Jennifer Marohasy

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The Apple on the Banana Again: Marcott Admits Temperature Spike Not Robust

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IT is terribly unfashionable to admit it, but I’ve just never been able to believe that the late 20th Century was particularly warm. This admission despite ‘the hockey stick’ graph that featured so prominently in the United Nation’s third IPCC assessment report, and despite that amazing looking chart in Al Gore’s movie that also showed a recent spike in global temperatures relative to the last many thousand years.

My key problem with the ‘the hockey stick’ has always been that the upward spike representing runaway global warming in the 20th Century was never of the same stuff as the rest of the chart. That is the spike is largely based on the instrumental temperature record i.e. the thermometer record, while the downward trending line that it was grafted on to, is based on proxies, in particular estimates of temperature derived from studies of tree rings.

It has always, for me, been a case of Michael Mann comparing apples and oranges, or to put it another way sticking an apple on the end of a banana.

The Michael Mann and Shaun Marcott Hockey Sticks

Worst the grafting was necessary because the proxy record, i.e. the tree ring record, shows that global temperatures have declined since about 1960.

Of course we know that global temperature haven’t declined since 1960, or thereabout, so there must be something wrong with the proxy record. This is known as “the divergence problem” and it is a problem, because if tree rings are not a good indicator of global temperature after 1960, how can they be a good indicator of global temperature prior to 1960?

Indeed there doesn’t appear to be a reliable method for reconstructing the last 100 or so years based on the standard techniques used to reconstruct the last 2,000, 4,000 and even 11,000 years of global temperature.

So when someone claims the past 10 years have been hotter than the past 11,300 years, as the Australian Broadcasting Commission did recently [1], there is good reason to cringe.

Of course the ABC didn’t make it up. They were reporting on the work of climate scientists recently published in a reputable journal. In particular a paper by Shaun Marcott and colleagues published in Science [2].

Sceptic, mathematician and blogger, Steve McIntyre, broke the original hockey stick into bits to do a thorough analysis, showing that the entire shaft, not just post 1960, was a fancy construct to create the impression of runaway global warming [3], and he’s done the same with this new Marcott fabrication [2].

While some who read this blog may cringe at my use of the word fabrication, it is more than justified because as Dr Marcott now admits in his own words[4]:

“[T]he 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. Our primary conclusions are based on a comparison of the longer term paleotemperature changes from our reconstruction with the well-documented temperature changes that have occurred over the last century, as documented by the instrumental record.”

In summary, Dr Marcott created the perception of a spike in temperatures the same way Michael Mann did in that first hockey stick paper that featured so prominently in the third IPCC report, by comparing apples and oranges… or perhaps best described as grafting an apple onto the end of a banana.

***

1. Earth on track to be hottest in human history: study . March 8, 2013
http://www.abc.net.au/news/2013-03-08/climate-study/4561164

2. A reconstruction of regional and global temperature for the past 11,300 years. Marcott et al.. Science, Volume 339, No. 6124, pages 1198-1201.
http://www.sciencemag.org/content/339/6124/1198.abstract

Abstract: Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (

3. see http://climateaudit.files.wordpress.com/2009/12/mcintyre-ee-2005.pdf and more http://climateaudit.org/multiproxy-pdfs/ and the latest http://climateaudit.org/2013/03/31/the-marcott-filibuster/

4. Response by Marcott et al. http://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/

Reader Interactions

Comments

  1. Neville says

    It’s amazing how Marcott etc released this paper and allowed the MSM to parrot their fraudulent nonsense and said nothing.

    But as McIntyre and others pulled apart the uptick and proved it couldn’t be trusted Marcott only then admitted the 20th century warming wasn’t robust.

    It’s what we could call a lie by omission. But how did they ever dream they could get away with this fraud?

    But you’re correct, proxy records have a real problem trying to match with the later instrumental records.

  3. spangled drongo says

    Good advice from Judith Curry:

    “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.”

  4. sp says

    From the NSF (and is now believed to be untrue):

    “The last century stands out as the anomaly in this record of global temperature since the end of the last ice age,” says Candace Major, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences. The research was funded by the Paleoclimate Program in NSF’s Division of Atmospheric and Geospace Sciences.

