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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Bart says:
Give me a break. Even linear fits over such time periods give pretty large uncertainties in trend. Fitting a quadratic is just fitting to noise. I will be interested to see if a few years from now you are still interested in doing quadratic fits…Or, how well you think a quadratic fit would have done back in, say, around 1998 or 1999. The only reason that you want to fit to a quadratic is because the noise is such that fitting to noise is a good thing now if you want to believe global warming is ending.
No, the plot that I linked to shows that the behavior over the last ~15 years is in very good agreement with what we would have predicted by linear extrapolation of the trend up to that point.
That’s just sophistry. How hard is it to understand the concept of a slow linear trend with fairly large amount of superimposed noise? You can simulate this, for heaven’s sake, and the point is that the noise dominates on short timescale but the underlying trend is what dominates at long timescales. Come on, Bart, you are an engineer, not a philosophy major. You should know this stuff.
Werner Brozek says:
Are you guys serious? You make one cherry-pick in one context and another cherry-pick in another? That’s rich!
And no, that is still not evidence that global warming stopped in September 1998. The fact that the trendline from 1975 to the present was slightly steeper than the trendline from 1975 to 1997 was just “icing on the cake” as far as I was concerned. I just pointed it out as an additional source of amusement for how pathetically weak the argument kadaka made was. However, the fact that you can cherrypick a date in 1998 and have that slope be slightly less steep than the trendline is irrelevant. The point is that, within errorbars, the trendlines are the same!
richardscourtney 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-1130754
referencing my comment 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-1130720
The Coal-Magazine Editor is lying again, or he has serious problems to understand statements in written English. I didn’t claim anything like this in the referenced comment or in any other comment.
What I actually said, in a comment before the referenced comment, was that the graph in the David Rose article in the Daily Mail is forged, because the starting point of the graph was manipulated. Data that actually start in August 1997 are presented as starting at the beginning of 1997. And in the referenced comment, I said, by doing so a time period of about 15 years is misleadingly presented as a time period of almost 16 years.
In the referenced comment I also speculated about the motives for the forgery.
bart 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-1130710
Your tautology is a red herring.
The trend from mid 1975 to including July 1997 is statistically significantly different from a Zero trend with more than 3 sigma, i.e., the probability to be wrong is less than 2 out of a thousand. The trends for the different data sets and the 2-sigma intervals are, using http://www.skepticalscience.com/trend.php (start date: 1975.5; end date: 1997.58):
GISSTEMP: 0.146+/-0.09
NOAA: 0.15+/-0.079
HADCRUT4: 0.161+/-0.081
I can successfully reject the Null hypothesis that the trend from mid 1975 to 1997 cannot be statistically distinguished from a Zero trend. I have delivered. I also can do the same for the time period from mid 1975 to today.
Since you assert global warming “stopped” or similar after 1997, the burden of proof is on you to demonstrate that the trend after the point in time, when global warming allegedly “stopped” is statistically significantly different from the statistically significant trend up to the point in time when global warming allegedly “stopped”. As long as you don’t do that you don’t have any argument for your claim that things have been different after 1997 or so, compared to the decades before this point in time. Eyeballing or gut feeling do not qualify as scientifically valid approaches to back up an assertion about the alleged “stopped” global warming or similar.
I do not have the burden of proof for your assertions.
I see Perlwitz is still writing and posting long comments arguing with people throughout his taxpayer-financed work day. Could he be any more corrupt and dishonest?
Get back to work on the job the public pays you for, Perlwitz, and quit wasting our time here.
D Böehm says:
October 31, 2012 at 10:47 am
“I see Perlwitz is still writing and posting long comments arguing with people throughout his taxpayer-financed work day.”
Actually from what he in fact blathers about suggests that the tax payer is saving money from having him diverted from whatever job he is being overpaid for. I wonder if his marching orders for today were to do just what he is doing.
joeldshore says:
October 31, 2012 at 10:24 am
Why a quadratic? Because, to put it as delicately as possible, your linear trend after 1997 sucks. There is clearly an increasing divergence from it.
You haven’t a leg to stand on. As I explained above, you are now trying to assert that something which cannot be disproven (at least, not on these terms) is thereby proven. That’s ridiculous.
“… the behavior over the last ~15 years is in very good agreement with what we would have predicted by linear extrapolation of the trend up to that point.”
