How Overpopulation Leads to Habitat Loss and Mass Extinction

Max Katz-Balmes

Since the beginning of the Common Era two thousand years ago, the human population has grown exponentially. At the time of Christ’s birth, approximately 200 million people roamed the planet (Southwick 159). That number now stands at about 7.4 billion people and continues to rise (World Population Data Sheet). However, while many believe that the global population will continue to follow this “J-shaped” growth pattern, population increases have actually slowed in recent years in part due to decreased fertility rates. While it took humankind 12 years to add its 6 billionth, 13 years were required to add its 7 billionth, the first time in history that the interval between billions has grown (Wise). But despite the decreased fertility rates, the population should continue to rise until at least 2050. A 2015 World Population Prospects report estimates “an 80% probability that the population of the world will be between 8.4 and 8.6 billion in 2030, between 9.4 and 10 billion in 2050 and between 10 and 12.5 billion in 2100” (Jones and Anderson). In other words, the global population will likely not decrease anytime soon.

What are potential issues with a large, perhaps excessively large, global population? Overpopulation is one of the most pressing problems faced by our society. Around the world, cities are becoming overcrowded, leading to the emergence of dirty slums that lack access to clean water, sanitation, and other basic human needs. Arable land is being replaced by sprawling, suburban developments. Climate change and air pollution are only exacerbated by an increased number of feet on the planet. Habitats are being destroyed. Entire ecosystems are being threatened. In fact, industrialization and overpopulation are helping to facilitate a mass extinction comparable to that of the dinosaurs. According to National Wildlife Federation, in a report titled Population and the Environment, “nearly 20 plant and animal species become extinct every hour” (Effects of Overpopulation).

Along with fueling massive animal extinction, population growth contributes heavily to habitat loss. Around the world, in low-density regions as well as in high-density ones, population pressures create incentive to clear and develop land, in particular forests. Deforestation not only eliminates land and destroys ecosystems, but also fragments and changes many animals’ migration patterns and makes them easier targets for poachers. In addition, the expansion of suburbs further and further away from urban areas clears significant amounts of natural land and puts many animals and plants in danger. To avoid the continuation of these patterns, humans must cease clear-cutting forests and promote vertical development rather than outward development.

Deforestation heavily contributes to habitat loss and mass extinction, and our forests continue to thin every year. In 2004, a Population Reference Bureau article stated that since the 1980s, “agricultural expansion, logging, development, and other human activities caused the deforestation of more than 120,000 square kilometers each year” (Meyerson). By contrast, only about 12,000 square miles per year was being reforested. Because of human actions, as well as natural climate shifts, forests today comprise less than half the area they did at their peak (Meyerson).

Overpopulation affects deforestation on a truly global scale, even in relatively uninhabited regions. From deforestation-overpopulation studies to date, a clear correlation exists between extremely low population density and maintenance of forests. Generalizing from these studies, at population densities less than two people per square kilometer, populations generally tend to be able to sustain themselves without agriculture and timber products (Meyerson). However, in many low-density regions, such as in many Amazonian areas, forests are being destroyed despite a lack of people. This would counter the claim that overpopulation leads to deforestation and habitat loss, except for the fact that most of this land clearing results from external factors such as demand for timber or livestock from high population regions of the globe (Meyerson). In order to satisfy the needs and desires of the ever-growing number of humans across the globe, forests continue to be destroyed in areas that do not depend on cleared land for survival.

The developed world also feels the effects of land clearing and habitat destruction. For instance, in Florida, from 1950-2000, the population rose at a rate of four percent annually. To accommodate the rapidly increasing population, almost of a quarter of the state’s land (all forest and wetland habitats) was cleared for human use. According to the Florida Department of Environmental Protection, “in 1990, about 19 acres per hour of forest, wetland, and agricultural land [were] being converted for urban uses” (Effects of Overpopulation). And because of this massive growth, Florida’s ecosystems, on the whole, are more threatened than the ecosystems in all other U.S. states.

