Validity of “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years”

It seems that Marcott et al isn’t all that it is cracked up to be. Dr. Easterbrook takes a good hard look at the paper.

Guest post by Dr. Don J. Easterbrook

(Note: Because of the far-reaching implications of the conclusions in this paper and the nature of the data, this review will be broken into several segments. This is Part I).

The news media has exploded with extraordinary claims of ‘unprecedented global warming’ asserted in a paper “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years” by Marcott, Shakun, Clark, and Mix in Science. A NY Times headline reads “Global Temperatures Highest in 4,000 Years,” and proclaims that global warming will “surpass levels not seen on the planet since before the last ice age.”

Here are some of the truly extraordinary assertions in the paper:

1. “Current global temperatures of the past decade … are warmer than during ~75% of the Holocene temperature history.”

2. “Global mean temperature for the decade 2000–2009 …. are, however, warmer than 82% of the Holocene”

3. ~0.6°Cof warming from the early Holocene (11,300 yr B.P.) to a temperature plateau extending from 9500 to 5500 yr B.P.. This warm interval is followed by a long-term 0.7°C cooling from 5500 to~100 yr B.P. (Fig. 1B).

4. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago.

5. “Global temperatures are warmer than at any time in at least 4,000 years.”

6. “Over the coming decades are likely to surpass levels not seen on the planet since before the last ice age.”

7. “Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time.”

8. Our global temperature reconstruction for the past 1500 years is indistinguishable within uncertainty from the Mann et al. (2) reconstruction

9. A cooling trend from a warm interval (~1500 to 1000 yr B.P.) to a cold interval (~500 to 100 yr B.P.), which is approximately equivalent to the Little Ice Age (Fig.1A). This similarity confirms that published temperature reconstructions of the past two millennia capture long-term variability, despite their short time span (3, 12, 13).

10. “Global temperature of the early20th century (1900–1909) was cooler than>95% of the Holocene.”

11. “Global temperature….. has risen from near the coldest to the warmest levels of the Holocene within the past century.”

12. A heat spike like this has never happened before, at least not in the last 11,300 years. “If any period in time had a sustained temperature change similar to what we have today we would have certainly seen that in our record. ” It is a good indicator of just how fast made-climate change has progressed. (Marcott quoted on CNN)

They arrived at these conclusions by “reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records” “largely derived from marine archives (~80%),” including paleoclimate temperature proxies such as alkenone, planktonic foraminifera Mg/Ca 23, fossil pollen, ice-core stable isotopes, and Mann et al. (2008) tree ring reconstructions. Although a list of sources of the data from the 73 sites is provided in an appendix, nowhere is any real data presented, so assessing the validity or accuracy of the original data is not possible without digging out all of the source papers. Just how accurate are these marine temperature reconstructions? We really can’t tell without any original data for specific sites. There are two issues here: (1) How accurately can the paleotemperatures be measured, and (2) how accurate is the dating of the material? The accuracy of the paleotemperature measurement depends on the method used and since multiple methods were used, the results are a mixture of varying accuracies. Dating marine fossils (80% of the samples used in the study) depends on radiocarbon measurements, and the marine lag effect. Radiocarbon in marine organisms is generally 400-800 years older than land organisms, so correction factors must be used, and this affects the accuracy of dates.

Eighty percent of the source data sites were marine, so temperatures from 80% of the data set used in this paper record ocean water temperatures, not atmospheric temperatures. Thus, they may reflect temperature changes from ocean upwelling, changes in ocean currents, or any one of a number of ocean variations not related to atmospheric climates. This in itself means that the Marcott et al. temperatures are not a reliable measure of changing atmospheric climate.

The paper consists entirely of complicated computer manipulations of data (definitely not light reading for anyone but computer modelers) and conclusions. As Andy Revkin (Dot Earth) points out, This work is complicated, involving lots of statistical methods in extrapolating from scattered sites to a global picture, which means that there’s abundant uncertainty.”

