True - but the point is even larger than that. The Greenland ice mass melting or AMOC stopping would be very dramatic, consequential outcomes. But would they cause civilization to collapse? Almost certainly not. While these are “tipping point” scenarios, it would still take centuries for Greenland ice mass to melt - “tipping point” simply means there’s no way to ever stop it. And the AMOC stopping would certainly make Europe a lot colder than today - but again, hardly likely to cause European civilization to collapse, just because temps got to 2-3 C below pre-industrial instead of above.
I am not assuming that there is very little probability of serious consequences from climate change. I am arguing that there is virtually no probability that climate change can result in consequences to people living in OECD economies that are sufficient to result in their civilizations collapsing. There can be quite serious consequences to climate change - as you point out, WWII was itself a catastrophe - without destroying civilization.
Maybe. I actually kind of doubt it - I think that the response of the OECD nations would be to try to help in different ways. Either helping everyone move to where they need to move to through disaster relief, or by agricultural programs so that people can stay where they are without starving - either direct imports or investing in agricultural reform so that the domestic food production that does adapt to changed monsoon patterns is more efficient. Because collective action problems and domestic politics make it all-but-impossible to “avoid that occurring,” but it’s much simpler to do the other things.