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What's going on with this? What's it mean? Who did it? How many other hockey stick graphs are there?
...
The IPCC’s consistent refusal to entertain any dissent, however well researched, which challenges its assumptions, is profoundly unscientific;
· Although its now famous “hockey stick” chart of temperatures over the last millennium, which inter alia featured prominently in the UK Government’s 2003 Energy White Paper, is almost certainly a myth, the IPCC refuses to entertain any challenge to it; ...
It’s only the active hard core warmers and the constructors of the stick, who stay put. But maintaining that position however obviously would also require the falsification of several newer reconstructions, the other evidence now. So that could be called against the odds.
McIntyre and McKitrick (MM), in one of their many false claims regarding the Mann et al (MBH98) temperature reconstruction, assert that the "Hockey Stick" shape of the reconstruction is an artifact of the "non-centered" Principal Components Analysis (PCA) convention used by MBH98 in representing the North American International Tree Ring Data Bank (ITRDB) data series. We already demonstrated the falsehood of this assertion here by showing (a) that the hockey stick pattern emerges using either the MM (centered) or MBH98 (non-centered) PCA conventions, but was censored by MM through an inappropriate application of selection rules for determining the number of Principal Component (PC) to retain, (b) that use of the correct number of PC series (5) to be kept with the MM (centered) convention retains the characteristic "Hockey Stick" pattern as an important predictor, and yields essentially the same temperature reconstruction as MBH98, and finally (c) the MBH98 reconstruction is recovered even if PCA is not used at all to represent the North American ITRDB Data (i.e., each individual tree-ring series is used as a predictor with equal weight in the analysis). The claim by MM that the hockey stick pattern arises as an artifact of the PCA centering convention used by MBH98 is seen to be false on multiple levels.
So another confirmation that there were are Medieval Warm Period and a Little Ice Age which is in concfict with the hockeystick.Internal and forced climate variability during the last millennium: a model-data comparison using ensemble simulations
Hugues Goosse, Hans Renssen, Axel Timmermann and Raymond S. Bradley
Abstract
A three-dimensional climate model was used to perform 25 simulations over the last millennium, which are driven by the main natural and anthropogenic forcing. The results are compared to available reconstructions in order to evaluate the relative contribution of internal and forced variability during this period. At hemispheric and nearly hemispheric scale, the impact of the forcing is clear in all the simulations and knowing the forced response provides already a large amount of information about the behaviour of the climate system. Besides, at regional and local scales, the forcing has only a weak contribution to the simulated variability compared to internal variability. This result could be used to refine our conception of Medieval Warm Period and Little Ice Age (MWP and LIA). They were hemispheric-scale phenomena, since the temperature averaged over the Northern Hemisphere was, respectively generally higher/lower during those periods because of a stronger/weaker external forcing at that time. Nevertheless, at local-scale, the sign of the internal temperature variations determines to what extent the forced response will be actually visible or even masked by internal noise. Because of this role of internal variability, synchronous peak temperatures during the MWP or LIA between different locations are unlikely.
A delicate detail: check the name of the last author against the B of MBH.In the present paper, the authors "address the question as to whether the MWP and the LIA are robust features which were forced by solar and volcanic activity or whether they are representations of internal climate noise." This is done via a three-dimensional climate model that was used to perform 25 simulations over the last millennium driven by what the authors believe to be "the main natural and anthropogenic forcing."
The results of these model runs were then "compared to available reconstructions in order to evaluate the relative contribution of internal and forced variability during this period."
What was learned:
The results of this "model-data comparison," in the words of Goosse et al., was that the MWP and LIA were found to e "hemispheric-scale phenomena, since the temperature averaged over the Northern Hemisphere was, respectively, generally higher/lower during those periods because of a stronger/weaker external forcing at that time."
With respect to the former of these periods, they say "the MWP was a hemispheric-scale phenomenon, at least, since the temperature averaged over the Northern Hemisphere was generally higher during the period 1000-1200 AD than during the following centuries," and they state that "this is the consequence of a global forcing, external to the climate system itself."
It matters because it concerns the validity of an influential scientific paper. Mann’s 1998 and 1999 papers (which I’ll call “MBH”) have been heavily cited and highly influential. The paleoclimate field seems to have organized itself around them: other papers since then have gained prominence in proportion as they appear to back up MBH, whereas papers that contradict it have little prospect of being published or are relegated to lower-profile outlets...
It matters because it exposes the uncomfortable reality about journal peer review. MBH(98) was published in Nature, considered by some the world’s “leading” scientific journal. Nature never verified that data were correctly listed: as it happens they weren’t. Nature never verified that data archiving rules were followed: they weren’t. Nature never verified that methods were accurately stated: they weren’t. Nature never verified that stated methods yield the stated results: they don’t...
