This seems like a general argument that "unexpected bad things might happen". I agree, sure - but this argument applies equally to, for example, alien invasions

This seems like a general argument that "unexpected bad things might happen". I agree, sure - but this argument applies equally to, for example, alien invasions or grey goo. The question I'm addressing is whether global warming will cause civilization to collapse or humans to go extinct. I claim no serious climate scientist thinks that.