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Feeding the Planet: An Evening with Alan Weisman

Feeding the Planet
Reported by
Nadia Jaber

Posted October 31, 2013


Alan Weisman, a journalist and nonfiction writer, came to the New York Academy of Sciences on September 25, 2013, to discuss his latest book, Countdown: Our Last Best Hope for a Future on Earth? Weisman considers difficult global issues in his work, peppering hard facts with compelling stories and extensive research. His previous book, A World Without Us, in which he imagines how our planet might adjust if humans disappeared, has been translated into 30 languages. In Countdown, Weisman explains why we need to address the global population crisis and offers some of the solutions to overpopulation he observed while traveling as a journalist. Feeding the Planet: An Evening with Alan Weisman was presented by Science & the City and the Sackler Institute for Nutrition Science.

Weisman's latest book is Countdown: Our Last Best Hope for a Future on Earth? It explores whether and how humans can sustainably thrive on Earth without crashing the global ecosystem. (Image courtesy of Alan Weisman)

Overpopulation is not a difficult concept to grasp: the human race has a capacity for explosive growth, but the earth has limited resources to support us. Weisman pointed out that these circumstances are incompatible. While it may be possible to grow more food through bioengineering and ingenious technologies, this effort could negatively impact the fragile balance of the environment. Weisman argues that limiting the population is a better option, since it can be achieved safely and more easily using technologies that already exist. He acknowledges this goal might be counter to our instincts, as reproduction is a primary raison d'être for living organisms, but he thinks we must consider the consequences and manageability of unrestricted species growth. To investigate how many humans the earth can sustain, Weisman visited 21 countries in two years, seeking to answer pertinent questions: How many people can fit on the planet? How much of nature must we preserve to ensure our own survival? Are there any precedents in religious texts or cultural stories that would support more conservative reproduction? Could we design an economy that does not depend on perpetual growth to prosper?

Weisman explained that two phenomena have caused the world population to skyrocket: modern medicine and new food technologies. Before modern medicine, many young children died of infectious diseases such as smallpox, and out of large families only one or two survived to adulthood. This high fatality rate disappeared with the advent of vaccines and medicines for infectious diseases. Weisman noted the drawback to our extended life expectancy: there are more people consuming more food for longer periods of time. Such dichotomies in population management are not uncommon—the solution to one problem often causes another.

An important advance in modern agriculture was the development of the Haber-Bosch process. In the early 1900s Fritz Haber discovered a chemical process that uses high pressure to produce ammonia from nitrogen in the air. Plants require nitrogen to grow, and ammonia provided a means to increase its availability. Carl Bosch increased the scale of Haber's reaction, allowing for the production of artificial nitrogen fertilizer. The resulting Haber-Bosch process is credited with supporting half the world's current population by dramatically increasing crop growth, and both men were awarded Nobel prizes. However, Weisman pointed out that their discovery is not without caveats—it depends on massive amounts of fossil fuel, produces greenhouse gases, damages oceans, and contaminates water supplies.

Later, in the 1960s, while industrial countries celebrated food surpluses, developing countries faced famine and malnutrition amid rising population growth. Western nations responded by redefining modern agriculture again. Interbred crops produced sturdier varieties that could grow year-round. The International Rice Research Institute (IRRI) and the International Maize and Wheat Improvement Center (CIMMYT) developed high-yield varieties of rice and wheat, respectively. These developments, termed the Green Revolution, saved countries like India and Pakistan from imminent famine by doubling the world's grain harvests. But much like the Haber-Bosch process, the Green Revolution is clouded with controversy. Populations in India and Pakistan are now growing very rapidly; Weisman observed that this growth is accompanied by increasing social mayhem in Pakistan and economic insecurity in India. He related the affliction of one farmer in India and described how the farmers "are all on each other's suicide watch" because they cannot support their families with Green Revolution farming techniques. High-yield crop varieties require large amounts of water and fertilizer, forcing farmers to take out loans to buy expensive drills and other materials to support the farm. Many farmers are in debt, and 270 000 Indian farmers have committed suicide since 1995.

