Is the Population Bomb Finally Exploding?

Anne H. Ehrlich, Paul R. Ehrlich

The quick answer to that question is “Yes.” But the finally requires qualification. The population bomb—the power of population size and its rapid growth to greatly darken the human future—has actually been exploding for many decades. It’s just that until recently people in general and the media in particular have not been paying attention. For example, the public has slowly awakened to the reality of climate disruption resulting from rising greenhouse-gas concentrations in the atmosphere. Increasing greenhouse gas emissions are directly connected to increasing numbers of human beings, but this is seldom mentioned in the media. Similarly, complaints on television and in the newspapers about American dependence on imported oil have been myriad, but the role of our ever-larger population—now more than 300 million in number—combined with profligate consumption habits in generating outsize demand for oil have been overlooked.

Instead, attention is now focused on how good it’s supposed to be that our population size isn’t declining. Thus an article in the New York Times Magazine (June 29, 2008) called America “a sparkling exception” to the very low birthrates in Europe and Japan. “Last year the fertility rate in the United States hit 2.1, the highest it has been since the 1960s and higher than almost anywhere in the developed world. Factor in immigration and you have a nation that is far more than holding its own in terms of population [sic]. In 1984 the U.S. Census Bureau projected that in the year 2050 the U.S. population would be 309 million. In 2008 it’s already 304 million, and the new projection for 2050 is 420 million.”

What a prospect! Think about it—if we had stayed at, say, 140 million people, the nation’s population at the time of World War II, consider how little oil we’d need to import now. And imagine what it will be like trying to supply energy to 420 million super-consumers in 2050. The population explosion in the United States has been virtually ignored, despite its clear connection to many of the country’s most pressing problems. The most obvious one, of course, is traffic congestion, especially in the increasingly antiquated urban transport system that generates much of the country’s air pollution. Closely related is the covering of much of the nation with a sprawl of energy-inefficient houses—the bedroom slums of tomorrow. We spend a great deal of time in the montane West, where what previously were open ranch lands (themselves hardly examples of wise land use) are rapidly being converted to ever-more-expensive-to-heat first and second homes with ever-less-secure sources of water.

Those obvious indicators of overpopulation are just the tip of the iceberg. In order to supply oil to a burgeoning population, the United States has organized its military so that something like half of its budget is designed to wield force wherever necessary to keep the petroleum “lifeblood” (actually poison pill) of the economy flowing. Much of the Pentagon’s planning today is pointing toward an eventual war with China over the energy resources of central Asia and Africa. In 2003, America launched its first great resource war in an attempt to control Iraq’s vast petroleum resources—at a cost of billions of dollars every month. Instead, the Iraq War expenditures could have funded a massive increase in the country’s research and development of alternative energy sources, done much to repair its disintegrating infrastructure and redesign it to meet coming challenges in the distribution of water and changes in energy/transport systems, and provided much better health care and education to its citizens. To support an excessive demand for energy and material goods, too many of Americans’ basic needs are going unmet.

The population factor in this dismal trajectory is even greater than meets the eye. The point is almost never made that every person added today to the U.S. (or virtually any other) population on average causes more damage to humanity’s critical life-support systems than the previous addition— everything else being equal. Human beings are smart—that’s how they became the dominant animal on Earth. Farmers didn’t settle first on marginal lands to struggle against poor soils and scarce water to grow their crops; they usually settled on the rich soils of river valleys. That of course is where most cities developed and where people are now paving over some of the richest soils to make room for homes, highways, factories, and the like and polluting previously pristine watercourses.

As a result, to support growing numbers, it is necessary to move to ever-poorer lands, drill wells ever deeper, or tap increasingly remote sources to obtain water—and then spend more energy to transport that water ever-greater distances to farm fields and homes. Our distant ancestors could pick up nearly pure copper on Earth’s surface when they started to use metals; now people must use vast amounts of energy to mine and smelt gigantic amounts of copper ore of ever-poorer quality, some of it in concentrations of less than 1 percent. The same can be said for other important metals. Equally, petroleum can no longer be found easily on or near the surface but must be gleaned from wells drilled a mile or more deep, often in inaccessible localities such as under continental shelves beneath the sea. But, of course, we should stop the use of petroleum as a fuel as rapidly as possible.

