New global warming scandal hits climate science

By Ian Wishart

The scientists behind a widely reported new climate change study suggesting we are currently in the warmest climate of the past four thousand years have had their work shredded in peer review, and been accused of skating close to scientific “misconduct”.

The paper, led by Oregon State University’s Shaun Marcott, claimed to have validated the discredited “hockey stick” graph and proven that modern temperatures were the highest in four millennia.

Their research was published in the prestigious journal Science and sparked worldwide media headlines. The New York Times trumpeted “Global temperatures highest in 4000 years”, while Associated Press went even further: “Heat spike unlike anything in 11,000 years”.

Now, the story is rapidly unraveling.

After being peer reviewed by skeptical scientists, Marcott et al were forced to  retract their biggest claim, admitting the so-called modern heat spike was not supported in the actual data after all:

“The 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes,” they admitted in a news release over Easter. In other words, there is no evidence to support the grand claims that swept through world media last month.

As other reports have shown, modern warmth is nowhere near the usual highs between ice ages.

One of the harshest critics, the usually moderate scientist Roger Pielke Jr, was so incensed after conducting his own analysis he has accused Marcott et al of skating close to scientific misconduct, and he is calling for a retraction and correction of the paper published by Science.

Climate Depot’s Marc Morano is calling for retractions and apologies from the New York Times and Associated Press as well.

 

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24 Comments

  1. The “cherry picking” epithet is the last refuge of religious fundamentalists like yourself, Ken, who are so wedded to a belief system that any study contradicting it must be “cherry picked”, rather than a scientific thesis requiring further testing. It is not the only paper showing such correlations….there is a very large scientific debate going on.

    I suggest you read Judith Curry’s website instead of your own posts, if you want a better appreciation of the scale of the debate.

  2. Ian, to repeat a lie a million time does not make it correct, Ian. At least in my book.

    But you are determined to live by a set of myths – you haven’t arrived at this hostility towards science by reason or evidence, and therefore reasson and evidence is not going to budge you, is it?

    By the way – global tempoeraure is very complex, and not well understood. Consequently anyone claiming to have found a single measurment to be “highly correlated” with global temperature is bound to be telling porkies, or is measuring global temperature and comparing it with itself.

    But I understand why you cherry-picked the article.

  3. Actually, for the millionth time Ken, and you have never addressed the specific question, Marcott, Clark et al hyped their findings and got utterly misleading claims published in science media and general media around the world.

    I have given several direct quotes above from Marcott that conflict with the limitations of the study.

    Slandering honest scientists? I don’t think so.

    Meanwhile, yet another peer-reviewed study backing up data in Air Con:

    Once again about global warming and solar activity
    K. Georgieva, C. Bianchi, and B. Kirov

    1 Solar-Terrestrial influences Laboratory, Bulgarian Academy of Sciences, Bl.3 Acad.G.Bonchev str. 1113, Sofia, Bulgaria
    2 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy

    Abstract. Solar activity, together with human activity, is considered a possible factor for the global warming observed in the last century. However, in the last decades solar activity has remained more or less constant while surface air temperature has continued to increase, which is interpreted as an evidence that in this period human activity is the main factor for global warming. We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to the underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is the geomagnetic activity which reflects all solar activity, and it is highly correlated to global temperature variations in the whole period for which we have data.

  4. I referred to the question of spikes not being detectable in proxy data in my previous comment – and suddenly you bring it up!!

    And as I say, there are arguments both ways on that one. I picked it up on my original reading, and was interested to see Michael Mann also raised the issue.

    This is an inevitable situation and other data, such as indications of possible mechanisms from CO2, etc., must be brought into consideration. There is some good discussion of this available.

    All this is part of good faith science – we are used to these situations.

    The fact is that the authors were honest about these limitations in their original paper and in internet discussion.

    Under your definition of apples and oranges we quickly run out of fruit because we would different ones for each time and site. Very silly – simple denial.

    Now none of these limitations, freely admitted limitations, very normal in scientific studies, warrants the malicious headlining and claims you made in this post.

    What about doing the ethical thing, Ian? Withdraw and apologise for slandering honest scientists.

  5. Ken, the problem with bringing in modern temperature readings to this particular study is that they are ‘high resolution’ datasets, capable of picking up short duration temperature spikes, whereas paleoclimate proxies are not high res, they are low resolution.

