Exponential growth of population

Figure 9. Exponential growth of population, energy utilization, and fertilizer production (Ref. 38)...

Every step in the process has inefficiencies that can be diminished but not eliminated. Also, every option has associated social and economic costs. Probably the one factor that overwhelms all other considerations is population growth. While some will think of this only in terms of their own country or community, the worldwide exponential growth of population together with the improvement in the standard of living should put the possible control of disposal by technical advances in perspective. 

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