Archives par mot-clé : Hockey Stick

climate-debate

The Hockey Stick Trial: How Science Died In A D.C. Courtroom

by R .Darwall, Feb 20, 2024 in ClimateChangeDispatch

“Science,” wrote the philosopher Karl Popper, “is one of the very few human activities – perhaps the only one – in which errors are systematically criticized and fairly often, in time, corrected.”

The sub-title of Popper’s 1963 book Conjectures and Refutations, in which he argued that science progresses through inspired conjectures checked by attempts to refute them through criticism, is “The Growth of Scientific Knowledge.” [emphasis, links added]

Now, a six-person jury in Washington, DC has refuted Popper’s formulation of the uniqueness of science, finding in favor of climate scientist Michael Mann in the defamation suit he brought against Rand Simberg and Mark Steyn dating back to 2012.

Central to Mann’s case was his attempt to reconstruct global temperature over the previous millennium – the iconic “hockey stick” graph.

The graph shows global temperatures purportedly falling for centuries and suddenly shooting upward with the advent of the Industrial Revolution.

Mann’s hockey stick representation was derived principally from selected tree-ring data based on the assumption that tree rings constitute accurate proxies for temperature and are not contaminated by confounding factors such as rainfall, seasonal variability, and levels of carbon dioxide in the atmosphere.

The results that Mann produced are also sensitive to decisions on and application of statistical techniques.

There can be little doubt of the hockey stick’s historical importance in developing and propagating what became the dominant scientific paradigm of climate change.

…

…

climate-debate

Sheenjek, Alaska: A Jacoby-MBH Series

by S. McIntyre, Dec13, 2023 in ClimateAudit

MBH98 used three Jacoby tree ring chronologies from Alaska: Four Twelve (ak031) – discussed here, Arrigetch (ak032) and Sheenjek (ak033). Sheenjek will be discussed in this article.

In our compilation of MBH98 in 2003, we observed that the Sheenjek chronology archived at NOAA Paleo was not the same as the “grey” version used in MBH98.   While we used the MBH98 version to benchmark our emulation of the MBH98 algorithm, we used the version archived at NOAA in our sensitivity analysis, both in our 2003 article and in our early 2004 submission to Nature.  In his reply to our submission, Mann vehemently protested that the “introduc[tion of] an extended version of another Northern Treeline series not available prior to AD 1500 at the time of MBH98” “introduce[d] problems into the important Northern Treeline dataset used by MBH98”:

Finally, MM04 introduce problems into the important Northern Treeline dataset used by MBH98. Aside from incorrectly substituting shorter versions of the “Kuujuag” and TTHH Northern Treeline series for those used by MBH98, and introducing an extended version of another Northern Treeline series not available prior to AD 1500 at the time of MBH98, they censored from the analysis the only Northern Treeline series in the MBH98 network available over the AD 1400-1500 interval, on the technicality that it begins only in AD 1404 (MBH98 accommodated this detail by setting the values for AD 1400-1404 equal)

The other “Northern Treeline series” referred to here was Sheenjek chronology ak033.crn.  I checked Mann’s assertion alleging that the data was “not available prior to AD1500 at the time of MBH98”. This was contradicted by NOAA, who confirmed that the chronology that we had used had been available since the early 1990s.

In the figure below, I’ve compared three Sheenjek chronology versions:

  • the MBH98 version from 1580-1979 (plus 1980 infill);
  • the ModNegExp chronology (dplR) calculated from measurement data (ak033.rwl), which, in this case, has been available since the 1990s. It covers period 1296-1979.
  • the archived chronology at NOAA (ak033.crn). Also covering the period 1296-1979.

The issues relating to Sheenjek are different than observed at Four Twelve.

Continuer la lecture de Sheenjek, Alaska: A Jacoby-MBH Series →

climate-debate

After 25 years, Mann’s Other Nature Trick Unraveled

by McIntyre, Nov 25, 2023 in WUWT

Stephen McIntyre has recently again fired up the seminal site for uncovering deficiencies in the works of Mann et al, ClimateAudit.org

His latest post ends a 25 year mystery surrounding the famous MBH98 paper. A Swedish engineer, Hampus Soderqvist, reversed engineered the reconstruction and deduced that:

Mann’s list of proxies  for AD1400 and other early steps was partly incorrect (Nature link now dead – but see  NOAA or here).  Mann’s AD1400 list included four series that were not actually used (two French tree ring series and two Moroccan tree ring series), while it omitted four series that were actually used.  This also applied to his AD1450 and AD1500 steps.  Mann also used an AD1650 step that was not reported.

Soderqvist’s discovery has an important application.