    So, for most of their Holocene stack, Marcott et al cannot find temperature spikes because their proxies are not capable of reading them, even if they were there.

    Knowing their proxies for the 20th century are crap, Marcott et al graft on high res instrumental data for the 20th century which can and does produce spikes.

    Lo and behold, we have the blade of a hockey stick, but only by comparing apples with oranges as I noted earlier.

    This isn’t science, it’s voodoo climatology.

    For those who need an analogy, think of a wide angle photograph of a scene. That’s low res data. Then think of telephoto shots that capture specific blurry objects in much greater detail from that same scene. That’s high res. The Holocene datasets were too low res to make comparisons with daily temperature records from the past century.

    Even Marcott admits as much: “Because the relatively low resolution and time-uncertainty of our data sets should generally suppress higher-frequency temperature variability, an important question is whether the Holocene stack adequately represents centennial- or millennial-scale variability.”

    Marcott went on to compare something he admitted may not be accurate even at a millennial scale, with readings taken on a daily scale, and then declared, ‘Voila!’.

    Give me a break.

  6. Bloody hell, Ian, you really are trying to avoid facts. Temperature is temperature, however, determined. One must worry about precision and calibration of course but there is no law of nature saying the data cannot be looked at collectively. After all, the independent studies, proxies and sites used all have their own peculiarities. And their own scientists and technicians. Often their own methids. It’s silly to exclude data because it was detemined by one particular instrumental method. Only someone trying to avoid the obvious would make such a claim.

    And I have quoted enough to show you that no attempt was made to hide the problems of proxy data in modern times. There was no “admission”. No story is “unravelling”. No one credible is seriously talking about withdrawing papers.

    Yes I have read criticisms of the paper. The ones you quite are notable for being basically opinions, littl consideration of facts, and make the same pepuroosefuk mistakes you make. Others are typical of the normal discussion and critique that goes on in healthy science. There will always be difference of evaluation and confindpfidenxe in interpretation. For example the question if whether we can exclude temperature spike like that seen in modern data from the bulk of the reconstructed record. There are valid arguments both ways, and also question of how relevant such issues really are.

    The critiques you are appealing to are childish and politically motivated. They are not credible – but then that is an issue which doesn’t concern you. You always start with a preconceived position – in this case a political, anti-science one.

  7. You just can’t get your denialist head around this, can you Ken?

    In their supplementary information posted online, the authors say they assumed for the purposes of the study that the core tops were dated to the present “unless otherwise noted in the original publication.” This told readers they were relying on their original dating, despite the fact the coretops had been redated by them in a way that critics have pointed out strongly impacted on their results.

    It was not until Easter weekend after mounting pressure that Marcott and Shakun admitted their original data for the modern period was not statistically robust and could not be used for the basis of any of their conclusions.

    Stripped of that, we are left with you and other denialists trying to argue that it was OK to use modern instrumental data, but that defeats the study, really as it compares apples with oranges. Either you have proxies that are valid and extensive enough to base conclusions on for the entire period you are studying, or you don’t. The significance of the study, as reported from interviews Marcott gave, is that his proxies backed up the instrument data, but as you and I have agreed above, no they didn’t because his proxies were worthless.

    You have been unable to find paragraphs supporting your defence in the paper, but I invite you to try harder.

    The fact that Georgia Tech’s head of climate science, Judith Curry, has endorsed the criticisms as valid should give you pause to ensure your defence actually stands up scientifically. So far, it has not.

    I would add that Dot Earth’s Andy Revkin is also concerned about Marcott’s hype in media interviews, compared against the later admissions:
    “there’s also room for more questions — one being how the authors square the caveats they express here with some of the more definitive statements they made about their findings in news accounts.”

  8. The actual data includes the proxies, the insturmental temperatures of the last century, and the predicted temperatures to 2001 as estimated for the different IPCC scenarios. They do make clear which they use. If you can’t understand that then you have a comprehension problem.

    Are you going to do the honest thing – withdraw and apologise?

  9. Actually Ken, look at my comment and then the evidence again. The so-called modern heat spike was not supported in the actual data (being their proxies). You argue it might be supported elsewhere. That’s all very well, but it wasn’t in their data. So I still made an accurate statement.

    Please find me the quote in Marcott et all that makes it clear their “paleotemperature stack is not statistically robust”, as opposed to the discussion of robustness as between Standard 5×5 and the area weighted infilled average.

