CAPS' Position

Population & Environment
By Ben Zuckerman, Vice President, Californians for Population Stabilization

How many people can the world support? What causes environmental damage? Not surprisingly, it's too many people using too much energy and resources. So, questions like "how many people can the Earth support?" have intrigued thinkers for centuries.

Different people have different value systems, hence this question has no right or wrong answer. For example, a person might believe that a world with lots of people whose average standard of living is low is preferable to one that contains fewer people but whose average standard of living is high. Or vice versa.

There is also the question of what one means by a high standard of living because, for many, this involves more than material goods. For example, for some, a simple life in the country with one car and lots of open space is a much higher standard of living than existence in a densely packed city no matter how much material wealth one might possess. So perhaps "quality of life" is a more appropriate guideline than "standard of living."

Finally, when asking how many people the Earth or the USA can support, one should also consider other creatures. Some people believe that plant and animal species have as much right to be here as humans and would set aside huge tracts of land to preserve regions like rainforests and wilderness. Others care little about other species and would be content, more or less, with a world that contained no wild nature but lots of humans along with their pets, commercial plants, and livestock.

At the present time, humans use about 40% of the solar energy captured by the biosphere (Tolba, M. K. 1995, Ambio Vol. 24 #1, p.66; Maurer, B. A. 1996, Biodiversity Letters Vol. 3, p.1). Should this usage exceed 80%, then the loss of biodiversity is likely to be catastrophic (Maurer 1996) and, effectively, the world will be devoted to humans and the plants and animals we cultivate. Biologists generally agree that, if people continue with business as usual, then this will be the world of the 22nd Century and, since extinction is forever, ever after.

Maintaining biodiversity has multiple values. First, as the dominant species on the planet, many people feel that we have an obligation to steward and safeguard other species. Second, many direct economic and other benefits accrue to us from non-human species. And third, other species provide ecosystem services without which human survival is not possible. These services include maintenance of the gaseous composition of the atmosphere, regulation of the hydrological cycle, pollination of crops, control of the vast majority of pests, and the generation and maintenance of fertile soils.

The Concept of Carrying Capacity 

When flying over the USA we cannot help but notice all of the "wide open spaces," especially in the West. Surely plenty of land is still available for many more Americans, yes? Problem is, there are reasons that these acres appear empty. Many are devoted to producing food or other materials we need to live. The average American has an "ecological footprint" of about 25 acres of biologically productive land. These acres supply a person with food, fiber and other resources as well as capacity for waste assimilation and disposal. So the many of us who are jammed into cities are already using much of the "empty" land.

Some land is empty because it has no carrying capacity. One obvious example is the continent of Antarctica; lots of land but no capacity to support human life. The Sahara desert is another example. And there are deserts and mountain ranges in the USA that contain few people because, without the expenditure of huge amounts of money, these places cannot sustain human life.

The Politics of Population 

Opinion polls consistently indicate that about 3/4 of Americans consider themselves environmentalists or at least profess to be concerned about the environment. Similarly, polls show that about 3/4 of Americans think there is too much immigration into the USA. So, there must be a very large overlap between these two groups and, thus, we might expect that many Americans sense that their environment is adversely impacted by massive immigration.

The two major parties have chosen to ignore rapid, immigration-driven, U.S. population growth, in particular, its environmental implications. Working hand in glove with the politicians are the media. In "How and Why Journalists Avoid the Population-Environment Connection," T. Michael Maher discusses how a "spiral of silence about population growth may be maintained by determined pronatalists, immigration advocates, and intimidated journalists." (This excellent study was published in the journal "Population and Environment," Vol. 18, March 1997, pp. 339-372.)

The links between population growth and environmental degradation, a few of which are mentioned below, simply never appear when journalists write about the environment. And unfortunately most people are either not smart enough or are insufficiently educated to see the connections without some help.

Since most Americans want cuts in immigration levels, why do they consistently elect politicians who support current levels? The problem is that, for most voters, immigration is not at the top of their list of concerns which might be headed by the economy, crime and education, for example. Therefore, the typical person will not be much concerned about immigration when (s)he goes to vote.

The Population-Environment Connection 

Parts of the USA are already remarkably densely populated. For example, California, which was effectively empty 100 years ago, is now more densely populated (has more people per square mile) than the continent of Europe. And, according to recent U.S. Census Bureau estimates, sometime around the year 2030, the population density in California will equal that in China now! This is the same China that has instituted a one child per family policy. California's population growth is essentially due entirely to immigration from abroad.

