Marcott issues a FAQ on their paper

This is from Real Climate, who played the “he who must not be named” game again in not pointing out criticisms. Gavin dissapoints.

UPDATE: McIntyre responded earlier today with The Marcott Filibuster

Marcott et al have posted their long-promised FAQ at realclimate here. Without providing any links to or citation of Climate Audit, they now concede:

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.

Otherwise, their response is pretty much a filibuster, running the clock on questions that have not actually been asked and certainly not at issue by critics. For questions and issues that I’ve actually raised, for the most part, they merely re-iterate what they already said. Nothing worth waiting for.

Read his entire post here: The Marcott Filibuster

I repost the Marcott FAQs here for discussion.

Summary and FAQ’s related to the study by Marcott et al. (2013, Science)

Prepared by Shaun A. Marcott, Jeremy D. Shakun, Peter U. Clark, and Alan C. Mix

Primary results of study

Global Temperature Reconstruction: We combined published proxy temperature records from across the globe to develop regional and global temperature reconstructions spanning the past ~11,300 years with a resolution >300 yr; previous reconstructions of global and hemispheric temperatures primarily spanned the last one to two thousand years. To our knowledge, our work is the first attempt to quantify global temperature for the entire Holocene.

Structure of the Global and Regional Temperature Curves: We find that global temperature was relatively warm from approximately 10,000 to 5,000 years before present. Following this interval, global temperature decreased by approximately 0.7°C, culminating in the coolest temperatures of the Holocene around 200 years before present during what is commonly referred to as the Little Ice Age. The largest cooling occurred in the Northern Hemisphere.

Holocene Temperature Distribution: Based on comparison of the instrumental record of global temperature change with the distribution of Holocene global average temperatures from our paleo-reconstruction, we find that the decade 2000-2009 has probably not exceeded the warmest temperatures of the early Holocene, but is warmer than ~75% of all temperatures during the Holocene. In contrast, the decade 1900-1909 was cooler than~95% of the Holocene. Therefore, we conclude that global temperature has risen from near the coldest to the warmest levels of the Holocene in the past century. Further, we compare the Holocene paleotemperature distribution with published temperature projections for 2100 CE, and find that these projections exceed the range of Holocene global average temperatures under all plausible emissions scenarios.

Frequently Asked Questions and Answers

Q: What is global temperature?

A: Global average surface temperature is perhaps the single most representative measure of a planet’s climate since it reflects how much heat is at the planet’s surface. Local temperature changes can differ markedly from the global average. One reason for this is that heat moves around with the winds and ocean currents, warming one region while cooling another, but these regional effects might not cause a significant change in the global average temperature. A second reason is that local feedbacks, such as changes in snow or vegetation cover that affect how a region reflects or absorbs sunlight, can cause large local temperature changes that are not mirrored in the global average. We therefore cannot rely on any single location as being representative of global temperature change. This is why our study includes data from around the world.

We can illustrate this concept with temperature anomaly data based on instrumental records for the past 130 years from the National Climatic Data Center (http://www.ncdc.noaa.gov/cmb-faq/anomalies.php#anomalies). Over this time interval, an increase in the global average temperature is documented by thermometer records, rising sea levels, retreating glaciers, and increasing ocean heat content, among other indicators. Yet if we plot temperature anomaly data since 1880 at the same locations as the 73 sites used in our paleotemperature study, we see that the data are scattered and the trend is unclear. When these same 73 historical temperature records are averaged together, we see a clear warming signal that is very similar to the global average documented from many more sites (Figure 1). Averaging reduces local noise and provides a clearer perspective on global climate.

Figure 1: Temperature anomaly data (thin colored lines) at the same locations as the 73 paleotemperature records used in Marcott et al. (2013), the average of these 73 temperature anomaly series (bold black line), and the global average temperature from the National Climatic Data Center blended land and ocean dataset (bold red line) (data from Smith et al., 2008).

New Scientist magazine has an “app” that allows one to point-and-plot instrumental temperatures for any spot on the map to see how local temperature changes compare to the global average over the past century (http://warmingworld.newscientistapps.com/).

Q: How does one go about reconstructing temperatures in the past?

A: Changes in Earth’s temperature for the last ~160 years are determined from instrumental data, such as thermometers on the ground or, for more recent times, satellites looking down from space. Beyond about 160 years ago, we must turn to other methods that indirectly record temperature (called “proxies”) for reconstructing past temperatures. For example, tree rings, calibrated to temperature over the instrumental era, provide one way of determining temperatures in the past, but few trees extend beyond the past few centuries or millennia. To develop a longer record, we used primarily marine and terrestrial fossils, biomolecules, or isotopes that were recovered from ocean and lake sediments and ice cores. All of these proxies have been independently calibrated to provide reliable estimates of temperature.

Q: Did you collect and measure the ocean and land temperature data from all 73 sites?

A: No. All of the datasets were previously generated and published in peer-reviewed scientific literature by other researchers over the past 15 years. Most of these datasets are freely available at several World Data Centers (see links below); those not archived as such were graciously made available to us by the original authors. We assembled all these published data into an easily used format, and in some cases updated the calibration of older data using modern state-of-the-art calibrations. We made all the data available for download free-of-charge from the Science web site (see link below). Our primary contribution was to compile these local temperature records into “stacks” that reflect larger-scale changes in regional and global temperatures. We used methods that carefully consider potential sources of uncertainty in the data, including uncertainty in proxy calibration and in dating of the samples (see step-by-step methods below).

NOAA National Climate Data Center: http://www.ncdc.noaa.gov/paleo/paleo.html

PANGAEA: http://www.pangaea.de/

Holocene Datasets: http://www.sciencemag.org/content/339/6124/1198/suppl/DC1

Q: Why use marine and terrestrial archives to reconstruct global temperature when we have the ice cores from Greenland and Antarctica?

A: While we do use these ice cores in our study, they are limited to the polar regions and so give only a local or regional picture of temperature changes. Just as it would not be reasonable to use the recent instrumental temperature history from Greenland (for example) as being representative of the planet as a whole, one would similarly not use just a few ice cores from polar locations to reconstruct past temperature change for the entire planet.

