century? (Heck, it is even a little less than 1 C per century if you take the flat periods of the 20th century into account?)
With refutations like that, who needs support? He argued against the notion that the data since 1997 is quite compatible extrapolation of the 1975-1997 trendline by showing that the trendline for the data from 1975 to the present is actually slightly STEEPER than the 1975-1997 trendline!
Quite a counterargument that!
Friends:
I see the troll is still being a pest at October 31, 2012 at 2:55 am. Not content with asserting it is a “l1e” to quote him verbatim, in support of his daft claim that global warming has not stopped, he says
.
And he clearly shows how “forged” that graph when his post links to these two graphs saying
.
/sarc on/The immense recent global warming and, therefore, the “forged” nature of Rose’s graph are clearly seen in the graphs he provides. /sarc off/
Richard
Richard,
Rose doesn’t even have the intelligence to label his graph correctly. A twelve year old could point that out to you . I would take what he says as fact extremely cautiously.
joeldshore:
Your post at October 31, 2012 at 4:23 am is a non sequitur.
I accepted YOUR assertion for sake of argument and addressed its implications. Using that assertion as an assumption I concluded – and you quoted my conclusion – saying
You have replied
Say what!?
It was YOUR assertion I assessed, not mine.
There WAS “this indefinite trend of temperatures rising”. I assumed the only change was AGW and then assessed that change using YOUR assertion.
If you now want to claim “this indefinite trend of temperatures rising” has stopped then you have to justify your new claim. And that will be a problem for you because nobody knows the cause of that rise.
You then dispute the analysis by kadaka (KD Knoebel) which also shows you are plain wrong. But that is his analysis so I leave it to him to justify it.
Richard
Nick Kermode:
Thankyou for your advice to me at October 31, 2012 at 5:32 am which says
I accept both your points, but I reply that Rose was merely saying the upward trend in global temperature stopped 16 years ago. The data says it did then stop.
The issue is not whether one agrees with Rose. It is whether one agrees with the data. I and others (e.g. Phil Jones) agree with the data. Indeed, the Met.Office has agreed Rose correctly presented the fact that – according to their data – discernible global warming stopped 15 years ago.
By the standards of newspaper journalists, Rose did rather well. As you say, the newspaper graphic was improperly labelled (which may have been a fault of the graphics editor and not Rose) but it was certainly NOT “forged” as the troll claims: it did present the data reasonably well when compared to many newspaper graphics and it did show the recent ‘flatline’ in global temperature as the Met.Office has agreed.
Richard
PS I enjoy your film reviews – and especially your rants – on BBC Radio 5. But I was disappointed in your history of James Bond films in your recent TV documentary.
vukcevic says:
October 31, 2012 at 1:31 am
In the name of established consensus you are to relinquish altogether the opinion that the sun is cause of any changes on the earth,
Just that geomagnetic storms cannot change the earth’s core and that therefore your correlation is spurious.
joeldshore says:
October 30, 2012 at 6:10 pm
“As you can see, the post mid-1997 data does not deviate in any marked way from the trend line one draws based on the data up until mid-1997.”
You have got to be kidding. There is a marked, long term negative curvature in the data set which flatly contradicts your hypothesis. Try fitting a quadratic.
joeldshore says:
October 30, 2012 at 6:16 pm
I’m sorry you are confused, Joel. But, I think the reason is because you have things upside down and backwards. Saying something can have happened is not the same as saying it did happen. Especially when that something is a long stretch of the imagination. It is true that I cannot rule out your hypothesis 100%, but you are not even above the 50% likelihood mark in supporting it.
The onus is on you and the CAGW crew to demonstrate that something is happening out of the ordinary, not me and the skeptics to show that something is not. Right now, there is nothing to indicate that anything out of the ordinary is going on.
You can hem and haw, and claim the reverse because you think something should be happening out of the ordinary, but that is only your personal bias. And, true science does not recognize the whims of a subset of investigators. Moreover, it is your side which is demanding a wrenching downgrade to our quality of life. Extraordianry claims, requiring extraordinary action, require extraordinary evidence. You have nothing dispositive to show.
What you DO have is behavior which is markedly diverging from your prognostication. As Courtney has pointed out several times, if your process is dominant then, by definition, it cannot be dominated by others. If you do not, cannot, say for certain what is happening, then acting on your belief is tantamount to leeching blood, or tossing virgins into the volcano. This is not science. It is superstition. It is very old school appeasement of your gods. I do not worship your gods, and I will not help you throw that lass into the molten depths.
Anyone who claims that global warming “stopped” or similar since about 1997 or so has the burden of proof to demonstrate that the global temperature trend since this point in time, when global warming allegedly “stopped”, is statistically significantly different from the previously statistically significant global warming trend in the decades up to same point in time. The statistical Null hypothesis, they have to successfully reject is in this case that the trend, which is the default case here, in the temperature record up to the point when global warming allegedly “stopped” has not changed since then.
If someone of the ones who state the assertion about the “stopped” global warming, is able to demonstrate that the Null hypothesis above can be successfully rejected, using proper statistical analysis, I will concede that they indeed have statistical evidence at hand, which indicates something has changed significantly in the global temperature record since 1997 or whatever point is claimed to be the one at which global warming allegedly “stopped”.