  10. What we have established Ian, and this is important for you, is that there was no retraction, “admitting the so-called modern heat spike was not supported in the actual data after all.” That the simple fact “the 20th century portion of our paleotemperature stack is not statistically robust” was actually in their paper.

    No admission, no retraction. Surely the ethical thing for a proper journalist to do is to retract your post and apologise.

    As for your continued refusal to acknowledge that the modern heat spike is evidenced not by proxy data, but instrumental data (to present) and predicted data based on IPCC scenarios (to 2100) I believe that is a childish attempt at confusion. Surely no literate adult would have such poor comprehension.

  11. Didn’t we establish that this bit “based on our Standard5×5 plus high-frequency addition stack (Fig. 3)” was “probably not robust”, and that they later admitted that their 20th and 21st century data was “not statistically robust”, in which case why did they nonetheless quote modern temperatures in that paragraph at all: “Our results indicate that global mean temper-ature for the decade 2000–2009 (34) has not yet exceeded the warmest temperatures of the early Holocene (5000 to 10,000 yr B.P .). These tem-peratures are, however, warmer than 82% of the Holocene distribution as represented by the Standard5×5 stack, or 72% after making plausible corrections for inherent smoothing of the high frequencies in the stack (6) (Fig. 3)”

    Their temperature data for the 20th and 21st century could not be relied upon in any way, they later admitted, yet their conclusions lead off with those temperatures. Remind me again how you were reconciling this?

    There is clearly a paragraph in their study somewhere that categorically states their own temp data for the 20th century was not statistically robust which is why they weren’t using it at all. I’m sure you can find that paragraph…

  12. Found the digital version. Here is the Para:

    “Our results indicate that global mean temper-ature for the decade 2000–2009 (34) has not yet exceeded the warmest temperatures of the early Holocene (5000 to 10,000 yr B.P .). These tem-peratures are, however, warmer than 82% of the Holocene distribution as represented by the Standard5×5 stack, or 72% after making plausible corrections for inherent smoothing of the high frequencies in the stack (6) (Fig. 3). In contrast, the decadal mean global temperature of the ear-ly 20th century (1900–1909) was cooler than >95% of the Holocene distribution under both the Standard5×5 and high-frequency corrected sce-narios. Global temperature, therefore, has risen from near the coldest to the warmest levels of the Holocene within the past century, reversing the long-term cooling trend that began ~5000 yr B.P . Climate models project that temperatures are likely to exceed the full distribution of Holocene warmth by 2100 for all versions of the temperature stack (35) (Fig. 3), regardless of the greenhouse gas emission scenario considered (excluding the year 2000 constant composition scenario, which has already been exceeded). By 2100, global average temperatures will probably be 5 to 12 standard deviations above the Holocene temperature mean for the A1B scenario (35) based on our Standard5×5 plus high-frequency addition stack (Fig. 3).”

  13. What I asked you was how you reconcile what the paper says with what Marcott stated publicly, and to supply quotes from the paper in support of your claims. I am waiting.

  14. Ah, Ian, you have now got a copy of the paper. Even quoting the bit I did about the recent temperature data not being robust. You know, the bit they repeated to questioners later and your reported as them being forced to admit.

    Care to retract your claim?

    Their work was independent, it was a reconstruction of the paleotemperatures and produced very similar results to others where they overlap. The issue of non-robust modern temperatures is a red herring because neither they or others rely on proxies for that. In the paper they clearly identify that modern instrumental data is used for modern temperatures.

    The authors do not suggest therir older data was not robust – you misrepresent them. Both Mann andf them reconstucted paleotemperatures and got simialr results. No question of lack of robustness there. And there comments about modern temoperatures, and forcasted tempoeratures, are clearly attributed to instrumental measuments and to projections from IPCC models and scenarios.

    It is extremely dishionest of you to attempt confusion here – their comments of lack of robustness rate to modern temperatures, not older ones. Their comments on recent temperatures relate to insturmental and projected dsta, not proxies.

    And the data in their paper, both their own and that taken from recent instrumental studies and IPCC projections, do overwhelmingly support their claims. Overwhelmingly.

    If you have a problem with the instrumental modern measurements and the IPCC projections be honest aboiut it and leave these authors alone – they are not responsible for these.