    “This research shows that we’ve experienced almost the same range of temperature change since the beginning of the industrial revolution,” says Major, “as over the previous 11,000 years of Earth history–but this change happened a lot more quickly.”

    http://www.nsf.gov/news/news_summ.jsp?cntn_id=127133

  5. Neville says

    Hold on a minute why didn’t Marcott include the uptick in an earlier paper? They were just trying it on, because they knew exactly what they were doing.

    Also Mann fully endorsed this study and still stands by his fraud as well. We should stop making excuses for people who have deliberately done the wrong thing.

  6. ianl8888 says

    Judith Curry’s comment:

    ” … send them to the RealClimate refugee and training camp”

    Waaay too late – Marcott et al started from there

    Also some circumstantial evidence that Mann was an anonymous reviewer of the paper

  7. sp says

    I think the key issue is that they should re-issue a new press statement to correct the earlier false statements.

    The general public remembers the headlines – “We are Doomed”, but the evidence supporting this statement is not there.

    I doubt there will be a new press release to correct the warmist propaganda.

  9. Neville says

    Amazing Robert Kennedy Jnr and some fool from the Met office told us just a few years ago that the poor future little kiddies wouldn’t know what snow was.

    Flannery and David Jones also insisted during the drought that this was the new norm and we wouldn’t see rains that could fill our dams anymore.

    Now Flannery etc are telling us to expect more heavy rainfall events and more often. Talk about making it up as you go along. Yet the MSM still parrot what these fools tell us and never ask an inconvenient question.

  11. Debbie says

    Awesome pic Jen!
    Apple on banana. Well done and well explained!
    I think your explanation about those proxies is excellent.
    Hope it was a tasty breakfast?

  12. spangled drongo says

    Yes Ian, I’m too soft. Marcott and Shakun probably deserve all they get.

  13. cohenite says

    “Marcott and Shakun probably deserve all they get”.

    Shakun especially, he started this garbage with his 2012 paper supposedly proving CO2 did not follow temp but preceded it.

  14. Larry Fields says

    Hi Jennifer,
    Well put! But you really should have used a green banana instead of a ripe one. By itself, a green banana–which symbolizes raw data–would not fit the predetermined narrative. As all horticulturalists know, an apple can cause rapid ripening in a banana. It’s those dastardly ethylene emissions. 🙂

  16. spangled drongo says

    Wonderful cartoon on the Climate Sceptics AGM notice. Under a heading of “carbon accounting”,
    one farmer, training his chooks to go to the loo, says to the other, “it turns out that the poop is worth more than the chicken”.

    Says so clearly what a load of poop is heading our way.

  17. Neville says

    Ian it’s a pity you didn’t live in the Eemian Interglacial because then you could really see a warming trend ( 8C higher than today) with SLs 4 to 8 metres higher than today.

    http://ca.news.yahoo.com/greenland-ice-core-hints-earths-next-big-melt-174348125.html

    So why was this NATURAL interglacial so much warmer than today and why is the Holocene cooler than the previous four interglacials?

    Of course there was only a tiny population of humans during those previous IGs so that doesn’t help the alarmists cause either.

  21. Neville says

    Yes Cohers but don’t forget our own GAIA brain Timmy. Yes we’re paying him too and he’s also our Chief Climate Commissioner as well.

    http://www.youtube.com/watch?v=SeNDSeknn_c

    Also his rain forecasts can predict severe ongoing drought and then heavier downpours and more flooding just a couple of years apart. A true genius. Of course ditto his fellow commissioner Will Steffen.

  22. Johnathan Wilkes says

    Murry Salby, professor of climate at Macquarie University:

    “The surface record … Is certainly not robust. The bureau’s record is routinely readjusted… And if the adjustments are understood, it is by few, if any, outside the bureau… ”

    They can huff and puff, but data adjustment was and remains the most contentious issue for me.

    Once “adjusted” data can mean anything and everything you want it to mean.

  24. Neville says

    I hope Jennifer has the time to look at Salby’s report mentioned above. The UAH satellite graph fo Australia since 1979 looks very interesting.

  26. el gordo says

    This man is an idiot.

