Does demographic entrapment challenge the two-child paradigm?

There has been a slowdown in the rate of increase of world population from 2.1% in 1970 to 1.8% in 1977. However there are no new technologies in prospect which suggest that farmers can restore the 3% increase in global grain production that took place annually from 1950 to 1984. Per capita grain has fallen 12% since 1984 and over the last 10 years the average annual increment in global grain has been 12 million tons. A local population is demographically trapped if it has exceeded or is projected to exceed the combination of: carrying capacity of its own ecosystem its ability to obtain food and its ability to migrate to other ecosystems. A severely trapped population faces the five alternatives of entrapment in varying combination. Rwanda is one of the most densely populated countries in Africa and has the highest total fertility in the world 8.5 children per woman. There is wide agreement that parts of the Indian subcontinent and much of Sub-Saharan Africa are demographically trapped. The World Bank estimates that if current food production and growth trends continue the food shortage for Africa will amount to 250 million tons of grain by 2020 or 20 times its current food gap. The world appears to be moving from a North/South polarity towards a rich/poor one in which Southern elites who are not trapped side with the North. If the current annual grain increment really is only 12 million tons of grain feeding 36 million people this calls for a one-child world if per capita grain is not to continue to fall. The most powerful argument for a one-child world is that if local communities need one-child families to avoid starvation or the other alternatives of entrapment the rest of the world should in the interests of equity do the same.