Q: Why only look at temperatures over the last 11,300 years?

A: Our work was the second half of a two-part study assessing global temperature variations since the peak of the last Ice Age about 22,000 years ago. The first part reconstructed global temperature over the last deglaciation (22,000 to 11,300 years ago) (Shakun et al., 2012, Nature 484, 49-55; see also http://www.people.fas.harvard.edu/~shakun/FAQs.html), while our study focused on the current interglacial warm period (last 11,300 years), which is roughly the time span of developed human civilizations.

Q: Is your paleotemperature reconstruction consistent with reconstructions based on the tree-ring data and other archives of the past 2,000 years?

A: Yes, in the parts where our reconstruction contains sufficient data to be robust, and acknowledging its inherent smoothing. For example, our global temperature reconstruction from ~1500 to 100 years ago is indistinguishable (within its statistical uncertainty) from the Mann et al. (2008) reconstruction, which included many tree-ring based data. Both reconstructions document a cooling trend from a relatively warm interval (~1500 to 1000 years ago) to a cold interval (~500 to 100 years ago, approximately equivalent to the Little Ice Age).

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. 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. Although not part of our study, high-resolution paleoclimate data from the past ~130 years have been compiled from various geological archives, and confirm the general features of warming trend over this time interval (Anderson, D.M. et al., 2013, Geophysical Research Letters, v. 40, p. 189-193; http://www.agu.org/journals/pip/gl/2012GL054271-pip.pdf).

Q: Is the rate of global temperature rise over the last 100 years faster than at any time during the past 11,300 years?

A: Our study did not directly address this question because the paleotemperature records used in our study have a temporal resolution of ~120 years on average, which precludes us from examining variations in rates of change occurring within a century. Other factors also contribute to smoothing the proxy temperature signals contained in many of the records we used, such as organisms burrowing through deep-sea mud, and chronological uncertainties in the proxy records that tend to smooth the signals when compositing them into a globally averaged reconstruction. We showed that no temperature variability is preserved in our reconstruction at cycles shorter than 300 years, 50% is preserved at 1000-year time scales, and nearly all is preserved at 2000-year periods and longer. Our Monte-Carlo analysis accounts for these sources of uncertainty to yield a robust (albeit smoothed) global record. Any small “upticks” or “downticks” in temperature that last less than several hundred years in our compilation of paleoclimate data are probably not robust, as stated in the paper.

Q: How do you compare the Holocene temperatures to the modern instrumental data?

A: One of our primary conclusions is based on Figure 3 of the paper, which compares the magnitude of global warming seen in the instrumental temperature record of the past century to the full range of temperature variability over the entire Holocene based on our reconstruction. We conclude that the average temperature for 1900-1909 CE in the instrumental record was cooler than ~95% of the Holocene range of global temperatures, while the average temperature for 2000-2009 CE in the instrumental record was warmer than ~75% of the Holocene distribution. As described in the paper and its supplementary material, Figure 3 provides a reasonable assessment of the full range of Holocene global average temperatures, including an accounting for high-frequency changes that might have been damped out by the averaging procedure.

Q: What about temperature projections for the future?

A: Our study used projections of future temperature published in the Fourth Assessment of the Intergovernmental Panel on Climate Change in 2007, which suggest that global temperature is likely to rise 1.1-6.4°C by the end of the century (relative to the late 20th century), depending on the magnitude of anthropogenic greenhouse gas emissions and the sensitivity of the climate to those emissions. Figure 3 in the paper compares these published projected temperatures from various emission scenarios to our assessment of the full distribution of Holocene temperature distributions. For example, a middle-of-the-road emission scenario (SRES A1B) projects global mean temperatures that will be well above the Holocene average by the year 2100 CE. Indeed, if any of the six emission scenarios considered by the IPCC that are shown on Figure 3 are followed, future global average temperatures, as projected by modeling studies, will likely be well outside anything the Earth has experienced in the last 11,300 years, as shown in Figure 3 of our study.

Technical Questions and Answers:

Q. Why did you revise the age models of many of the published records that were used in your study?

A. The majority of the published records used in our study (93%) based their ages on radiocarbon dates. Radiocarbon is a naturally occurring isotope that is produced mainly in the upper atmosphere by cosmic rays. This form of carbon is then distributed around the world and incorporated into living things. Dating is based on the amount of this carbon left after radioactive decay. It has been known for several decades that radiocarbon years differ from true “calendar” years because the amount of radiocarbon produced in the atmosphere changes over time, as does the rate that carbon is exchanged between the ocean, atmosphere, and biosphere. This yields a bias in radiocarbon dates that must be corrected. Scientists have been able to determine the correction between radiocarbon years and true calendar year by dating samples of known age (such as tree samples dated by counting annual rings) and comparing the apparent radiocarbon age to the true age. Through many careful measurements of this sort, they have demonstrated that, in general, radiocarbon years become progressively “younger” than calendar years as one goes back through time. For example, the ring of a tree known to have grown 5700 years ago will have a radiocarbon age of ~5000 years, whereas one known to have grown 12,800 years ago will have a radiocarbon age of ~11,000 years.

For our paleotemperature study, all radiocarbon ages needed to be converted (or calibrated) to calendar ages in a consistent manner. Calibration methods have been improved and refined over the past few decades. Because our compilation included data published many years ago, some of the original publications used radiocarbon calibration systems that are now obsolete. To provide a consistent chronology based on the best current information, we thus recalibrated all published radiocarbon ages with Calib 6.0.1 software (using the databases INTCAL09 for land samples or MARINE09 for ocean samples) and its state-of-the-art protocol for site-specific locations and materials. This software is freely available for online use at http://calib.qub.ac.uk/calib/.

By convention, radiocarbon dates are recorded as years before present (BP). BP is universally defined as years before 1950 CE, because after that time the Earth’s atmosphere became contaminated with artificial radiocarbon produced as a bi-product of nuclear bomb tests. As a result, radiocarbon dates on intervals younger than 1950 are not useful for providing chronologic control in our study.

