The end of the hockey stick?

Anthony Watts has this layman's summary of a rather lengthy, technical discussion on why the global warming hockey stick - isn't.

For my green Christian family: Consider this breaking news an important discussion on the science of global warming, not an attempt to undermine your faith or encourage anybody to dodge our stewardship of the planet.

Grace and peace,

Don

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1- In 1998 a paper is published by Dr. Michael Mann. Then at the University of Virginia, now a Penn State climatologist, and co-authors Bradley and Hughes. The paper is named: Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations. The paper becomes known as MBH98.

The conclusion of tree ring reconstruction of climate for the past 1000 years is that we are now in the hottest period in modern history, ever. See the graph http://www.ncdc.noaa.gov/paleo/image/mann/manna_99.gif

Steve McIntyre, a Canadian mathematician in Toronto, suspects tree rings aren’t telling a valid story with that giant uptick at the right side of the graph, implicating the 20th century as the “hottest period in 1000 years”, which alarmists latch onto as proof of AGW. The graph is dubbed as the “Hockey Stick” and becomes famous worldwide. Al Gore uses it in his movie An Inconvenient Truth in the famous “elevator scene”.

2- Steve attempts to replicate Michael Mann’s tree ring work in the paper MBH98, but is stymied by lack of data archiving. He sends dozens of letters over the years trying to get access to data but access is denied. McIntyre and Ross McKitrick, of the University of Guelph publish a paper in 2004 criticizing the work. A new website is formed in 2004 called Real Climate, by the people who put together the tree ring data and they denounce the scientific criticism:

http://www.realclimate.org/index.php/archives/2004/12/false-claims-by-mcintyre-and-mckitrick-regarding-the-mann-et-al-1998reconstruction/

3- Years go by. McIntyre is still stymied trying to get access to the original source data so that he can replicate the Mann 1998 conclusion. In 2008 Mann publishes another paper in bolstering his tree ring claim due to all of the controversy surrounding it. A Mann co-author and source of tree ring data (Professor Keith Briffa of the Hadley UK Climate Research Unit) used one of the tree ring data series (Yamal in Russia) in a paper published in the Philosophical Transactions of the Royal Society in 2008, which has a strict data archiving policy. Thanks to that policy, Steve McIntyre fought and won access to that data just last week.

4- Having the Yamal data in complete form, McIntyre replicates it, and discovers that one of Mann’s co-authors, Briffa, had cherry picked 10 trees data sets out of a much larger set of trees sampled in Yamal.

5- When all of the tree ring data from Yamal is plotted, the famous hockey stick disappears. Not only does it disappear, but goes negative. The conclusion is inescapable. The tree ring data was hand picked to get the desired result.

These are the relevant graphs from McIntyre showing what the newly available data demonstrates.

http://www.climateaudit.org/wp-content/uploads/2009/09/rcs_chronologies1.gif

http://www.climateaudit.org/wp-content/uploads/2009/09/rcs_merged.gif

UPDATE: Related information on the "hockey stick" source data:

In addition to providing another reason to reject the “science is settled” dogma, disappearance of the Jones-Wigley data is of direct relevance to EPA’s pending endangerment finding. The Jones-Wigley temperature record is part of the evidence on which EPA bases its judgment that “air pollution” from greenhouse gas emissions “endangers public health and welfare.”

Use of the Jones-Wigley temperature record in a rulemaking clearly flouts federal data quality standards. Under OMB guidelines implementing the Federal Data Quality Act, data quality consists of four elements: objectivity, utility to users, integrity of information, and reproducibility in the case of “influential scientific or statistical information.”

Now, if the original Jones-Wigely data have been destroyed, then it is impossible to assure “integrity of information.” For all we know, Jones and Wigley goofed in their calculations or choice of methodologies, or even manipulated the data to produce a pre-determined result. By the same token, it is impossible to “reproduce” the Jones-Wigley temperature record, because there are no data to reproduce it from. Yet, as a factual basis of both the IPCC reports and the EPA endangerment finding, Jones-Wigley indisputably qualifies as “influential scientific or statistical information.”