Whether it is air pollution in the cities or sprawl in the suburbs, farmland conversion in the valleys or deforestation in the mountains, Americans aFor example, California, which was effectively empty 100 years ago, is now more densely populated (has more people per square mile) than the continent of Europe.re destroying the natural systems that keep us alive physically and spiritually. Each year we pave over an area about equal to the state of Delaware for more roads, housing developments, shopping malls and industry. For most resources including energy, per capita U.S. consumption has stabilized, but overall use is increasing, driven higher by continuing growth of the U.S. population.

An example of this phenomenon is U.S. beef consumption. "Running" cattle often comes with a high environmental price: displacement and killing of native wildlife (such as wolves, coyotes, bears, and cougars that might prey on livestock), streambank and soil erosion, fecal coliform contamination of water, desertification, etc. This is true both here in the U.S. or elsewhere, wherever U.S. beef comes from. Since 1970, per capita U.S. beef consumption has declined by about 15%. But, over the same period, U.S. population increased by about 1/3. So people living in the USA now eat substantially more beef, in total, than they did in 1970. (Meat production uses 37% of the world's grain output, but only 5% of Americans are vegetarians.)

At the same time that total meat consumption is going up, the National Marine Fisheries Service is cutting allowable catches because of perceived sharp declines in numbers of fish. Many fishes have been "harvested" to near commercial extinction both in U.S. waters and worldwide.

According to the Nature Conservancy, 1/3 of U.S. plant and animal species are already at risk of extinction. Causes of this biological devastation are many, but they all come back, more or less, to humans expropriating habitats of other species for our use. And the more of us there are, the more we must expropriate. According to a report published in 1997 in Science (vol. 277, p. 1116) the leading causes of species endangerment are: urbanization; agriculture; outdoor recreation and tourism development; interactions with non-native species; domestic livestock and ranching activities; reservoirs and other running water diversions; pollution; mineral, gas, oil, and geothermal extraction or exploration; and on and on.

Water scarcity is a problem that many, particularly those who live in the Southwest, can relate to. But scarcity is turning up all over America, even in places as wet as Long Island, New York and South Florida. In Florida, the toxic pollution generated by the dense population is permanently destroying underground aquifers, rivers and wetlands. Sixty-five percent of the 3900 square miles of the Everglades have been drained or diverted to agricultural centers and urban areas such as Miami. Thus, the Everglades has lost 93% of its wading bird population since the 1930s, while the human population has grown at a rate 2.5 times faster than the national average.

Nationwide, ground water aquifers are being depleted 25% faster than they are recharged. Of our original 221 million acres of wetlands, only 103 million remain. And despite the federal government's official no-net-loss of wetlands policy, a 1997 U.S. Fish and Wildlife Service report indicated that about 1 million wetland acres were lost, mostly on agricultural lands, between 1985 and 1995.

Although we are focusing on the U.S. environment, destruction of the natural world to satisfy our needs is enormous elsewhere too. According to a report in the January 1998 newsletter of the Environmental Defense Fund, "the U.S. is the #1 importer of mahogany, the product most responsible for Amazon deforestation." And half of our imported plywood results from destruction of Indonesia's rain forests. Our appetite for wood and minerals motivates the road builders who open tropical rain forests to poor settlers, resulting in the slash-and-burn forest clearing that is condemning countless species to extinction. Further growth of the U.S. population will only increase these demands.

Isn't Overconsumption the Real Culprit? 

Some would say that the real problem is high U.S. consumption rather than population (even though we are now the third most populous country after China and India). And truly, although U.S. per capita consumption is now roughly stabilized, still we should try hard to lower it. Unfortunately, because high consumption is an integral part of our culture, diminishing it significantly will be a slow and difficult process.

Those few environmentally positive actions we take, such as recycling, are much more than offset by our dreams of a big energy-inefficient home in the suburbs. Fulfillment of this dream accelerates destruction of farmland and increases automobile usage, not to mention all of the materials involved. In 1998 gas prices tumbled as more and more people purchased gas-guzzling sport utility vehicles, hardly the way to cut consumption.

Most of the 75% of Americans who profess to be concerned about the environment are, more or less, heavily invested in the soaring stock market. But these companies are often the very ones that most despoil the environment. Many of them are multinational in nature and their tentacles (our tentacles) extend to sensitive lands abroad; half of the world's industrial output is generated by multinational corporations. Similar considerations apply to banks in which we have savings deposits.

