Global Demographic Change: Dimensions and Economic Significance

摘要

Until the early eighteenth century, global population size was relatively static and the lives of the vast majority of people were "nasty, brutish, and short." Since then, the size and structure of the global population have undergone extraordinary change. More than three decades have been added to life expectancy, with a further gain of one or two more decades commonly projected for this century. World population has increased by an order of magnitude to over 6 billion and is projected to reach 9 billion by mid-century. Past and projected additions to world population have been, and will increasingly be, distributed unevenly across the world. The disparities reflect the existence of considerable heterogeneity in birth, death, and migration rates, both over time and across national populations, races, and ethnic groups. Coupled with the projected increase in global population is a complicated set of age structure dynamics, including a near tripling of the population aged 60 and older by the year 2050.