by P. Gosselin, Apr 19, 2022 in NoTricksZone
A 2021 study appearing in Nature Communications by Buentgen et al reports on the results of a double-blind experiment of 15 different groups that yielded 15 different Northern Hemisphere summer temperature reconstructions. Each group used the same network of regional tree-ring width datasets.
What’s fascinating is that ll groups, though using the same data network, came up with a different result. When it comes to deriving temperatures from tree-rings, it has much to do with individual approach and interpretation. Sure we can follow the science, but whose results?
The 15 groups (referred to as R1–R15) were challenged with the same task of developing the most reliable NH summer temperature reconstruction for the Common Era from nine high-elevation/high-latitude TRW datasets (Fig. 1):Cropped from Figure 1, Buentgen et al
by P. Gosselin, Mar 29, 2022 in WUWT
A new paper published in open access publishing MDPI looks at seven prominent hemispheric and global temperature reconstructions for the past 2000 years (T2k).
The analysis conducted by the authors found that some reconstructions “differed from each other in some segments by more than 0.5 °C” whilst some show negligible pre-industrial climate variability (“hockey sticks”).
Those showing variability would suggest natural factors playing a greater role than those that claim climate had been rather constant over the past 2000 years.
Abstract: Global mean annual temperature has increased by more than 1 °C during the past 150 years, as documented by thermometer measurements. Such observational data are, unfortunately, not available for the pre-industrial period of the Common Era (CE), for which the climate development is reconstructed using various types of palaeoclimatological proxies. In this analysis, we compared seven prominent hemispheric and global temperature reconstructions for the past 2000 years (T2k) which differed from each other in some segments by more than 0.5 °C. Whilst some T2k show negligible pre-industrial climate variability (“hockey sticks”), others suggest significant temperature fluctuations. We discuss possible sources of error and highlight three criteria that need to be considered to increase the quality and stability of future T2k reconstructions. Temperature proxy series are to be thoroughly validated with regards to (1) reproducibility, (2) seasonal stability, and (3) areal representativeness. The T2k represents key calibration data for climate models. The models need to first reproduce the reconstructed pre-industrial climate history before being validated and cleared for climate projections of the future. Precise attribution of modern warming to anthropogenic and natural causes will not be possible until T2k composites stabilize and are truly representative for a well-defined region and season. The discrepancies between the different T2k reconstructions directly translate into a major challenge with regards to the political interpretation of the climate change risk profile. As a rule of thumb, the larger/smaller the pre-industrial temperature changes, the higher/lower the natural contribution to the current warm period (CWP) will likely be, thus, reducing/increasing the CO2 climate sensitivity and the expected warming until 2100.
by K. Richard, Mar 31, 2022 in NoTricksZone
Two weeks before Dr. Michael E. Mann and colleagues published their 23 April 1998 “hockey stick” chart in Nature, a peer-reviewed journal published a paper asserting “an overwhelming majority of climate scientists” (50 out of 60) view catastrophic human-caused global warming – and even global warming itself – as an “unsupported assumption”.
At the time, satellite data indicated the lower troposphere had cooled by 0.13°C between 1979 and 1994. The Arctic had cooled by -0.88°C since the 1940s.
It was thought the IPCC had just (1995) perpetrated a “disturbing corruption of the peer-review process” in manipulating the conclusions of scientists to support favored government policies.
by Gavin, Feb 2, 2020 in RealClimate
We have now updated the model-observations comparison page for the 2021 SAT and MSU TMT datasets. Mostly this is just ‘another dot on the graphs’ but we have made a couple of updates of note. First, we have updated the observational products to their latest versions (i.e. HadCRUT5, NOAA-STAR 4.1 etc.), though we are still using NOAA’s GlobalTemp v5 – the Interim version will be available later this year. Secondly, we have added a comparison of the observations to the new CMIP6 model ensemble.
