The Tree Ring Circus July 28, 2010Posted by honestclimate in Discussions.
Tags: climate change, Climategate, global warming, ipcc, michael mann
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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