Controversially, ignoring ethical aspects, you could eliminate most violent crime by killing off the poorest people in each country. You could prevent child abuse by killing children. You could encourage any kind of behavior you want by randomly killing people who disobey your demands. Wouldn't life be great if you were an authoritarian dictator with no morals.
Apart from the fact that this is logical fallacy, all your examples are not civilisation ending scenarios.
If we both are on a cliff face and you fell off, and now you are dangling connected by rope to only me. Standard movie trope.
Now because of your weight my only options are to cut the rope - you die, or wait and we both die. This is more accurate example we are talking about here, not killing poor people because 'crime'.
Also I would like to point out that poor people are not root cause of crime. So you are not tackling actual problem, only applying band-aid solutions. But that's a tangential topic.
Sure. But neither does inciting murder. Some problems can't be solved just by being angry enough to kill people you hate. The oil industry will continue no matter who you kill or how dangerous it becomes because everyone and their dog will be throwing money at whoever can supply oil.
I am too old and cynical to be angry at anybody, my point was that (ignoring ethical matters) the likely spawning of environmental extreme groups would act as an incentive equalizer for the current status quo.
There is too big of an asymmetry with the current situation: profits, tax incentives, lobbying, and regulatory capture. This is not something that the average person can address from within the existing judiciary system.
At the moment you will need either something that will make carbon emissions unprofitable, or an epiphany from those abusing the status quo, that would lead to de facto climate regulation. Neither of those will happen without some incentive (positive or negative).