– The direction of the (expected) changes is clear
– Globe is warming
– It’s due to us
– It’s bad news
– Carbon is forever; Aerosols are not
– Uncertainty + Inertia = Danger
That is the short version of what scientists know about climate change.
And a normative statement:
– Science should inform policy measures. We are used to that regarding human health; we should also get used to it regarding climate change.
update: See here for a more elaborate description of the scientific consensus on climate change.