World Population Growth Exceeding Ecological Carrying Capacity

Achieving population stability through reproductive health education and family planning is necessary to sustain Earth’s natural systems.

| April 2016

World population growth

Earth’s rapid population growth has created an increased demand for resources such as water, lumber, soil, and livestock. Stabilizing world population is crucial to preserving vital environmental resources.

Photo by Fotolia/Stéphane Bidouze

Full Planet, Empty Plates: The New Geopolitics of Food Scarcity (W. W. Norton and Company, 2012) by Lester R. Brown explains why world food supplies are tightening, and what we need to do about it. A leading environmentalist, Brown examines the factors contributing to global food shortages. The following selection taken from Chapter 2: The Ecology of Population Growth discusses how increased human demand is depleting Earth’s natural resources.

The Ecology of Population Growth

Throughout most of human existence, population growth has been so slow as to be imperceptible within a single generation. Reaching a global population of 1 billion in 1804 required the entire time since modern humans appeared on the scene. To add the second billion, it took until 1927, just over a century. Thirty-three years later, in 1960, world population reached 3 billion. Then the pace sped up, as we added another billion every 13 years or so until we hit 7 billion in late 2011.

One of the consequences of this explosive growth in human numbers is that  human demands have outrun the carrying capacity of the economy’s natural support systems — its forests, fisheries, grasslands, aquifers, and soils. Once demand exceeds the sustainable yield of these natural systems, additional demand can only be satisfied by consuming the resource base itself. We call this overcutting, overfishing, overgrazing, overpumping, and overplowing. It is these overages that are undermining our global civilization.

The exponential growth that has led to this explosive increase in our numbers is not always an easy concept to grasp. As a result, not many of us — including political leaders — realize that a 3 percent annual rate of growth will actually lead to a 20-fold growth in a century.

The French use a riddle to teach exponential growth to schoolchildren. A lily pond, so the riddle goes, contains a single leaf. Each day the number of leaves doubles — two leaves the second day, four the third, eight the fourth, and so on. Question: “If the pond is full on the thirtieth day, at what point is it half full?” Answer: “On the twenty-ninth day.” Our global lily pond may already be in the thirtieth day.

The most recent U.N. demographic projections show world population growing to 9.3 billion by 2050, an addition of 2.3 billion people. Most people think these demographic projections, like most of those made over the last half-century, will in fact materialize. But this is unlikely, given the difficulties in expanding the food supply, such as those posed by spreading water shortages and global warming. We are fast outgrowing the earth’s capacity to sustain our increasing numbers.

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