However, claims based on “eyeballing” and similar offered here in the thread by Mr. Coal-Magazine Editor, who is probably going to write his PhD thesis soon where he refutes global warming using “eyeballing”, and by other “skeptics” are not a scientifically valid approach to provide evidence for the assertion of the “stopped” global warming.
The “skeptics” have not delivered so far. Herewith, I challenge them to deliver.
And, let us not forget the article at hand, which now shows that late 20th century average temps are no higher than they have been in the past. So, now the AGW crew has a completely circularized argument on their hands:
A) increasing CO2 is causing rising temps
B) temps appear not to be rising now, or even out of the ordinary, but they will become so because increasing CO2 is causing rising temps
C) therefore, AGW is real
They are reduced to saying that the lull in rising temps does not disprove the hypothesis, therefore the hypothesis is proved. And, through the looking glass we go.
Jan P Perlwitz says:
October 31, 2012 at 7:47 am
“…has the burden of proof to demonstrate that the global temperature trend since this point in time, when global warming allegedly “stopped”, is statistically significantly different from the previously statistically significant global warming trend…”
Nonsense. If the current trend is not statistically different from the previous trend, then the previous trend is not statistically different from the current. Which is to say, the whole shebang is not statistically significant in proving anything.
The burden is on you to prove otherwise. I challenge you to deliver.
Bart:
Your post at October 31, 2012 at 7:51 am was fortuitously timed. Clearly, you could only have written it before seeing the post from the troll which was sent for moderation only four minutes earlier (at October 31, 2012 at 7:47 am).
However, your post provides a precise description (minus untruths and ad homs) of the contents of that post from the troll.
The defence rests, M’Lord.
Richard
I see the forging of the graph in the Daily Mail article,
http://www.dailymail.co.uk/sciencetech/article-2217286/Global-warming-stopped-16-years-ago-reveals-Met-Office-report-quietly-released–chart-prove-it.html#ixzz29E78OR9H
in the context of the assertions that are made in the Daily Mail article, particularly this one:
This means that the ‘plateau’ or ‘pause’ in global warming has now lasted for about the same time as the previous period when temperatures rose, 1980 to 1996. Before that, temperatures had been stable or declining for about 40 years.
The intention is to deliver the message that the recent time period is different to what had been observed in the time before since 1980. For that reason, about 15 years (August 1997 to August 2012) are lied into almost 16 years, and those are compared to the period 1980 to 1996, that is, to a 17-year period. In this way, it is disguised that time periods, which actually have different lengths are being compared. Two years can make a big difference in the temperature trend and its statistical significance.
joeldshore says:
October 31, 2012 at 3:32 am
They are in fact quite close…and, furthermore, your trendline from 1975 to present is actually STEEPER than the one from 1975 to 1997. Do you think that is compatible with the claim that global warming stopped in 1997?
There are two different issues here that were not explicitly explained. The slope IS flat on Hadcrut3 from March 1997. (I know this will change to April 1997 once the September anomaly of 0.520 gets incorporated into woodfortrees.) However global warming did not stop until September of 1998. So if one takes the slope from 1975 to September 1998 and then from 1975 to the present, the slope is in fact less steep for the latter. And this IS compatible with a slightly changed claim that global warming stopped in September of 1998. Is that better? See
http://www.woodfortrees.org/plot/hadcrut3gl/from:1975/plot/hadcrut3gl/from:1975/to:1998.67/trend/plot/hadcrut3gl/from:1975/trend/plot/hadcrut3gl/from:1997.16/trend
Friends:
In the post at October 31, 2012 at 8:11 am the troll is spinning so fast it is surprising he does not drill himself into the ground.
He claims the graph of Rose is “forged” because it does not also show another graph for a different time period.
On that basis, Rose would be guilty of forging the Mona Lisa if he painted a house but did not also paint a boat.
Richard
From joeldshore on October 31, 2012 at 3:32 am:
Follows from what you said about the Tami site graph.
“…here is a graph that shows in blue the data and trend for 1975-mid 1997…”
“Then in red is the data from mid-1997 to the present with the red line just being the blue trend line extrapolated to the present.”
As a continuation of the blue trend line to the present, the correct terminology would have been the red line is an extension of the blue line. Thus red and blue together describe a single line. And this is what the graph shows. So 1975 to 1997 lies exactly on 1975 to present, as the graph shows. But that’s not what real graphs from the real data show.
And there you’ve just stated it. One trend line from 1975 to 1997, with an extension there’d be a 1975 to present trendline, they would not deviate in any significant way. This is absolute basic geometry here, just playing with line segments. Why don’t you understand what you’ve said?
I suppose another possible interpretation of what you said is an extension of the 1975 to 1997 line from 1997 to present is indistinguishable from a 1997 to present line. Except this is clearly not the case from the graphs I provided, and claiming this is true would be fraudulent.
Because you provided a graph as proof that shows an EXACT lining up, that’s why.
You expect a rising series of flat steps to have a steeper slope than the steps. That’s how a staircase works.
Your obsession with making global warming conform to a linear trend is noted, even if the instrumental record is better described by alternating warming and cooling stages with a general upward trend. We’ve entered a cooling stage. Why is that so hard to accept?