From Readers

Your Letters and Comments

We received many letters on “The Depopulation Bomb” by Philip Longman in the July-September 2006 issue. Some of you questioned why we would even run such a story in a conservation magazine. We were skeptical, too, and hotly debated the topic in our editorial office. In the end, we decided to run the piece for two reasons. First, the demographic data and trends that Longman points to checked out with the United Nations’ Population Division database. And second, Longman pushes us to think beyond the familiar. It is certainly true that growing populations and consumption threaten biodiversity. But what Longman brings to the table are societal implications of population decline (e.g., political and economic instability) that are not often part of the dialogue in our community. We are accustomed to thinking that population decline is all good, the polar opposite of the runaway population growth that has been so detrimental. But human ecology and population dynamics are more subtle than that. We wanted to start looking at this without fear or favor. It’s part of what we strive for in the pages of Conservation In Practice—a fresh take on issues, ideas, and research that may catch you off guard but hopefully will always make you think.

Thanks for your thoughtful comments.—The Editors

Unstated Assumptions
I was aghast to read Phillip Longman’s misleading article “The Depopulation Bomb” (July-September 2006). The figures shown accurately depict one common prediction for demographic trends in the future. But after describing these predictions, Longman makes broad claims about the negative environmental impacts of a decrease in human population that are not substantiated by the data presented. And he never discusses potential environmental impacts of ongoing population growth.

For example, he writes: “3 billion persons living in sprawling McMansions and driving SUVs will make more pollution than a world of 9 billion who have, out of necessity, learned to shun sprawl, eliminated auto dependency, and developed alternative cleaner forms of energy.” Even if the population does decline gradually, which is debatable, it will be years before the population reaches 3 billion, by which time resources are likely to be severely limiting, even for a population of that size.

Moreover, this statement makes huge assumptions about the lifestyles of residents under different popula tion growth scenarios. Longman also states that “as societies age, the cost of health care and pensions can consume resources that would otherwise be available for investment in cleaner energy and conservation.” The current U.S. economy is growing rapidly according to traditional economic indicators, yet we are making relatively little investment in cleaner energy, suggesting weak correlation between resource availability and investment in cleaner energy.

It is not that the generalizations that Longman makes are entirely untrue. Rather, his statements about the negative effects of depopulation are likely to be true only under a restricted set of assumptions that are not stated. He offers a list of generalizations that do not stem from the data presented, and these generalizations are completely one-sided. In short, I found this article to have poor scholarly rigor and to lack adequate critical analysis to be published in a journal that advertises itself as a teaching resource.

KAREN HOLL

Department of Environmental Studies

University of California, Santa Cruz

One-dimensional Picture
We were surprised that Conservation In Practice allowed Phillip Longman to paint a one-dimensional picture of human population trends in the 21st century. If there is a “Depopulation Bomb,” it has a very long fuse—the world is likely to continue in growth mode for the next 50 to 70 years. The “birth dearth” that Longman writes about is real, but it is far from universal, and some of the world’s poorest and most populous countries are still experiencing rapid growth.

“Population momentum” (the tendency for populations to increase, even with lower birth rates, because of a large number of women in the child-bearing years) rules out any decline in the near future. The United Nations says the world will have between 9 and 11 billion people by 2050. Some countries, including Kenya, have reversed recent trends and have actually increased birth rates. Meanwhile the U.S. population (with replacement-level fertility but high immigration) is nearing 300 million. The U.S. Census Bureau predicts that 400 million will be reached in fewer than 40 years.

The environmental consequences of an additional 3 billion people far outweigh the consequences of a declining population 75 years from now. Environmentalists should be celebrating that world population growth will likely peak as early as 2050, the result of a concerted worldwide effort to empower women to exercise family planning. We should also celebrate and, indeed, strive for the possibility of a future downsized world population at a level that is compatible with long-term environmental sustainability.

We worry that a misguided concern about uncertain consequences of eventual negative population growth could jeopardize the tremendous gains made in stabilizing world population growth, resulting in a peak population of billions more than currently projected and a delay in timing by decades. Longman’s article tells only part of a very complex story.

DON A. WEEDEN

Weeden Foundation

New York, New York

JIM MOTAVALLI

E/The Environmental Magazine

Norwalk, Connecticut

Carbon per Capita Impact
“The Depopulation Bomb” offers a nuanced view of how a decline in population could slow our transition to a carbon-reduced lifestyle. But there are several flaws in Longman’s argument. For instance, he makes the case that increased pension funds for the burgeoning elderly population siphon investment money for cleaner energy. However, given the spending trends of our government, investment in hydrogen and renewable energy is already far down the priority list. Moreover, there are other ways to cover the costs of an aging population. Ultimately, the carbon per capita impact is of utmost importance, and carbon growth generally trumps energy efficiency. While Longman makes a strong case that depopulation could have negative hidden consequences, the balance of population growth on the environment is still negative.

TODD NELSON

Colorado Springs, Colorado

False Alternatives
Phillip Longman’s article “The Depopulation Bomb” uses the classic deception of false alternatives to miraculously defuse the twin threats of overpopulation and overconsumption. His choices: 3 billion people living in McMansions or 9 billion people living green. What the endless forms of life most beautiful deserve is a world population of 3 billion people (and falling) who are treading lightly on the planet. This is the biodiversity-friendly option Longman oddly fails to consider.

JOHN MONSEN

Los Angeles, California

Quixotic Arguments
Phillip Longman’s “The Depopulation Bomb” is utterly quixotic and out of step with conventional projections. Most demographers have seen two simultaneous trends occurring: a decline in global fertility rates and a lag time between fertility control and a burgeoning population of youths in the highest-fertility age groups. According to United Nations median growth scenarios, 3 billion people will be added to the planet in this century, and that is if all the couples in the world resort to replacement-size families in the next few generations. If they don’t, then world population could hit 13 billion. Whether 9 or 13 billion, the issues for conservation are clearly marked.

In the same issue of Conservation In Practice (July-September 2006), you highlight the recent Proceedings of the National Academy of Sciences paper by M. Carillo et. al in which the authors describe latent extinction-risk hotspots as “areas where the number of people is expected to rise extremely rapidly within the next decade.” Indeed, while 45 percent of all countries have achieved population stabilization, 55 percent of all nations have not. Conservationists should not be lulled into believing that human demographic pressure is going to get easier. It won’t.

DR. MICHAEL TOBIAS

Dancing Star Foundation

Los Angeles, California

Unanswered Questions
I am writing in response to “Environmental Heresies” (April-June 2006). Mr. Brand may be overly worried about depopulation. Although it is true that this is an issue in some developed countries, it is not likely to be so in many less developed countries any time soon.

Next, in response to the question about conservation and development, Mr. Brand states, “Öcity dwellers have the smaller footprint.” Much of a city dweller’s footprint on the environment is indirect. It would seem to me that just the average energy use per city dweller must be higher than for a rural dweller, and that alone will constitute a larger footprint.

Finally, Mr. Brand repeats the myth that nuclear power is non-polluting. In some regards, this is correct. But nuclear waste has a half-life on the order of a quarter-million years. What exactly does he propose we do with this extremely dangerous material that will be around for 25 times as long as the whole of human history since the discovery of agriculture? And what of the possible interaction between that waste and terrorism? And what of the thermal pollution? The answer to our energy problems lies just beyond our atmosphere, where the sun provides virtually limitless energy at no cost and with no pollution at all.

RANDY MADDOX

Innovative Concepts

Alexandria, Virginia