Arabica coffee, which makes up most of the speciality market, grows well only in a narrow band of temperature and rainfall, typically on hillsides at altitude in the tropics. As those regions warm, the suitable band moves uphill, and there is a limit to how far it can move before the hill ends. Farmers in Central America have already abandoned lower plots and planted higher ones. Where no higher ground exists, the choice is between a different crop and a different variety.