The Infamous "Hockey Stick" Curve and Other Inconvenient Truths
Corrected version of original post on 3/1. My apologies to any early readers of uncorrected edition.
The cult of anthropogenic "global warming" spearheaded by so many Chicken Littles spouting such nonsense as "the question is no longer in doubt" and "human caused global warming is settled science" has taken a real beating recently as more and more credible (and subject matter accredited) scientists speak out on the weaknesses of the fundamental assumptions underlying the proposition that humans are significantly impacting climate. The so-called "hockey stick" curve of Mann, Bradley, and Hughes (1998, M. E. Mann, R. S. Bradley, and M.K. Hughes, "Global-scale Temperature Patterns and Climate Forcings over the Past Six Centuries," Nature 392, p. 779-87) purporting to represent 600 years of estimated global temperature change has been held up regularly by Chicken Littles and their gurus at the Intergovernmental Panel on Climate Change (IPCC) as "proof" that greenhouse gases such as CO2 are responsible for an "unprecedented" rise in global temperatures over the past few decades. In 1999's version the curve was expanded back to 1,000 years of estimated global temperature change (1999, M. E. Mann, R. S. Bradley, and M.K. Hughes, "Northern Hemisphere Temperatures during the Past Millennium: Inferences, Uncertainties and Limitations," Geophys Res Lett 26, p. 759-62). These "hockey stick" curves, often referred to as simply MBH98 and MBH99, are often matched with graphs showing estimated levels of atmospheric CO2 where a strong correlation is shown. This leads the Chicken Little cultists to conclude that increased atmospheric CO2 from humans burning fossil fuels is causing global temperatures to skyrocket. This is junk science at its worst.
While the scenario described might appear to provide a reasonable and strong case for the Chicken Little brigade to believe that burning fossil fuels is leading to an "unprecedented" climate catastrophe of global proportions, the inconvenient facts are:
The MBH98 "hockey stick" curve is bogus. More about that below.
Correlation is not the same as causation (the famous "stork and baby" correlation is a straightforward example), and, indeed, a proper understanding of climate history reveals that greenhouse gases are more likely to be a response to global temperature change than a cause. While a strong correlation certainly does not preclude causation, it is insufficient on its own to conclude causation. Supporting evidence of a different nature must be provided to confirm any causation from a strong correlation. The "stork and baby" illustration demonstrates that it is not the storks that are responsible for an increase in the population of babies, rather, it is the greater village population that is responsible for more village housing that, in turn (after a time lag), provides greater nesting opportunities for storks (thus increasing the stork population). What might appear at first to be "cause and effect" is often found to be just the reverse!
The oversimplified "greenhouse gas" model of the Chicken Littles is not sustainable by scientific evidence. That simplified model suggests that climate warms or cools merely as a consequence of rising or falling levels of greenhouse gases. Such belief is unscientific nonsense and ignores the many factors that contribute to climate change (thermohaline circulation is a prime example of a strong climate influence ignored by the simplistic "greenhouse gas" model).
Climate change science is far more complex than even our most complex prediction models are capable of emulating. Neither is the science well enough understood to model, nor does the capability exist to provide reliable data to drive such a model even if the science were well enough understood and the model of the necessary complexity developed. It is simply not possible to validate or verify the accuracy of such a model within any reasonable margin of error that would allow sensible conclusions to be drawn from such a model (if it existed and if the data to drive it could be collected).
Finally, one needs to consider the origin of the carbon that is the key ingredient of the demonized fossil fuels that release CO2when they are burned to produce heat or energy.
These are the inconvenient truths that Chicken Littles either have not been exposed to or are simply incapable of accepting.
Examining The Roots of the Cult - The Hockey Stick Curve
Let's examine the IPCC's infamous "hockey stick" curves MBH98 (140 year history) and MBH99 (extended back to a 1,000 year history).
But before questioning the nature of the MBH98 graph, it is important to understand a little history of the IPCC's temperature profile for the past 1,000 years. In 1990, the IPCC's First Report featured a temperature profile going back to 900 AD. This profile showed two distinct climate periods on the order of several hundred years each. The first, spanning about 300 years (1000 AD to 1300 AD) is well documented and known as the Medieval Warm Period (MWP). The curve, developed by C. K. Folland, et al (1990), showed the MWP as what Folland termed "exceptionally warm" and "[a] period of widespread warmth ... notable in that there is no evidence that it was accompanied by an increase in greenhouse gases". The other climate period, from roughly 1500 AD to 1700 AD (though one could argue it spanned 1400 AD to about 1860 AD), is known as the Little Ice Age (LIA) and is well known for its markedly colder winters in North America and Europe (though global evidence for this cold period exists). The sharp warming that began after 1860 was tempered by a prolonged gradual cooling during the middle 20th century that ended in the late 1970s.