    ”We have seen this basic shift in the climate system, where natural events are amplified because there is more energy in the system,” he said. ”The different lines of evidence all point to this conclusion.”

    Will Steffen

  31. el gordo says

    Thanx Neville, the high resolution is better.

    Interesting there is no Younger Dryas, which is most pronounced in Gisp2.

  32. Neville says

    EG I think you’ll find that Marcott et al started their study 11,300 years BP and therefore missed out on the YD by two hundred years at 11,500 years BP.

    I suppose it would be inconvenient to have a whopper uptick of 10C in just ten years near the start of your study.
    Afterall the MSM went beserk about a whopping 0.7c of warming over the last 100 years didn’t they?

  33. el gordo says

    Thanks again Neville, saved me making a fool of myself elsewhere. Nancy Green gets a guest post at Watts… much amusement.

    ‘There is a message in Marcott that I think many have missed. Marcott tells us almost nothing about how the past compares with today, because of the resolution problem. Marcott recognizes this in their FAQ. The probability function is specific to the resolution. Thus, you cannot infer the probability function for a high resolution series from a low resolution series, because you cannot infer a high resolution signal from a low resolution signal. The result is nonsense.’

  36. Minister for Common Sense says

    http://us4.campaign-archive1.com/?u=c920274f2a364603849bbb505&id=b299463205&e=c70dd621be

    Just two points from me, for what they may be worth.

    1. The GWPF news updates where they assemble the main news items for the week dealing with energy and GW.

    In aggregate they continue to reveal what an complete dogs break fast it has been.
    Idiot academics peddling a non problem and government policy makers under the thrall of the many hypocritical greeny NGOs turning that into an even bigger mess. But it seems that the market and common sense has thankfully prevailed and is minimising the damage

    No doubt this will send the village idiots and apologists for GW alarmism into a foot stomping tanty

    2. The Ch 2 program last night on the BBC our earth, was excellent.

    How any one watching that well prepared, well scripted and well presented program could harbor doubts about the almost complete irrelevance of a few extra molecules of CO2, when set against all the other forces at work is beyond me

  38. sp says

    And in 2009 we were told:

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

    An already relentless melting of the Arctic greatly accelerated this summer—a sign that some scientists worry could mean global warming has passed an ominous tipping point.

    One scientist even speculated that summer sea ice could be gone in five years.

    “The Arctic is screaming,” said Mark Serreze, senior scientist at the government’s snow and ice data center in Boulder, Colorado.

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

    THE ARTIC IS SCREAMING!!!

  40. Bob Fernley-Jones says

    Jen,
    I’m curious; by showing a little more than half an apple on top, are you inferring that apple-proxies show the NH to be warming more than the SH? Whilst that might be a good correlation with observations, might I say that we should not jump to conclusions on stuff like cause and effect, or even relevance! (re dubious AGW connections to increasing hamburger sales and piracy)

  41. Neville says

    A good graph comparing the Vostok Holocene with Marcotts effort.

    http://www.rockyhigh66.org/stuff/marcott_spikes.gif Now that’s what I call spikes. BTW the spike at the end of Marcott is actually 1940, therefore well before the later big increase in co2 emissions.
    Probably level of about 300 ppmv and almost entirely natural anyway.

  42. Avatar photojennifer says

    Hi Bob

    You are perhaps looking for more meaning than originally intended in my picture. I was making breakfast and thought I had found a way of providing insight into the Marcott hockey stick…

    Best Jen

  43. el gordo says

    ‘Now that’s what I call spikes.’

    Any idea what caused that spike at Vostok just before 8000 bp?

  44. Neville says

    Just had a bit of a read at Wikipedia and even they quote the recent study of Greenland temps. See below….

    A paper on Greenland’s temperature record shows that the warmest year on record was 1941 while the warmest decades were the 1930s and 1940s. The data used was from stations on the south and west coasts, most of which did not operate continuously the entire study period.[36]

    While Arctic temperatures have generally increased, there is some discussion over the temperatures over Greenland. First of all, Arctic temperatures are highly variable, making it difficult to discern clear trends at a local level. Also, until recently, an area in the North Atlantic including southern Greenland was one of the only areas in the World showing cooling rather than warming in recent decades,[37] but this cooling has now been replaced by strong warming in the period 1979–2005.[38

    This is the 2006 study by Vinther, Briffa, Jones et al that Lomborg used in “Cool It.” page 83.
    There was a very warm period in Greenland from about 1931 to about 1963 or 32 years.