Objectively speaking, it just ain’t so.
“How hard is it to understand the concept of a slow linear trend with fairly large amount of superimposed noise?”
Not at all difficult. But, the existence of a concept does not establish a general rule. I can simulate all kinds of stuff. A computer program can verify the mathematics of a model, but it does not verify the model itself. Only empirical data can do that. And, that data is no longer cooperating with your narrative.
“I will be interested to see if a few years from now you are still interested in doing quadratic fits…”
We could play that game all day long. I will be interested to see if a few years from now the IPCC still exists, and their proponents and hangers-on haven’t been tarred and feathered in the streets, because the odds are looking pretty good that we are on the cusp of a sharp downturn. Appeals to an imaginary future in which you will be vindicated are not particularly compelling.
kadaka (KD Knoebel) says:
October 31, 2012 at 8:50 am
“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?”
Hear, hear!
Jan P Perlwitz says:
October 31, 2012 at 10:44 am
“The trend from mid 1975 to including July 1997 is statistically significantly different from a Zero trend with more than 3 sigma, i.e., the probability to be wrong is less than 2 out of a thousand.”
Based on what statistical model? If you do not have a valid statistical model, your confidence intervals are useless.
“I do not have the burden of proof for your assertions.”
You have the burden of proving your assertions, i.e., that your prognostications for catastrophic anthropogenic global warming are valid.
D Böehm:
At October 31, 2012 at 10:47 am I think you are being a little unfair to the troll when you write
His “job the public pays [him] for” is to use his computer to fabricate fictions which are intended to mislead the public. And he is doing that here.
Richard
kadaka says:
Fine…Perhaps “extension” would have been a little bit clearer than “extrapolation”, although I don’t see extrapolation as all that bad. Furthermore, I still don’t understand why you would think it would be necessary for the trendlines for 1975-1997 and 1975-present to fall EXACTLY on top of each other in order to include the trend shows no evidence of markedly changing.
No…It is not simple geometry. If global warming had stopped, we’d expect the data after 1997 to clearly fall away from the extension of the 1975-1997 trend line up to the present. That hasn’t happened: http://tamino.files.wordpress.com/2012/10/crumod2.jpg
Because there is no evidence of any statistically-significant deviation from the original trendline. Not even close.
Bart says:
No it doesn’t and no there isn’t: http://tamino.files.wordpress.com/2012/10/crumod2.jpg
Then why did you engage in word games when you are smart enough to understand the concept of a linear trend plus noise. Even if you don’t believe that is what is involved here, you can’t dismiss the possibility just by appealing to silly logical sophistry.
joeldshore:
It seems that you have not expressed your meaning clearly in your post to kadaka at October 31, 2012 at 12:02 pm because you say
Obviously you intended to say something other than your words I have quoted because both kadaka and Bart have shown you that the trend HAS fallen away since 1997. Indeed, everybody (except the troll whose self-serving falsehoods are irrelevant) agrees there is no significant trend since 1997. Even the UK Met,Office agrees.
So, I would appreciate a clarification which explains what you did intend to say.
Richard
joeldshore says:
October 31, 2012 at 12:07 pm
Continuing to insist something which is clearly visible isn’t is not worthy of a response. You and Jan can dress it up in a simulacrum of science, but you are not fooling anyone but yourselves.
And, as I have emphasized repeatedly to your seemingly deaf ears, it is not enough for you to establish a “possibility”, even if that is what you had done. There are endless possibilities for all manner of catastrophes. Why should your fear of any particular one lay a claim on how I live my life?
joeldshore says:
October 31, 2012 at 10:29 am
The point is that, within errorbars, the trendlines are the same!
I agree with respect to my two lines starting from 1975, but not for HadCRUT4 starting from 1997. (I will also concede that Rose’s graph has the x axis displaced by about 6 months.) As for the 16 years, as near as I can tell, Rose started from January 1, 1997 and went to August 31, 2012 and while that is actually 15 years and 8 months, he rounded it to the nearest year and came up with 16 years. Now whether or not this is acceptable may depend on who your intended audience is. The slope from January 1, 1997 to August 31, 2012 on HadCRUT4 is 0.00474896 per year or 0.047/decade. Is this significant at the 95% level?
