When a hockey stick becomes just a straight piece of wood, with splinters...

Climate change/global warming evangelists have long treasured the infamous "hockey stick" graph, that purports to show the rapid increase in global warming that is being attributed to anthropogenic events in the 20th century. Indeed, the IPCC report (remember the 2500 "scientists" who authored this baloney?) needed, and depended on it.

Steve McIntyre, retired Canadian climatologist/statistician, took exception to the statistical methods used to create the "stick", especially the upturned "blade" of anthropogenic global warming (AGW), and pursued the derivation of this upturn, both directly and in print with Ross McKitrick of the University of Guelph, (and author, with Christopher Essex, of Taken by Storm, The Troubled Science, Policy, and Politics of Global Warming), believing, rightly so, that it was unsupportable by the math.

The tale is long and convoluted, and paints an ugly picture of climate science gone very bad, of political meddling, pandering and malfeasance. McIntyre has chronicled much of this highly technical story at his website Climate Audit, but the story is difficult for lay readers to piece together.

Kim at Bishop Hill blog has put together a lengthy lay chronology of the story of the stick, and sheds light on how badly the world has been misled by the IPCC, Al Gore, and a pliant leftist media.

There's discussion of the Hill article at Climate Audit, here, and Roger Pielke Jr. has written more discussion here at Prometheus: Science and Policy Blog. Its important to note McIntyre's commentary to the Bishop Hill piece, here, in the comments.

McIntyre:
[...]

People have argued - if the Stick is wrong, then the situation is much worse than we think it is. My answer to that is simple: well, if it's wrong, then we should know and govern ourselves accordingly; if it means policy action is more urgent, then so be it. But we should not thank the authors whose withholding of data and obstruction has made it so much harder to detect the error than it should have been. And if this is a risk, other people besides me should have taken some initiative in vetting the Stick.

The other issue that it speaks to is the form of due diligence. Whether or not the Stick was a "real" argument, it was clearly represented by IPCC as an important argument. That's what caught my attention, not that I thought that it would be particularly easy to break. It was said to be important.

There's a definite foolhardiness and contemptuousness of the public by the IPCC and, in particular, the core of the Hockey Team. The Wahl and Ammann process has been publicized at a popular blog; a lot of people have followed this particular story. Every step of the process has been publicly documented. You'd think that they'd have been extra diligent in their reviewing. Instead, what we see is one thing botched after another and one sly maneouver after another.

If this is representative of how climate articles are written and how climate peer reviewing is done, what a pathetic performance. They might say - well, this is a bad example. To which I'd say, well, you knew that it was in the public eye, it should have been a good example, why wasn't it?

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Bishop Hill:

At some time or another, most people will have seen the hockey stick - the iconic graph which purports to show that after centuries of stable temperatures, the second half of the twentieth century saw a sudden and unprecedented warming of the globe. This was caused, we were told, by mankind burning fossil fuels and releasing carbon dioxide into the atmosphere. For a while, the hockey stick was everywhere - unimpeachable evidence that mankind was damaging the planet - an impact that would require drastic measures to reverse. The stick's most famous outing however was just a couple of years ago when it made a headlining appearance in Al Gore's drama-documentary, An Inconvenient Truth. The revelation of the long, thin graph with its dramatic temperature rise in the last few decades, and the audience gasps that accompanied it, is something of a key moment for many environmentalists.

Shortly after its publication, the hockey stick and its main author, Michael Mann, came under attack from Steve McIntyre, a retired statistician from Canada. In a series of scientific papers and later on his blog, Climate Audit, McIntyre took issue with the novel statistical procedures used by the hockey stick's authors. He was able to demonstrate that the way they had extracted the temperature signal from the tree ring records was biased so as to choose hockey-stick shaped graphs in preference to other shapes, and criticised Mann for not publishing the cross validation R2, a statistical measure of how well the temperature reconstruction correlated with actual temperature records. He also showed that the appearance of the graph was due solely to the use of an estimate of historic temperatures based on tree rings from bristlecone pines, a species that was known to be problematic for this kind of reconstruction....

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In other words, far from confirming the scientific integrity of the hockey stick, Wahl and Amman's work confirmed McIntyre's criticisms of it! McIntyre's first action as a peer reviewer was therefore to request from Wahl and Amman the verification statistics for their replication of the stick. Confirmation that the R2 was close to zero would strike a serious blow at Wahl and Amman's work.

Caspar AmmanWahl and Amman's response was to refuse any access to the verification numbers, a clear flouting of the journal's rules. As a justification of this extraordinary action, they claimed that they had shown that McIntyre's criticisms had been rebutted in their forthcoming GRL paper, despite the fact that the paper had been rejected by the journal some days earlier. At the start of July, with his review of the CC paper complete, McIntyre took the opportunity to probe this point, by asking the journal to find out the anticipated publication date of the GRL paper. Wahl and Amman were forced to admit the rejection, but they declared that it was unjustified and that they would seek publication elsewhere.

[...]

As 2005 neared its end, two important events loomed large. The first was the year end deadline for submission of papers for the IPCC's Fourth Assessment Report on the state of the climate, and realisation soon dawned on McIntyre and the observers of the goings-on at GRL:

the IPCC needed to have the Wahl and Amman papers in the report so that they could continue to use the hockey stick, with its frightening and unprecedented uptick in temperatures. Mountains were going to be moved to keep the papers in play.

[...]

That the statistical foundations on which they had built this paleoclimate castle were a swamp of misrepresentation, deceit and malfeasance was, to Wahl and Amman, an irrelevance. For political and public consumption, the hockey stick still lived, ready to guide political decision-making for years to come.