    Also, if you have a problem with the details of the method descriptions, take it up with the journal (and good luck with that). Perhaps you and I, not using radiocarbon dating methods, are not familair with the calibrations required but certainly workers in the area are. The attribution of year zero to coretops seems obvious to me, especially when you consider both the poor calibration for recent times and disruption of surface – maybe more deail is required, maybe not. That’s an editorial decision. You cant seriously suggest any deception??

    But nothing you have raised presents a problem for the conclusions – which don’t really depend on extreme accuracy for ages – especially as proxies are not involved in their comments on recent temperatures.

    It’s a simple beat-up. Which we have come to expect from climate change deniers. But its a pretty pathertic one. You guys are getting realy desperate, aren’t you.

  15. Ah, not quite Ken. I asked you for the passage that describes their methodology. Not just what they did but the justification for it. Why, for example, did they presume coretops to be year zero (1950)?

    In their paper they write: “Without filling data gaps, our Standard5×5 reconstruction (Figure 1A) exhibits 0.6°C greater warming over the past ~60 yr B.P. (1890 to 1950 CE) than our equivalent infilled 5° × 5° area-weighted mean stack (Figure 1, C and D). However, considering the temporal resolution of our data set and the small number of records that cover this interval (Figure 1G), this difference is probably not robust.”

    That passage clearly illustrates that the 0.6C difference between the Standard5x5 reconstruction and their area-weighted main stack findings is “probably not robust”. Why then did Marcott go on to say, and I quote:

    “What’s striking is that the records we use are completely independent, and produce the same result.”

    But as you’ve noted in your comment initially, Marcott wasn’t relying on his own figures to “produce the same result” as Michael Mann because his own figures were not “robust”.

    Can you explain his statement or was he making things up on the hoof like you climate deniers do so often?

    Now, he then follows it up in the interview by saying, and I quote:

    “What we found is that temperatures increased in the last 100 years as much as they had cooled in the last 6,000 or 7,000. In other words, the rate of change is much greater than anything we’ve seen in the whole Holocene.”

    No it’s not. We’ve just agreed that his own figures never showed this.

    Where in the Marcott et al paper do you find the passages that support those statements? Again, an accurate quote please.

  16. Actually, specific descriptions are in the supplementary data. For example:
    “All radiocarbon dates were calculated with Calib6.0”

    They also discuss the procedure they used for cores: “Ages were linearly extrapolated beyond bottommost dates, and assumed to be 0 yr BP at core tops unless otherwise noted in the original publication. ”

    You can download the supplementary material from:
    http://www.sciencemag.org/content/339/6124/1198/suppl/DC1

    Perhaps you should?

  17. Please quote the verse (accurately) in their study that discloses the recalibration methodology. Then quote the passage that explains their coretop re-dating methodology. This from the actual study please.

  18. No, they didn’t “artifically” re-calibarate their radiometric dates. They used modern calibration data to produce more accurate dates. This moved the dates (determined by original workers) by various small amounts, but larger for older samples. Yes, it’s described in their paper.

    Now, do you think that theyy should have used the incorrectly (because of poorer data in the old days) calibrated dates for the old samples?

    Do you seriously want to argue they have done something wrong?

    Is this all you have to go on Ian – to manufacture and mislead?

    Have you read the paper? If not, perhaps you better had because there are a number of people telling big lies about it. Lies that are easily caught out. It’s going to be ver5y damaging for your credibility to naively repeat those lies, isn’t it?

    Or perhaps you don’t worry about credibility?

  19. Ken…if you read Marcott et al carefully, can you tell me where it discloses that they artificially re-calibrated all radiocarbon dates?

  20. And you continue to ignore the fact that all this was in the oringial paper. No false claims were made.

    Really, Ian – perhaps you should read that paper – or is that agianst yoiuyr religion – considering the facts?

  21. Actually Ken…My original posts encapsulated the story in my own words. You also ignore Shaun Marcott himself overselling it in media interviews….

    Once again you prove that former Socialist Unity Party supporters are so anti-intellectual that they evidently cannot read or comprehend; evidence that a left-wing communist lifestyle addles your brain cells.