Without any original data to assess, how can we evaluate the validity of the conclusions? The only way is to check the conclusions against well-established data from other sources. As Richard Feynman eloquently described the scientific method, once hypotheses (conclusions) are set out, their consequences can be checked against experiments or observations. If a hypothesis (conclusion) disagrees with observations or experiments, it is wrong. It doesn’t make any difference how beautiful the hypothesis (conclusion) is, how smart the author is, or what the author’s name is, if it disagrees with data, experiments, or observations, it is wrong. Period. So let us apply this method to the conclusions of this paper and test them to see if they are right or wrong.

First, let’s test the Marcott et al. 11,300 year temperature curve against the GISP2 Greenland ice core oxygen isotope record (Alley, 2000) (Figure 1 below). The Greenland ice core data is widely considered to be the ‘gold standard’ of quantitative paleo-temperature measurements with thousands of accurately dated analyses covering many thousands of years. From the Alley (2000) curve, it is readily apparent that temperatures during virtually all of the period from 10,000 to 1,500 years ago were warmer than at present and 85% of the past 10,000 years were warmer than present. The curve extends to 95 years ago, but even if we add 0.7°C for warming over the past century (dashed line), temperatures were still dominantly warmer than present.

clip_image002

Figure 1. Comparison of Greenland ice core temperatures and Marcott et al. temperatures for the past 10,000 years. (Top curve modified from Alley, 2000 based on data from Cuffy and Clow; bottom curve modified from Marcott et al., 2013)

Let’s compare this to the Marcott et al. conclusion “Current global temperatures of the past decade … are warmer than during ~75% of the Holocene temperature history” and “Global mean temperature for the decade 2000-2009 ….are warmer than 82% of the Holocene”(lower curve, Figure 1). The Marcott et al. conclusion is totally at odds with the Greenland ice core data. But why should we believe the ice core data rather than the Marcott et al. computer generated curve? Well, the ice core curve is based on thousands of isotope measurements that reflect paleotemperatures and the chronology is accurate to within about 1-3 years, whereas the Marcott et al. curve is essentially based on computer-manipulated data with multiple data types using different technologies with varying accuracy and chronology accurate only within hundreds of years. Marcott et al. assert that this doesn’t matter over a period as long as 10,000 years. But, of course, the accuracy of a body of data depends on the sum of the accuracies of its individual components, e.g. you can’t claim microscopic accuracy from a bulldozer, no matter how you manipulate the data.

What about the global implications of the Greenland ice core data? The cores come from specific sites on the Greenland ice sheet, so doesn’t the data pertain just to those particular places? That’s true, but the real question is does it mirror the global climate? The answer to that is definitely yes—correlation of temperatures from the ice cores with global glacial fluctuations is clear and unequivocal. Even small fluctuations of ice core paleo-temperatues can be accurately correlated with advance and retreat of glaciers globally (this topic will be expanded later). In addition, modern Greenland temperatures mimic global temperatures—comparison of temperature records from weather stations in Greenland with global temperatures confirm that Greenland marches in lock step with global climate (Figure 2). Thus, we can conclude that paleo-temperatures in Greenland ice cores are representative of global temperatures.

clip_image004 clip_image006

Figure 2. Comparison of Greenland temperatures

Let’s look at some specific features of the Marcott et al. curve. As shown in more than 3,000 publications, the Medieval Warm Period (MWP) is widely recognized to have been somewhat warmer than present Figure 1). In the past 10,000 years, at least six other warm periods of magnitude equal to the MWP occurred; nine other warm periods that were 0.5°C warmer than the MWP occurred; two warm periods that were 1°C warmer than the MWP occurred; and three warm periods that were 1.5°C warmer than the MWP occurred. All of these periods warmer than the MWP clearly contradict the Marcott et al. conclusions.

The Marcott et al. conclusions that “Current global temperatures of the past decade … are warmer than during ~75% of the Holocene temperature history” and “Global mean temperature for the decade 2000-2009 ….are warmer than 82% of the Holocene” are clearly contrary to measured, accurate, real-time data and thus fail the Feynman test, i.e., they are wrong.

This rebuttal addresses only part of the Marcott et al. paper. To include analyses of all the issues would take a much longer response, so this is just Part 1. The next part will consider some or all of the remaining conclusions listed at the beginning.

References

Alley, R.B., 2000, The Younger Dryas cold interval as viewed from central Greenland: Quaternary Science Reviews, vol. 19, p.213-226.