    Then it cooled from 1964 to about 1988 and has increased since that time to near the temps of the warmer 1930s and 40s.

  46. hunter says

    Jennifer,
    It is great to see you posting so frequently and so well.
    The AGW hype is approaching self-parody, but the political class seems, as is typical, mostly ignorant of the facts.
    The failure of Marcott has implications for what ever is left of the Mann made global warming hockey stick.
    It comes back to trying to understand how AGW hype become such a bullet to the heart of the rational thinking of so many: How did so many otherwise smart people fall for AGW and its faux religious hype?

  47. Neville says

    Interesting new study shows an increase in the Greenland ice sheet since the end of the LIA.

    http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00373.1

    Here is the abstract from the study, 1840 to 1996. That’s a 12% or 86 Gt per year increase. That’s 30% higher than the 1600 to 2009 period suggesting an accelerating trend in ice accumulation.

    Rather stuffs up a lot of theories. How much more ice do these ratbags want? Seems to correlate with the NAO.

    Abstract

    Ice core data are combined with RACMO2 regional climate model (RCM) output (1958-2010) to develop a reconstruction of the Greenland ice sheet net snow accumulation rate (Ât(G)) spanning years 1600-2009. Regression parameters from RCM output regressed on 86 ice cores are used with available cores in a given year resulting in the reconstructed values. Each core site’s residual variance is used to inversely weight the cores’ respective contributions. The interannual amplitude of the reconstructed accumulation rate is damped by the regressions and is thus calibrated to match that of the RCM data. Uncertainty and significance of changes is measured using statistical models.

    We find a 12% or 86 Gt y-1 increase in ice sheet accumulation rate from the end of the Little Ice Age in ~1840 to the last decade of the reconstruction. This 1840-1996 trend is 30% higher than that of 1600-2009, suggesting an accelerating accumulation rate. The correlation of Ât(G) with the average surface air temperature in the Northern Hemisphere(SATNHt) remains positive through time, while the correlation of Ât(G) with local near-surface air temperatures or North Atlantic sea surface temperatures is inconsistent, suggesting a hemispheric-scale climate connection. We find an annual sensitivity of Ât(G) to SATNHt of 6.8% K-1 or 51 Gt K-1.

    The reconstuction, Ât(G), correlates consistently highly with the North Atlantic Oscillation index. Yet, at the 11-year time scale, the sign of this correlation flips four times in the 1870-2005 period.

    Corresponding author address: box.11@osu.edu

  48. el gordo says

    …off topic…

    Part of Tony Abbott’s IPA speech the other night….

    ‘John, there is one campaign where you will not prevail – namely your urgent advice to me in the IPA Review last August to be more like Gough Whitlam.

    ‘You had a great deal of advice for me in that particular issue and I want to assure you that the Coalition will indeed repeal the carbon tax, abolish the Department of Climate Change, abolish the Clean Energy Fund.

  51. James Mayeau says

    Well I had the apple and banana for breakfast.

    Next time you’ll need to carefully archive the evidence before you eat it.

  52. spangled drongo says

    If that “apple and banana stick” aren’t robust, maybe they’re just “restin”:

  53. sp says

    Climatologists are no Einsteins, says his successor:

    “I just think they don’t understand the climate,” he said of climatologists. “Their computer models are full of fudge factors.”

    A major fudge factor concerns the role of clouds. The greenhouse effect of carbon dioxide on its own is limited. To get to the apocalyptic projections trumpeted by Al Gore and company, the models have to include assumptions that CO-2 will cause clouds to form in a way that produces more warming.

    “The models are extremely oversimplified,” he said. “They don’t represent the clouds in detail at all. They simply use a fudge factor to represent the clouds.”

    http://blog.nj.com/njv_paul_mulshine/2013/04/climatologists_are_no_einstein.html

  56. Bob Fernley-Jones says

    Hi Jen,
    I’ve been wondering if maybe you could present your apple-proxies to the Science journal and ask if their reviewers for the Marcott et al paper might offer an opinion on your analysis…. especially as to which of the two is the more robust in the latter half of the 20th century.