After recalibrating all radiocarbon control points to make them internally consistent and in compliance with the scientific state-of-the-art understanding, we constructed age models for each sediment core based on the depth of each of the calibrated radiocarbon ages, assuming linear interpolation between dated levels in the core, and statistical analysis that quantifies the uncertainty of ages between the dated levels. In geologic studies it is quite common that the youngest surface of a sediment core is not dated by radiocarbon, either because the top is disturbed by living organisms or during the coring process. Moreover, within the past hundred years before 1950 CE, radiocarbon dates are not very precise chronometers, because changes in radiocarbon production rate have by coincidence roughly compensated for fixed decay rates. For these reasons, and unless otherwise indicated, we followed the common practice of assuming an age of 0 BP for the marine core tops.

Q: Are the proxy records seasonally biased?

A: Maybe. We cannot exclude the possibility that some of the paleotemperature records are biased toward a particular season rather than recording true annual mean temperatures. For instance, high-latitude proxies based on short-lived plants or other organisms may record the temperature during the warmer and sunnier summer months when the organisms grow most rapidly. As stated in the paper, such an effect could impact our paleo-reconstruction. For example, the long-term cooling in our global paleotemperature reconstruction comes primarily from Northern Hemisphere high-latitude marine records, whereas tropical and Southern Hemisphere trends were considerably smaller. This northern cooling in the paleotemperature data may be a response to a long-term decline in summer insolation associated with variations in the earth’s orbit, and this implies that the paleotemperature proxies here may be biased to the summer season. A summer cooling trend through Holocene time, if driven by orbitally modulated seasonal insolation, might be partially canceled out by winter warming due to well-known orbitally driven rise in Northern-Hemisphere winter insolation through Holocene time. Summer-biased proxies would not record this averaging of the seasons. It is not currently possible to quantify this seasonal effect in the reconstructions. Qualitatively, however, we expect that an unbiased recorder of the annual average would show that the northern latitudes might not have cooled as much as seen in our reconstruction. This implies that the range of Holocene annual-average temperatures might have been smaller in the Northern Hemisphere than the proxy data suggest, making the observed historical temperature averages for 2000-2009 CE, obtained from instrumental records, even more unusual with respect to the full distribution of Holocene global-average temperatures.

Q: What do paleotemperature reconstructions show about the temperature of the last 100 years?

A: Here we elaborate on our short answer to this question above. We concluded in the published paper that “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.” This statement follows from multiple lines of evidence that are presented in the paper and the supplementary information: (1) the different methods that we tested for generating a reconstruction produce different results in this youngest interval, whereas before this interval, the different methods of calculating the stacks are nearly identical (Figure 1D), (2) the median resolution of the datasets (120 years) is too low to statistically resolve such an event, (3) the smoothing presented in the online supplement results in variations shorter than 300 yrs not being interpretable, and (4) the small number of datasets that extend into the 20th century (Figure 1G) is insufficient to reconstruct a statistically robust global signal, showing that there is a considerable reduction in the correlation of Monte Carlo reconstructions with a known (synthetic) input global signal when the number of data series in the reconstruction is this small (Figure S13).

Q: How did you create the Holocene paleotemperature stacks?

A: We followed these steps in creating the Holocene paleotemperature stacks:

1. Compiled 73 medium-to-high resolution calibrated proxy temperature records spanning much or all of the Holocene.

2. Calibrated all radiocarbon ages for consistency using the latest and most precise calibration software (Calib 6.0.1 using INTCAL09 (terrestrial) or MARINE09 (oceanic) and its protocol for the site-specific locations and materials) so that all radiocarbon-based records had a consistent chronology based on the best current information. This procedure updates previously published chronologies, which were based on a variety of now-obsolete and inconsistent calibration methods.

3. Where applicable, recalibrated paleotemperature proxy data based on alkenones and TEX86 using consistent calibration equations specific to each of the proxy types.

4. Used a Monte Carlo analysis to generate 1000 realizations of each proxy record, linearly interpolated to constant time spacing, perturbing them with analytical uncertainties in the age model and temperature estimates, including inflation of age uncertainties between dated intervals. This procedure results in an unbiased assessment of the impact of such uncertainties on the final composite.

5. Referenced each proxy record realization as an anomaly relative to its mean value between 4500 and 5500 years Before Present (the common interval of overlap among all records; Before Present, or BP, is defined by standard practice as time before 1950 CE).

6. Averaged the first realization of each of the 73 records, and then the second realization of each, then the third, the fourth, and so on, to form 1000 realizations of the global or regional temperature stacks.

7. Derived the mean temperature and standard deviation from the 1000 simulations of the global temperature stack.

8. Repeated this procedure using several different area-weighting schemes and data subsets to test the sensitivity of the reconstruction to potential spatial and proxy biases in the dataset.

9. Mean-shifted the global temperature reconstructions to have the same average as the Mann et al. (2008) CRU-EIV temperature reconstruction over the interval 510-1450 years Before Present. Since the CRU-EIV reconstruction is referenced as temperature anomalies from the 1961-1990 CE instrumental mean global temperature, the Holocene reconstructions are now also effectively referenced as anomalies from the 1961-1990 CE mean.

10. Estimated how much higher frequency (decade-to-century scale) variability is plausibly missing from the Holocene reconstruction by calculating attenuation as a function of frequency in synthetic data processed with the Monte-Carlo stacking procedure, and by statistically comparing the amount of temperature variance the global stack contains as a function of frequency to the amount contained in the CRU-EIV reconstruction. Added this missing variability to the Holocene reconstruction as red noise.

11. Pooled all of the Holocene global temperature anomalies into a single histogram, showing the distribution of global temperature anomalies during the Holocene, including the decadal-to century scale high-frequency variability that the Monte-Carlo procedure may have smoothed from the record (largely from the accounting for chronologic uncertainties).