Cuffey, K.M. and Clow, G.D, 1997, Temperature, accumulation, and ice sheet elevation in central Greenland through the last deglacial transition: Journal of Geophysical Research 102:26383-26396

Marcott, S.A, Shakun, J.D., Clark, P.U., and Mix, A.C., A Reconstruction of Regional and Global Temperature for the Past 11,300 Years: Science, vol. 339, p. 1198-1201.

==============================================================

Geologist Dr. Don J. Easterbrook, Emeritus Professor at Western Washington University, who has authored eight books and 150 journal publications. His CV is here

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Kurt in Switzerland

“Thus, we can conclude that paleo-temperatures in Greenland ice cores are representative of global temperatures.”
Just because a strong correlation was found in the 20th century doesn’t mean that this some correlation would also exist throughout the Holocene.
Kurt in Switzerland

lurker, passing through laughing

Yet again the AGW prmotion industry relies on data with dubious provenance, doubtful precision and no real controls to make extraordinary claims.

j ferguson

Thank you Dr. Easterbrook for going over this paper. It is a bit dismaying that it should be receiving the widespread attention it is, including the NBC Nightly News, given that it is as shaky as you have shown us.
It is equally dismaying that when the thing is thoroughly demolished, that never makes it to the mass media.

Reblogged this on If You Voted For It — You Own It and commented:
We will not hear anything from the local lefty crickets on this post, as it does not fit the AGW Cults play book.

jack morrow

You can refute them everyday but they will continue their story because they are getting money to do so. Until the money stops , we will have to get use it.

michael hart

Haven’t read the paper (paywalled), but something to look out for: I recall (correctly, I hope!) the withdrawn Gergis paper as covered by Steve MacIntyre at Climate Audit-
http://climateaudit.org/2012/07/24/was-gergis-et-al-withdrawn/
-made use of a sweeping set of various proxies welded into a grand synthesis. I think they used a whole bunch of coastal proxies as generally representative of the oceans.
During time periods when ice sheets are expanding/contracting and sea levels falling/rising, would it be possible to find any worse proxies than those located near the coast?

Doubting Rich

Kurt in Switzerland
Dr Easterbrook did not confine his evidence to the temperature records. He pointed out that the Greenland data closely follow another reliable proxy, glacial extent.

Theo Goodwin

Marcott and friends included Mikey’s hockey stick:
“8. Our global temperature reconstruction for the past 1500 years is indistinguishable within uncertainty from the Mann et al. (2) reconstruction.”
Why would anyone do that? Mikey’s hockey stick is the poster child for how not to do research in paleoclimatology. In “hiding the decline,” the Team demonstrated that they had no concept of the empirical research necessary to validate the proxies that they used to obtain temperature measurements. When their proxies (trees rings) declined, giving evidence of lower temperatures rather than higher, they replaced their own data with thermometer readings that showed higher temperatures. But their real shortcoming as scientists was revealed in their lack of desire to discover what caused the decline in their proxies. They undertook no empirical research on proxies to learn what caused changes in them. Unfortunately for the field of paleoclimatology, the lack of empirical research to determine what actually causes their proxies (tree rings in this case) to grow or not is all but universal. In recent years, some fourteen years after publication of the hockey stick, Briffa has taken some steps to remedy The Team’s lack of curiosity. But that research has not informed The Team’s hockey stick.
All proxy data must be subjected to rigorous experimentation for the purpose of validation. One cannot simply assume, as The Team did, that you know what causes changes in the growth patterns of your proxies. Until paleoclimatology addresses this need for validation, paleoclimatologists can hardly call themselves scientists.
Marcott and friends simply bundle 73 studies that use proxies. The fact that they included Mann’s hockey stick demonstrates that they are uninterested in empirical science. At this late date, some fifteen years after publication of the hockey stick, there is no reason that we should have to address the scientific or moral errors involved in the hockey stick research and publication. I am shocked that NSF and one of its program directors would publicly express support for Marcott’s paper.

