a) Your characterization of the released emails and data is... well, bullshit.
Corrupting peer review by blackballing 'unreliable' voices, conspiring to oust "troublesome" journal editors, keeping published papers out of the IPCC "even if we have to redefine what the peer-review litterature is", etc. is not "playing with scenarios".
Rigging your models to paper over huge flaws (I.e. tree rings not being good temperature proxies) is not "playing with scenarios".
Deleting data and programs rather than keeping them open for review, even when illegal, is not "playing with scenarios".
And the sheer incompetence on display in their modelling is most certainly not "playing with scenarios".
And so on.
Now, moving on to the issue of extrapolation: We don't know either way, but we can make educated guesses.
- We now know that some of the leading people in the field behave in a corrupt manner to reach their preordained conclusions.
- We have long known that the field has built up a perverse incentive structure, where holding "correct" views yields career advancement and public prestige, while holding "incorrect" views leads to career death and public ostracism.
Needless to say, good science is rarely produced under those conditions.