As we’ve discussed previously, the CMIP6 ensemble contains a dozen models (out of ~50) with climate sensitivities that are outside the CMIP5 range, and beyond the very likely constraints from the observations. This suggests that comparisons to the observations should be weighted in some way. One reasonable option is to follow the work of Tokarska et al (2020) and others, and restrict the comparison to those models that have a transient climate response (TCR) that is consistent with observations. The likely range of TCR is 1.4ºC to 2.2ºC according to IPCC AR6, and so we plot both the mean and 95% spread over all all models (1 ensemble member per model) (grey) and the TCR-screened subset (pink).
CMIP6 model means and spreads since 1979 (reader friendly version).
by K. Richard, Jan 31, 2022 in NoTricksZone
Since 2019,there have been over 350 peer-reviewed scientific papers published showing no warming in the modern era and/or much warmer temperatures than today when CO2 levels ranged from 180 to 280 ppm (Holocene, Pleistocene).
Below is the link to the updated (now including 2021) database of non-hockey temperature records from locations across the world.
These hundreds of papers suggest a) Earth was multiple degrees warmer than today throughout much of the last 11,700 years (Holocene), and b) there has been nothing unusual about temperature changes in the modern era.
The first 8 papers on the 2021 list are shown below as samples.
Zhou et al., 2021 South China Sea ~4°C warmer SST during the Middle Holocene…1994-2004 coldest temperatures of the last 6000 years.
by P. Homewood, Aug 19, 2021 in NotaLotofPeopleKnowThat
McIntyre is promptly on the job again. Here is his post of August 11, basically dismantling the new Hockey Stick. If you have a taste for a lot of technical detail, I urge you to read the whole thing. But the gist is actually simple. This time these people were not going to get caught furtively “hiding the decline.” Instead, they announce boldly that they are simply going to exclude any data that do not fit the narrative that they are putting forth.
McIntyre goes through multiple of the data series that contribute to the “shaft” of the new stick. Most just appear to be random fluctuations up and down. But then there are the few key series that show the sharp 20th-century uptick needed to support the Hockey Stick narrative. One such series is the McKenzie Delta tree ring series from Porter, et al., of 2013. McIntyre goes back to that Porter article and quotes the passage that describes how the researchers chose those trees that would contribute to the series:
by F. Menton, Aug 16, 2021 in ClimateChangeDispatch
What with the ongoing catastrophe in Afghanistan and the earthquake in Haiti, among other news, you may have failed to notice that the UN IPCC came out on Monday with substantial parts of its long-awaited Sixth Assessment Report on the state of the world’s climate.
This is the first such assessment issued by the IPCC since 2014. The most important piece is the so-called “Summary for Policymakers,” (SPM), a 41-page section that is the only part that anyone ever reads.
The IPCC attempts to cloak itself in the mantle of “science,” but its real mission is to attempt to scare the bejeezus out of everyone to get the world to cede more power to the UN.
Beginning with its Third Assessment Report in 2001, the lead technician for the IPCC to generate fear has been the iconic “hockey stick” graph, supposedly showing that world temperatures have suddenly shot up dramatically in the last 100 or so years, purportedly due to human influences.
The 2001 Third Assessment Report thus prominently featured the famous Hockey Stick graph, derived from the work of Michael Mann and other authors. Here is that graph from the 2001 Report:
They took “hide the decline” to extremes that had never been contemplated by prior practitioners of this dark art. Rather than hiding the decline in the final product, they did so for individual trees: as explained in the underlying article, they excluded the “divergent portions” of individual trees that had the temerity to have decreasing growth in recent years. Even Briffa would never have contemplated such woke radical measures.
