I completely agree with you that agriculture will be changed in some areas, but I'd like to know why you think it might become literally impossible in some area

I completely agree with you that agriculture will be changed in some areas, but I'd like to know why you think it might become literally impossible in some areas. The big change will not be in the temperature, but in water supply. But irrigation is a quite well explored technology and how we can have thriving countries setup in the middle of literal deserts, though often in today's global world nations optimize for what's easiest and import as necessary instead of going through the effort to ensure self sufficiency.