John Tillman

Kurt:
Dr. Easterbrook stated that the Greenland ice core data do mirror global climate both since 1880 (Fig 2) & for paleo-temperatures. He wrote (& will write more):
“Even small fluctuations of ice core paleo-temperatues can be accurately correlated with advance and retreat of glaciers globally (this topic will be expanded later)….(Discussion of modern data.) Thus, we can conclude that paleo-temperatures in Greenland ice cores are representative of global temperatures.”
Please note also these references, dealing with the end of the Pleistocene & early Holocene:
Alley, R.B., 2000, The Younger Dryas cold interval as viewed from central Greenland: Quaternary Science Reviews, vol. 19, p.213-226.
Cuffey, K.M. and Clow, G.D, 1997, Temperature, accumulation, and ice sheet elevation in central Greenland through the last deglacial transition: Journal of Geophysical Research
102:26383-26396

numerobis

Warming over the past century has been about 0.8C globally, but about double that in the Arctic. I don’t know the precise value for the location of the ice core; could be more or less.
Regardless, the climate in one point is not the global climate. The Marcott paper (like an old paper by Mann et al) is notable precisely because they do the hard work of trying to get a global picture. You can’t refute their results by saying that in one location the results are different.

Steve Keohane

Thanks Dr. Easterbrook for this presentation. It is a real can of worms. In looking through any files I might add as information, I have a series of circumpolar histories by Amanda Graham, from Yukon college, an educator with an interest in circumpolar studies. In what I have read in a few of the paleo-histories, everything seems to observational science. No CO2, hysteria nor other editorializing. Haven’t found any gross inconsistencies with what I’ve read over the past fifty years,archeologically. There may be clashes with ‘climate science’.
http://ycdl4.yukoncollege.yk.ca/~agraham//nost202/timetables.htm

Peter Miller

“BS baffles brains” is one of the oldest cons in the world.
Very simply, it means if you want to sell a concept or something, which you know to be rubbish, you surround it with complicated, unverifiable ‘proof’. In addition, You elevate your language to a level where few can understand it.
Mining scams and this type of climate science have a lot in common; I have uncovered lots of the former. In the case of ‘climate science’, the more obvious cases of BS are trumpeted by the likes of the BBC and the Guardian in the UK and by Al Gore’s cronies in the US.
If there is no raw data and/or all complicated, unexplained re-interpretations of other research, then the new findings are almost 100% guaranteed to be complete BS.
For most geologists, it is difficult to tell the methodologies apart of mining scams and much of today’s climate science.

RHS

How well can a record be interpreted when the record is written/created over several thousand years? Marine sediments would seem very difficult to “read” since there is ocean circulation and sediments from today may take over a year to be deposited. It just seems easy to find any message one would want…

scarletmacaw

Correct me if I’m wrong, but doesn’t the Ice core data measure temperature by using the O18/O16 ratio? If so, wouldn’t that ratio be tied to the global atmospheric concentrations rather than local, so that the ice core data DOES measure global temperature?

‘The paper consists entirely of complicated computer manipulations of data (definitely not light reading for anyone but computer modelers) and conclusions. ”
Nonsense. There is nothing very complicated in the paper. When a reviewer tells you that easy is hard, you should ignore the reviewer because he has just disqualified himself.

Theo Goodwin

numerobis says:
March 11, 2013 at 9:39 am
“Regardless, the climate in one point is not the global climate. The Marcott paper (like an old paper by Mann et al) is notable precisely because they do the hard work of trying to get a global picture. You can’t refute their results by saying that in one location the results are different.”
What? A global picture? Eighty percent of their proxies are marine. Oceans are rife with changes that are peculiar to oceans. Marcott and friends did no empirical research to explore relevant oceanic changes for the purpose of validating their proxies. All of their work was done on models. Will we ever find a paleoclimatologist with instincts for the empirical? I believe that the answer is no.

OssQss

Who funded this ? I want to know if they wasted my tax dollars or $oros money………

MarkW

Anybody who includes tree ring data in any attempt to reconstruct past temperatures, has already indicated that they have no desire to model past climates.

Proud Denier

Both my wife and I reacted the same to the Marcott graph. Obviously it is the proxy data that is flawed.

MarkW

numerobis says:
March 11, 2013 at 9:39 am

I’m guessing that you didn’t actually read the article. Dr. Easterbrook gave evidence, with citations as to why the Greenland data accurately mirrors global temperatures.