All of the paving, drilling, fertilizer manufacturing, pumping, smelting, and so on needed to provide the goods and services for Americans, as well as their consumption of them, produces greenhouse gases and thus tightens the connection between population and global heating. The environmental destruction caused by past and future activities of our population will be with us for a long time, and the severity of future impacts will be determined by how the present population and its future additions behave toward our common environment—and by the size of those additions.

On that front, there is some good news. A main goal of The Population Bomb, first published in 1968—to promote policies that would lower fertility and eventually start a decline toward a sustainable global human population size—has started to be achieved. Rather than doubling in thirty-five years, as would have happened if the 1968 growth rate had persisted, we may not reach that level—7 billion—until 2013, forty-five years after The Bomb was published. With the exception of the United States, populations in the industrialized world have essentially stopped growing and in some cases have begun to shrink. And many developing nations (including China, with the world’s biggest population) have followed suit and are on track to reverse their growth within a few decades. But others, mostly very poor nations, still have high birthrates and rapid growth. That growth may cause the world population to add 2 to 3 billion more people before growth stops.

Although demographic trends are moving—if too slowly— in the right direction, the list of environmental threats uncovered since 1968 is extremely alarming, all exacerbated by our species’ large and growing numbers. In 1968, Sherwood Rowland and Mario Molina had not yet discovered the ozone-destroying potential of freons. If they had not published a paper pointing this out in 1974, life on the land surface of Earth might well have become impossible. In 1968, Norman Myers was a decade from calling world attention to the rampant destruction of tropical forests, and even ecologists had not fully realized the impact of biodiversity loss on the ecosystem services upon which society depends. The quantities of toxic pollutants and their global spread—both related to burgeoning numbers of consumers of food and manufactured products—were not widely recognized. Furthermore, scientists had yet to discover the enormous threat posed by novel hormone-mimicking pollutants that were part of this population-related toxification of the planet. Many of those chemical compounds may be more dangerous in trace amounts than in high concentrations.

Although The Population Bomb discussed the increasing threat of novel epidemics associated with denser populations, malnutrition, and high-speed transport, AIDS, SARS, West Nile virus, and the like had not yet appeared, and the increasing failure of antibiotics due to the evolution of resistance in bacteria was not widely understood. Soon after The Bomb was published, then-Surgeon General of the United States William H. Stewart testified to Congress that it was time to “close the book on infectious diseases.” To the contrary, the human population was exploding, and more and more people were being pressed into contact with the animal reservoirs that have been the sources of our infectious diseases. Population growth made transfer of pathogens to Homo sapiens and the maintenance of infectious diseases in the human population more likely. This decay of our epidemiological environment is extremely serious, and the resulting personal tragedies are heartrending.

In June 2008 while in South Africa, we talked extensively with a colleague who is training university students in conservation biology. He says it haunts him that roughly a quarter of his bright young students whose skills and talents are so needed by their nation are likely to die young of AIDS. But even that terrible situation could be eclipsed if the Chinese duck-pig-person agricultural system, which apparently serves as a generator of new flu strains, produces one as lethal, or even more lethal, than the strain in 1918–1919 that ravaged humanity.

The enormous increase in the human population—it’s doubled just since 1965—has had its chief impact on our life-support systems through increasing consumption. In recent years, the connection between consumption and environmental deterioration has become increasingly clear, and consumption (as measured by GDP) has been expanding faster than population in much of the world. Many environmental scientists, including ourselves, believe that overconsumption—consumption that reduces the sustainability of civilization—will prove much more difficult to cure than the overpopulation that multiplies its effects. So far, unfortunately, there are no consumption condoms or buying-spree morning-after pills.

The combined impacts of more people, with each on average consuming more, has never been more evident. It is clearest in the way our gigantic population is exhausting the capacity of the environment to safely absorb effluents. These effluents are not just the greenhouse gases that we dump into the atmosphere that can dangerously alter the climate. They also include those toxic chemicals that now pollute soil, water, and ice from pole to pole and agricultural and other sources of the runoff from the land surface that damages coral reefs and creates oceanic “dead zones” in which valuable sea organisms can’t survive. The capacity of the oceans to take up carbon dioxide is a two-edged sword—on one hand reducing the threat of global heating and on the other making the oceans more acidic and dramatically threatening ocean life.