Even with the best of intentions, because of inertia built into the infrastructure of our country, meaningful change in overall consumption will take a long time. An example from Los Angeles illustrates the problem. In 1997 a group of environmentalists welcomed the new head of the L.A. Dept. of Water and Power, a man with demonstrated concern for the environment. His vision is to power L.A. with renewable energy, specifically solar power. His first step is to equip 100,000 houses. But when asked, thinking optimistically, how long this might take, his response was, "about 25 years." So, even when we have a government official with special sympathies for the environment, it still will take, optimistically, 25 years to switch a tiny fraction of the homes in L.A. to solar power. And most government and private leadership is not so motivated.

If the U.S. continues to accept current levels of legal and illegal immigrants, then the U.S. population could double in 80 years. Because of considerations outlined in the previous two paragraphs, the time required to halve our per capita energy consumption is unlikely to be less than 80 years. Thus, in the absence of better immigration laws, we can be pretty sure that the total U.S. ecological footprint will not be smaller in the year 2100 than it is in 2000 and it might be much bigger.


The unforgivable thing is that we know all of the above. But we refuse to do anything about it, falling back on our old faith in a limitless continent and open frontiers that will last forever. A huge unfilled political econiche awaits anyone with the courage to say enough is enough.

Sprawl Facts

  • To feed our growing population California is losing over 100,000 acres of farmland annually to urban sprawl. (American Farmland Trust)
  • The contiguous United States lost 41 million acres (over 64,000 square miles) to development from 1982 to 2007. (2007 National Resources Inventory, U.S. Department of Agriculture, Natural Resources Conservation Service)
  • If the same rate of cropland loss were to continue to 2100, the U.S. would lose about 106 million acres of its remaining 377 million acres of cropland, or nearly 30 percent. (U.S. Natural Resources Conservation Service, Center for Immigration Studies)

Natural Resources Facts

  • The demand for fresh water will increase six-fold in the next 70 years and by 2050 half of the world's population will be living without direct access to fresh water. (UNFPA State of the World Population)
  • More than 100 million Americans live in urban areas where the air is officially classified by the EPA as unsafe to breathe. (Natural Resources Defense Council)
  • The world is in the midst of a mass extinction unlike any since the extinction of the dinosaurs 65 million years ago. Extinction rates are currently estimated anywhere between 100 to 1,000 times greater than normal. (National Wildlife Federation)
  • Between 50% and 70% of the world's population lives in coastal areas. If current warming rates continue, thermal expansion of the oceans and melting of polar ice caps will cause sea levels to rise. Increased flooding from higher tides and stronger storm systems could destroy coastal farmland, habitats and wildlife populations as well as damage cities and impose huge costs. (NOAA)
  • Experts estimate that 75% of the total decline in global forest cover took place during the 20th century, with most occurring in just the last 40 years. Within this same period, the human population has expanded at a rate never before experienced in our history. (Population Action International)

Consumption Facts

  • Calculate your Ecological Footprint
  • If the entire world consumed resources at the average American consumption level, more than 4 Earths would be needed to support us all! (Global Footprint Network)
  • One child in the United States impacts the environment as much as 280 children in Haiti. (US EPA)
  • The US has 5% of the world's population, yet we consume over 25% of the world's resources. (US EPA)
  • With less than 5% of the world's population, the U.S. emits more than 20% of the world's greenhouse gases. (US Department of Energy)

Additional Resources

The Environmental Argument for Reducing Immigration into the United States  
By Philip Cafaro and Winthrop Staples III

Forsaking Fundamentals: The Environmental Establishment Abandons U.S. Population Stabilization
By Leon Kolankiewicz and Roy Beck,

Sprawl in California: A Report on Quantifying the Role of the State's Population Boom
By Roy Beck and Leon Kolankiewicz

Weighing Sprawl Factors in Large U.S. Cities
By Leon Kolankiewicz and Roy Beck

Outsmarting Smart Growth: Population Growth, Immigration, and the Problem of Sprawl
By Roy Beck, Leon Kolankiewicz, and Stephen Camarota

Population Growth: The Neglected Dimension of America’s Persistent Energy/Environmental Problems
By Leon Kolankiewicz

Immigration to the United States and World-wide Greenhouse Gas Emissions
By Leon Kolankiewicz and Stephen Camarota

Just When You Thought You Could Bank On It
By Michael Tobias