. It matters because it exposes the uncomfortable reality about the IPCC. The IPCC’s use of the hockey stick was not incidental: it is prominent throughout the 2001 report. Yet they did not subject it to any independent checking: revealing an astonishingly cavalier attitude to the quality of their case. This raises the question of whether anything in the report was subject to serious, independent checking.
... etc
The physical basic mechanism of greenhouse gas effect is well understood. More greenhouse gas causes basically more warming, there is little doubt about that. However a basic 0.6-0.8 degrees warming for each doubling of CO2 is something else than 1.4 – 5.8 degrees. Now, the climate is a highly chaotic process and the weak warming signal of CO2 forcing may either be amplified or weakened by “feedback” factors or it may be dwarfed by much stronger climate forcings. These uncertainties cause the debate in climate science.
Consequently, the analysis of climate behaviour hinges on empiric “forensic” evidence and reconstructions with multiple assumptions and hence a field full of fallacies, trip wires and diversions. Now, it matters conclusively if the initial attitude towards the research about the current warming is either “CO2 guilty until proven innocent” or “CO2 innocent until proven guilty”. For some reason the strong urge to protect the environment and the obvious main perpetrator being mankind and especially the sceptics of course, seemed to have caused a slight bias towards “guilty, guilty, guilty, guilty, guilty, guilty until proven…errm no… guilty anyway”
Synopsis
In the global-warming debate, definitive answers to questions about ultimate causes and effects remain elusive. In Global Warming: Myth or Reality? Marcel Leroux seeks to separate fact from fiction in this critical debate from a climatological perspective. Beginning with a review of the dire hypotheses for climate trends, the author describes the history of the 1998 Intergovernmental Panel on Climate Change (IPCC) and many subsequent conferences. He discusses the main conclusions of the three IPCC reports and the predicted impact on global temperatures, rainfall, weather and climate, while highlighting the mounting confusion and sensationalism of reports in the media. After taking a hard look at the reality of the greenhouse effect, the ?evidence? from climate models, and the models? limitations, Leroux postulates alternate causes of climate change and analyzes the trends for global temperatures, rainfall patterns, and sea level. He poses the ?heretical? question if warming may be considered a benefit in some regions. Finally Leroux suggests a number of priorities for climatologists to better understand processes of climate change, to integrate them into climate models, and to predict accurately future changes in climate. This timely and controversial book lays out the scientific case of the sizable skeptical scientific community who challenge the accepted wisdom.
but I think you leave an incorrect impression that somehow RealClimate exists merely to defend the HS from M&M and Climateaudit. By referring to Stefan and William as if they protaganists (they are not) as opposed to just being interested observers, you leave the impression that RealClimate is somehow synoymous with Mann, Bradley and Hughes.
It is one of those odd ironies that the figure that everyone keeps talking about is actually the least important from the point of view of understanding climate responses to forcing.
The debate about the hockeystick is techically not really relevant. We have achived our main goal, namely that the premature claims that the issue of millennial temperature reconstructions was mostly solved have been broadly rejected. One or two years ago it was hard to publish results which were inconsistent with the MBH reconstruction; now everybody agrees that there may be more to it. The jury is still out and I expect that consensus will settle on something with significant larger variations in the shaft of the hockeystick.
Having said this - the debate about the hockeystick is most significant when it comes to the culture of our science. Posting the hockeystick as key evidence in the SPM and Synthesis Report of the IPCC was simply stupid and evidence for what Bray calls post-sensible science - as science which is encroached by moral entrepreneurship. Or post-normal science. We have more cases of this type of claims-making, which is usually a mix of "good" political intentions and personal drive for the limelight. Have we, as a community, become better in rejecting such claims? I am afraid, we have not.
64 climate reconstructions, based on regression of temperature fields on multi-proxies and mutually distinguished by at least one of six standard criteria, cover an entire spread of millennial histories. No single criterion is
accountable for the spread, which appears to depend on a complicated interplay of the criteria. The uncertainty is traced back to the fact that regression is applied here in an extrapolative manner, with millennial proxy variations exceeding the standard calibration scale by a factor of
5 and more. Even if linearity still holds for that larger domain the model error propagates in a way that is proportional to both the estimation error and the proxy variations, and is thus extrapolated accordingly. This is
particularly critical for the parameter-loaded multiproxy methods. Without a model error estimate and without techniques to keep it small, it is not clear how these methods can be salvaged to become robust.
