The change in the ipcc seems to have happened between the third report (Kyoto protocol) and fourth report.
There’s a different head of the ipcc for starters. But it’s the difference in science content that is most telling.
For the first and third reports (haven’t read the second), the dominant picture is “climate change has both positive and negative aspects, the negative ones dominate.”
For the fourth report, the dominant picture is “these are the alarmist predictions, how accurate are they really”.
Do you see the difference? For the fourth report, all the positive consequences of climate change are excluded. Which results in a much more biased overall perspective.
I find that the level of scholarship is less for the fourth report as well. For starters, it’s dumbed down. Then there’s the format, which seems to be all extrapolating trends from data series.
As another example, the graph showing world rainfall anomaly as a function of time shows the data togerther with six different smoothing methods. The data speaks for itself, it’s random. At most one smoothing method should be plotted – the best – and even that gives an erronous interpretation of future trends. The mind that would would include six smoothing methods is a mind with zero knowledge of stochastic processes.