Decide on your desired conclusion and then just exclude any data that refuses to go along. This is the “science” on which our world leaders are off spending multiple trillions of taxpayer dollars.
by Dr H. Masson, Aug 16, 2021 in ScienceClimatEnergie
This note is a reaction to the reintroduction by IPCC in the SPM (Summary for Policy Makers) of AR6 of a hockey stick curve, initially introduced by Michael Mann in AR4, and that disappeared in AR5, after the devasting analysis made by Mc Intyre and Mc Kritick, showing the methodological flaws made by Michael Mann. This new curve does not seem to appear in the extended report AR6, inducing some doubt about its scientific meaning, but at the same time underlying the political use IPCC intends to make of it, as a weapon of mass manipulation aimed to alert the media and afraid people.
All this justifies some deeper insight in the methodologies used by IPCC to generate this figure.
The hockey stick graph given in fig 6, which is supposed to be a reliable image of the “raw data” presented in fig 2, is a “fake” and results from misuse of data mining techniques, based on fairy hypotheses that cannot longer be accepted. As an exercise in critical thinking, the reader is invited to find the intentional methodological bugs introduced in this parodic note.
by P. Homewood, Aug 16, 2021 in NotaLotofPeopleKnowThat
That there has been 1.1°C of warming since 1850 is not especially controversial. There is some disagreement about the degree to which it reflects the “recovery” from the mini-Ice Age (when there were Ice Fairs on the Thames among other events not seen today) and the effects of increased CO2 emissions.
The controversial part is the removal of temperature oscillations commonly thought to have occurred over the course of the past 2,000 years. These include warming that was known to have occurred in Roman times and again in the tenth century when the Vikings colonised Greenland until 1250, and the cold period 1400-1700. Such events are downgraded as being either exaggerated or localised.
The earlier iteration of the IPCC 2021 picture was the notorious hockey stick fabrication by Michael Mann. Mann cherry-picked data from tree rings and spliced together incongruent data sources, and reported his “findings” in a 1998 paper. Like the latest IPCC report, this showed a flat temperature trend until the 20th Century, then a sharp rise.
The IPCC in its 2001 report used Mann’s graph as its poster child to substantiate human-induced global warming. In the years after 2001 the IPCC quietly dropped Mann’s “hockey stick”. Its discreditating was completed by 2009 release of confidential emails (dubbed “Climategate”), which showed Michael Mann as the conductor of other climate scientists seeing a need to eradicate the “medieval warming period” in order to make the case that the modern warming is unique.
The chicanery under which this strategy was conducted resulted in legal cases. Canadian scientist Tim Ball called Mann a fraud, Mann sued and the subsequent court case lasted a decade before finding against Mann. (Mann has managed to string out another case that he brought against Mark Steyn for even longer).
But in the 2021 climate review the “hockey stick” is again the main feature.
by F. Menton, Aug 26, 2021 in ManhattanContrarian
The Michael Mann “Hockey Stick” is suddenly back in the news. It’s been so long since we have heard from it, do you even remember what it is?
The “Hockey Stick” is the graph that took the world of climate science by storm back in 1998. That’s when Mann and co-authors Raymond Bradley and Malcolm Hughes published in Nature their seminal paper “Global-scale temperature patterns and climate forcing over the past six centuries.” A subsequent 1999 update by the same authors, also in Nature (“Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations”) extended their reconstructions of “temperature patterns and climate forcing” back another 400 years to about the year 1000. The authors claimed (in the first paragraph of the 1998 article) to “take a new statistical approach to reconstructing global patterns of annual temperature . . . , based on the calibration of multiproxy data networks by the dominant patterns of temperature variability in the instrumental record.” The claimed “new statistical approach,” when applied to a group of temperature “proxies” that included tree ring samples and lake bed sediments, yielded a graph — quickly labeled the “Hockey Stick” — that was the perfect icon to sell global warming fear to the public. The graph showed world temperatures essentially flat or slightly declining for 900+ years (the shaft of the hockey stick), and then shooting up dramatically during the 20th century era of human carbon dioxide emissions (the blade of the stick).
by K. Richard, Sep 24, 2020 in NoTricksZone
A new 1735-2015 temperature reconstruction (Heeter et al., 2020) using Western US tree ring proxies shows peak 1940s warmth and post-1950s cooling. This is the same region Dr. Michael Mann used tree ring data to construct his famous hockey stick graph.