FOR IMMEDIATE RELEASE
June 22, 2006
MATT DEMPSEY 202-224-9797
INHOFE SAYS NAS REPORT REAFFIRMS 'HOCKEY STICK' IS BROKEN
Washington, D.C.-Sen. James Inhofe (R-Okla.), Chairman of the Committee on Environment and Public Works commented on today's congressionally commissioned review by the National Academy of Sciences that shows that Dr. Michael Mann's "hockey stick" study was flawed, specifically refuting some of its most often-cited conclusions.
The National Academy of Sciences' "Surface Temperature Reconstructions
for the Last 2000 Years" noted in their summary that there were "relatively warm conditions centered around A.D. 1000 (identified by some as the 'Medieval Warm Period') and a relatively cold period (or 'Little Ice Age') centered around 1700." The hockey stick constructed by Mann and his colleagues purported to show temperatures in the Northern Hemisphere remained relatively stable over 900 years, then spiked upward in the 20th century.
"Today's NAS report reaffirms what I have been saying all along, that Mann's 'hockey stick' is broken," Senator Inhofe said. "Today's report
refutes Mann's prior assertions that there was no Medieval Warm Period
or Little Ice Age."
The NAS report also stated that "substantial uncertainties" surround Mann's claims that the last few decades of the 20th century were the
warmest in last 1000 years. In fact, while the report conceded that temperature data uncertainties increase going backward in time, it acknowledged that "not all individual proxy records indicate that the recent warmth is unprecedented...'
In addition, the NAS report further chastises Mann, declaring "Even
less confidence can be placed in the original conclusions by Mann et al.
(1999) that 'the 1990's are likely the warmest decade, and 1998 the
warmest year, in at least a millennium ...'"
"This report shows that the planet warmed for about 200 years prior to
the industrial age, when we were coming out of the depths of the Little
Ice Age where harsh winters froze the Thames and caused untold deaths.
"Trying to prove man-made global warming by comparing the well-known
fact that today's temperatures are warmer than during the Little Ice Age
is akin to comparing summer to winter to show a catastrophic
temperature trend."
Earth is hottest it's been in 2,000 years, study says
By JOHN HEILPRIN
The Associated Press
WASHINGTON - The Earth is running a slight fever from greenhouse gases, after enjoying relatively stable temperatures for 2,000 years.
The National Academy of Sciences, after reconstructing global average surface temperatures for the past two millennia, said Thursday the data are "additional supporting evidence ... that human activities are responsible for much of the recent warming."
Other new research showed that global warming produced about half of the extra hurricane-fueled warmth in the North Atlantic in 2005, and natural cycles were a minor factor, according to Kevin Trenberth and Dennis Shea of the National Center for Atmospheric Research, a research lab sponsored by the National Science Foundation and universities.
NAS: schizofrenic climate report
The theory about an unprecedented global warming, described by James Inhofe as the greatest hoax ever perpetrated on the American people, was essentially downgraded from "certain" to "plausible"
A catchy subtitle was needed because much of the material that follows is boring and confusing, and it is not my fault. ;-)
Typo: The title should say "schizophrenic". Thanks, Benjamin. I don't want to change it now because it would break some links.
The #1 news on cnn.com right now is about the
Climate synthesis report of the National Academy of Sciences
that you can buy, for $42.30, here, but you can also see the pages freely here; the executive summary is also for free, much like the audio. Other sources are here. However, I don't recommend you to waste your money for this new audit of the climate reconstructions. It is a document that tries to make everyone happy which makes it schizophrenic. On one hand, they admit that there has almost certainly been the Little Ice Age and quite plausibly also the Medieval Warm Period - in both cases it is something that the hardcore alarmists wanted to deny for the last 10 years.
Because of the MWP and the large uncertainties before 1600, we can only say that the current temperatures are warmest in 400 years, not more, the panel says. In other words, it's warmer now than in the Little Ice Age. Well, this is why the Little Ice Age is called in this way. On the other hand, however, they try to promote the idea that it could "plausibly" (original report) or even "likely" (CNN's translation or "spin") still be warmer today than in the Middle Ages, and maybe the current temperatures are highest in the last 1000 or 2000 years.
Well, maybe the geologists are also wrong and they temperatures are highest in millions of years. Such "maybe" sentences are completely meaningless. If someone cannot defend a statement at the 99% confidence level, he should close his or her mouth because sentences without sufficiently strong evidence required by scientific standards are nothing else than brainwashing and manipulation.
I am happy that in different parts of the report, the panel at least confirms that Mann's statement that the 1990s were the hottest decade in a millenium and 1998 the hottest year - and similar statements that had filled the media so many times in the past - are unjustifiable by existing data (go to 47:00 of the audio or so), despite 10 years of passionate statements that these insights are definitive, ever more definitive, and that the debate was over.