Crops grown using Green Revolution techniques lack genetic variety and thus are more susceptible to disease—one kind of pest or disease can eliminate an entire crop. These crops therefore require extensive use of pesticides, which create additional environmental and biological hazards. Many food scientists, including Norman Borlaug, who helped develop high-yield wheat, believe that the Green Revolution was not a comprehensive solution to food crises; it merely bought us time to find a better one. According to Weisman, the Green Revolution in fact exacerbated food scarcity and overpopulation, because increased food production led to population growth and further demand for more food. He believes that relying on human ingenuity to solve food scarcity by engineering crops with even better yields will take too long and, like the Green Revolution, would probably lead to more problems. The advisability of further agricultural development is complicated by the greenhouse gases emitted by growing populations and agriculture itself—livestock and their byproducts account for about 50% of total emissions. Weisman explained, "We can't keep assuming that technology is going to keep stretching our limits on this planet, because everything that stretches finally breaks at some point or another."

The global population increases by one million people every 4.5 days. It stands at 7.2 billion and by the end of this century is projected to increase to 11 billion. If we all adopted China's one-child policy, the population would instead fall to 1.6 billion by the end of the century. However, Weisman noted that such a restrictive policy is not only "repellant," but impractical. Instead, he suggests a non-coercive voluntary approach, modeled after one he observed in Iran. After the 1979 Islamic revolution, Iran's newly formed government preached that citizens should "be fruitful and multiply," in order to build a large army to defend against invading troops from Iraq, and birthrates increased dramatically. After the war, however, Iran had a high population of jobless, angry young men, prompting their director of planning and budgets to calculate how many people the country could support. As a result, the government began advocating a "one is good, two is enough" philosophy. Iran supported vasectomies for men when a couple decided their family had reached a comfortable size. Doctors set up clinics offering condoms and tubal ligations. The government required couples to attend a family planning class before marriage and encouraged education for women and girls; educated women tend to delay childbearing until after their schooling and tend not to have more than two children.

Remarkably, Iran reached replacement rate (an average of two children per woman) a year faster than China did with its one-child policy. With the exception of the required premarital family planning class, Iran's policy was voluntary, and citizens complied. Weisman highlighted female education, which he calls a "win-win-win" situation, as the most effective contraceptive in all the countries he visited. Italy, for example, has one of the lowest fertility rates and one of the highest percentages of female PhDs. Weisman noted that although Iran's policy was rescinded in 2012, it has been described by the United Nations as "the most successful and humane family planning program on Earth."

A significant advantage of a family planning approach for population management is that contraceptive technologies already exist—the only barrier is effective distribution. Weisman related accounts of women walking barefoot to collect contraceptives and medicines delivered by horseback in developing nations. Families are realizing that conserving their resources for a few children provides those children with the best chance for a good life. Raising and educating a child is expensive; doing so for five or six children is near impossible for many families. If contraception became widely available, the global population could decrease to 6 billion by the end of the century. This effort would cost $8.5 billion annually; Weisman noted that this amount is far less than the United States spent on the wars in Iraq and Afghanistan in one month. If female education became available to all, the population could fall to 6 billion by the middle of the century. Weisman therefore proposes that countries consider a voluntary plan that encourages family planning, makes contraceptives freely available, and advocates female education.

To illustrate the extent to which it is beneficial to preserve natural habitats, Weisman related examples from China, Nepal, the Philippines, and Japan, where seemingly small changes to solve a specific problem resulted in marked improvements to the local ecosystem. In Japan, the extinction of wild oriental white storks prompted a shift to organic farming. Storks bred in captivity could not be released as a result of the toxicity of pesticides used in rice paddies; but organic farming techniques provided a safe nesting area for the storks, and their presence increased tourism to the area and stimulated the economy. These examples suggest that by protecting the delicate balance of our ecosystem, humans may benefit in unexpected ways.