12. Compared the histogram of Holocene paleotemperatures to the instrumental global temperature anomalies during the decades 1900-1909 CE and 2000-2009 CE. Determined the fraction of the Holocene temperature anomalies colder than 1900-1909 CE and 2000-2009 CE.

13. Compared global temperature projections for 2100 CE from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change for various emission scenarios.

14. Evaluated the impact of potential sources of uncertainty and smoothing in the Monte-Carlo procedure, as a guide for future experimental design to refine such analyses.

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60 thoughts on “Marcott issues a FAQ on their paper

  1. New FAQ question for all forthcoming climate papers:

    Q. What did Steve McIntyre think of your statistical methodology?

  2. Let’s see. How can you compare 1900-1909 and 2000-2009 with a subset smoothed to approx 300 years. There could have been warm periods 3-4C warmer than present that would NOT have shown up in the research.

    Does this mean that a one year warming or cooling spike has relevance?

    Have all of these folks forgotten basic statistics?????

  3. I suppose given that it is Easter, it is only fitting that they’ve responded with an answer that looks good on the outside but is completely hollow.

    A more serious comment to follow. These guys have not only failed to answer the main questions raised in regard to their paper, but they have opened the door for some new ones.

  4. Looking at RealClimate, I note that Gavin doesn’t want to have anything to do with admitting that the press coverage and original statement by a co-author was hypobolic about the uptick. I guess it’s a matter of “let’s pretend that didn’t happen”.

  5. “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.”

    But we include them in the graph anyway, should a mainstream press draw their own conclusions. It is OUR science, after all.

  6. ‘…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. Our primary conclusions are based on a comparison of the longer term…’

    This is the interesting part for me. There WAS a conclusion in the paper on comparison of last cent rate of change with rate of whole Holocene. This Seems to say that the comparison was with the instrument data uptick and not Marcott’s proxy Uptick. Hmmm. And the fall back may be that it was not a ‘primary’ conclusion. And so as I have said before, this is back to the marcott thesis. Why the change for the Science paper? The comparison with the thesis is problematic to their new rationale.

  7. it is fascinating to see what the great climate scientist Michael Mann said was the “key” implication of the paper before the big smokescreen was needed at Real Climate. Are there going to be public corrections of this and all similar remarks that were spread through the media weeks ago? They can’t actually say anything about the rate or magnitude of recent decades compared to the previous 4,000 or 11,000 years, based upon the paper.

    [Michael Mann to Revkin, March 7, 2013]

    “The key take-home conclusion is that the rate and magnitude of recent global warmth appears unprecedented for at least the past 4,000 years and the rate at least the past 11,000….

  8. “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.”

    You published the graph with the uptick. Therefore, the uptick is one of your conclusions. The graph with the uptick must be replaced with a graph that does not contain the uptick.

  9. The video that Steve linked showed a smart aleck kid all aglow from undue praise and publicity after telling Pres. Obama that in the 20th century temperatures were “boom, outside the elevator”. If he understood now just how foolish that he will seem to be twenty years on, he would go home and cry himself to sleep tonight.

  10. “A word as cunningly hidden in its maze of confused drapery as a fieldmouse in a nest of coloured ribbons….” – James Joyce (“Finnegans Wake” 1939)

    FRAUD.

  11. Apparently, from this day forward, when an article claiming CAGW is published we are to visit “Real Climate” to read the Apology for the article. Real Climate can begin a corner named “CAGW Apologetics.” Fitting for a religion.

  12. I guess I’m old fashioned, but it seems to me that if your carefully researched, sourced, written, and peer reviewed paper needs a post-publication FAQ…

    You’re doing it wrong. The paper itself; without ever getting to the question of content.

  13. In addition to the “filibuster” as SteveM has called it, this FAQ raises two new important questions in my mind. One of the first indicators that there was a major problem with this paper was the fact that the thesis did not have the “uptick” but that that the published version did. Since the thesis came first, substantive additional work had to be done to produce the uptick. Pressed for answers on how the uptick was arrived at, Marcott responded to SteveM that the uptick was “not robust”. Pressed for answers, they are backing away from the uptick as fast as they can:

    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.

    If you read the balance of the remarks, including the discussion at RealClimate, they are not only backing away from the uptick itself, but at the same time trying to assert that it wasn’t the main point of the paper. They don’t come right out and say it, but the implication is that the alarmist headlines were not of their doing.

    Really.

    Question 1; Are the authors seriously claiming that they knew that the uptick could not be considered representative of global temperatures but went to the additional effort of creating it for the published version of the paper and yet are not responsible for the perception created and the resulting headlines?

    Question 2; Are the authors stating for the record that their work does not corroborate Michael Mann’s as Dr Mann has been claiming?

    In attempting to divert attention from the uptick and casting it as an unimportant part of the paper, Marcott et al have scored a massive own goal. It is clear by their own admission that the uptick is garbage, that they knew it was garbage, and that they went to substantive effort to create and include it for the sole purpose of publicizing it. They’ve not only scored a massive own goal, they’ve run into the net behind the ball, dragging the entire team with them.

  14. After Mann’s early effusions re Marcott et al, did anyone really expect this much delayed Filibuster After Questions™ to appear anywhere other than in the highly protected cloisters of RC”!? Well, OK … it might have appeared (and might still!) at the home of their sister cloister downunder, aka SkS.

    But that aside, assuming that co-author Peter U. Clark, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University. and Peter Clark, Oregon State University** are one and the same, I suppose that the proof will be in whatever pudding the IPCC’s AR5 WG1 manages to, uh … cook up.

    ** “Peter Clark, Oregon State University” is listed as a CLA for AR5 WG1 Ch.13

    Even Revkin – who has always done his level best to support The Team (and its affiliates) – is finding it challenging to carry their PR water for them on this.

  15. Q: Is the rate of global temperature rise over the last 100 years faster than at any time during the past 11,300 years?

    A: Our study did not directly address this question because the paleotemperature records used in our study have a temporal resolution of ~120 years on average, which precludes us from examining variations in rates of change occurring within a century.

