"Hadley expresses temperature changes in terms of deviations from the 1961 to 1990 average. In 2002 the rounded global temperature for land and sea was 0.46 above that average. In the next five years it was: 0.46, 0.43, 0.48, 0.42, and 0.40. The figures for the date centre are calculated slightly differently, but they too show no trend over the period in question.


What does this mean? Some global warming sceptics say these figures disprove the basic hypothesis of global warming, that rising greenhouse gas emissions automatically produce rising temperatures. Some have looked back to 1998, an unusually hot year (0.52 on Hadley's list) and said that global warming actually stopped back then. They conclude that after 10 years we can now say global warming is over, and we face the possibility of global cooling."

"Proper statistical analysis relies on a kind of blindness."

"What Duffy did is look at his data, and try to find a way of presenting it that appeared to support his pre-selected conclusion. And he managed to find one. He didn't show a complete analysis - he couldn't, because a complete analysis would have refuted his argument. So he selectively chose a way of analyzing the data that would produce the desired results: he looked at the data to find the longest period where trend analysis would show what he wanted - and he stopped there."