The famous MBH98 reconstruction was a splice of 11 different stepwise reconstructions with steps ranging from AD1400 to AD1820. The proxy network in the AD1400 step (after principal components) consisted 22 series, increasing to 112 series (after principal components) in the AD1820 step.  Mann reported several statistics for the individual steps, but, as discussed over and over, withheld the important verification r2 statistic.  By withholding the results of the individual steps, Mann made it impossible for anyone to carry out routine statistical tests on his famous reconstruction.

However, by reverse engineering of the actual content of each network, Soderqvist was also able to calculate each step of the reconstruction – exactly matching each subset in the spliced reconstruction.  Soderqvist placed his results online at his github site a couple of days ago and I’ve collated the results and placed them online here as well.  Thus, after almost 25 years, the results of the individual MBH98 steps are finally available.

Remarkably, Soderqvist’s discovery of the actual composition of the AD1400 (and other early networks) sheds new light on the controversy about principal components that animated Mann’s earliest realclimate articles – on December 4, 2004 as realclimate was unveiled. Both articles were attacks on us (McIntyre and McKitrick) while our GRL submission was under review and while Mann was seeking to block publication. Soderqvist’s work shows that some of Mann’s most vehement claims were untrue, but, oddly, untrue in a way that was arguably unhelpful to the argument that he was trying to make. It’s quite weird.

Soderqvist is a Swedish engineer, who, as @detgodehab, discovered a remarkable and fatal flaw in the “signal-free” tree ring methodology used in PAGES2K (see X here).  Soderqvist had figured this out a couple of years ago. But I was unaware of this until a few days ago when Soderqvist mentioned it in comments on a recent blog article on MBH98 residuals.

https://climateaudit.org/2023/11/24/mbh98-new-light-on-the-real-data/

The post is a long and technical one to which I cannot do proper justice, and I suggest reading the original at Climate Audit

climate-debate

Monday Mirthiness – Mike Mann’s Hockey Team ‘will keep those papers out somehow’

by A. Watts, Aug 28, 2023 in WUWT

Remember the famous quote from the head of the UK Climate Research Unit, Dr. Phil Jones that was laid bare in ClimateGate?

…I can’t see either of these papers being in the next IPCC report. Kevin [Trenberth] and I will keep them out somehow, even if we have to redefine what the peer-review literature is!

Dr. Phil Jones – ClimateGate emails

These guys never learn. Josh writes on Twitter:

Mikey’ The Trick’ Mann at work…Another story about ‘scientists’ trying to bury papers and evidence they don’t like. It’s Climategate deja vu. Read about it here https://quadrant.org.au/opinion/doomed-planet/2023/08/how-science-is-done-these-days/

and here: The Climategate Gang Rides Again!

 

Shameless abuse of science…but then again, we know Mann has no shame, only hubris

climate-debate

The IPCC And The Infamous Hockey Stick Graph

by CCD Editor, July 25,2022 in ClimateChangeDispatch

Ron Barmby, author of  “Sunlight on Climate Change: A Heretic’s Guide to Global Climate Hysteria” (Amazon, Barnes & Noble) spoke with Mike Ryan of TNT Radio (TNT Radio (podbean.com) about what he uncovered in the recent IPCC report, Climate Change 2021: The Physical Sciences Basis.

Ron’s findings: after being made famous by Al Gore and adopted by the IPCC, then being made infamous by its historical and statistical failings and subsequently dropped by the IPCC, the hockey stick temperature graph is back!

And a new narrative is being introduced that carbon dioxide has been demoted to causing only half of human global warming to date.

Mike discusses with Ron the four things wrong, and often in conflict with, the report itself with the latest doomsday science from the IPCC. LISTEN:

…

climate-debate

Follow the Science: But Which Results? Using Same Tree Ring Dataset, 15 Groups Come Up With 15 Different Reconstructions

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 

…

climate-debate

Climate Past Far From Settled: 7 Major Temperature Reconstructions Find No Agreement

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.

climate-debate

A Brief Summary Of How ‘Global Warming’ Science Has Changed Since 1998

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.

…

climate-debate

Another dot on the graphs (Part II)

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).

….

…

better to know...?, climate-debate

105 More Non-Global Warming/Non-Hockey Stick Temperature Records Added To The Database In 2021

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.

Over 350 Non-Hockey Sticks (2019-2021)

Zhou et al., 2021  South China Sea ~4°C warmer SST during the Middle Holocene…1994-2004 coldest temperatures of the last 6000 years.

…

…

climate-debate

New IPCC report resurrects the Hockey Stick

by Clintel,  26 Aug 2021

Every IPCC report is accompanied by this kind of ritual dance. The IPCC itself declares in somewhat woolly language (because the IPCC is officially policy neutral) that it is 2 minutes to 12 after which activists, politicians and the media go wild and declare that it is already 2 minutes past 12. This time it was no different.

