Buying Time

Unceasing population growth, especially rapid growth, can accelerate the evolution of problems relating to the environment, economic development, national and community security, and individual well-being.

Population growth shortens the time and reduces the options available for citizens and their governments to address these problems, and it raises the risk that otherwise manageable challenges will turn into crises and disasters. When policymakers struggle to resolve increasingly complex social, economic and environmental problems, their proposals rarely attract the consensus and public support needed for implementation. By themselves, neither slower population growth nor an end to that growth would solve these problems. Either, however, would offer societies more time to search for solutions.

The Likelihood of Surprises Even if a particular environmental trend seems unthreatening or manageable today, we should not rule out sudden and dramatic changes that occur as population-related pressures exceed critical natural thresholds. A simple example of such a natural threshold is the freezing point of water, which stays in liquid form as the air gets colder until it reaches 32 degrees Fahrenheit‹and city streets that once were merely wet become sheets of hazardous ice.

On farmland a threshold may emerge when farmers find their crops no longer grow well because, after years of seemingly harmless soil erosion, root growth is constrained by bedrock a foot beneath the soil surface. Such threshold effects could create havoc in areas related to climate, food or water supply, or infectious disease.

Our knowledge about the interactions of human beings and the physical and biological worlds is incomplete. Only rarely can we predict the existence or location of natural thresholds before we cross them, and we may fully understand them only in retrospect. Even in today's world the impacts of past population growth are less obvious, the past may be a poor guide to the impacts of population growth in the future. The population momentum inherent in today's population structure means that even if the world¹s current population posed no serious risk to the environment, future population growth–and hence greater risk–is all but certain.