The Folland curve (1990) with its MWP stands as a clear refutation to the notion that warming at the end of the last decade was "unprecedented" during the past 1,000 years. It is worth noting that even if no MWP had existed, climate history is full of countless warm periods where changes like those experienced during the 1990s were routine (see Inconvenient Facts and More Inconvenient Facts). In short, there is nothing "unprecedented" about climate warming suddenly and it has happened countless times both before humans existed and after the earliest humans trod the Earth.
Clearly, if one is to maintain that humans burning fossil fuels are causing climate to warm in a way that is "unprecedented," then the inconvenient reality of the MWP and LIA must be attacked. Enter Mann, et al, with their 1998 and 1999 "hockey stick" charts.
In a single stroke, the "hockey stick" curves, MBH98 and MBH99, claimed the Medieval Warm Period and Little Ice Age never existed! Instead of a four century long warm period (well documented by historical records of farming and early settlements in high latitudes, ice core samples, coral reef data, etc.), the Mann et al curves show a fairly linear and gently decreasing temperature trend until the 20th century when suddenly "unprecedented" temperature increases are noted from about 1900 to 1940 and again from the late 1970s through the end of the century.
What the IPCC fails to tell you about this curve is instructive. Data prior to the 20th century are estimated from a variety of sources (tree ring data, ice cores, historical accounts). Data from the 20th century forward is taken from official temperature records (not estimates). Thus, the "hockey stick" curve has been manufactured by combining incompatible data in the form of 100 years of real data grafted onto a 900-year history of estimated temperatures. The graph of historical CO2 over the past 1000 years cited by the IPCC suffers from the same grafting of historical estimates from one source with actual measurements from an entirely different source! Those who would deceive you will use these two charts to correlate rising temperatures with rising levels of atmospheric CO2 and conclude that the high correlation shown proves causation! Is it possible to be any less scientifically rigorous?
As M. Leroux questions in Global Warming, Myth or Reality (2005), "... are the two data series, whether they represent CO2 or whether they represent temperatures, truly comparable, and can they be fitted together in this way? This 'apples and oranges' procedure recalls closely that followed by Hansen in 1988, unleashing the 'greenhouse panic': the end of his curve (Chapter 2, Figure 4, p. 33) juxtaposed a thermal value established over five months with mean annual temperature values, a procedure devoid of any scientific rigour!"
Thus constructed, the 'hockey stick' curve shows (and spectacularly!) that 'the rapidity and duration of warming during the 20th century were much greater than in any of the nine preceding centuries'. It is a crude trick, which seems to have begotten a mania, but it would seem that it still 'works'! The views of Mann et al. (1998) were in fact immediately endorsed by the IPCC, which in so doing quickly forgot its previous reports, and the curve appeared in the Third Report as an additional 'proof' of the exceptional nature of recent climatic evolution. It became 'one of the great propaganda icons of the United Nations climate change machine' (Corcoran, Financial Post, 13 July 2004). Of course, for the IPCC (2001), the MWP now became ipso facto less warm ('... appears to have been less distinct, more moderate in amplitude'), and similarly, the LIA 'can only be considered as a modest cooling of the northern hemisphere' (IPCC 2001). When one considers the habitual and justifiable reluctance of scientists to take on broad new ideas, one can only marvel at the speed with which the IPCC 'changed its clothes'. Such haste might even seem suspect. We are certainly no longer moving in the realm of science here!
This 'warming' may well have been without precedent during the last 1,000 years, but this seems not to be long enough for the IPCC! The period in question had to be extended: from the original 600 years (1998), through 1,000 years (1999), and finally to two millennia, according to Jones and Mann (2004), who pushed the starting point back by 1,800 years, and even beyond, though, obviously, the same conclusions were reached. And the conclusions will always be the same, as long as the thermal curve used relies upon the trick of mixing incompatible data: one can blithely go back in time as far as one cares to, knowing that the curve will terminate every time with the 'reconstituted' temperatures (Figure 46, p. 212)! And of course, the culprit will always have to be identified, in line with the dogma of the IPCC, in words like: 'modeling and statistical studies indicate that such anomalous warmth cannot be fully explained by natural factors, but instead, require a significant anthropogenic forcing of climate' (Mann et al., 2003), or again, with greater affirmation, 'only anthropogenic forcing of climate, however, can explain the recent anomalous warming in the late 20th century' (Jones and Mann, 2004). This, however, is to go beyond simple research into the evolution of temperature, and on into the realms of propaganda, or what Essex and McKitrick (2002) called 'nescience': they justifiably asked 'whether statistical methods can detect a human influence on climate'.
