Found it on an extensive website on global warming, which was so big that I haven't read much of it, though there are some interesting graphs that take relatively little time to view.
The following text is rather big, but it may be a valuable insight into the IPCC scientific method of peer review and the birth of the hockey stick graph...
Oh and I found this funny certainly if it's true:http://ourworld.compuserve.com/homepages/dp5/warm.htm]3. IPCC pseudoscience challenged (...) In support of its claim that the 1990s were the warmest decade and 1998 the warmest year for a millennium wrote:see fig. 3.1[/url]). The graph shows fairly constant temperatures for the last millennium followed by a dramatic rise in the 20th century (the blade of the hockey stick). The accepted view before that, as embodied in a graph in the IPCC’s 1990 report (fig. 3.2), was that the world had undergone a Medieval Warm Period that was warmer than today.
In the 1990 graph, the current warming falls within the range of natural historical variation* [note by lythium: the graph is 17 years old and it does appear temperature rises above the medieval period now], whereas the hockey stick graph makes it look anomalous and alarming. The existence of the Medieval Warm Period and the Little Ice Age, and further back the Dark Ages Cold Period and the Roman Warm Period, had been accepted in textbooks for decades. But such natural climate fluctuations are an embarrassment to the hypothesis that mankind is mainly to blame for the present warming. Indeed, one global warming zealot, in an unguarded moment, stated: ‘We have to get rid of the Medieval Warm Period’ (see Deming, 1995, p. 249). That is exactly what Mann’s team did.
Statistical experts Ross McKitrick and Steve McIntyre published a critique of the hockey stick in the peer-reviewed journal Energy and Environment in 2003 and further critiques in 2005 ([url]http://www.climateaudit.org;[/url] McKitrick, 2005). They criticized MBH98/99 for inappropriate data selection and incorrect use of statistical methods. They had great difficulty getting the necessary information from Michael Mann, who put many obstacles in their path. He refused to release his computer code, saying that ‘giving them the algorithm would be giving in to the intimidation tactics that these people are engaged in’ and that ‘if we allowed that sort of thing to stop us from progressing in science, that would be a very frightening world’!
The MBH temperature reconstruction was based mainly on bristlecone-pine datasets, even though the IPCC had recommended against reliance on bristlecone pines because 20th century CO2 fertilization accelerated annual growth, creating a false impression of exceptional recent warming. Moreover, their statistical model had given these datasets 390 times more prominence than the other datasets they had used. McKitrick and McIntyre found that MBH’s statistical methods nearly always produce a hockey stick shaped graph, even when random numbers are used. They also discovered that MBH had excluded from their calculations a dataset covering the later medieval warm period, which had been stored in a computer file marked ‘Censored-Data’. After correcting these various errors, they found that the 15th century contained an extensive warm period with a higher temperature than the late 20th century.
Prior to McIntyre and McKitrick’s work, no palaeoclimatologist had attempted to replicate MBH98/99. In fact, many climate scientists derided the very idea! The fact that the flawed MBH98 paper passed peer review for Nature magazine speaks volumes. So does the fact that Nature, along with other leading peer-reviewed scientific journals, refused to publish McIntyre and McKitrick’s 2003 article exposing the flawed graph. Only after prolonged pressure did the editors of Nature publish a correction by MBH, who falsely claimed that the flaws made no difference to their results.
The IPCC itself never made any attempt to verify the MBH98/99 findings. This may have something to do with the fact that the lead author of the chapter that gave prominence to the Mann study was none other than Michael Mann himself! Some senior climate scientists have severely criticized the system that allows such conflicts of interest. But it remains in place for the fourth IPCC assessment report, due out in February 2007. As reviewers of the next IPCC report, McIntyre and McKitrick (2006) write:
we have expressed concerns to the IPCC about prominent use of graphics and empirical results from the lead authors’ own freshly published papers, which have not been in print long enough to have undergone adequate, independent review and assessment ...
Independent review is also hindered by the unscientific practice of refusing to disclose datasets and calculations.
The US House of Representatives’ science committee asked the National Academy of Sciences (NAS) to evaluate the criticisms of Mann’s work and assess the larger issue of climate reconstructions. In its report (July 2006), it accepted virtually all the criticisms of the hockey stick, and said that Mann’s data and methodology did not permit him to claim with confidence that 1998 was the warmest year of the millennium or the 1990s the warmest decade. But it still stated that his reconstruction was ‘plausible’ as studies by several other scientists had also concluded that the 20th century was warmer than the Medieval Warm Period.
Another analysis of the hockey stick paper was carried out by a panel of three independent statisticians appointed by the US House of Representatives’ energy and commerce committee. Its report (July 2006) states that the criticisms made by McKitrick and McIntyre are ‘valid and compelling’. Referring to the small band of scientists who dominate the field of climatology, the panel’s leader, Edward Wegman, says:
[T]here is a tightly knit group of individuals who passionately believe in their thesis. However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their own public positions without losing credibility. (Wall Street Journal, 2006)
‘In other words,’ says the Wall Street Journal, ‘climate research often more closely resembles a mutual-admiration society than a competitive and open-minded search for scientific knowledge.’
Regarding the claim that many other studies support Mann’s conclusions, the panel points out that the scientists concerned often work with Mann, and tend to use the same datasets. McIntyre and McKitrick (2006) comment:
We’ve attempted to replicate these other studies as well, only to run into one obstacle after another in identifying data and methods – similar to the problems that led to the original congressional questions about the Mann study. In one case, the authors even refused to identify the sites from which data was collected for their study!
Despite these pointless obstacles, we know enough about the ‘other studies’ to be confident that none of them meets the methodological standards now recommended by the panel. In fact, somewhat remarkably, two of the most recent studies even continue to use Mann’s discredited principal components series [bristlecone pines].
The hockey stick graph was featured six times in the IPCC’s 2001 report, and has been a key weapon in the campaign to convince the public and politicians of the dangers of human-caused warming. Although the graph has been convincingly discredited, the IPCC has not issued an apology or correction and continues to use it in its publications. The Canadian government circulated a copy of the graph to every household in the country, but it too has not circulated any correction.
Gore claims that global warming endangers polar bears even though polar bear populations are increasing in Arctic areas where it is warming and declining in Arctic areas where it is cooling. He states that polar bears ‘have been drowning in significant numbers’ – based on a report that four drowned polar bears were found in one month in one year, following an abrupt storm!
