Human overpopulation is an animal rights issue as well as an environmental issue and a human rights issue. Human activities, including mining, transportation, pollution, agriculture, development, and logging, take habitat away from wild animals as well as kill animals directly. These activities also contribute to climate change, which threatens even the most remote wild habitats on this planet and our own survival.

According to a survey of the faculty at the SUNY College of Environmental Science and Forestry in April of 2009, overpopulation is the world's worst environmental problem. Dr. Charles A. Hall went so far as to say, “Overpopulation is the only problem.”

Definition

Overpopulation occurs when a population has exceeded its carrying capacity. Carrying capacity is the maximum number of individuals of a species that can exist in a habitat indefinitely without threatening other species in that habitat. It would be difficult to argue that humans are not threatening other species.

Current Estimates and Projections

According to the U.S. Census, there were six billion people in the world in 1999. On October 31, 2011, we hit seven billion. Although growth is slowing, our population continues to grow and will reach nine billion by 2048.

Paul Ehrlich and Anne Ehrlich, authors of “The Population Explosion,” explain:

The entire planet and virtually every nation is already vastly overpopulated. Africa is overpopulated now because, among other indications, its soils and forests are rapidly being depleted—and that implies that its carrying capacity for human beings will be lower in the future than it is now. The United States is overpopulated because it is depleting its soil and water resources and contributing mightily to the destruction of global environmental systems. Europe, Japan, the Soviet Union, and other rich nations are overpopulated because of their massive contributions to the carbon dioxide buildup in the atmosphere, among many other reasons.

More than 80% of the world’s old growth forests have been destroyed, wetlands are being drained for real estate development, and demands for biofuels take much-needed arable land away from crop production.

Life on earth is currently experiencing its sixth major extinction, and we are losing an estimated 30,000 species per year. The most famous major extinction was the fifth one, which occurred about 65 million years ago and wiped out the dinosaurs. The major extinction that we are now facing is the first that is caused not by an asteroid collision or other natural causes, but by a single species—humans.

Effects of Conservation

Consuming less may be a way for us to live within the carrying capacity of the planet, but as Paul Ehrlich and Anne Ehrlich explain, “Overpopulation is defined by the animals that occupy the turf, behaving as they naturally behave, not by a hypothetical group that might be substituted for them.” We should not use the hope or the plan to reduce our consumption as an argument that humans are not overpopulated.

While reducing our consumption is important, worldwide, per capita energy consumption increased from 1990 to 2005, so the trend does not look good.

Lesson from Easter Island

The effects of human overpopulation have been documented in the history of Easter Island, where a human population with finite resources was nearly wiped out when their consumption increased beyond what the island could sustain. An island once lush with diverse plant and animal species and fertile volcanic soil became nearly uninhabitable 1,300 years later. The population peak on the island has been estimated between 7,000 and 20,000 people. Trees were cut down for firewood, canoes, and wooden sleds for transporting the carved stone heads for which the island is known. Because of deforestation, the islanders lacked the resources necessary to make ropes and seaworthy canoes. Fishing from shore was not as effective as fishing out on the ocean. Also, without canoes, the Islanders had nowhere to go. They wiped out sea birds, land birds, lizards, and snails. Deforestation also led to erosion, which made it difficult to grow crops. Without adequate food, the population crashed. A rich and complex society that erected now-iconic stone monuments was reduced to living in caves and resorted to cannibalism.

How did they let this happen? Author Jared Diamond speculates

The forest the islanders depended on for rollers and rope didn't simply disappear one day-it vanished slowly, over decades... In the meantime, any islander who tried to warn about the dangers of progressive deforestation would have been overridden by vested interests of carvers, bureaucrats, and chiefs, whose jobs depended on continued deforestation. Our Pacific Northwest loggers are only the latest in a long line of loggers to cry, "Jobs over trees!"

Potential Solutions

The situation is urgent. Lester Brown, President of Worldwatch, stated in 1998, "The question is not whether population growth will slow in the developing countries, but whether it will slow because societies quickly shift to smaller families or because ecological collapse and social disintegration caused death rates to rise."

The most important thing we as individuals can do is choose to have fewer children. While cutting back on your personal consumption of resources is laudable and may reduce your environmental footprint by 5%, 25%, or maybe even 50%, having a child will double your footprint, and having two children will triple your footprint. It is virtually impossible to compensate for reproducing by consuming less yourself.

Although most of the population growth over the next few decades will take place in Asia and Africa, global overpopulation is as much a problem for “developed” countries as it is for third world countries. Americans constitute only five percent of the world’s population, but consume 26% of the world’s energy. Because we consume so much more than most people around the world, we can have the most impact when we choose to have fewer children or no children.

Internationally, the United Nations Population Fund works for gender equality, access to birth control, and the education of women. According to the UNFPA, “Some 200 million women who would like to use contraceptives lack access to them.” Women should be educated not only about family planning but also generally. World Watch has found, “In every society where data are available, the more education women have the fewer children they bear.”

Similarly, the Center for Biological Diversity campaigns for "the empowerment of women, education of all people, universal access to birth control and a societal commitment to ensuring that all species are given a chance to live and thrive."

Additionally, raising public awareness is essential. While many environmental organizations focus on small steps with which few can disagree, the topic of human overpopulation is much more controversial. Some claim that there is no problem, while others might see it as solely a third world problem. As with any other animal rights issue, raising public awareness will empower individuals to make informed choices.

Potential Human Rights Violations

The solution to human overpopulation cannot include human rights violations. China’s one-child policy, though arguably successful in curbing population growth, has led to human rights violations ranging from forced sterilizations to forced abortions and infanticide. Some population control proponents advocate offering financial incentives for people not to reproduce, but this incentive would target the poorest segment of society, resulting in racially and economically disproportionate population control. These unjust results cannot be part of a viable solution to human overpopulation.