Today, an overpopulated world—one in which people are depleting their natural capital rather than living on the “interest” from it—is facing one of the severest food shortages in modern history, and no second green revolution is in sight. Many elements are involved in the current crisis, most of them political and economic, because enough food is presently produced to give everyone in the world today a healthy diet. But even maintaining that level of production seems problematic in the face of many adverse factors, including further population growth. In addition to problems such as deteriorating lands in many areas, climate change threatens to further undermine food security. The frequency of droughts and floods in prime agricultural regions is rising suspiciously. It seems likely that humanity has already committed itself to nearly a millennium of continuously shifting rainfall patterns that will require enormously expensive, constant readjustment of civilization’s water-handling infrastructure for agricultural (and industrial and domestic) use. Further melting of central Asia’s glaciers will increasingly jeopardize water supplies and irrigation systems supporting some 1.4 billion people in China and South Asia, and the disappearance of glaciers in the Andes will deplete the water supplies of cities like Lima, Peru, and Quito, Ecuador, as well as those needed by local agriculture. California, the largest agricultural state in the United States, is dependent for storage of irrigation water on the snowpack of the Sierra, a resource threatened by global heating. Grain production is already being reduced globally by climate change, and many essential crops (especially wheat and rice in South Asia) are growing near their temperature limits.

In our view, humanity should be steering large amounts of money into efforts to drastically limit the flow of greenhouse gases into the atmosphere, as well as into such practices as breeding crop strains more tolerant of high temperatures and less water. Instead, civilization is fighting to get more fossil fuels to burn and, in the face of a bungled economy, striving to find a way to fire up the old perpetual-growth machine that threatens to bring down civilization. People are paving over more farmland for “development” and converting staple grains to biofuels to feed SUVs, while climate change further undermines the production of food for people. Indeed, the ignorant rush to produce biofuels, with little consideration of its human or ecosystem impacts, is a major reason for recent increases in food prices and (of course) hunger. And rapidly escalating demand for animal products in countries such as China and India is putting further pressure on the capacity of humanity to produce and equitably distribute food and on the needs for water and petroleum (whose use is heavily embedded in industrialized agricultural systems). Loss of pollinators and natural pest-control services, the creation of oceanic “dead zones,” and the impacts of deforestation (often in aid of agriculture) on climate all undermine the ability of Homo sapiens to feed itself and avoid catastrophe. And above all, the most overpopulated nation on the planet, the United States (it is only third largest in numbers, but its high per-capita consumption make it easily outrip China and India), is taking no steps to halt and reverse its population growth and wasteful consumption. While the recent financial meltdown may slow or halt some of those trends, we fear that they will be reignited.

The political fallout from the energy-climate-food situation will probably be grim. Humanity faces the very real prospect of more resource wars as ever-larger populations struggle over dwindling supplies of oil and shifting patterns of water availability. The 1967 Arab-Israeli war was partly over water; the Iraq War is largely an attempt to keep oil flowing to our SUVs. The deaths and suffering caused by the latter conflict are especially tragic, as petroleum is a resource that we should be trying to use far less of. If we keep seeking and burning more and more, that will greatly increase the odds of catastrophic climate change. Just using the fields already opened, much less seeking new places to drill, could speed civilization down the drain. Invading Iraq to get control of its huge oil reserves was the intellectual equivalent, if we were short of food, of invading a nation to get control of its supply of cyanide.

Of at least equal concern is the current pressure to increase the use of coal for electricity in too many parts of the world, including the United States, where energy companies have proposed building dozens of new coal-burning power plants in the next decade or so. Coal, of course, is the fossil fuel whose burning, given current technology, releases the most carbon dioxide per unit of energy provided. Even worse, China’s galloping development includes the building of one to two very inefficient coal-burning plants a week. The result is horrendous air pollution and a national rise in greenhouse gas emissions that exceeded those of the United States (the previous world record-holder) in 2007. India, too, is turning to coal to accelerate its development, and even some European countries are considering more use of coal. Even though there is much discussion of capturing the CO2 from coal-fired plants and storing it deep underground, methods are far from proven (and may in any case not be practical in many locations), they are likely to be very expensive, and most old or new plants cannot be easily converted to using them. Reducing coal-burning is, if anything, even more urgent than phasing out dependence on petroleum.

