Well, we know that even if humanity vanished overnight, carbon dioxide driven warming will continue, just because of the time taken to remove co2 from the atmosphere.

We have increasingly better ideas of how the world will look like...and if we have ranges then we have an idea of how sensitive climate is to carbon.

All of which directly point to the fact that the world will warm, and it's a question of how fast. The question of how long this will go on, is beyond science because it's a political question - warming will stop years after we stop adding to the heat cycle.

I'm also a bit confused as to how you say "we don't know what the earth at +5 looks like", because countries (other than America) are already deploying resources to manage migration and movement, we know other countries and islands will disappear with sea level rises. I know my country has been grappling with water scarcity issues, and people don't argue about global warming, the same way they don't argue about evolution.

Matter of fact the only major country I know which actively engages and exports denialism is America. India and China are fighting for economic stability, but no one doubts that this is a crisis that has to be solved.

I'm confuxsed by your question, as most of these are answered to some degree or the other on the net or on Reddit. You could just head to a r/science climate AMA and get your answers.