Now that the media hype around the report has subsided somewhat, it is time to take a calm look at some of the claims in the new IPCC report and also at what the IPCC leaves unsaid or gives less attention to in its Summary for Policy Makers (SPM). I made a first attempt last week in an interview in the popular Studio BLCKBX: “Alarmist IPCC report offers hope” (in Dutch but with English subtitles).

Hockey stick
Back to the opening words in our national news program: “climate change is accelerating”. Most people will let these words pass almost without thinking and will assume “it must be true”. For insiders like me, however, this new conclusion in the IPCC report was downright surprising! The claim is based on a brand new hockey stick graph (the graph at the very top of this article). This graph was the opening graph in the Summary for Policy Makers. So it is a piece of evidence that the IPCC wanted to give a lot of attention. Coupled with yet another graph – with which the IPCC claims to ‘prove’ that the warming since 1850 is mainly due to greenhouse gases – the message was the following: “due to human influence (read: CO2 and other greenhouse gases), the earth has warmed at a rate unprecedented in the last 2000 years”.

Without exaggeration, I would not be writing this article now if, way back in 2004, when I worked at the popular science monthly Natuurwetenschap & Techniek, I had not been asked by my chief editor to write an article about “a hockey stick graph”. It became the beginning of a two-month quest that ended with a long article (English version here) in which the hockey stick graph in the third IPCC report in 2001 was smashed to smithereens by two Canadian researchers (Stephen McInytre and Ross McKitrick). This experience and especially the reactions to it from the field (the unwillingness to acknowledge the criticism of McIntyre and McKitrick) triggered me to start investigating more climate claims, which eventually led to the publication of my book (in Dutch) De Staat van het Klimaat.

The controversy surrounding the hockey stick, especially to be found on Stephen McIntyre’s blog climateaudit.org was a central theme in the climate debate for years. It was ultimately also the cause of climategate, an affair in which thousands of e-mails from prominent IPCC authors were hacked and put online. The emails were examined by various committees of enquiry but were ultimately dismissed as a storm in a teacup. But in my book, I show that several emails do shed a very questionable light on the integrity of the IPCC authors involved.

In any case, there is even a hefty book on this matter written by Andrew Montford and it would be going too far to go into it all again. After climategate, all those closely involved became fed up with the subject. And in the fourth (2007) and fifth (2013) IPCC reports, the IPCC did not publish a prominent hockey stick either. But lo and behold, in the sixth IPCC report the hockey stick is back in all its glory. Or as McInytre puts it: “the IPCC is addicted to hockey sticks”.

Where does this attraction to the hockey stick come from? A long time ago, in 1995, a climate researcher once wrote: we have to get rid of the Medieval Warm Period. There is much historical evidence that around the year 1000 it was also warm on Earth. The Vikings went to Greenland, called it Greenland (and not e.g. Iceland), farmed there and managed to survive for several centuries. This kind of information is unwelcome (for the IPCC) because this warm period suggests that even without CO2 emissions it was warm on Earth in the recent past. How warm exactly? Warmer than now? And if so, what caused the warming? There is no simple answer to these questions, but with the introduction of hockey sticks the IPCC suggests there is. Take a closer look.

…

…

climate-debate

Another Round Of Anti-Science From The IPCC

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:

…

unclassified

Another Round Of Anti-Science From The IPCC (With A NEW Hockey Stick!)

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:

 

…

…

 

McIntyre comments:

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.

climate-debate

How to build your hockey stick graph

by Dr H. Masson, Aug 16, 2021 in ScienceClimatEnergie

Introduction

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.

…

…

Conclusion

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.

better to know...?, climate-debate

The UN IPCC buries two millennia of fluctuating temperatures

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.

…

unclassified

Michael Mann “Hockey Stick” Update: Now Definitively Established To Be Fraud

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).

…

…

climate and geology

Scientists Find Peak 1940s Warmth, Post-1950s Cooling In The Same Western US Region Where Hockey Sticks Emerged

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

climate-debate

Tree Rings & Michael Mann’s Hockey Stick

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.

…

climate-debate

L’Optimum Climatique Médiéval : ce Grand Oublié !

by A. Préat, 29 novembre 2019 in ScienceClimatEnergie

1/ Introduction

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.

…

better to know...?, climate-debate

Michael Mann Refuses to Produce Data, Loses Case

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.

 

…

climate-debate, to keep an eye on...

Hockey Stick Groundhog Day

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.

…

…

climate-debate, to keep an eye on...

12 New Papers Provide Robust Evidence The Earth Was Warmer During Medieval Times

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

climate-debate

No Hockey Sticks: Studies Reveal Long-Term Lack of Warming

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.

…

climate-debate

Busted Hockey Sticks: 35 Non-Global Warming Papers Have Been Published In 2019

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.

…