Too many people: Completing the global demographic transition
There is reasonable concern based on historical evidence and projecting current trends that humans tend towards “overshoot and collapse” population dynamics, first increasing carrying capacity and population via extending geographical range, new technologies, displacing other species and appropriating more NPP. The paper reviews ideas and practices to promote intentional “demographic transitions” to lower fertility rates in human populations, based on an evolving literature and experience with successful and unsuccessful demographic transitions in dozens of countries. The paper aims to synthesize ethical, economic, cultural, political and marketing/public opinion aspects of “lessons learned” into a coherent summary outline of how to accomplish population reduction on a case by case basis adapted to local circumstances. A previous ESA poster developed an argument for K*, an optimum human population chosen collectively by humanity, of half a billion, most living in large cities on a green planet. Reversing population growth offers an opportunity to avoid Malthusian resource limits and thereby to avoid increases in density dependent mortality. During the past century a “natural experiment” has occurred with fertility declines at varying rates in dozens of countries, totaling 48% of world population. What lessons can be learned relevant to completing a universal fertility transition?
While average global fertility fell over the past century, divergence occurred, so country fertility rates vary from less than 1 to 7. This variation causes exponential population decline in the low and exponential growth in the high groups. Therefore, the world historical fertility trajectory could be u shaped, first falling then rising as “cultural selection” sends low fertility groups towards vanishing percentages of total population. High fertility norms are deeply embedded in some cultures and worldviews that still prefer large families. Demographic transition theory discusses “direct” and “indirect” determinants of fertility transitions. Probably the most effective transitions have involved “all of the above” in a package of social change linked to other kinds of reforms like improving governance, education, health care and the status of women and effective public relations/education campaigns using sophisticated marketing techniques. Demographic transitions are intentional major social change and thus do not occur automatically, in isolation from other kinds of modernization, nor without investment of effort and resources by individuals, governments and other organizations. By a process of trial and error a great deal has been learned about how to move rapidly to lower fertility rates.