Though past climates in no way show a link between greenhouse gases and temperature (cf. Chapter 9), the montage of the 'hockey stick', and its partisans, provide the IPCC with its 'ultimate weapon'!
Leroux goes on to observe:
The controversy generated by the 'infamous hockey stick' (Daly, 2001) is still very much with us, and rightly so, as the IPCC rejects out of hand existing, patient research and the findings of much serious investigation, based on historical records and archaeological, botanical, and glaciological work from many different parts of the world. These studies are the fruit of long years of research by experienced scientists, and we need only cite here some of the best known contributors: Lamb (1965, 1977, 1984); Mayr (1964); Le Roy Ladurie (1967); Alexandre (1987); Grove (1988) ... the list is very long. The IPCC thus demonstrates the shortness of its memory, and/or at least the limits of its 'climatological culture'!
During the MWP, between 1000 and 1300, the Arctic icecap melted back considerably, and was not present in the vicinity of either Iceland or Greenland between 1020 and 1200. In southern Greenland, the mean annual temperature was between 2-4°C higher than it is today. A stormier period set in after about 1250, and sea travel became more difficult. Around 1340, the Vikings' sea routes lay further to the south, and after 1410, communication by sea ceased. In central and western Europe, the climatic optimum occurred between 1150 and 1300, and the limits for crop growing and viniculture edged northwards by 4 or 5 degrees. The 'gentle twelfth century', with its mild winters and dry summers, gave way to the 'golden age' (according to Scottish history) of the thirteenth, the most beneficent of all in terms of weather, good harvests and increasing trade. North America also experienced a warm and relatively dry period, though after 1300, conditions became cooler and wetter. A similar example around this same time was that of sub-Saharan Africa, where rain was abundant, and the great and prosperous Sahelian/Sudanian empires flourished between 1200 and 1500 (Mauny, 1961; Toupet, 1992).
The decline into the LIA saw an increase in storm activity, heavy rains, snowfalls, and waves of cold. Also observed, according to the IPCC (1990), were 'extensive glacial advances in almost all alpine regions of the world'. Cold did not dominate continuously throughout this period, but 'the Little Ice Age was probably the coolest and most globally extensive cool period since the Younger Dryas' (IPCC, 1990), and climatic conditions were particularly severe between 1550 and 1850.
A fairly extensive discussion of an attempt to replicate the MBH98 curve that led to the discovery of serious errors in the MBH98 data is described Dr. Ross McKitrick in Shattered Consensus edited by Patrick J. Michaels. In Shattered Consensus, McKitrick details the attempt of Steven McIntyre to reproduce the MBH98 curve after it became clear that there had been no peer review nor any prior attempt to replicate the MBH98 results!
Rather than recite the gory details of McIntyre and McKitrick's efforts to verify and validate the MBH98 and MBH99 charts, I will leave that for the reader to pursue by reading Chapter 2, pages 20-49 of Shattered Consensus. The "bottom line" is that McIntyre and McKitrick discovered:
No peer review of the MBH98 and MBH99 papers was ever performed.
Several significant errors were discovered in the data sets used that created the illusion that the Medieval Warm Period never existed.
When standard methodology is applied to the erroneous data, curves similar to the MBH98 and MBH99 charts are produced.
When corrected data is analyzed using standard methodology, the MBH98 and MBH99 charts are shown to be erroneous in their absence of any MWP and the consequent conclusions of MBH98 and MBH99 that late 20th century warming is "unprecedented" is shown to be unsupported.
Mann et al will not share their methodology (though they did make data records available), so it is impossible to reproduce their charts precisely. (This failure to disclose their methodology speaks volumes about their lack of rigorous scientific method.)
The revelations of Leroux, McIntyre, and McKitrick that demonstrate the false picture depicted by the MBH98 and MBH99 "hockey stick" curves is stark testimony to the completely unjustified impact those curves have had on the IPCC's stance regarding anthropogenic forcing of climate change. Two charts that were never peer reviewed, whose authors refuse to share their methodology, and whose conclusions cannot be duplicated by rigorous scientific method, have, nevertheless, been used by the IPCC, politicians, and journalists worldwide to fuel a massive propaganda campaign that misrepresents the impact burning fossil fuels has on global climate.
