All scientific work is incomplete - whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge we already have, to postpone action that it appears to demand at a given time. Who knows, asks Robert Browning, but the world may end tonight? True, but on available evidence most of us make ready to commute on the 8:30 next day.
The increasing frequency of extreme weather events, droughts and floods is in line with what climate scientists have been predicting for decades - and evidence is mounting that what's happening is more severe than predicted, and will get far worse still if we fail to act.