    From CA: http://climateaudit.org/2013/03/31/the-marcott-filibuster/#comment-408588

    “If the 20th century portion of their reconstruction does not have the same uptick as the instrumental record, we would conclude that it could have missed similar swings in earlier centuries as well, so the absence of such swings in the earlier part of their graph tells us nothing about the presence or absence of decadal and century-scale warming events. Likewise, an annual or decadal observation from the modern instrumental record cannot be compared against values from their reconstruction, if their reconstruction is not capable of resolving events at that time scale.

    “But that is precisely what they do in Figure 3 of their paper, and it is the basis of their claim that “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.” Without the uptick in their proxy reconstruction this kind of statement could never have been made. The presence of the uptick in the proxy graph validates their comparison of the instrumental record against the proxy record. By admitting that the uptick is not robust and cannot be a basis for any conclusions they have undermined their own findings, root and branch. ”
    ======

    Somebody’s telling a fib.

  16. Good point Theo. Looks to me like most of the past couple of years falls in that “GAWG Apologetics” corner.

    The paper is another shining example of Skeptical Science Syndrome<b/.

    The fever has distorted so many young minds…….the peril of it all.

  17. bones says: “If he understood now just how foolish that he will seem to be twenty years on, he would go home and cry himself to sleep tonight.”

    Maybe a lot less than twenty years. When the wheels finally start to come off the AGW scam in the MSM, they could come off very quickly, possibly within a matter of weeks from start to finish.

  18. The Marcott et al FAQ was an April Fools’ Day joke played by Gavin and the guys at RC, right? If true, it was a good one. It sure got me revved up. If not, then I think tomorrow will prove that Gavin’s embrace of this idiocy has consequences for his own credibility.

  19. IF this is an FAQ about Marcott 2013, then why is Figure 1 about non-Marcott data that only Figure in the FAQ?

    Caveat-emptor is an element of salesmanship, not science.

  20. “They did not discuss or explain why they deleted modern values from the Md01-2421 splice at CA … Or the deletion of modern values from OCE326-GGC300.”

    Their non-answer is an answer. It means they don’t have a good answer. If they did, they would have provided it to put an end to the controversy. Now they’re just hoping they can ignore such questions long enough for the issue to fade away.

  21. Don’t miss Roger Pielke, Jr’s blog article on problems with how the paper has been promoted and represented:

    Pielke, Jr. on the large gap between PR for the paper and what the authors now claim for the paper in their FAQ

    Let me be perfectly clear — I am accusing no one of scientific misconduct. The errors documented here could have been the product of group dynamics, institutional dysfunction, miscommunication, sloppiness or laziness (do note that misconduct can result absent explicit intent). However, what matters most now is how the relevant parties respond to the identification of a clear misrepresentation of a scientific paper by those who should not make such errors.

    That response will say a lot about how this small but visible part of the climate community views the importance of scientific integrity.

  22. If the data is in your favor, argue the data,
    If the stats are in your favor, argue the stats,
    If both are against you, post it at RealClimate.

  23. As I commented at CA earlier, the FAQ are also posted at Marcott’s web page here:

    http://proglacial.com/Public%20Links/FAQ%20-%20Holocene%20Temperatues.html

    The FAQ text is in an image so that search engines will not find it.

    The date of revision for the FAQ at the bottom of the page is incorrectly given as 3/29/12 which is only one year off. It too needs to be “redated”.

    The date at RC is given as 3/31/13 so the FAQ may have been published two days earlier at Marcott’s site.

  24. “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.”

    So what came in media and what the authors blasted about to journalists is rubbish. Said now by the same authors.
    Newspeak of Pravda proportions.

  25. There seems to be a general view that this conclusion was not in the Science article but only in the promo. However, my reading of the paper is that this conclusion is in the paper:

    “Our results indicate…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.”

    I think they would now say the comparison is not with Marcott’s proxy up tick but the CRU instrument data in Mann08

  26. As pointed out in comments at Climate Audit:
    Marcott said this: “In 100 years, we’ve gone from the cold end of the spectrum to the warm end of the spectrum,” Marcott said. “We’ve never seen something this rapid. Even in the ice age the global temperature never changed this quickly.”
    Link: http://science.time.com/2013/03/08/recent-heat-spike-unlike-anything-in-11000-years/

    Now Marcott says:
    “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.”

  27. @RHL

    Decent points that could do with an answer (good luck there)

    However now it’s in text format on WUWT it should be a lot easier to index.

    I wonder where the text version was, or was it just diligently transcribed for the purpose of this post?

  28. berniel says: April 1, 2013 at 12:56 am
    “I think they would now say the comparison is not with Marcott’s proxy up tick but the CRU instrument data in Mann08″

    No, they said it at the time. What’s missing from your quote:
    “Our results indicate that global mean temperature for the decade 2000–2009 (34) has not yet
    exceeded…”

    That (34) is a reference to Brohan et al – ie the CRU part of CRU/EIV.

    In fact they are referencing their Fig 3, on which their discussion of comparison with recent (and future) is based. And the caption there is clear:
    “instrumental means for 1900–1909 and 2000–2009 CE (vertical black lines),”

  29. The ‘uptick’ wasn’t in Marcott’s thesis, and has nothing to do with the rest of the reconstruction. So I wonder who’s inspired idea it was to put it in the Science paper (for PR purposes?) and cause chaos. I think we should be told.

  30. Jacob and Philip Shehan:

    Please keep your posts coming because I am enjoying your expressions of desperation. Indeed, Philip Shehan, observing the number and frequency of your posts is like watching the flailing arms of a drowning man.

