Hansen says we are at or past the tipping point.
I say if so, then reducing CO2 is useless
So Hansen doesn't say that it's useless, and you don't say it either (at least not in that statement), you just say that if Hansen is right, than reductions are useless.
Then I disagree with Hansen (and not just about the tipping point issue), and partially agree with you. Depending on the exact nature of the tipping point, reduction of CO2 may or may not be useless. If we assume that severe AGW problems are unavoidable no matter what we do, its possible that reducing CO2 might reduce the severity of the unavoidable and still serious problems.
OTOH, with the same assumptions, reducing CO2 might make things worse. If it doesn't make a huge difference in the temperature, but does have a massive economic cost, than we might be less able to deal with the problems, and adapt to new conditions.
Of course I don't think that such a tipping point has happened, is about to happen, or can be demonstrated at all (at least absent it actually happening, and the results being realized, and the results being an extremely massive disaster, which is a scenario I don't consider likely). |
