Cuba is exhibit A in lack of capacity to adjust to a post fossil fuel future w/o some sort of energy substitute. They remain one of the most import dependent countries in the world.  Imports which it can pay for because it gets dirt cheap oil and has a flourishing tourist industry.  Africa would also be completely screwed minus the massive industrial ag surpluses. In general the poorer the country is the less margin it has to adjust to lower amounts of food in the world - they already eat less, and more of their calories come in the form of basic starch crops rather than meat and processed food.