Matthew R Marler

You have made 2 good points:
1. The data are measures of marine temperatures;
2. The reconstruction is different from the reconstruction based on the Greenland ice core data.
The paper itself is good. I am suspicious of the large upward exclusion at the far right-hand edge of the figure, but I have not yet found any specific reason to distrust it. I have not yet read all of the supporting online material. They present comparisons of the mean temps for different parts of the globe. They computed the uncertainty intervals using bootstrapping, and the infilled missing data using the regularized EM algorithm; and they present the differences that arose among the different methods.

manicbeancounter

Within the paper, is there a list of the proxies, with location and period covered?
The withdrawn Gergis Australasian temperature at least had such a list the data proxies. A quick look found no proxies on the mainland of Australia, but a number well outside the study area. Also, the further back in time that one went, the smaller the number of proxies.
The major conclusions of that paper – that the 1990s was the warmest decade of the millenium was the result of the inclusion a coral data set from Palmyra Atoll – over 1300 miles outside the study area and with data that looks decidedly at odds with any other temperature reconstructions.
http://manicbeancounter.com/?s=gergis
Steve McIntyre also raised some valid issues on Gergis, that probably apply here as well.
For him, the proxy selection method was crucially important.

Lance Wallace

Judy Curry has a link to a site that has done some interesting analysis by the blogger “Hank H” that deserves wider notice. He finds using the nine proxies that extend into the 20th century that no hockey stick is visible.
http://suyts.wordpress.com/2013/03/10/the-hockey-stick-resurrected-by-marcott-et-al-2012/

No matter what the data and no matter what the uncertainty, the solution is always the same: stop the future! Prohibit the use of stored energy in the form of petroleum, coal, and atomic fuels. Revert mankind to the technological status of the dark ages or even the stone ages along with the massive attendant drop in the number of living humans. It is 20,000BC or nothing.
In any other field, such a thing would be called for what it is: a fraud, a scam, or a religion (as if there is any real difference). Yet our politicians go along with it and we keep voting them into office. It appears that we are doing it to ourselves as we dance as puppets on strings. However, even our puppeteers are puppets dancing on strings. Who then is controlling the strings? No one but the ideas we hold as unquestionable and unquestioned. Shouldn’t we at least ask why?

Paul Matthews

You don’t in fact need to look at any other papers topsee that this paper is nonsense, at least as regards the upward spike at the right hand end. It’s all there in their own graphs. (Matthew Marler you can’t have looked very hard!)
Look at fig S5 in the Supplementary material (not paywalled, anyone can get this).
fig S5 shows a reconstruction based on sites near the equator. There’s no hockey stick at all! Similarly S6 shows sites in Norway – again no spike.
Their sec 6 and fig S10 shows that the number of proxies falls off from the total number of 73 to a very small number, so the spike must be just from a very small number of proxies. Fig S10 also shows that the picture is completely different at different latitudes – at 30-60S for example the temperature shot up 250 yrs ago and then levelled out, while at 60-90S it spikes up then back down again.
In Sec 7 and fig S12 they test the sensitivity of their result to the choice of ‘time-step’. They claim that ‘some small differences occur’. But you only need to glance at fig S12 to see that this is
false – the spike is entirely dependent on the choice of the ‘time-step’, and disappears if a larger timestep is used. A first rule of numerical methods is that if this happens your result is meaningless.

NIWA accept that in New Zealand temperatures were much higher for most of the Holocene.
http://notalotofpeopleknowthat.wordpress.com/2013/03/10/warmer-holocene-confirmed-in-new-zealand/

Bob from the UK

There´s too much evidence that doesn´t fit with the conclusions of Marcott et al. Glaciers in Europe were actually further back in the past than they are now and also there´s ample evidence from the Viking colonisation of Greenland being warmer. Don Easterbrook´s conclusions fit the evidence and there are no contradictions. I remember reading his predictions of cooling quite a long time ago and I´m quite impressed that the climate is responding accordingly. Certainly temperate latitutes in the Northern Hemisphere are experiencing colder winters and if I´m correct the glacial retreat has slowed down. One can see a trend,

john robertson

Timing is self explanatory, AR5.
Standard IPCC team work, on queue and schedule.
Grab the headlines, ignore the data and claim perfection.
Once again, the claims of precedent and certainty, exceed the data.
If you buy these claims of unprecedented warmth in 70-80% of last 11000 years,as meaningful wrt to global history, I have some Unicorn fence you really must have.

