A simple moral principle:
When a future change is framed as a problem which we might hope our political system to solve, then the only acceptable reason to talk about the consequences of failing to solve that problem is to scare folks into trying harder to solve it. If you instead assume that politics will fail to solve the problem, and analyze the consequences of that in more detail, not to scare people but to work out how to live in that scenario, you are seen as expressing disloyalty to the system and hostility toward those who will suffer from that failure.
Adopted circa 2019
Obligatory Seriousness: