WEBCommentary Editor

Author: Bob Webster
Date:  February 20, 2007

Topic category:  Other/General

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:

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[1] 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!"

Leroux continues:

Leroux goes on to observe:

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[3] in Shattered Consensus edited by Patrick J. Michaels[2]. In Shattered Consensus, McKitrick details the attempt of Steven McIntyre[4] 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:

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.

Bob Webster
WEBCommentary (Editor, Publisher)


[1] 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)."

[2] 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.

[3] Ross McKitrick is Associate Professor in the Department of Economics at the University of Guelph, Ontario.

[4] 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.

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