Locknuts on 15 December 2016
This statement actually rings pretty true. The feedbacks in the climate are not properly understood. This is why the climate sensitivity estimates for a doubling of Co2 haven't really changed from 3C + or - 1.5C since I think 1992.
Also, this is just one factor. The Earth's climate is incredibly complex. We know that Co2 causes warming but the rest is really up in the air (pardon the pun).
They are slowly narrowing things down the more we learn and the more research is done, but overall Trump is right: nobody really knows to a point where we should be legislating on this stuff.