To assess whether economic growth can be sustained by a shrinking population, Weisman again turned to Japan. The population of this small island nation is waning, in part because of the increased availability of contraceptives and the legalization of abortion in 1949. Traditional economists believe that constant growth is the only sign of economic success and fear that a labor shortage will severely damage the economy. Japanese economist Akihiko Matsutani offers a different prognosis. In light of the declining population, combined with the 2011 tsunami and resulting nuclear power accident at Fukushima, he envisions an economy centered on light industry instead of heavy industry, which requires more capital, bigger production plants, and more labor. He also believes that spreading light industry throughout the country rather than concentrating labor in large cities would help to alleviate urban overcrowding. Matsutani, the author of Shrinking-population Economics: Lessons From Japan, predicts that fewer workers and reduced working hours will greatly improve quality of life.

In the question and answer session, the audience voiced concerns about how to promote the policies Weisman suggested. One audience member asked how contraception or family planning might be received by people with conflicting religious beliefs. Weisman advised looking for instances in religious teachings that support more conservative reproduction. In Mormon history, for example, the church relaxed its teachings because many women died during childbirth after giving birth too frequently. In the biblical story, Joseph had only one wife and two sons in a society that supported polygamy, a practice he believed would result in food scarcity, and he advised Egypt's Pharaoh in favor of conservative growth. Another audience member asked how to instigate meaningful conversations about family planning and environmental conservation. Weisman conceded that "population ... is a loaded, political term for many people," but he suggested that leading with the idea of female education is helpful. Bill Ryerson from the Population Media Center mentioned that communication platforms such as educational soap operas and street theater have been effective, especially because they are not forceful or didactic.

Weisman concluded by likening population management to restructuring a company that needs to downsize: it can either "brutally" fire a large portion of its work force, or it can use attrition to gradually reduce its numbers, hire fewer employees, and simply do more with less. He wonders whether our population already exceeds the practical limits of the earth's resources, and somberly argues that we are facing a population crash. "Either we manage it gracefully or nature will do it to us, brutally."

Use the tab above to find multimedia from this event.

Presentation available from:
Alan Weisman (Author)

Presented by

  • Science and the City
  • The Sackler Institute for Nutrition Science

Feeding the Planet: An Evening with Alan Weisman



Matsutani A. Shrinking-population Economics: Lessons From Japan. Int'l house of Japan; 2006.

Weisman A. Countdown: Our Last, Best Hope for a Future on Earth? New York, NY: Little, Brown and Company. 2013.

Weisman A. The World Without Us. New York, NY: Thomas Dunn Books; 2007.

Websites and Articles

The Central Intelligence Agency. The World Factbook. Country comparison: total fertility rate. 2013.

International Food Policy Research Institute. Green Revolution: Curse or Blessing? 2002.

International Maize and Wheat Improvement Center. What we do.

International Rice Research Institute. About IRRI.

Matsutani A. Portrait of a depopulating society — diversifying values and a more mature prosperity. 2005.

Population Media Center. Who we are: Mission.

Smil V. Detonator of the population explosion. Nature. 1999;400:415.

Weisman A. The World Without Us. About the Author. 2007–2008.

Zwerdling D. 'Green Revolution' trapping India's farmers in debt. NPR. 2009.


Alan Weisman

Alan Weisman


Alan Weisman is the author of several books, including the acclaimed The World Without Us. His work has been selected for many anthologies, including Best American Science Writing. An award-winning journalist, his reports have appeared in Harper'sThe New York Times MagazineThe Atlantic MonthlyDiscoverVanity FairWilson QuarterlyMother Jones, and Orion, and have been featured on NPR. (Author photo credit: Bill Steen)

Nadia Jaber

Nadia Jaber is a PhD student studying protein homeostasis at Stony Brook University, where she is also working on a health communications certificate. She hopes to combine her scientific knowledge with her passion for writing and communication to help the public empower themselves with science.


Presented by

  • Science and the City
  • The Sackler Institute for Nutrition Science