    The issue is clear.
    1.
    Marcott provided a thesis which showed declining global temperature through the Holocene with recent global temperature being the lowest for about ten thousand years. However, fluctuations in the global temperature show recent periods of warming and cooling which coincide with the Minoan, Roman and Medieval warm periods and generate the Little Ice Age (see the diagram in the above article).
    2.
    This was a refutation of the assertions of the ‘Hockey Team’ – and especially of the Hockey Stick graph of Mann, Bradley and Hughes (MBH) – which say recent global temperature is higher than for thousands of years and global temperature rise accelerated in the twentieth century.
    3.
    Marcott was encouraged to amend his graph by various improper statistical tricks which provided a sharp up-tick in the twentieth century. Also, the recent thermometer-derived data were added to the graph to increase the misleading implication of recent and unprecedented temperature rise in the twentieth century.
    4.
    The misleading and improper version of the graph was submitted to Science by Marcott, Shakun, Clark, and Mix, and it was accepted for publication.
    5.
    The paper which presented the misleading and improper version of the graph was trumpeted to the media as being an indication of recent unprecedented global warming.
    6.
    Investigations, notably by McIntyre, revealed the misleading version of the graph was a construct of improper statistical procedures.
    7.
    Had the graph not been exposed as being misleading and generated by improper statistical procedures then Marcott would certainly have obtained the same career benefits as Mann obtained from the MBH ‘Hockey Stick’ graph.
    8.
    Providing improper and misleading information for personal gain is commonly thought to be fr@ud but – as Pielke points out – in this case it does not fulfil certain definitions of scientific fr@ud.
    9.
    The ‘Hockey Team’ are attempting damage limitation by pretending that the ‘up-tick’ at the end of the misleading and improper graph is not important. But this is patently false because the ‘up-tick’ was the message trumpeted about the graph.

    So, Jacob and Philip Shehan, please keep your posts coming. They cannot obscure the facts of the issue but they provide great laughs.

    Richard

  31. Moderator:

    I have stupidly made a post (addressed to Jacob and Philp Shehan) on this thread when it should have been posted on another thread.

    I have now posted it on the correct thread.

    Please feel free to delete it from this thread or – if you think its contents are appropriate – also leave it on this thread.

    Richard

  32. As a general rule of thumb, ANY climate related graph that looks like a hockey stick can probably be safely ignored, or is easy enough to find glaring fault with. Except the graph that shows the number of dollars wasted on climate “science”. That’s all too credible.

  33. I looked at their “NewScientist” local-temp website – This is interesting because a few years back, I stumbled across “WolframAlpha,” a site where you should be able to enter scientific-y questions and get decent answers.
    They have a blank space for your question, just like you type a search into google search engine.
    It then chugs away and hopefully returns an answer.
    So, years ago, I started entering cities across the U.S., then the planet, with which I was familiar.
    I entered something like this:

    http://www.wolframalpha.com/

    “average temperature cairo past 60 years”
    You can vary how far back, depending upon how far back the data source goes.

    On the NewSCientist check-your-hometown app, I see climbing temps at most of the cities I checked out, on a quick introductory tour.
    On WolframAlpha, I see flat lines all over the globe.

    So, apparently, someone figured out that this WolframAlpha thing was out there, and they needed to counter that influence with their won that has hockey sticks everywhere versus hockey ice.

  34. They now claim, after the media somehow picked up on the uptick, that it was not the main point of the paper.
    This is exactly how Mann has cahracterized what happened with his dissertation – the hockey stick was noticed, and propelled him, unexpectedly, into the climate wars.

    I have a hard time believing this in either case. For Mann in 1994-1996, as he decided on his diss and developed it, he was surrounded by people who believed in the global warming. Projection of the future was certainly the most interesting thing to anyone around.

  35. Marcott & al’s conclusion that modern temperatures are greater than ‘x%’ of the Holocene is not supported by the data. Their reconstruction does not have the resolution to support such a claim. There could be hundreds of spikes in the actual temperatures from the Holocene much warmer than at present and they would simply have averaged them out.

    Marcott & al would need to average out modern temperatures to the same resolution as their reconstruction before any conclusion can be drawn. This would drop modern temperatures at the endpoint by about 0.4 C (assuming a 0.8C rise over 120 years), which would make modern temperatures unremarkable in comparison to the past.

    Marcott & al cannot simply compared the magnitude of two series if the resolution is not matched and obtain a meaningful result. Yet this is what they have done in their conclusion, which suggests that their conclusion is flawed.

  36. jorgekafkazar says:
    March 31, 2013 at 8:54 pm

    bones says: “If he understood now just how foolish that he will seem to be twenty years on, he would go home and cry himself to sleep tonight.”

    Maybe a lot less than twenty years. When the wheels finally start to come off the AGW scam in the MSM, they could come off very quickly, possibly within a matter of weeks from start to finish.
    ===================================================================
    Much as I’d like to believe it, CO2-based CAGW will not end with a bang. It’s not even going to end with a whimper, but simply a move to the next big scare. The LSM are not about to say “DOH! What idiots we were!”

    IMO, most in the LSM are complicit, not dupes. Where is the widespread coverage of the criticism of Marcott et. al. that led to these FAQ’s? Where are the LSM pointers to this ruckus?

  37. AlexS says:
    April 1, 2013 at 12:38 am

    “So what came in media and what the authors blasted about to journalists is rubbish. Said now by the same authors.
    Newspeak of Pravda proportions.”

    Very well said. Marcott’s critics, especially McIntyre, are very polite and focus on the science. They ask only for a retraction. But Marcott and supporters created a parallel offense in the media and it deserves the name of “Newspeak of Pravda proportions.” There needs to be a website dedicated to the pursuit of Newspeak offenses.

  38. The 300-year smoothing is the key: it has removed the natural range on a time period pertinent to CAGW, the 30-60 year period.

    As noted in comments before this one, the actual variation on a 30-year basis could be of the same magnitude of the last 30 years. If temps during the Holocene could be shown to have that much natural variation, one could not exclude the recent variation as being largely, at least, natural.

    We look at the wide range or amplitude of specific proxies as being mostly error around a mean, but that is intuitively not true for all proxies through all of their periods. Some of the big swings are real. What the natural range is, is THE question when looking to whether the post-1965 time is “unprecedented”.

  39. This isn’t a filibuster, but a 4 corners offence. They are simply waiting out the clock until summer.

  40. davidmhoffer says:
    March 31, 2013 at 8:06 pm

    Really.