A new Scandinavian temperature reconstruction (Seftigen et al., 2020) that’s “skillfull in characterizing past temperature changes over the past one to two millennia” finds there
by P. Homewood, June 14, 2020 in NotalotofPeopleKnowThat
Somehow what starts as a perfectly sensible review morphs into Michael Mann and his discredited hockey stick!
But, as the review itself admits, tree rings tell you more about rainfall than temperature, Indeed, in a much better review in Newsweek, we read how the book reveals in detail the effect that a long period of drought had on the declining Roman Empire in the 4thC.
In fact Mann’s Hockey Stick was hopelessly flawed in many ways. (I would recommend Andrew Montford’s book, “The Hockey Stick Illusion”, for anyone interested.
For a start, the Hockey Stick was based on shonky statistics, which were guaranteed to produce a hockey stick curve regardless of the data fed into it. This was because of the way Mann used Principal Component analysis. In simple terms, Mann’s statistics blew out of all proportion any data which showed a hockey stick effect and ignored all other data.
Secondly, as far as tree rings were concerned, it was heavily dependent on bristlecone pines. It has long been known that the marked increase in bristlecone growth in the 19th and 20thC is due to CO2 fertilization, not temperature. When bristlecones are taken out of Mann’s analysis. the hockey stick disappears.
Thirdly, when tree ring and other proxy data diverged from rising temperature data in the late 20thC, Mann ignored the proxies and spliced the temperature data onto his graph.
There are also a whole host of other major flaws in the Hockey Stick, not related to tree rings.
by A. Préat, 29 novembre 2019 in ScienceClimatEnergie
Comme rappelé dans un précédent article (ici) les événements hyperthermiques sont fréquents tout au long de l’histoire de la Terre. Bien que fréquents et étudiés avec détail, force est de reconnaître que le ‘fin’ mot de leur origine n’est toujours pas connu, sauf à leur attribuer à tous un lien de parenté avec l’un ou l’autre des gaz dits à effet de serre, sans qu’une démonstration en bonne et due forme soit présentée. C’est ce que décortique l’article paru dans SCE (ici) pour un des événements hyperthermiques les plus intenses (événement PETM pour Paleocene-Eocene Thermal Maximum) s’étant déroulé au début de l’ère Cénozoïque il y a environ 56 millions d’années.
Rappelons la succession de ces événements au Cénozoïque, d’abord l’événement PETM, ensuite E-O (Eocene-Oligocene transition with climatic shift), MMCO (Mid-Miocene Climatic Optimum), MPTO (Mid-Pliocene Thermal Optimum) et depuis environ 10 000 ans l’Optimum Holocène. Ces événements montrent tous que la Terre a régulièrement connu de longues périodes chaudes avec des ‘températures moyennes globales’ plus élevées que l’actuelle (voir par exemple Cronin 2010, également mentionné sur de nombreux sites web). L’indicateur climatique communément utilisé , la température moyenne globale est loin d’être parfait (ici et ici). Il ne faut donc pas prendre au pied de la lettre cette notion de ‘température moyenne globale’ car déjà pour aujourd’hui elle est plus que discutable, et pour le passé elle est plus qu’inconnue. Mais il n’en reste pas moins vrai que lors des événements hyperthermiques ou des optima climatiques la température était plus élevée qu’actuellement, nous le savons grâce à de nombreux indicateurs ou ‘proxies’ (voir plus loin). Ces événements ne concernent pas uniquement le Cénozoïque (y compris l’Holocène) mais l’ensemble de l’échelle des temps géologiques au-delà du Cénozoïque, avec parfois des températures fort supérieures à celles du Cénozoïque, comme par exemple au Permien (ici).
