Citrus is adequately adapted to production conditions in three major climate types. Climate change is expected to affect each in different ways. In this chapter, we discuss the mechanisms of tolerance and sensitivity to stresses associated with soil and air moisture, salinity, air temperature, and ambient carbon dioxide. Variations in most of these conditions are expected to pose challenges to citrus production. Increased ambient carbon dioxide is expected to partially mitigate growth losses due to most other environmental stresses. Access to sufficient quality and quantity of irrigation water is the major hurdle for future production. Opportunities for germplasm improvement exist in selecting or developing commercial cultivars with increased tolerance to soil water deficit, flooding, salinity, and high and low temperatures, as well as genotypes with improved growth responses to elevated carbon dioxide.