    Question 1; Are the authors seriously claiming that they knew that the uptick could not be considered representative of global temperatures but went to the additional effort of creating it for the published version of the paper and yet are not responsible for the perception created and the resulting headlines?

    Question 2; Are the authors stating for the record that their work does not corroborate Michael Mann’s as Dr Mann has been claiming?
    ———————-
    Bravo David! I’m sick of people sidestepping this issue with the ‘oh, but it’s not Marcott et. al’s fault that the uptick got sensationalized!’ Talk about people sticking their heads in the sand. Your post nails this point.

  41. Stuff in RealClimate is not officially connected to Science, so this FAQ blob won’t show up in The Literature. Why aren’t they dealing with questions in the pages of Science?

  42. I followed the link to http://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/ and found most of the discussion there to be polite and aimed at producing light rather than heat.

    There are a few comments about the lack of robustness, rightly pointing out that the original paper also commented on this and it wasn’t new news to have it repeated in the FAQ. Whether it was given enough prominence in the paper is another question of course. Gavin points out, “The main point of the paper is the Holocene reconstruction. As you get to the end, there is data drop out which increases uncertainty. Deciding where to end it is a judgement call and as long as the increase in uncertainty is made clear (and it was), I don’t see that the authors have done anything untoward. People are always free to draw their own conclusions from papers”. While that is true as far as it goes, I wonder if people were not encouraged to draw particular conclusions? Certainly it seems that those who drew conclusions regarding the “uptick” were not silenced or corrected by the paper’s authors.

    I find it odd that the redating of coretops is dismissed by Gavin with the words, “They specifically state that this reconstruction is not going to be useful for the recent period – there are many more sources of data for that which are not used here – not least the instrumental record”. So you have to ask why they bothered to do the redating if they never intended the latter part of the curve to be important. Also, the acknowledgement that the instrumental record has been grafted on to the proxy record is a useful confirmation of their techniques. Gavin’s explanation of the difference between the PhD thesis and the paper is that 2 years have elapsed and “there has clearly been further work done on the reconstruction since then”. But if that “work” led to results that were to be non-robust, why bother including them? I get the impression there was a desire to get the uptick message across subliminally in a way that could be denied later.

    Overall, it seems that the messages we’re intended to take from all this are:
    1. the Holocene reconstruction is valid
    2. although short-term upticks could be present elsewhere, the ice cores would spot them
    3. it’s valid to add an (adjusted, re-adjusted, re-re-adjusted) instrumental record to the graph but that wasn’t the main point of the paper and we shouldn’t be focusing on it.

    Whether they were the messages the MSM received is debatable.

  43. “Marcott et al …. they now concede: 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes…..”

    Actually, they really don’t concede anything; they restate for a more general audience…but they have already said that, but you might have missed it:

    This is this from their paper: “Without filling data gaps, our Standard5×5 reconstruction (Fig. 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 (Fig. 1, C and D). However, considering the temporal resolution of our data set and the small number of records that cover this interval (Fig. 1G), this difference is probably not robust. Before this interval, the gap-filled and unfilled methods of calculating the stacks are nearly identical (Fig. 1D).”

    Marcott FAQ: “….and therefore is not the basis of any of our conclusions.”

    because they don’t need to remeasure the 20th century for their conclusions, lots of other people have done that:

    Again from their paper: “Our results indicate that global mean temperature for the decade 2000–2009 (34) has not yet exceeded the warmest temperatures of the early Holocene (5000 to 10,000 yr B.P.).”

  44. trafamadore is what is known as an “enabler’. He condones Marcott’s scientific misconduct [or incompetence] because it supports his agenda. That is about as far from science as you can get.

  45. Wow –

    Structure of the Global and Regional Temperature Curves: We find that global temperature was relatively warm from approximately 10,000 to 5,000 years before present. Following this interval, global temperature decreased by approximately 0.7°C, culminating in the coolest temperatures of the Holocene around 200 years before present during what is commonly referred to as the Little Ice Age. The largest cooling occurred in the Northern Hemisphere.

    Holocene Temperature Distribution: Based on comparison of the instrumental record of global temperature change with the distribution of Holocene global average temperatures from our paleo-reconstruction, we find that the decade 2000-2009 has probably not exceeded the warmest temperatures of the early Holocene, but is warmer than ~75% of all temperatures during the Holocene. In contrast, the decade 1900-1909 was cooler than~95% of the Holocene. Therefore, we conclude that global temperature has risen from near the coldest to the warmest levels of the Holocene in the past century. Further, we compare the Holocene paleotemperature distribution with published temperature projections for 2100 CE, and find that these projections exceed the range of Holocene global average temperatures under all plausible emissions scenarios.

    Okay. . .

    Umm… “culminating in the coolest temperatures of the Holocene around 200 years before present during what is commonly referred to as the Little Ice Age.

    And then, children. what should happen when we come out of the coolest temperatures 200 years ago? All together now, “IT GETS WARMER!

    And, let’s see, , ,
    “we find that the decade 2000-2009 has probably not exceeded the warmest temperatures of the early Holocene, but is warmer than ~75% of all temperatures during the Holocene.

    What this means, children, is that the 2000-2009 period was in the MIDDLE 50%, if on the edge of it. Do any of you think that with 25% of the Holocene warmer than the last decade that there is anything catastrophic about the last decade? Why do you think so, Freddie? Oh, you aunt Belinda said we are heating up the planet too much? Freddie, what do YOU think yourself? Did the planet survive the other times it was like the warmest 85% or 95%? Yes, Freddie, it is still here, and yes, it survived long enough to get a lot cooler 200 years ago. And to get to NOW, right? So, Freddie, do you think your aunt is right? Do you think we could still get warmer and the world would be okay? Are you satisfied that we are doing okay? Ok, I don’t want you to be alarmed.

    And. . .
    “In contrast, the decade 1900-1909 was cooler than~95% of the Holocene.”