2/ L’Optimum Climatique Médieval
Revenons aux temps actuels, c’est-à-dire aux temps historiques. Plusieurs Optima Climatiques se succèdent depuis environ 6000 ans, avec pour la période la plus proche de nous, c’est-à-dire environ 3500 ans, la succession des Optima Climatiques Minoen, Romain, Médiéval et Actuel (Figure 1). Le plus récent est l’Optimum Climatique Médiéval (OCM) dont l’acmé se situe aux alentours de l’an mil. S’agissant de températures à peine plus élevées (1,5°C cfr ici et Le Roy Ladurie, 1967, également 1.0-1.4°C in Easterbrook, 2011), la délimitation précise de cet intervalle par rapport aux périodes encadrantes est difficile et l’OCM est finalement compris du 8ème au 13ème siècle (= le ‘petit optimum du Moyen Age’ d’environ 700 à 1350 sensu Le Roy Ladurie, 1967).
Figure 8 (cfr. Figure 5 in Préat, 2019). Capture d’écran de la Figure 8 de Scafetta (2019) : On the reliability of computer-based climate models. IJEGE, 19, 49-70. En comparant les deux courbes on peut se demander si l’on parle de la même chose! (RWP Roman Warm Period, DACP Dark Age Cold Period ou période froide post-romaine, MWP Medieval Warm Period, LIA Little Ice Age, CWP Current Warm Period). Pour rappel la courbe A du haut, est la fameuse courbe en forme de hockey de Mann et al. 1998 du GIEC.
by P. Homewood, August 26, 2019 in NotaLotofPeopleKnowThat
Some years ago, Dr. Tim Ball wrote that climate scientist Michael Mann “belongs in the state pen, not Penn State.” At issue was Mann’s famous “hockey stick” graph that purported to show a sudden and unprecedented 20th century warming trend. The hockey stick featured prominently in the IPCC’s Third Assessment Report (2001), but has since been shown to be wrong. The question, in my view, is whether it was an innocent mistake or deliberate fraud on Mann’s part. (Mann, I believe, continues to assert the accuracy of his debunked graph.) Mann sued Ball for libel in 2011. Principia Scientific now reports that the court in British Columbia has dismissed Mann’s lawsuit with prejudice, and assessed costs against him.
What happened was that Dr. Ball asserted a truth defense. He argued that the hockey stick was a deliberate fraud, something that could be proved if one had access to the data and calculations, in particular the R2 regression analysis, underlying it. Mann refused to produce these documents. He was ordered to produce them by the court and given a deadline. He still refused to produce them, so the court dismissed his case.
by P. Homewood, August, 1, 2019 in NotaLotofPeopleKnowThat
Some ancient history
Fifteen to twenty years ago, Michael Mann and colleagues wrote a few papers claiming that current warming was unprecedented over the last 600 to 2000 years. Other climate scientists described Mann’s work variously as crap, pathetic, sloppy, and crap. These papers caught the interest of Stephen McIntyre and this led to the creation of his Climate Audit blog and the publication of paperspointing out the flaws in these hockey stick reconstructions. In particular, Mcintyre and his co-author Ross McKitrick showed that the method used by Mann and colleagues shifted the data in such a way that any data sets that showed an upward trend in the 20th century would receive a stronger weighting in the final reconstruction. With this method, generation of a hockey-stick shape in the temperature reconstruction was virtually guaranteed, which M&M demonstrated by feeding in random numbers to the method.
by K. Richard, July 29, 2019 in NoTricksZone
Claims that modern temperatures are globally warmer than they were during Medieval times (~800 to 1250 A.D.) have been contradicted by a flurry of new (2019) scientific papers.
Southern Ocean/SE Pacific (SSTs)
The Medieval Warm Period (1100 years BP) was 1.5°C warmer than today (14°C vs. 12.5°C) in the SE Pacific or Southern Ocean.