I find it remarkable that this “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years” by Shakeum Bakeum Mix (or whomever) gets such acclaim and even adoration, without much thought whatsoever. It seems painfully obvious to me that, if your so-called “science” comes up with the politically correct result, then everyone will smile and nod.
How is it Truth has taken on the appearances of a spoil sport and party pooper who the “in crowd” does not want around?
In comparison, voices such as Dr. Don J. Easterbrook’s will seem harsh. You cannot be agreeable when you do not agree. However Truth must be spoken.

DayHay

numerobis
March 11, 2013 at 9:39 am
Please see below:
http://wattsupwiththat.com/2009/04/11/making-holocene-spaghetti-sauce-by-proxy/
However, does GISP2 still apply to Greenland?
So the study isn’t really accurate for Greenland, but does come up with a “global” number that does correlate somewhere? Which region would that be then?

Paul Matthews

Another thing to look at is the numbers in the excel file that you can get as part of the supplementary info (database S1)
http://www.sciencemag.org/content/339/6124/1198/suppl/DC1
The first few numbers in their “standard” reconstruction are:
0.60 -0.10 -0.26 -0.26 -0.19 -0.16 ….
and these are at 20 year intervals.
So that impressive looking spike at the right hand end consists of only 1 data point!

Steve McIntyre

Although a list of sources of the data from the 73 sites is provided in an appendix, nowhere is any real data presented,

This is untrue. Marcott provided a dataset with proxy data as used for the 73 proxies.
There are many issues with this paper. It is very unhelpful to carelessly make this sort of criticism.
I’ve looked closely at their data and will be commenting on the article.

Robert of Ottawa

Only 73 sites? Hmm …

Steve McIntyre

The comparison to GISP ignores an essential aspect of the Holocene. Orbital changes impact NH and SH differently and a comparison against a high-latitude NH proxy is hardly decisive.
Again, there are huge problems and defects with this paper, but this particular criticism is not necessarily a criticism..
Many of the ocean proxies used by marcott have the distinctive NH high-latitude Holocene Optimum pattern. The issues lie elsewhere.

TomRude

Mosher: if you slam Easterbrook then slam Revkin too “This work is complicated, involving lots of statistical methods in extrapolating from scattered sites to a global picture, which means that there’s abundant uncertainty.” What’s good for the goose should be good for the gander.

Paul Matthews

The next question is, where do these numbers at 20 year intervals come from?
Looking through the excel file you can see that almost all of the proxies don’t have 20 year resolution. It says in the paper that the average is 120 years.
You can also see, looking at the proxies, that they don’t have a spike at the end (which we’ve already seen from their own figs 5 and 6).
I can only see one proxy, Agassiz-Renland, that has 20 year resolution and goes up in the last few points. Somehow they must have skewed their averaging so that this has a huge weighting for its final few points.
This paper is a classic in climate science, surpassing even Mann’s greatest work.

One admission that Marcott does make is that the LIA was the coldest period of the Holocene.
And we are surprised we have warmed up a bit since?

Jeff Condon

If anyone has a copy of the pay walled paper, can they please forward it to me at my gmail acocunt- jeffid1@…
Thanks,
Jeff

Mindert Eiting

Lance Wallace: Thanks for the link. Hank’s diagnosis is that the nine most recent proxies were adapted to Mann’s data. Is that true? I would like to know whether the most recent proxies were selected because of correlations with the surface temperature record.
Theo Goodwin: If measurements from two sources diverge, one of them may be wrong or both. I have serious doubts about the surface temperature record since 1970. Where this record is used hockey sticks seem to appear as symptoms.

Jimbo

Over and Judith Curry’s there’s another deconstruction underway by Rud Istvan. Here’s a sample.

