An anonymous reader writes "Berkeley physics professor Richard A. Muller writes that a key study showing a sudden 'hockey stick shape' increase in global temperature may be flawed from bad mathematics. Stephen McIntyre and Ross McKitrick say that Michael Mann's computer program handled data normalization incorrectly and exaggerated data with a hockey stick shape." Update: 10/18 18:26 GMT by J : Alas for the environment, it looks like McKitrick and McIntyre have been refuted. "In previous rounds of the debate, Lambert has shown that McKitrick messed up an analysis of the number of weather stations, showed he knew almost nothing about climate, flunked basic thermodynamics, couldn't handle missing values correctly and invented his own temperature scale. But Tim's latest discovery really takes the cake."