The trend may now be changing for the worse, however. Since about 1990 global grain production has risen only slightly and, despite slower rates of population growth, grain supplies per capita have fallen. In the worst case, Africa now produces nearly 30% less food per person than it did in 1967 (54, 117). The reasons for the change in the trend include not only rapid population growth on the demand side, but also higher population densities in traditional agricultural areas, fragmentation of small farmsteads, poor land management, and inappropriate agricultural and economic policies, all of which suppress supply (47, 117).

With one-third of world population lacking food security now, FAO estimates that world food production would have to double to provide food security for the 8 billion people projected for 2025 (98, 99). By 2050, when world population is projected to be over 9 billion, the situation would be even more challenging. At current levels of consumption, without allowing for additional imports of food, Africa would have to increase food production by 300% to provide minimally adequate diets for the 2 billion people projected in 2050; Latin America would have to increase food production by 80% to feed a projected 810 million people; and Asia's food production would have to grow by 70% to feed the 5.4 billion people projected. Even North America would have to increase food production by 30% to feed a projected 384 million people in 2050 (36, 85).

Rapid population growth not only pushes up demand for food but may also be starting to diminish supply as well (8, 33, 35, 99). As people try to obtain higher yields from heavily used natural resources, soil loss worsens, fresh water becomes scarcer, and pollution increases. As a result the developing world's capacity to expand food production may well be shrinking, not expanding (8, 22, 53, 65, 97, 100).