  57. James Mayeau says

    I’ve been wondering if maybe you could present your apple-proxies to the Science journal and ask if their reviewers for the Marcott et al paper might offer an opinion on your analysis

    No Bob. Not until those dudes pony up an apology for Jen, from bad mouthing her four years ago for first reporting there had been no warming since 1998.

    Now that those dudes from the Science journal have caught up with current events, there’s some other laundry that needs their attention.

  59. Bob Fernley-Jones says

    James and Jen,
    Yep I agree James there be lots of dirty laundry embraced by the Sciencemagazine editorship, (and also in the Naturerag and in other stuff/media including the ABC), but I just thought it would be fun and appropriate. (if rather challenging for the faceless Science reviewers).
    BTW, as an enginnear not only can I spell most three-syllable words, but I also have a sense of humour, despite what you may have heard about my profession.

    Neville,
    Re Bolter’s interview with Bob Carter, thanks for link, and I’ll eagerly peekaboo tomorrow. Bob C is great, and amongst other things I’m pretty shore he can even spell four-syllable words!

  60. John Sayers says

    “BTW, as an enginnear (sic) not only can I spell most three-syllable words, but I also have a sense of humour, despite what you may have heard about my profession.”

    yup my problem for years.

  61. el gordo says

    Bob Carter is great and if Abbott fails to secure both houses in the election, then Bob maybe needed in any Double Dissolution debate.

  63. Neville says

    Interesting to read that Briffa, Jones, Vinther et al paper again and look at their table 1.

    If we look at the annual temp for Greenland in the decade 1851-60 we have a temp of minus -2.1c. ( annual)

    Then if we look at the decade 1981-90 we have an annual temp of minus-2.5c

    Then if we look at the decade 1991-2000 we have an annual temp of minus -2.1c.

    Luke states that Alley’s graph ended in 1855 and we can now show above that the period from 1980 to 2000 was 0.3 C colder than the decade 1851-60. That’s a period of twenty years.

    So the Alley Greenland graph I linked to finished at a slightly warmer temp in 1855 than the year 2000 and that temp period was cooler than the previous 60 years of the 20th century.

    Here is that study. http://www.cru.uea.ac.uk/cru/data/greenland/vintheretal2006.pdf The Table 1 is on page 11.

    Interesting how the recent winters and springs ( 1980 – 2000 ) were colder than the 1851- 60 period as well.

  64. Neville says

    I was just re-reading Lomborg’s book and especially his section on SLR and looking at the Royal Society’s graphs again on Antarctica and Greenland.

    http://rsta.royalsocietypublishing.org/content/364/1844/1709/F4.large.jpg Of course the Antarctic ice mass ( all models negative for SLR) is about nine times the size of Greenland’s ice mass. ( all models positive for SLR )

    But the rate of the negative SLR trend from Antarctica is also greater than the positive trend from Greenland, particularly as the graphs extend towards 2300 or another 300 years.

    But the Gore Hansen SLR trend until 2100 is about 6 metres or 20 feet, while the IPCC expects Greenland to contribute just 3.5 cm by 2100, or about 1.4 inches.

    So how do Gore and Hansen have any credibility at all and why do they have so much influence ,support and promotion in the MSM?

    Remember also that the IPCC 4th report states that about 29 cm ( about 1 foot) of SLR would be expected by 2100, but 21cm ( 8.5 inches) of that rise would be due to thermal expansion.

    So what does all this really tell you about the claims of impending dangerous SLR and the ongoing CAGW scare as well?

  66. el gordo says

    ‘Don’t look now, but maybe a scientific consensus exists concerning global warming after all. Only 36 percent of geoscientists and engineers believe that humans are creating a global warming crisis, according to a survey reported in the peer-reviewed Organization Studies. By contrast, a strong majority of the 1,077 respondents believe that nature is the primary cause of recent global warming and/or that future global warming will not be a very serious problem.’

    James Taylor in Forbes Magazine