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The Tree Ring Circus July 28, 2010

Posted by honestclimate in Discussions.
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The Tree Ring Circus

By John Dawson
Quadrant Online, July 28, 2010

The Hockey Stick Illusion is the shocking story of a graph called the Hockey Stick. It is also a textbook of tree ring analysis, a code-breaking adventure, an intriguing detective story, an exposé of a scientific and political travesty, and the tale of a herculean struggle between a self-funded sceptic and a publicly funded hydra, all presented in the measured style of an analytical treatise. The hero of the story is Steve McIntyre, honourably assisted by fellow sceptics, especially by Ross McKitrick. The villain is Michael Mann, dishonourably assisted by global warming alarmists, especially by his “Hockey Team”. The bare bones of the Hockey Stick story are as follows.

In its First Assessment Report published in 1990, the Intergovernmental Panel on Climate Change (IPCC) presented the conventional view of climate history: that around a thousand years ago there was a Medieval Warm Period, followed by a Little Ice Age, followed by the Current Warm Period that has not yet reached the temperatures experienced during the Medieval Warm Period. In 1995 the IPCC’s Second Assessment Report presented that view again but introduced some doubt about the Medieval Warm Period, suggesting that further investigation was required. It had dawned on global warming crusaders that the Medieval Warm Period was a huge problem for the Anthropogenic Global Warming (AGW) hypothesis and that fame and fortune awaited a scientist who could get rid of it.

The scientist who took the prize was a brash and ambitious American paleoclimatologist, Dr Michael Mann. With two of his more senior colleagues, Mann set about investigating the earth’s temperature over the last millennium by scouring the world’s research projects that had detected past temperatures by way of temperature “proxies” such as tree rings. The amount of data they collated and the sophistication of their statistical analysis, claimed Mann, ensured that their conclusions would be more “robust” than those of previous studies. Their first peer-reviewed paper (MBH98) was published in the prestigious journal Nature in 1998 and their second (MBH99) was published in Geophysical Research Letters (GRL) in 1999. The graphed summation of these papers wiped the Medieval Warm Period and the Little Ice Age out of the picture and replaced them with a flat-lined handle declining slightly from 1000 to 1900 then bending upwards into a twentieth-century blade of rapidly rising temperatures.

This “Hockey Stick” graph was immediately seized by AGW crusaders. Typical of the reaction was that of Gerry North of Texas A&M University who enthused: “The planet had been cooling slowly until 120 years ago, when, bam!, it jumps up … We’ve been breaking our backs on [greenhouse] detection, but I found the 1000-year records more convincing than any of our detection studies.” Almost overnight the Hockey Stick became the new gold standard of paleoclimatology.

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1. John Dawson - August 5, 2010

PS: Michael Mann and his team are still running to form. For a summary of the latest round go to

Since September 2008, Mann and his disciples have maintained the argument that the erroneous use Dr Tiljander’s study didn’t matter because they could validate their Hockey Stick without it, and without tree rings. But they have been forced to surreptitiously concede that without Tiljander and tree rings they can’t validate their Hockey Stick earlier than 1500 AD, which means they can’t validate it at all.

This back down was slipped into a rationalization in Mann et al 2009, and into an unscrupulous attack on McIntyre and Montford on realclimate.org, where the moderator’s obfuscations included this little gem: “the exact level of medieval warmth is not a very interesting scientific question” anyway.

So what about the widely publicized claims made in 2008 that a Hockey Stick could be validated without tree rings and even extended from 1000 to 1300 years? The team is still trying to bluff its way through, trusting that the scientific community will not want to scrutinize their past claims, and that the media will carry the AGW crusade forward on the next round of alarmism.

2. Jack Watch - August 19, 2011

I’m a bit of a graph fan myself, and have been intrigued by natural response graphs seen in the various scientific disciplines. One of my favorites is, and has been the hysteresis type of response curve. It has character; and one might intuit, a human nature. The inertia or stubbornness of a system, or resistance to change if you will. I’ve seen this demonstrated in general physics as it demonstrated the magnetic flux (? its been a while) as a function of applied current in the standard electromagnet. There is resistant to the initial stable state, but it (magnetic field) conforms with increasing current. And when the driving force is removed the material’s finds itself returning to a new location as a point of origin. The current is reversed and a similar, but negative, reaction occurs. I’ve seen papers demonstrating a similar response of global ice accumulation to changes in global temperature. The point here being that the trip back to the “presumed equilibrium” may not be along the same (acceptable) pathway. If one were to apply a hysteresis type of response to this situation, one might find themselves in a global ice-age of biblical proportion. Question: Is this something we want the current people (world governments) to be in control of, given their records of achievements over the last century?

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