Exponential Population Growth and Doubling Times: Are They Dead or Merely Quiescent?

Abstract

“Exponential Growth” and “Doubling Times”: Use of these popular population buzzwords of the last half of the twentieth century was fully justified by the growth rates of that period. However, those growth rates have now all but disappeared and so have the underlying reasons that those buzzwords made sense. Misuse of such expressions today costs credibility. Though the world's population growth certainly does remain vigorous and robust, creating many reasons for concern, nowhere today is growth projected as exponential. The essence of exponential growth is analyzed and distinguished from exponential curves, and non-exponential growth. Several types of current population growth are recognized, none being exponential. In periods of non-exponential growth, a “Doubling Time” calculated from a single annual growth rate is grossly erroneous and often absurd. Other standard measures of growth are needed. United Nations projections should include figures for percentage growth by 2025 and 2050.