    For the record, Dr Judith Curry whose comments on this have been drawn to your attention previously is Professor of Climate Science at Georgia Tech and Chair of the Atomspheric and Earth Sciences division…her comments on Marcott are temperate, and she blames your mates at RealClimate for leading Marcott astray scientifically:

    This case is an interesting one in the sociology of climate science. Some concerns and questions:

    Are there still no checks and balances in the paleoclimate community (outside of the efforts of Steve McIntyre, JeanS et al.)?
    In terms of the hyping of this story, I am prepared to give Marcott and Shakun somewhat of a pass given that they are recent Ph.D. recipients. Alan Mix and Peter Clark are the senior authors. And the paper was also hyped by a NSF Program Manager. What kind of advice did they give Marcott and Shakun in all this?
    Marcott scored points in my book by communicating with Steve McIntyre, and for some measure of honesty in his response. I wonder how his response landed on RealClimate. Here is a suspicion: Marcott was subsequently contacted by one of the RealClimate principals, providing advice against engaging with McIntyre, sympathy that they are being attacked by deniers, and providing support and a safe refuge on RealClimate.
    I see this as a struggle for the souls of two young climate scientists. Will they (i) decide to care primarily about science, and embrace the values of transparency and public accountability, answer questions about their research, and engage with skeptics in the interest of improving their research; or (ii) do they aspire to Mike Mann-style celebrity and plan to join the RealClimate warriors against auditing and skepticism?
    JC advice to Marcott and Shakun: I understand how tough it is for a young Ph.D. scientist to make their mark in academia and obtain a desirable permanent position. Celebrity can be seductive, but engaging with the media is associated with many potential pitfalls. I encourage you to read my essay published a few years ago at DotEarth entitled: An open letter to graduate students and young scientists in fields related to climate research:

    What has been noticeably absent so far in the ClimateGate discussion is a public reaffirmation by climate researchers of our basic research values: the rigors of the scientific method (including reproducibility), research integrity and ethics, open minds, and critical thinking. Under no circumstances should we ever sacrifice any of these values . . .

    JC advice to NSF and the universities: We are not doing a good enough job in educating our young scientists about the specific ethical challenges faced by scientists working in the climate field. Lets share/generate some wisdom and develop better guidance for dealing with these issues (something for NRC COSEPUP to take on).

    JC advice to the skeptical blogosphere: Lets get to the bottom of this, but while doing so I remind you that one element of this is the struggle for the scientific souls of two promising young scientists. Please don’t overegg the pudding and inadvertently send them to the RealClimate refugee and training camp. Cordially invite them to engage, and work with them to try to change the culture in the paleoclimate community.

    Stop lying to the world through Open Parachute Ken, and start engaging with genuine debate yourself.

  22. Ian, what about putting this in your own words now.?

    But it is shocking for you to ignore what was written in the actual paper and then quote at length criticisms from a climate change denier who, for his writing, also did not read the paper.

    How do you sleep straight at night.

  23. Actually Ken…they blasted it in a superhyped fashion through press releases and Science, letting a lie go around the world, and only highlighting the truth after being challenged.

    Please note that Shaun Marcott himself made the false claims in newspaper interviews (directly quoted in the Pielke analysis below, so clearly he was content to spread the lie.:

    This from Pielke jr:

    Arguments over data and methods are the lifeblood of science, and are not instances of misconduct.

    However, here I document the gross misrepresentation of the findings of a recent scientific paper via press release which appears to skirt awfully close to crossing the line into research misconduct, as defined by the NRC. I recommend steps to fix this mess, saving face for all involved, and a chance for this small part of the climate community to take a step back toward unambiguous scientific integrity.

    The paper I refer to is by Marcott et al. 2013, published recently in Science. A press release issued by the National Science Foundation, which funded the research, explains the core methodology and key conclusion of the paper as follows (emphasis added):
    Peter Clark, an OSU paleoclimatologist and co-author of the Science paper, says that many previous temperature reconstructions were regional and not placed in a global context.

    “When you just look at one part of the world, temperature history can be affected by regional climate processes like El Niño or monsoon variations,” says Clark.

    “But when you combine data from sites around the world, you can average out those regional anomalies and get a clear sense of the Earth’s global temperature history.”

    What that history shows, the researchers say, is that during the last 5,000 years, the Earth on average cooled about 1.3 degrees Fahrenheit–until the last 100 years, when it warmed about 1.3 degrees F.
    The press release clearly explains that the paper (a) combines data from many sites around the world to create a “temperature reconstruction” which gives a “sense of the Earth’s temperature history,” and (b) “that history shows” a cooling over the past 5000 years, until the last 100 years when all of that cooling was reversed.