…..The paper itself said, “…our temperature stack does not fully resolve variability at periods shorter than 2000 years…”
Evaluate a 300-year MWP using methods lacking 300 year resolution and voila! The MWP turns into a blip diminished by the colder periods on each side…….
http://judithcurry.com/2013/03/11/lets-play-hockey-again/

Philip Richens

Paul Matthews mentioned the odd spike in the last data point of the 5×5 reconstruction. Maybe worth adding that this final 0.7K rise is for the period 1920-40, which is in fact where the reconstruction finishes. I’ve also looked at the individual proxy data, and it is not at all obvious to my inexpert eye how how the spike arises – although I imagine that the records may be well-correlated only towards the end of the reconstruction. I’m looking forward to seeing Steve McIntyre’s analysis in due course.

Jeff Norman

Dr. Don,
Thank you for making the effort. I sincerely hope that your subsequent parts are less superficial and allusionally ad hominen. Personally I would have assumed the individual data sets had been properly calibrated unless specifically demonstrated no to be calibrated. Good luck.
Numerous people have pointed out the consistency of the reported error margins and the bizarre modern spike in the averaged data. Much to look at.

One of the most damning is:
6. “Over the coming decades are likely to surpass levels not seen on the planet since before the last ice age.”
So, the authors of the study turned from attempting science to carnival prognostication. It’s not like the warming hasn’t taken a break over the last 16 years, and that there’s been this whopping .28F increase in global temps from 1990-2012. The report degenerated into alarmism and advocacy.

Theo Goodwin

Judith Curry has a guest post at her site. The following is the conclusion of her comment:
There doesn’t seem to be anything really new here in terms of our understanding of the Holocene. Mike’s Nature trick seems to be now a standard practice in paleo reconstructions. I personally don’t see how this analysis says anything convincing about climate variability on the time scale of a century.
I cannot imagine a harsher criticism of the state of paleo reconstructions.

arthurpeacock

Lionell Griffith says:
March 11, 2013 at 10:55 am

…a fraud, a scam, or a religion (as if there is any real difference).

That wasn’t necessary or helpful.

robinedwards36

What is required is the data file that holds the actual numbers from which their graphics were derived. Experience (and I hope common sense) tells me that one should trust nothing in the bizarre world of climatography until you have accessed the data (numbers) that lie behind the often fancy graphics. Thus, I really want to see the data for the last 200 years in numerical format. Only then can I make a considered judgement regarding the current rate of temperature change, or even the current temperature as put forward by the authors. Paywalls don’t help, do they?

robinedwards36

Minutes later! Now I see that the data are available. Good! The authors seem to very forthcoming in providing links and suggesting (to me) some Google search terms. I like that.

RomanM

Lance Wallace (@ March 11, 2013 at 10:40 am:
Only 25 of the 73 proxies actually have any data into the 20th century, and none of those shows a hockey stick shape either.
The hockey stick is created by randomly varying the proxy temperatures and their estimated dates and then interpolating into 20 year intervals. This is done 1000 times for each proxy thus creating 1000 new sets of data. These are each anomalised with a base of their mean for the years 4500-5500 BP where all of the proxies have some observations. There is also some sort of infillling of proxies as well, but I haven’t looked into that yet.
These results are averaged using some sort of area weighting.

Theo Goodwin

Mindert Eiting says:
March 11, 2013 at 11:59 am
“Theo Goodwin: If measurements from two sources diverge, one of them may be wrong or both. I have serious doubts about the surface temperature record since 1970. Where this record is used hockey sticks seem to appear as symptoms.”
Mindert, Thanks for the shout-out to the lonely empiricist. None of our temperature records, including records of anomalies, are worth the paper they are recorded on. That is, they are worthless if you are interested in factual data rather than trends. Hey, if one is interested in trends only then he should just push ahead, no data is needed.
We have made a start with the ARGO project but it is just a start. If NSF and other funding agencies were serious they would suspend funding until they convene a balanced committee that can reach decisions on what data collection technologies are needed.
The genie in the movie Aladdin: Cosmic Power and an itsy-bitsy living space.
The skeptic in climate science: Cosmic Theory and an itsy-bitsy factual basis.

Given their statement that the LIA was the coldest point in the Holocene, and given some of the large variations in temperatures that we know about over the last 10000 years, it is difficult to see how a degree of warming since can have exceptional in historical terms.