In Phil Jones’ interview from February 2010:
“B – Do you agree that from 1995 to the present there has been no statistically-significant global warming
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level.”
I know it is a bit more complicated than that, but if 0.12 C/decade is NOT significant over 15 years, I do not see how 0.047/decade over a slightly different 15 years and 8 months can be significant. Is Jones using a different criteria?
http://www.woodfortrees.org/plot/hadcrut4gl/from:1997/plot/hadcrut4gl/from:1997/trend
From joeldshore on October 31, 2012 at 12:02 pm:
You provided a graph with a single straight line segment, AC, point A at 1975, C at present. You specified AB, B at 1997, with BC being an extension of AB, thus implicitly specifying AB and BC as on AC. AB must exactly line up with AC by definition. Simple geometry.
What is this “clearly fall away”? The slope of 1997-present is clearly far less than the slopes of 1975-1997 and 1975-present. For that graph to pretend otherwise is dishonest.
The slopes by WFT:
1975 to start of 1997 is 0.0158627°C per year.
1975 to present is 0.0170183 per year.
Start of 1997 to present is 0.00474896 per year.
1997 to present is only 29.9% of 1975 to 1997 rate.
1997 to present is only 27.9% of 1975 to present rate.
You would claim that is not a statistically-significant deviation?
richardscourtney says:
I said exactly what I intended to say.
(1) Look at the picture: http://tamino.files.wordpress.com/2012/10/crumod2.jpg The data from 1997 to present are still basically following the extension of the trendline that was drawn through the 1975-mid 1997 data.
(2) I didn’t say what the trend did. I said what the data itself did. Trends over short time periods in noisy data are very noisy. A trend is basically a derivative and derivatives of noisy data are extremely noisy unless you take it over periods long enough that the trend overwhelms the noise.
(3) No, what the Met Office says is that the trend since 1997 doesn’t quite meet 95% significance level as being different from 0. However, it also doesn’t meet the 95% significance level as being any different than the trend up to 1997. Trends over short periods in noisy data are very noisy so that leads to huge errorbars on trend estimates and makes silly claims such as “global warming stopped in 1997” blatant falsehoods.
kadaka says:
Duh…but that is not what I am talking about. What I am talking about is the fact that the DATA don’t deviate from the line AC. If the DATA were falling off that extension of the linear trend line from 1975 to 1997, then that might be evidence that the warming was really slowing down. However, the data aren’t showing any sign of doing that.
And, you can see by looking at slopes over other historical time periods during the last 40 years that the slopes can vary significantly over such time periods because, as I explained above, the slope is a very noisy metric in a system with noise except if you look over large enough time periods that the trend dominates the noise. In particular, the big El Nino in 1998 and the general La Nina conditions over the last few years have a huge effect on the slope over the 15 year time period.
But, looking at what the plot that I showed you is a more robust measure of what is happening because rather than letting the noise of ENSO dominate things, it looks overall at whether the data has continued to follow the upward trendline from pre-1998. And, the answer is that it has, despite the normal ups-and-downs due to the noise.
Yes. For the reasons discussed above. The errorbars on the slope estimate over 15 years or less is still large. (Heck, even over 20+ years, it is not so small.)
Werner Brozek: What you are missing is the fact that just because the trend since a certain time is not statistically-significant does not mean that global warming has stopped at that time, particularly when the difference of the trend from the longer term trend is not statistically-significant either. It just means we don’t have good enough statistics on the trend.
Look, if you want to say that it is POSSIBLE (in the sense of >5% chance) from the data that global warming stopped in 1998, then that might be a correct conclusion…But there is no real evidence to support the claim that it did. And you have to open up your mind to all sorts of claims, such as the one that starting in January of this year, global warming has accelerated to the point where the warming rate is now 0.4 C per year…which is roughly what I just read us the trend in the UAH data since that time. That is more than 20 times the long-term rate!
Werner, you are correct as usual. But why start at 1975? Looking at a much longer time span, we see that the long term [natural] global warming trend is not accelerating. The green line shows that long term, the trend is actually decelerating.
And the past decade shows that [natural] global warming has stalled, despite a large rise in [harmless, beneficial] CO2.
