But then a growing number of academics began to raise doubts about Mann and his graph. This culminated in 2003 with a devastating study by two Canadians showing how Mann had not only ignored most of the evidence before him but had used an algorithm that would produce a hockey stick graph whatever evidence was fed into the computer. When this was removed, the graph re-emerged just as it had looked before, showing the Middle Ages as hotter than today.It is hard to recall any scientific thesis ever being so comprehensively discredited as the "hockey stick". Yet the global warming juggernaut rolled on regardless, now led by the European Union. In 2004, thanks to a highly dubious deal between the EU and Putin's Russia, stage four of the story began when the Kyoto treaty was finally ratified.
An interesting (and skeptical) look at the politics of global warming.