For a start, scientific evidence is always incomplete and never finally convincing. And it is always possible to go on claiming that the data have been misinterpreted. Meanwhile the call for 'more research' is often just a stalling tactic. By then, of course, the politicians will have forgotten all about it. So will the public.
Words come cheap.
I think the threat of environmental disaster is the wrong motive for environmental action. Some Greens try to justify their prophecies of global apocalypse by pointing out that fear is a good spur to action. I doubt it. Fear does not lead to action, but to a desire to avoid facing up to reality. Only if we develop a coherent positive vision of the kind of world we want to see will we be able to capture people's creative imaginations and their energies.