Suburban sprawl also contributes heavily to habitat loss and mass extinction. According to the National Wildlife Federation, “The conversion of natural areas for homes, offices, and shopping centers has become one of the most serious threats to America’s native plant and animal species” (Ewing and Kostyack). As the population grows, more land is needed to provide housing and jobs, and development stretches farther and farther away from urban areas. And with increased sprawl likely comes increased habitat loss and degradation. In fact, in the first quantitative study of the sources of animal endangerment in California, scientists discovered that sprawl threatens California’s animals more than any other factor (Ewing and Kostyack). Low-density outward development destroys acres among acres of natural land and destroys the homes of thousands of plant and animal species, putting many in danger of population decline or even extinction.

Habitat loss, in particular deforestation, also fragments and alters animal migration patterns. Not only are animal species unable to survive in the remnants of forested land left behind, but the “fragmentation of forests due to road, agriculture and human settlement development also impacts on wildlife by reducing the corridors used to move or migrate” (Forest Animals Threatened). For example, years of illegal clear cut logging in the Monarch Butterfly Biosphere Reserve in Mexico has impacted the migration corridors for the endangered monarch butterfly. Millions of monarch butterflies migrate to the reserve annually for the winter months, but a thinning forest has the potential to change that as only an intact, continuous forest canopy can protect the monarchs “from both freezing cold during winter storms and from excessive warmth during the days” (“Deforestation in Monarch Butterfly Reserve”).

Deforestation also makes animals easier targets for poachers, as hiding and camouflage become more difficult. For these reasons, many species’ numbers subside and some eventually cease to exit (Forest Animals Threatened). In fact, the Convention on Biological Diversity (CBD) approximates that human-led deforestation in the past 100 years has reduced the number of species living in forests by more than 30 percent (Forest Animals Threatened).

In many countries around the world, overpopulation fuels habitat loss and places many plant and animal species in peril. As the author of the Audubon publication, Population and Habitat: Making the Connection, suggests, “The destruction of the natural world we see across the globe today is “fallout” from the human population explosion that has occurred over the course of the last 50 years” (Effects of Overpopulation). Population pressures require forests to be cut down for agriculture, cleared for development, or harvested unsustainably for human consumption. In addition, rapid growth in the demand for suburban housing has pushed human development farther and farther away from cities, destroying more habitats and endangering more species. To avoid a continuation of the “sixth mass extinction,” humans must stop clear-cutting forests and attempt to promote vertical development rather than sprawl. If we, as a species, don’t change our behavior, other species will continue to die off, biodiversity will be threatened, and ecosystems will be threatened.

Works Cited

“Deforestation in Monarch Butterfly Reserve.” National Aeronautics and Space Administration, 7 Mar. 2008. Web. 02 Dec. 2016.

Effects of Overpopulation: Wildlife and Habitat Destruction. Rep. Negative Population Growth, Aug. 2013. Web. 2 Dec. 2016.

Ewing, Reid, and John Kostyack. Endangered by Sprawl: How Runaway Development Threatens America’s Wildlife. Rep. National Wildlife Federation, n.d. Web. 2 Dec. 2016.

Forest Animals Threatened. Rep. United Nations Environment Programme, 2013. Web. 2 Dec. 2016.

Jones, Sam, and Mark Anderson. “Global Population Set to Hit 9.7 Billion People by 2050 despite Fall in Fertility.” The Guardian. Guardian News and Media, 29 July 2015. Web. 02 Dec. 2016.

Meyerson, Frederick A.B. “Population Growth and Deforestation: A Critical and Complex Relationship.” Population Reference Bureau, June 2004. Web. 02 Dec. 2016.

Southwick, Charles H. Global Ecology in Human Perspective. New York: Oxford UP, 1996. Print.

2016 World Population Data Sheet. Rep. Population Reference Bureau, 2016. Web. 2 Dec. 2016.

Wise, Jeff. “Forget Overcrowding. The World Population Could Start Declining.” Slate Magazine. The Slate Group LLC, 09 Jan. 2013. Web. 02 Dec. 2016.


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