Stephen Hawking has been talking about Earth becoming like Venus: unliveable.
Generating conditions such as those on Venus, is probably unlikely – and its probably not useful to mention them, as it gives people an excuse not to believe anything about ecological crisis, or to cop out from action, claiming these are just tales of gloom and doom, nothing real.
I have also heard tales of gloom and doom my entire life. However, it is true that we only avoided nuclear war by the finest of margins. Both Russia and the US were about to make mistaken responses on several occasions, and it was only the reluctance of the people on the ground to launch that saved us. We have depended on individual people acting according to their conscience and understanding. They risked unapproved action. Avoiding catastrophe now, requires the same conscience and understanding and action.
It is a simple matter of logic that you cannot keep destroying, and demanding more from, the environment that you depend on for ever. It would seem that we are reaching the ends of what we can demand from the world in quite a few different systems, some of which get no media attention at all (peak phosphorus for example). The breaking of these systems will produce massive tumult and destruction.
If we continue as we are doing, conditions for any complex civilisation will get more and more precarious. Continuing is not a conservative policy, it is a destructive one.
It is not Trump’s withdrawal from the Paris Agreement that is the problem. It is Trump’s slackening of rules which allow corporations to poison people and the environment, together with his regulative hostility to renewables that is the problem.
Basically, action in the US has to be at the State level. It has to refuse more coal mines and coal based power stations and phase out those which exist. We have to stop fracking, and stop the leakage of gas through crappy pipelines. We have to encourage renewables. We have to make corporations responsible for the pollution and poison they produce. There are no economic externalities in a (more or less) closed system. Non of this will be easy and it may have deleterious consequences as we sort things out and change expectations.
It will involve a massive political conflict, but Trump just makes this explicit. Under Clinton it would have been obstruction in Congress, and the hope that things will be alright. Under Trump there is no Congressional obstruction to destruction, and people have to take back their own power and conscience. There is no alternative. It is up to you and your ability to cooperate with others.