The central point is the fact that whether CO2 is low or high, the [natural] global warming trend remains the same. It is not accelerating, despite much higher CO2. The only rational conclusion: ∆CO2 does not cause ∆T. In fact, just the opposite is true. And there is still no empirical evidence to support AGW.
joeldshore:
In your reply to me at October 31, 2012 at 4:59 pm you say
I would appreciate it if you did not accuse others of “blatant falsehoods” when they state clear and unblemished fact and you are stating blatant falsehoods. We already have the other troll doing that.
However you look at it, the data says global warming stopped 16 years ago. Reasons why it stopped are not known but it is a blatant falsehood to pretend otherwise.
Your excuses are becoming pathetic. For example you said that if global warming had stopped 16 years ago then the long term trend since 1970 would have declined by inclusion of the period after 1997 in the trend. kadaka showed it declined by ~28%. You then moved the goal posts.
I can understand the other troll trying to protect his pay, but I fail to understand why you refuse to accept the simple truth that global warming stopped 16 years ago.
Face reality. It is what it is, and it is incapable of caring what you want it to be.
Richard
joeldshore says:
October 31, 2012 at 4:59 pm
“The data from 1997 to present are still basically following the extension of the trendline that was drawn through the 1975-mid 1997 data.”
No, they aren’t. The trend line is slashing diagonally through them. This is a surreal argument, and it’s not making any headway. Why do you persist?
1. richardscourtney says:
October 31, 2012 at 5:49 pm
joeldshore:
In your reply to me at October 31, 2012 at 4:59 pm you say
(3) No, what the Met Office says is that the trend since 1997 doesn’t quite meet 95% significance level as being different from 0. However, it also doesn’t meet the 95% significance level as being any different than the trend up to 1997. Trends over short periods in noisy data are very noisy so that leads to huge errorbars on trend estimates and makes silly claims such as “global warming stopped in 1997″ blatant falsehoods.
I would appreciate it if you did not accuse others of “blatant falsehoods” when they state clear and unblemished fact and you are stating blatant falsehoods. We already have the other troll doing that.
However you look at it, the data says global warming stopped 16 years ago. Reasons why it stopped are not known but it is a blatant falsehood to pretend otherwise.
Your excuses are becoming pathetic. For example you said that if global warming had stopped 16 years ago then the long term trend since 1970 would have declined by inclusion of the period after 1997 in the trend. kadaka showed it declined by ~28%. You then moved the goal posts.
I can understand the other troll trying to protect his pay, but I fail to understand why you refuse to accept the simple truth that global warming stopped 16 years ago.
Face reality. It is what it is, and it is incapable of caring what you want it to be.
Richard
===================================================================
This reminds of a conversation I had once. Someone I know father-in-law had recently passed. He said he’d served on the Battleship Oklahoma. I asked if his father-in-law was at Pearl Harbor. He said no, he’d served in the Korean War. I told him that the USS Oklahoma had been sunk at Pearl Harbor and never raised. He insisted his father-in-law had served on the Oklahoma escorting a carrier in Korea. He was adamant. It was obvious he believed what he was saying. I thought, “Maybe we named another type of ship after the Oklahoma?” I did a little searching and found out that we did have a heavy cruiser named the Oklahoma City that escorted a carrier during the Korean War. I asked if his father-in-law had been on the USS Oklahoma City. His eyes lit up and he said, “YES!” I told him that the Oklahoma City was a heavy cruiser and not a battleship. His reply was, “What’s the difference!”
I didn’t reply.
I sent him a link to the veterans of the USS Oklahoma City in case his wife wanted to let them know about their shipmate.
What more could I do?
richardscourtney says:
Well, if you stop saying false things, I’ll stop pointing them out. But I am not holding my breath!
And already we have another falsehood. In fact, kadaka found ( 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-1131098 ):
So, I don’t know where you got the claim that you make about what he showed. What he actually showed is that the trend from 1975 to present is LARGER than the trend from 1975 to the start of 1997.
What he does show is that the slope from 1997 to the present is only 28% of the slope from 1975 to the present, but that is doing what I have explained again and again you can’t do. The error bars on such a claim, if properly computed, would be so huge as to make the claim meaningless.
Bart says:
It is? http://tamino.files.wordpress.com/2012/10/crumod2.jpg
Gunga Din says:
Nice story and it indeed well illustrates the problem here. Richard Courtney could not distinguish the difference between what I talked about and the claim that kadaka made even though that difference was clear as day. You only had to look at the numbers kadaka wrote down!