"Rainfed agriculture in marginal areas in semi-arid and sub-humid regions is mostly at risk," an FAO statement quoted Director-General Jacques Diouf as saying.
In contrast, the industrialised countries are likely to gain in production potential, Diouf said.
"Crop yield potential is likely to increase at higher latitudes for global average temperature increases of up to 1 to 3 degree centigrade depending on the crop and then decrease beyond that," he said.
"On the contrary, at lower latitudes, especially in the seasonally dry tropics, crop yield potential is likely to decline for even small global temperature rises, which would increase the risk of hunger," he added.
Greater frequency of droughts and floods would affect local production negatively, especially in subsistence sectors at low latitudes, Diouf added.