Of course, many factors are involved in today’s environmental destruction besides growth in brute numbers of people, in wasteful consumption, and in per-capita GDP. These include incompetent leadership, a general human failure to pay much attention to long-term problems, misplaced scientific priorities, criminal behavior by individuals and governments, runaway greed, exploitation of the poor, and views of human behavior based on faith rather than reason. It is stunning to think that in the twenty-first century the United States had a president who seriously believed he was talked to by a supernatural monster and a vice-presidential candidate who was even crazier. Both promoted the decimation of human life-support systems and never mentioned the cause: a steady drumbeat of ever-more people, even the richest of them often still wanting to consume more.

Still, there are bright spots in this otherwise grim picture, and climate disruption and its already visible consequences should help to force the needed changes. Alternatives to fossil-fuel based energy systems exist, and more could emerge if appropriate efforts were made to find and develop them. The current food crisis, partly catalyzed by a misguided attempt to supplement oil supplies with grain-based ethanol, may result in long-overdue support for improved agricultural systems, especially in the world’s poorest regions. At least until the financial meltdown, rising energy costs were causing significant changes in peoples’ transportation choices in the United States and elsewhere. And growing awareness of the consequences of climate change is leading to modifications of insurance policies and zoning regulations governing development of ocean shores and areas subject to severe storms and flooding. Most heartening in the United States has been a surge of activity in developing energy policies to curb global warming by state and local governments, and there is now some hope that a new reality-based federal government will follow suit.

The scientific community has long spoken out unambiguously on the need to change humanity’s course. For instance, the 1993 World Scientists’ Warning to Humanity, signed by 1,500 leading scientists, including more than half of the Nobel Laureates in science, declared: “Human beings and the natural world are on a collision course. Human activities inflict harsh and often irreversible damage on the environment and on critical resources. If not checked, many of our current practices put at serious risk the future that we wish for human society and the plant and animal kingdoms, and may so alter the living world that it will be unable to sustain life in the manner that we know. Fundamental changes are urgent if we are to avoid the collision our present course will bring about.”

In the same year, the academies of science of the world put out a statement on population that said in part: “The magnitude of the threat . . . is linked to human population size and resource use per person. Resource use, waste production and environmental degradation are accelerated by population growth. They are further exacerbated by consumption habits. . . . With current technologies, present levels of consumption by the developed world are likely to lead to serious negative consequences for all countries. . . . As human numbers further increase, the potential for irreversible changes of far-reaching magnitude also increases.” Of course, how one balances such statements against the insights of George W. Bush, Sarah Palin, Rush Limbaugh, or editorial writers for the Wall Street Journal each person can judge for herself.

In some areas, humanity has changed course. As we mentioned above, population growth is slowing. Birthrates have dropped over much of the world, especially in the industrialized countries of Europe and Japan and even in China, India, and many other developing countries. This has largely been a function of educating women and giving them job opportunities, and of government programs providing access to contraception and safe abortion (and in China a dramatic and controversial program aimed at making a one-child family the norm). The drop in fertility in Europe, leading to population shrinkage in some countries, has been especially cheering because many are high-consuming nations where each person puts much pressure on our life-support systems.

Sadly, that the beginning “fizzle” of the population bomb in Europe is one of the few positive demographic trends is often totally misunderstood. In a rapidly growing population, a high proportion of people are young; on the other hand, the fraction of people over sixty-five is typically quite small—on the order of 5 percent or less. By contrast, as population growth slows, the proportions of people in different age classes change dramatically. In industrialized nations with slowing or no growth, the proportion of people under age fifteen has become smaller, making up less than 20 percent of the population, while the older age groups have grown to about the same proportion. Traditionally, people between the ages of fifteen and sixty-five are considered to be members of the “productive” ages—that is, capable of holding jobs and supporting children and the elderly. United Nations demographers project that as birthrates continue to fall, the worldwide proportion of people over sixty will more than triple, from about 600 million to nearly 1.9 billion in 2050, accounting for more than 20 percent of the global population and as much as 30 to 40 percent in some countries with dwindling populations.

