Mann’s got an interesting problem. His various hockey sticks show incredibly low temperature variability until about 1850 or so. But his and his counterparts models assume the climate temperature system is dominated by very high positive feedbacks that multiply even tiny changes to forcings into large temperature swings. These two points of view are extraordinarily hard to reconcile.
Similarly, climate alarmists assume that some sort of natural phenomenon is hiding or masking warming for the last decade. Given their forecasts, this has to be a pretty muscular phenomenon, but at the same time they have to argue that natural factors are not muscular enough to have cause much or any of the temperature increases in the 1980s and 1990s.
The ability to handle cognitive dissonance is important in climate science.