    The conclusions of the press release were faithfully reported by a wide range of media outlets, and below I survey several of them to illustrate that the content of the press release was accurately reflected in media coverage and, at times, amplified by scientists both involved and not involved with the study.

    Examples of Media Coverage

    Here is Justin Gillis at the New York Times, with emphasis added to this excerpt and also those further below:
    The modern rise that has recreated the temperatures of 5,000 years ago is occurring at an exceedingly rapid clip on a geological time scale, appearing in graphs in the new paper as a sharp vertical spike.
    Similarly, at the NY Times Andy Revkin reported much the same in a post titled, “Scientists Find an Abrupt Warm Jog After a Very Long Cooling.” Revkin included the following graph from the paper along with a caption explaining what the graph shows:

    Revkin’s caption: A new Science paper includes this graph of data providing clues to past global temperature. It shows the warming as the last ice age ended (left), a period when temperatures were warmer than today, a cooling starting 5,000 years ago and an abrupt warming in the last 100 years.
    Revkin concluded: “the work reveals a fresh, and very long, climate “hockey stick.”” For those unfamiliar, a hockey stick has a shaft and a blade.

    Any association with the so-called “hockey stick” is sure to capture interest in the highly politicized context of the climate debate, in which the iconic figure is like catnip to partisans on both sides. Here is Michael Lemonick at Climate Central:
    The study… confirms the now famous “hockey stick” graph that Michael Mann published more than a decade ago. That study showed a sharp upward temperature trend over the past century after more than a thousand years of relatively flat temperatures. . .

    “What’s striking,” said lead author Shaun Marcott of Oregon State University in an interview, “is that the records we use are completely independent, and produce the same result.”
    Here is Grist.org, which refers in the passage below to the same figure shown above:
    A study published in Science reconstructs global temperatures further back than ever before — a full 11,300 years. The new analysis finds that the only problem with Mann’s hockey stick was that its handle was about 9,000 years too short. The rate of warming over the last 100 years hasn’t been seen for as far back as the advent of agriculture.

    To be clear, the study finds that temperatures in about a fifth of this historical period were higher than they are today. But the key, said lead author Shaun Marcott of Oregon State University, is that temperatures are shooting through the roof faster than we’ve ever seen.

    “What we found is that temperatures increased in the last 100 years as much as they had cooled in the last 6,000 or 7,000,” he said. “In other words, the rate of change is much greater than anything we’ve seen in the whole Holocene,” referring to the current geologic time period, which began around 11,500 years ago.
    Back to more mainstream outlets, here is how Nature characterized the study, offering a substantially similar but somewhat more technical description of the curve shown in the figure above:
    Marcott and his colleagues set about reconstructing global climate trends all the way back to 11,300 years ago, when the Northern Hemisphere was emerging from the most recent ice age. To do so, they collected and analysed data gathered by other teams. The 73 overlapping climate records that they considered included sediment cores drilled from lake bottoms and sea floors around the world, along with a handful of ice cores collected in Antarctica and Greenland.

    Each of these chronicles spanned at least 6,500 years, and each included a millennium-long baseline period beginning in the middle of the post-ice-age period at 3550 bc.

    For some records, the researchers inferred past temperatures from the ratio of magnesium and calcium ions in the shells of microscopic creatures that had died and dropped to the ocean floor; for others, they measured the lengths of long-chain organic molecules called alkenones that were trapped in the sediments.

    After the ice age, they found, global average temperatures rose until they reached a plateau between 7550 and 3550 bc. Then a long-term cooling trend set in, reaching its lowest temperature extreme between ad 1450 and 1850. Since then, temperatures have been increasing at a dramatic clip: from the first decade of the twentieth century to now, global average temperatures rose from near their coldest point since the ice age to nearly their warmest, Marcott and his team report today in Science.
    And here is New Scientist, making reference to the exact same graph:
    Shaun Marcott of Oregon State University in Corvallis and colleagues have compiled 73 such proxies from around the world, all of which reach back to the end of the last glacial period, 11,300 years ago. During this period, known as the Holocene, the climate has been relatively warm – and civilisation has flourished.

    “Most global temperature reconstructions have only spanned the past 2000 years,” says Marcott.

