'Hockey stick' graph statistically insignificant

Every good hockey mom knows that you don’t compare apples and oranges but some scientists think it is ok to compare temperature data that comes from thermometers, Tree rings, Ice samples and other data to come up with a graph and smooths data so much that it doesn’t even have midevel warming period noticeable in the graph.  if the graph is so accurate where is that increase?  Well, even though this study didn’t find fraud on the part of the assembler of the graph it just wouldn’t look good if there were spikes in warming when their were no automobiles.

What about the warming that occurs every five thousand years or so in the Sahara Desert?  It is disingenuous to not include data that shows times of warming less man–made pollution.  Do these folks really believe that people wouldn’t fact-check Al Gore?

Professor David Hand said that the research – led by US scientist Michael Mann – would have shown less dramatic results if more reliable techniques had been used to analyse the data.

Prof Hand was among a group of experts charged with investigating the “climategate” email scandal that engulfed the University of East Anglia’s Climatic Research Unit (CRU) last year.

Sceptics claimed that the hacked messages showed scientists were manipulating data to support a theory of man-made global warming.

However the review, led by Lord Oxburgh into the research carried out by the centre, found no evidence of ”deliberate scientific malpractice”.

Lord Oxburgh said the scientists at the research unit arrived at their conclusions ”honestly and sensibly”.

But the reviewers found that the scientists could have used better statistical methods in analysing some of their data, although it was unlikely to have made much difference to their results.

That was not the case with some previous climate change reports, where “inappropriate methods” had exaggerated the global warming phenomenon.

Prof Hand singled out a 1998 paper by Prof Mann of Pennsylvania State University, a constant target for climate change sceptics, as an example of this.

He said the graph, that showed global temperature records going back 1,000 years, was exaggerated – although any reproduction using improved techniques is likely to also show a sharp rise in global warming. He agreed the graph would be more like a field hockey stick than the ice hockey blade it was originally compared to.

“The particular technique they used exaggerated the size of the blade at the end of the hockey stick. Had they used an appropriate technique the size of the blade of the hockey stick would have been smaller,” he said. “The change in temperature is not as great over the 20th century compared to the past as suggested by the Mann paper.”

via ‘Hockey stick’ graph was exaggerated – Telegraph.

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Here is the other side of the story

The hockey graph was first published in a 1999 paper (pdf) by Michael Mann and colleagues, which was an extension of a 1998 study in Nature. The graph was highlighted in the 2001 report of the Intergovernmental Panel on Climate Change (IPCC).

Since 2001, there have been repeated claims that the reconstruction is at best seriously flawed and at worst a fraud, no more than an artefact of the statistical methods used to create it (see The great hockey stick debate).

Details of the claims and counterclaims involve lengthy and arcane statistical arguments, so let’s skip straight to the 2006 report of the US National Academy of Science (pdf). The academy was asked by Congress to assess the validity of temperature reconstructions, including the hockey stick.

via Climate myths: The ‘hockey stick’ graph has been proven wrong – environment – 16 May 2007 – New Scientist.

Climate myths: The ‘hockey stick’ graph has been proven wrong

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