Mann suddenly started to say that he never said that he was certain that the current era is the warmest era in the last 1000 years and, on the contrary, he always emphasized that their research was meant to show how uncertain these numbers are. Well, we probably live in different Universes because in this Universe, he said it roughly 350 times and 870,000 articles have been written about this extraordinary statement. This confusion - more precisely these untrue assertions - are discussed at 19:20 of this real audio from the press conference.
You're exactly one click from verifying that various media and the RealClimate group blog are just trying to fool you completely.
If you go to 25:30 of this audio, a distinguished NAS scientist explains that the belief that Mann's results were definitive were not Mann's fault but rather the climate science community's fault. ... At 35:00 into the audio, they discuss Mann's flawed usage of the principal component analysis. At 37:30, they discuss why the bristlecone pines are not good temperature proxies. At 50:00, a panel member answers "Yes" to the question whether he is saying that the odds than Mann is right are around 2:1 - which means "almost completely uncertain".
At 53:40, a desperate activist / journalist tries to criticize the NAS panel that they used the word "plausible". How could this have happened? ;-) The same crazy journalist even says that there is no evidence for string theory but we can say it's "plausible". I assure this comrade that string theory is much more plausible than a catastrophic global warming. ;-) Around 54:30, they also agree with your humble correspondent that quantitative estimates of "Bayesian" confidence levels in this context (and similar contexts) are meaningless and the real uncertainty can't be quantified. Near 57:00, Myron Ebell asks about the divergence problem - the fact that the current proxies don't show the warming measured directly by thermometers. He is answered that the problem is there, indeed, and it might be hand-waved away by some very vague comments about moisture. At 59:30, another passionate eco-journalist complains against the word "plausible". How can you say it is less plausible if there is no evidence against [except for those paid by the oil company, he would normally say]? ;-) He is again explained that we just don't know, and there is a lot of natural climate variability that increases the uncertainty. Around 1:03:00 into the audio, it is being discussed how much money is being wasted for climate research whose insights are ever more murky and questionable, despite hundreds of papers. At 1:06:30, they say that the variability - and thus also the uncertainty - is higher than thought previously.
Although the NAS members say and write a lot of wise and correct things (and things that I've been saying for months if not years), of course, there are many other examples of schizophrenia of their document and its interpretation.
On one hand, they concede that virtually every single criticism of the "hockey stick graph" has been valid and the methodology of Mann, Bradley, and Hughes is unsatisfactory because of all these reasons (besides the examples above, also lacking statistical skill for individual years, problems with unavailable data and secret computational software - go to 16:20 of the audio for the transparency issues). On the other hand, they are using graphs from papers that are criticizable because of the very same reasons and they essentially encourage the reader to think that these reconstructions are trustworthy even though the actual content of the chapters 9 and 11 leads to the opposite conclusion. The most penetrating and freely available analysis of the document was written by
Steve McIntyre
who has been - together with Ross McKitrick, his collaborator - the world's principal auditor of the climate reconstructions and some very useful comments on that page are also offered by Eduardo Zorita and others. I think that the whole field of "global climate science" has become a political game where people are looking for a compromise or, as many of them openly call it, a consensus.
The recent developments in science have shown that some statements in the past decade are scientifically undefendable and some papers have simply been wrong but those people just don't have enough courage and integrity to admit this fact openly which is why they only soften their language and generate logically inconsistent bureaucratic hybrids. It will take a lot of time to restore the integrity of climate science but we may hope that the NAS panel made the first steps towards this goal.
...cont'd
The fabled hockey stick graph is a temperature reconstruction graph created by scientist Michael E. Mann and colleagues in the late 1990s. It shows a sharp increase in global temperatures in the 20th century, resembling the shape of a hockey stick.
The hockey stick graph was created using a statistical method called principal component analysis, which combines various proxy data such as tree rings, ice cores, and historical records to estimate past temperatures. The graph was later updated with more accurate data and improved methods.
The accuracy of the hockey stick graph has been debated among scientists and skeptics. Several studies have confirmed the general shape of the graph, but there have been criticisms of the data and methods used. Overall, the scientific consensus is that the hockey stick graph accurately represents the recent warming trend.
The hockey stick graph is a visual representation of the increase in global temperatures over the past century. It shows that the Earth's climate is rapidly warming, and that this warming is likely due to human activities such as burning fossil fuels and deforestation. The graph also shows that the current rate of warming is unprecedented in the past 2,000 years.
The hockey stick graph is important because it provides evidence for the reality of climate change and the role of human activities in driving it. It has been a key piece of evidence in international climate change reports and has influenced policy decisions. The graph also highlights the urgency of taking action to mitigate the impacts of climate change.