    Marcott’s graph shows temperatures rising slowly after the ice age, until they peaked 9500 years ago. The total rise over that period was about 0.6 °C. They then held steady until around 5500 years ago, when they began slowly falling again until around 1850. The drop was 0.7 °C, roughly reversing the previous rise.

    Then, in the late 19th century, the graph shows temperatures shooting up, driven by humanity’s greenhouse gas emissions.

    The rate of warming in the last 150 years is unlike anything that happened in at least 11,000 years, says Michael Mann of the Pennsylvania State University in University Park, who was not involved in Marcott’s study. It was Mann who created the original hockey stick graph (see upper graph here), which showed the change in global temperatures over the last 1000 years.

    Over the Holocene, temperatures rose and fell less than 1 °C, and they did so over thousands of years, says Marcott. “It took 8000 years to go from warm to cold.” Agriculture, communal life and forms of government all arose during this relatively stable period, he adds. Then in 100 years, global temperatures suddenly shot up again to very close to the previous maximum.
    It seems clear that even as various media took different angles on the story and covered it in varying degrees of technical detail, the articles listed above accurately reflected the conclusions reflected in the NSF press release, and specifically the “hockey stick”-like character of the new temperature reconstruction. Unfortunately, all of this is just wrong, as I explain below. (If you’d like to explore media coverage further here is a link to more stories. My colleague Tom Yulsman got punked too.)

    The Problem with the NSF Press Release and the Subsequent Reporting

    There is a big problem with the media reporting of the new paper. It contains a fundamental error which (apparently) originates in the NSF press release and which was furthered by public comments by scientists.

    In a belatedly-posted FAQ to the paper, which appeared on Real Climate earlier today, Marcott et al. make this startling admission:
    Q: What do paleotemperature reconstructions show about the temperature of the last 100 years?

    A: Our global paleotemperature reconstruction includes a so-called “uptick” in temperatures during the 20th-century. However, in the paper we make the point that this particular feature is of shorter duration than the inherent smoothing in our statistical averaging procedure, and that it is based on only a few available paleo-reconstructions of the type we used. Thus, the 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions.
    Got that?

    In case you missed it, I repeat:
    . . . the 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes . . .
    What that means is that this paper actually has nothing to do with a “hockey stick” as it does not have the ability to reproduce 20th century temperatures in a manner that is “statistically robust.” The new “hockey stick” is no such thing as Marcott et al. has no blade. (To be absolutely clear, I am not making a point about temperatures of the 20th century, but what can be concluded from the paper about temperatures of the 20th century.)

    Yet, you might recall that the NSF press release said something quite different:
    What that [temperature reconstruction] history shows, the researchers say, is that during the last 5,000 years, the Earth on average cooled about 1.3 degrees Fahrenheit–until the last 100 years, when it warmed about 1.3 degrees F.
    So what the paper actually shows is the following, after I have removed from the graph the 20th century period that is “not statistically robust” (this is also the figure that appears at the top of this post):

    Surely there is great value in such an analysis of pre-20th century temperatures. And there can be no doubt there will be continuing debates and discussions about the paper’s methods and conclusions. But one point that any observer should be able to clearly conclude is that the public representation of the paper was grossly in error. The temperature reconstruction does not allow any conclusions to be made about the period after 1900.

    Does the public misrepresentation amount to scientific misconduct? I’m not sure, but it is far too close to that line for comfort. Saying so typically leads to a torrent of angry ad hominem and defensive attacks, and evokes little in the way of actual concern for the integrity of this highly politicized area of science. Looking past the predictable responses, this mess can be fixed in a relatively straightforward manner with everyone’s reputation intact.

  24. Ian, you are really guilty of something far less than objectivity (or even professional integrity) here with your claim quoting the authors:

    “The 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes,” they admitted in a news release over Easter. In other words, there is no evidence to support the grand claims that swept through world media last month.”

    Sure, this is a clarification by them after the event but look what they wrote in their original paper in referring to the period 1890-1950 CE:

    “However, considering the temporal resolution if our data set and the small number of records that cover his interval (Fig.1G) this difference is probably not robust.”

    They in fact relied on other data for the comparison with recent temperatures.

    Far from an “admission” that you claim this was simply a clarification in response to questions. And probably from questioners who had not read the paper.

    The authors make very clear they do not rely on their proxy data for recent temperatures – there are plenty of studies around which provided them with far more precise to data than that.

    “Retraction of paper” – in your dreams.

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