Seconding this! It's not "in the year 2050, all the shit will hit the fan." It's "everywhere will be getting a little more extreme every decade, on average." There are various extreme thresholds (too hot or cold, wet or dry) beyond which human life cannot thrive. The point of "fcked" in a given region would occur when the conditions move beyond that threshold. This is why regions where humans already live close to that climatological threshold - deserts, vulnerable coastlines, dangerous monsoon regions - will be some of the first to go.