See also here
by Vijay Jayaraj, May 16,2019 in WUWT
A new temperature reconstruction, using proxy temperature measurements from locations in central Asia, has revealed that there has been no warming in the past 432 years.
The Global Warming “Hiatus” or Pause
The word “hiatus” became popular in recent years after the discovery of a pause or hiatus in global warming. There has been a lack of warming in the atmosphere since 1999, despite the predictions of computer climate models.
by Kenneth Richard, March 22, 2019 in NoTricksZone
Could a transition in paleoclimate reconstruction be underway? More and more, scientists aren’t hiding statements or graphical depictions of the lack of modern warming or the much-warmer Holocene past.
A compilation of 35 papers from across the globe indicate that modern climate is not unusual, remarkable or unprecedented, and that large regions of the Earth were as warm or warmer than now when CO2 concentrations were much lower (260 to 350 ppm).
This development continues apace with the trends from the last two years, when 253 non-hockey stick papers were published.
by Anthony Watts, March4, 2019 in WUWT
After years of trying to suppress their release, and finally being ordered to be released by a judge, they are now public, and we have them here. This will remain as a “top post” for a day, new stories will be below this one.
There’s quite a treasure trove, but also some duplications from previous releases.
by Anthony Watts, February 19, 2019 in WUWT
That’s direct quote from Scott Adams in this video he posted yesterday. Well worth your time.
by K. Richard, December 13, 2018 in NoTricksZone
Almost immediately after it was introduced to the public, the lead author of Marcott et al. (2013) squelched the narrative that said the hockey-stick-shaped reconstruction he and his colleagues produced is a robust representation of modern global-scale temperature changes.
In an interview with Marcott published by RealClimate.org, it was acknowledged that the “uptick” does not represent a global-scale reconstruction, as it is based on only a few proxy records and lacks statistical significance.
Despite this admitted lack of supporting evidence for the 20th century’s “uptick”, the Marcott et al. (2013) “hockey stick”-shaped graph has nonetheless been unskeptically cited by other authors nearly 700 times.
by P. Gosselin, October 26, 2018 in NoTricksZone
By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
(Text translated by P Gosselin)
The hockey stick controversy over a temperature reconstruction of the past 2000 years represents an important stage in the climate debate. At around the turn of the millennium, the authors of the “hockey stick chart” suggested that the pre-industrial climate was monotonous and uneventful. The Medieval Warm Period and Little Ice Age described in many parts of the world climatically must have been very similar. But that’s hard to understand if you look at the wide variety of case studies.
Cover-up absurdity, then forced to correct
Later, the authors improved and presented a corrected version, which again showed stronger climatic fluctuations. Quite a science story. You can read about it here.
In addition to this scientific rush job, the debate about the hockey stick also showed that climate data really must be made publicly available. This is all the more important if the science is used for far-reaching policies. Data and results obtained thereof must be verifiable. At the time no one wanted the data to be released. Today in retrospect that was quite an absurdity — similar to smoking in a large open office.
by K. Richard, August 2, 2018 in NoTrickZone
During 2017, there were 150 graphs from 122 scientific papers published in peer-reviewed journals indicating modern temperatures are not unprecedented, unusual, or hockey-stick-shaped — nor do they fall outside the range of natural variability. We are a little over halfway through 2018 and already 108 graphs from 89 scientific papers undermine claims that modern era warming is climatically unusual.
For the sake of brevity, just 13 (15%) of the 89 new papers are displayed below.
The rest of the non-hockey-stick scientific papers and graphs published thus far in 2018 can be viewed by clicking the link below.
by K. Richard, May 10, 2018 in NoTricksZone
During 2017, there were 150 graphs from 122 scientific papers published in peer-reviewed journals indicating modern temperatures are not unprecedented, unusual, or hockey-stick-shaped — nor do they fall outside the range of natural variability. We are a little over 4 months into the new publication year and already 81 graphs from 62 scientific papers undermine claims that modern era warming is climatically unusual.