What is unsustainable population growth?

by Henry Barbaro

One of the four pillars upon which NumbersUSA was built is the recommendations of the President’s Council on Sustainable Development, established by President Bill Clinton in 1993. In the executive summary of its final report, the Council stated that “reducing immigration levels is a necessary part of population stabilization and the drive toward sustainability.”

But what is “sustainable,” and what do we mean when referring to “unsustainable” growth. As one of the most often-used – and perhaps abused or misunderstood – words in today’s environmental vernacular, the connotation of “sustainable” refers to an activity that supposedly can continue indefinitely. In addition, Dr. Al Bartlett, an internationally-recognized advocate for population stabilization, provides a thorough examination of the term “sustainability” in his 2011 paper, “The Meaning of Sustainability.”

Sustainability defined

The United Nations provides a clear and concise definition of sustainability — “meeting the needs of the present without compromising the ability of future generations to meet their own needs.”  Sustainability has come to mean continual environmental stewardship, where natural resources are managed and conserved for the distant future.

This begs the question – do we need to conserve our natural resources so that they are available for future generations forever, even if said resources are not renewable?  Certainly not a realistic target for any scientific forecast model.

Many centuries ago, the Iroquois Indians developed the “seventh generation” principle, which states that the decisions made today (should result in a sustainable world seven generations into the future. Assuming 25 years per generation, seven generations is about 175 years. A long time, but a meaningful guideline for determining whether a practice is truly “sustainable.”

Can population growth be sustainable?

According to Dr. Al Bartlett, “sustainable population growth” is an oxymoron because continuous population growth cannot be sustainable due to the finite nature of Earth’s resources. Within the boundaries of a limited land area, a truly sustainable population is one that has essentially stopped growing. This also assumes that the area is not already “overpopulated,” (i.e., has not exceeded its “carrying capacity”). An area that is overpopulated is by definition “not sustainable.”

What does unsustainable population growth look like?

Unsustainable population growth can be observed in nature when a population grows until it encounters a limiting resource (e.g., food), and exceeds the environment’s “carrying capacity.”  Subsequently, the population can suffer a dramatic dieback. Animals low in the food chain, such as rodents, experience diebacks most often. Without pressure from predators or other limiting factors, these “opportunistic” species reproduce rapidly, consume food sources to depletion, and then experience a population crash due chiefly to starvation. This graph depicts the difference between a population suffering a severe dieback and a moderately fluctuating population relative to carrying capacity.

Thanks to Tom Murphy for the figure

Although there has never been a worldwide human dieback, with a sudden and significant decline in global human population, there have been cases in history and pre-history where localized populations have crashed due to factors like disease outbreaks (e.g., Europe’s Black Death in the 1340’s), famine, wars, and environmental disasters (e.g., Yangtze River Flood in 1931). But even with the potential for future population declines due to pervasive factors like pandemics, a worldwide dieback is improbable, at least for the foreseeable future.

America’s unsustainable population trajectory

Although America’s population growth is unsustainable, it is unlikely we will someday experience a future dieback from a calamitous shortage of food or water. However, the incremental yet relentless loss of resources inevitably will lead to acute shortages (e.g., drinking water, farmland, energy) that will force Americans to take drastic measures (e.g., desalinization). Also, as is typical with how resources are distributed, the victims of such scarcities probably will be lower income people.

America currently is mining (not replenishing) a wide range of its natural resources, including groundwater supplies, farmland, fossil fuels, minerals (e.g., sand and gravel, copper, iron), open space, and rare species habitat. It seems certain that this trend will continue and that future generations will face more severe shortages of drinking water, fossil fuels, wilderness, and arable land.

Although not resource scarcities directly tied to consumption, the following factors relate to quality-of-life for Americans and have been diminishing (worsening) as our nation’s population grows – affordable housing, resiliency to extreme weather events, access to natural areas (e.g., beaches and waterfront, national parks, recreation opportunities), traffic capacity, and protection of fragile lands (e.g., wetlands, floodplains, coastline, desert, steep slopes, and fire-prone areas).

Unsustainable population growth at the state level

At a smaller scale, many states in our nation also are experiencing unsustainable population growth, especially relative to foreign immigration. Massachusetts, for example, is the only state with a right-to-shelter law. Adopted in 1983, the law was meant for homeless families and pregnant women, and was never intended to provide support to many thousands of destitute migrants. After two years of Biden’s open-border policies, Governor Healey declared a state of emergency (August 2023) because the state’s emergency shelter system had exceeded its capacity of 7,500 families (or 24,000 individuals).

Since then, it has become plainly obvious that Massachusetts’ migrant crisis cannot continue indefinitely and is undeniably “unsustainable.”  Why?  Now that the capacity of emergency shelters has been exceeded, eventually the next publicly funded backstop to become overwhelmed likely will be rental-assisted housing. And last, state and municipal tax budgets will begin to crash, which will result in cutbacks to social services such as health care and schooling. This just one example of how today’s rapid influx of immigrants is causing serious liabilities for the future.

Conclusion

Today’s generation of Americans is failing in terms of being responsible resource stewards on behalf of future generations. There are three primary reasons why America’s population growth is unsustainable, and why we are hurtling toward a more depleted, desperate, and chaotic future –

1. Loss of Biodiversity – Of the world’s nations, the U.S. ranks #6 for the greatest number of endangered species. According to the U.S. EPA, over 1,300 of America’s plant and animal species are endangered or threatened. As America’s population soars, vast areas of habitat, lands, and waters are damaged, fragmented, and/or destroyed.

• Shortages/ permanent losses – Examples include drinking water, fossil fuels, wilderness, arable land, and natural lands that, before human encroachment, provided resilience to extreme weather events. Such lands include floodplains, wetlands, deserts, fire-prone areas, steep slopes, and hurricane-prone coastlines.

• Lower quality of Life – With relentless population growth comes more crowding and high-density living, more traffic congestion, fewer housing options, more recreational conflicts (e.g., hikers / hunters, motorized versus non-motorized recreationists), more pollution (water, air, noise), more crime, more solid waste, less open space, more air traffic, and fewer sacrosanct and sacred areas (e.g., tribal heritage, wilderness, scenic) – carved up by subdivisions, mines, clearcuts, transmission lines, highways, wind turbines, and solar farms. Even wealthy Americans will experience the consequences of excess population growth.

There is no country on earth, including America, where it would be sustainable to assimilate more than one million immigrants year after year, decade after decade, plus their offspring. If this unsustainable trend continues, then greater harm will befall future generations of Americans, i.e., a lower quality of life, and less of a share in the fading “American dream.”  We already know that future generations will not enjoy the same quality of life and living opportunities that we have had – especially those who will feel a deep connection to what’s left of the natural world and a sense of loss for what has vanished. Although it’s not too late to change course, it is critical that America achieve a sustainable population at once.