    So, students. even 100 years after the coolest temperatures of the Holocene 200 years ago, the temperatures were still at the 5th percentile of the Holocene. And, children, what does that mean? All together now, “IT WAS COLD!”

    And finally. . .
    “Further, we compare the Holocene paleotemperature distribution with published temperature projections for 2100 CE, and find that these projections exceed the range of Holocene global average temperatures under all plausible emissions scenarios.”

    Now, class, do we know what “AVERAGE” means? That’s right, Billy, it means at the 50% mark. And is 75% bigger or smaller than 50%? Anybody? Anybody? Right, Susie, 75% is bigger, so what does that mean? Johnny? Right, in this case bigger means warmer. Good!

    So, class, what did we learn today? Yes, that it is now warmer than the coldest part of the Holocene. Is that good or bad? Right, Melissa, it is good. We do not want to be the coldest part of the Holocene, do we? What else did we learn? That 75% is not the hottest part of the Holocene, right, Sharon. And that the Holocene is a long time, yes, Donald. And all together now, “WE CAN STOP WORRYING ABOUT IF THE WORLD IS GOING TO SURVIVE! HOORAY!”

    Now, let’s all thank Mr Marcott for making us all feel safer, “THANK YOU, MR. MARCOTT! YEAY!”

    Steve Garcia

  46. trafamadore:

    I am writing to seek clarification of your post at April 1, 2013 at 11:53 am.

    Am I right in thinking the important datum in your post is “April 1″?
    And your post is an All Fools Day joke?

    Richard

  47. As we slip inexorably, in fits and starts perhaps, toward the next ice age, we will finally have something that ISN’T ‘unprecedented’. Looking at the graph dispassionately, I see, and I’m sure the Hockey Team sees something really scary – something this paper is screaming out at us if any credence can be given to the reading of the sediments. The desperate puny sliver of a defensive uptick only serves to accentuate the gloomy message of this data. The interglacial temperature of the Holocene peaked 7,000 YEARS AGO! It is a dark thing to behold. Using exactly the same results, I would hope that I would be awarded a PhD for concluding that an icy future can’t be too far away. Unless I’ve overestimated the intelligence the concensus, the flurry of post thesis activity and misdirection has been a defibrillator to hide the real decline. Their stepping back a few paces so quickly in the face of the critical analysis that has been pouring forth is out of character for these guys. They want things to go quiet and be forgotten about. I hope for humanities sake that the paleo part of the analysis was badly done and that this stark decline isn’t real.

  48. trafamdore;
    Marcott FAQ: “….and therefore is not the basis of any of our conclusions.”
    >>>>>>>>>>>>>>>>>>>>>>

    So they published some data that was not the basis for any of their conclusions. Is that common in your world trafamadore? Publishing data that has nothing to do with the conclusions? Publishing data that the authors admit is meaningless AND has nothing to do with the data? Publishing data prominently as if it IS part of the conclusions and IS meaningful when you’ve already admitted in advance that the opposite is true is “science” in your world?

    An amusing anecdote from the weekend. I heard a portion of a radio call in show in which a woman complained that she had been in three traffic accidents involving deer, all within close proximity to highway deer crossing signs. She demanded to know why the deer crossings were being located in such dangerous places and suggested repeatedly that it would make far more sense to put them in low speed traffic zones such as school crossings. Two curious thoughts crossed my mind:

    1. Was it April 1st? But no, it wasn’t (at the time I mean) and as the conversation went on, it became increasingly clear that the woman was completely serious. Which led to my second thought, which I swear is exactly what went through my mind at the time:

    2. Is trafamadore, like this caller, as stupid as s/he seems? Or simply smart enough to know that people as dumb as that radio caller exist and can be suckered by clear explanations that it is OK to knowingly publish garbage as long as you admit in an obscure footnote that it is garbage?

    • for all those people wasting time on trafamdore…

      He’s a university biologist, mainly into genetics. Like many of the life sciences people he feels his views on science more than he understands it.

      Trying to get him to understand these hard science issues will be a challenge. According to “ratemyprofessors” he doesn’t get very high marks from his students as they find it difficult to communicate with him, as do we.

  49. I’ll be eagerly awaiting the local news tonight on KCRA followed by the NBC Nightly News where they’ll announce that they were wrong in their previous report about it being warmer now than at anytime in the last 11,000 years. /sarc

  50. Here’s a few more ‘Frequently Asked Questions’ concerning Marcott, et al. 2013:

    Why is the “Team” at Real Climate so heavily invested in this fraudulent paper?

    Given that Marcott’s thesis bears little resemblance to the ‘Science’ paper, how much did the “Team” at Real Climate contribute to the ‘Science’ paper?
    Which members of the “Team” helped process the data that shows an uptick in recent temperatures (when the original data did not)?
    Which members of the “Team” condone the re-dating of cores used in this paper?
    Which members of the “Team” condone spicing thermometer data onto proxy data (to hide the decline shown by that same data)?
    Which members of the “Team” helped write the FAQ’s and then help answer their own questions?

  51. Has anyone noticed from the temperature anomaly plot (Figure 1) that:-

    1.
    The temperature anomaly in the year 2000s is only about 0.5degC warmer than the 1880s.
    2.
    The Team estimate that Krakatoa depressed gloal temperatures by up to about 1.2degC for 3 to 5 years. If you take into account the effect of the claimed cooling caused by Krakatoa, then the 1880s would be warmer than the 2000s.
    3.
    The temperature anomaly in the year 200s is only about 0.2degC warmer than 1940.

    Conclussion: Present temperatures do not appear alarming. Where is the uptick?

    Obviously it is completely inappropriate to graph/splice on a thermometer data set onto a different proxy data set, but if this were to be done, with a view to putting matters into perspective, then one would splice on the thermometer record taken only from stations in the same geographical area as the proxies used in the proxy study. If the figure 1 temperature anomaly is spliced onto the Holocene proxy reconstruction, there is no uptick. I also question whether one could claim that current temperatures are warmer than 75% of those in the past 11,000 years of the Holocene.

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