This momentous change has aroused alarm among the innumerate and led to the ridiculous idea that the United States—with an average family size of 2.1 children compared with Europe’s 1.5—is, as stated previously, a “sparkling” exception. A few demographers and many politicians and commentators have expressed grave concern about the future of social security programs to support the elderly, predicting dire problems for people in the proportionally shrinking productive age groups who will be burdened with caring for their aged parents. They want to keep populations growing, to avoid the shift toward an older-age composition, not realizing that that will increase the chances of a catastrophic collision with nature. Their view neglects the trade-off represented by having proportionately fewer children to educate and support as the population ages. It also ignores that it is much easier (and socially more beneficial) for people over sixty-five to be economically productive than those under fifteen.

And it overlooks that crime and terrorism, everything else being equal, are reduced by an older-age composition because of relative shrinkage of the young-adult age group. In developing nations that still have high birthrates, more than half the population may be under twenty years of age, and another quarter may be between twenty and thirty-five. The youthful-age composition of these populations, in the context of poverty, high unemployment, poor health care, limited education, gross inequity, and repressive government creates fertile conditions for a desire to challenge the power of the affluent. The majority of terrorists behind the attacks of September 11, 2001, were young adult men, the demographic group responsible for most crime globally. The ages of suicide terrorists have generally ranged between sixteen and thirty.

And, of course, unless one is so ignorant as to think the human population can grow forever, encouraging more population growth now just delays the inevitable. Sooner or later the age composition change must occur, and any disruptions it will cause will need to be dealt with by our descendants in an even more overpopulated, resource-depleted, and environmentally devastated world.

As scientists have repeatedly warned, we would need more than another Earth to support even today’s human population sustainably. Humanity has exceeded our only planet’s carrying capacity. While environmentally triggered collapses such as those that afflicted the Sumerians, the Classic Maya, and the Easter Islanders were once strictly regional, the potential today, we repeat, is for a worldwide catastrophe. As we explain in The Dominant Animal, which gives details on the topics touched on in this article as well as explaining how humanity got into this mess, we need to work much harder to start population declining everywhere, reduce wasteful consumption (especially of fossil fuels), and find positive ways to reconfigure the human enterprise if we’re to reach a sustainable civilization.

Blissful ignorance of the population contribution to our troubles at least is beginning to change—especially in the blogosphere. “Malthus is back now, along with his outriders: famine, pestilence, and war”—that’s how blogger and author Jim Kunstler put it. It is clear that serious steps to change our “business as usual” course are not likely to come from governments unless large segments of the population demand them. It is up to all of us to help generate that demand and to start a global discussion of how to design a sustainable society. Today’s economic disaster may give us an opportunity to do that. Our very dominance as a species today threatens to be our own undoing. Global collapse is not a pretty prospect, and only all of us collectively can prevent that denouement.

Further Reading

  • Ehrlich, P. R. The Population Bomb. New York: Ballantine Books, 1968.
  • Ehrlich, P. R., and A. H. Ehrlich. One with Nineveh: Politics, Consumption, and the Human Future (with new afterword). Washington, D.C.: Island Press, 2005.
  • ———. The Dominant Animal: Human Evolution and the Environment. Washington, D.C.: Island Press, 2008.
  • Ehrlich, P. R., and D. Kennedy. “Millennium Assessment of Human Behavior: A Challenge to Scientists.” Science 309 (2005): 562–63.
  • Homer-Dixon, T. The Upside of Down: Catastrophe, Creativity, and the Renewal of Civilization. Washington, D.C.: Island Press, 2006.
  • Klare, M. T. Resource Wars: The New Landscape of Global Conflict. New York, N.Y.: Henry Holt, 2006.

Anne H. Ehrlich

Anne H. Ehrlich is a Senior Research Scientist in Stanford University's Department of Biology.

Paul R. Ehrlich

Paul R. Ehrlich is Bing Professor of Population Studies


The quick answer to that question is “Yes.” But the finally requires qualification. The population bomb—the power of population size and its rapid growth to greatly darken the human future—has actually been exploding for many decades. It’s just that until recently people in general and the media in particular have not been paying attention. For …

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