Arithmetic, Population, and Energy
The following is a small excerpt from the acedemic paper of Dr. Albert Bartlett, Department of Physics, University of Colorado at Boulder.
A friend recently tried to reassure me by asserting that there remained undiscovered under our country at least as much oil as all we have ever used. Since it has been about 120 yr since the first discovery of oil in this country, he was sure that the undiscovered oil would be sufficient for another 120 yr. I had no success in convincing him that if such oil was found it would be sufficient only for one doubling time or about a decade.
As the reader ponders the seriousness of the situation and asks, "What will life be like without petroleum?" the thought arises of heating homes electrically or with solar power and of traveling in electric cars. A far more fundamental problem becomes apparent when one recognizes that modern agriculture is based on petroleum-powered machinery and on petroleum-based fertilizers. This is reflected in a definition of modern agriculture: "Modern agriculture is the use of land to convert petroleum into food."
Item: We have now reached the point in U.S. agriculture where we use 80 gallons of gasoline or its equivalent to raise an acre of corn, but only nine hours of human labor per crop acre for the average of all types of produce.12
Think for a moment of the effect of petroleum on American life. Petroleum has made it possible for American farms to be operated by only a tiny fraction of our population; only 1 American in 26 lived on a farm in 1976. The people thus displaced from our farms by petroleum-based mechanization have migrated to the cities where our ways of life are critically dependent on petroleum. The farms without the large number of people to do the work are also critically dependent on petroleum-based mechanization. The approaching exhaustion of the domestic reserves of petroleum and the rapid depletion of world reserves will have a profound effect on Americans in the cities and on the farms. It is clear that agriculture as we know it will experience major changes within the life expectancy of most of us, and with these changes could come a major further deterioration of world-wide levels of nutrition. The doubling time (36 - 42 yr) of world population (depending on whether the annual growth rate is 1.9 % or 1.64 %) means that we have this period of time in which we must double world food production if we wish to do no better than hold constant the fraction of the world population that is starving. This would mean that the number starving at the end of the doubling time would be twice the number that are starving today. This was put into bold relief by David Pimentel of Cornell University in an invited paper at the 1977 annual meeting of AAPT-APS (Chicago, 1977):