The closed carbon loop
One aspect that has been overlooked in the debate over the climate impact of increased atmospheric CO2 from burning fossil fuels is the realization that fossil fuels are derived from long dead plant matter. Just as with today's plant life cycle, those ancient carbon-based plants developed by absorbing atmospheric CO2 through photosynthesis and using the carbon to promote growth while releasing oxygen as a by-product. Consequently, whatever CO2 is released back into the atmosphere by the burning of fossil fuel today was at one time in the past part of the atmospheres CO2 component. So it is false to suggest that rising levels of atmospheric CO2 are "unprecedented" or are even dangerous. The release of CO2 into the atmosphere by burning fossil fuel is simply a part of a long term carbon recycling process.
It is worth considering how much ancient atmospheric CO2 is still locked in worldwide deposits of fossil fuels (coal, gas, oil, peat). Because new carbon is not being added to the Earth's environment the carbon cycle is a closed loop on Earth. Consequently, based on the amount of unrecovered fossil fuel that still exists, it would appear that much higher levels of atmospheric CO2 have existed in Earth's past - a past that evidently included vast amounts of plant life.
A Well Known Chicken Little - Just Another Dupe?
Take a disillusioned politician who, as Vice President, had risen to just shy of the pinnacle of power in the United States. Now suppose that politician should seek what he views the ultimate pinnacle of power only to suffer a particularly humiliating electoral defeat (losing his home state handily, where a victory would have been sufficient to earn him the electoral votes needed to win the Presidency). What do you get? A lost soul searching desperately for a cause. Add a smattering of ignorance to the kind of tripe the IPCC has been generating over the past decade, and, presto, you end up with a politician with a near maniacal Chicken Little complex - none other than Al Gore.
Gore's knowledge of climate science is about on the level of his claim to have "invented" the internet. Yet it is easy to see how he could be so easily duped into believing the junk science put out by the highly anti-United States folks at the United Nations who just happen to be the parent agency responsible for the IPCC.
Do you want your views on climate change shaped by the same organization responsible for the "oil for food" scandal in Iraq under Hussein? I certainly hope not.
 Marcel Leroux describes his qualifications on the subject of climatology thus: "Doubly a doctor, from University and from the state, in Climatology, I am a member of the Société Météorologique de France and of the American Meteorological Society. As a Professor of Climatology, my employer is the French Republic, which has adopted the official religion of 'climate change', to which I do not adhere. I am not beholden to any 'slush fund' and my Laboratoire de Climatologie, Risques, Environnement (LCRE), in spite of its links with the Centre National de la Recherche Scientifique (CNRS), has never received any funding from this state institution, certainly by reason of heresy. I am neither a militant nor an amrchair 'eco-warrier', but I live in the countryside, near the little village of Vauvenargues, near Aix-en-Provence, on the 'Grand Site Sainte Victoire' (immortalised by the painter Paul Cézanne), a listed and protected area of mountains and wild forests. I grow vegetables in my (small) 'organic' kitchen garden. I am naturally inclined to question things, and I am basically a Cartesian, living by René Descartes' primary precept of 'never assuming anything to be true which I did not know evidently to be such' (Discours de la Méthode, 1637)."
 Patrick J. Michaels is research professor of environmental sciences at the University of Virginia, state climatologist for Virginia, and senior fellow in environmental studies at the Cato Institute in Washington, D.C. Michaels is past president of the American Association of State Climatologists and was program chair for the Committee on Applied Climatology of the American Meteorological Society. He is the author of four books and hundreds of technical and popular articles on climate and its impact on ecosystems and economies.
 Ross McKitrick is Associate Professor in the Department of Economics at the University of Guelph, Ontario.
 Stephen McIntyre is a former mining executivewho holds a B.S. degree in pure mathematics. He is most prominent as a critic of the IPCC's temperature record of the past 1000 years developed by Mann, Bradley and Hughes.
Biography - Bob Webster
Bob Webster, a 12th-generation descendent of both the Darte family (Connecticut, 1630s) and the Webster family (Massachusetts, 1630s) is a descendant of Daniel Webster's father, Revolutionary War patriot Ebenezer Webster, who served with General Washington. Bob has always had a strong interest in early American history, our Constitution, U.S. politics, and law. Politically he is a constitutional republican with objectivist and libertarian roots. He has faith in the ultimate triumph of truth and reason over deception and emotion. He is a strong believer in our Constitution as written and views the abandonment of constitutional restraint by the regressive Progressive movement as a great danger to our Republic. His favorite novel is Atlas Shrugged by Ayn Rand and believes it should be required reading for all high school students so they can appreciate the cost of tolerating the growth of unconstitutional crushingly powerful central government. He strongly believes, as our Constitution enshrines, that the interests of the individual should be held superior to the interests of the state.
A lifelong interest in meteorology and climatology spurred his strong interest in science. Bob earned his degree in Mathematics at Virginia Tech, graduating in 1964.