They say that a good man is hard to find. But in some countries, the opposite is true: a good woman is hard to find—because it’s hard to find women at all. According to a recent article by the BBC, the Chinese city of Lianyungang has eight men for every five women. Ninety-nine cities in China have gender ratios as high as 125 (125 men for every 100 women, or a 5:4 ratio).

But China is not alone. India has a gender ratio of 113, and the ratio in Asia as a whole is 104.4. In the United States, by contrast, the rate is 97, meaning that there are more women than men.

Gender imbalances are caused by cultural and economic preferences for male children, which contribute to sex-selective abortion and female infanticide. Over 60 million girls are “missing” in Asia as a result of these practices.

Furthermore, some government policies may intensify these gender preferences. China’s one-child policy, for example, may cause concern among parents, particularly in rural areas, that having a female child endangers their family’s future. Government policies intended to combat skewed gender ratios, such as bans on prenatal ultrasounds for the purpose of determining the baby’s sex and bans on sex-selective abortion, have proven ineffective.

Unbalanced gender ratios have consequences that reach beyond just the mothers and children involved. According to Valerie Hudson, high gender ratios leave many men without prospects for marriage, which may mean these men have fewer incentives to contribute peacefully to society. The men with the slimmest prospects for marriage are likely to be unemployed, poor, and uneducated, so they are already at increased risk for violent behavior. Hudson cites statistical evidence showing links between high gender ratios and higher rates of violent crime, drug use, trafficking, and prostitution.

Hudson and co-author Andrea den Boer cover these links in greater detail in their book Bare Branches: The Security Implications of Asia’s Surplus Male Population. In the 11th issue of the Environmental Change and Security Report, Richard Cincotta takes issue with some of the statistical methods that Hudson and den Boer use. He argues that what is important is not nationwide gender ratios, but the number of “marriage-age men” (25-29 years old) and “marriage-age women” (20-24).

While there may be some debate over whether the relationship between gender ratios and violent behavior is a causal one, there is little doubt about what causes the gender imbalances in the first place. An end to preferences for female children will be beneficial not only to girls and women, but to societies as a whole.

Photo Credit: A subway in China, courtesy of flickr user 俊玮 戴.

The newest podcast from the Wilson Center’s Project on Emerging Nanotechnologies highlights how engineers are using nanotechnology to develop more efficient and cost-effective ways to desalinate seawater and purify wastewater. In the future, these new water purification technologies could be adapted for use in poor countries where access to safe water is limited. The podcast is the third in the “Trips to the Nano Frontier” series, which also includes podcasts on green nanotechnology and nanomedicine. The full series is available online.

The Center’s Environmental Change and Security Program (ECSP) also produces an original podcast series. ECSP’s podcasts, which feature interviews with leading scholars and practitioners, have examined the role of gender in population, health, and environment programs; the challenges and opportunities presented by urban population growth; and the link between international trade and aid policies and conflict.

The Economist’s recent story “How to deal with a falling population” rightly states that a growing global population does not inevitably exhaust the earth’s resources, and that a shrinking population poses several serious threats to nations.

But the article downplays the impact of a large population. The total number of people on the planet has both global and local consequences. On the global level, each additional resident contributes to climate change, and this contribution is growing for citizens of developing countries making the transition to more western, carbon-consuming lifestyles. While 6.6 billion people have not yet run the oil derricks dry, large local populations have already had significant effects on local resources. In many parts of the world, women and children walk for hours to obtain water, firewood, and other basic needs.

The story seems to suggest that we should wait for governments to solve the problem of climate change. Yet many, including the author of one of the articles in The Economist’s September 2006 survey of climate change, are skeptical that politics can single-handedly and responsibly address this issue.

While governments work on large-scale policies, everyday people can influence natural resource consumption and climate change by focusing on population issues. One of the most effective ways to do this is by expanding access to family planning programs. Concerns about the possibility of coercion accompany all family planning efforts, but regulated, well-managed family planning programs tend to produce positive side effects, increasing women’s empowerment and education and expanding employment opportunities for both men and women.

It is important for governments and international institutions to craft prudent, long-term policies to address climate change. Yet we must also remember that the choices that ordinary individuals make can have significant positive impacts on health, economic development, and the environment.

I started taking courses at Berkeley last night—sort of. From the comfort of my own home (and comfy couch), I listened to Professor Nathan Sayre’s “Natural Resources and Population” course lectures on my iPod. I can take the course at my own pace, following along with the online course syllabus and listening in whenever I want. The only foreseeable drawback is that Professor Sayre will not call on me when my brain is teeming with questions.

Berkeley isn’t the only university opening its classrooms to eager dilettantes. Stanford University, Texas A&M;, Duke University, Penn State, and many more universities and colleges are offering free, downloadable podcasts of myriad elective and core courses.

National Public Radio (NPR) and National Geographic have teamed up to produce “Climate Connections,” a year-long series that explores, in its own words, “How we are shaping climate” and “How climate is shaping us.” This fascinating, first-rate series should appeal to non-experts as well as those more familiar with these issues.

NPR and National Geographic produce stories for the series independently, but link extensively to one another’s contributions. Both organizations’ websites offer a wealth of compelling—and sometimes sobering—stories on the connections between people and climate. For instance, NPR’s most recent “Climate Connections” story examines how the gas flares that are produced in the Niger Delta when oil companies burn off surplus natural gas are releasing vast amounts of carbon dioxide into the air and likely sickening nearby residents.

Both websites are filled with interactive features: National Geographic has a “Grade Your Climate IQ” quiz and an animated climate change simulation, while NPR’s website allows viewers to find past “Climate Connections” stories by navigating around a map of the world. I encourage you to listen in or log on to this excellent, cross-cutting series.

Climate change, biodiversity, air pollution, deforestation, water scarcity, and other environmental issues share a common denominator that lies quietly beneath the higher priorities of the environmental movement: population pressure.

Scholars, policy analysts, and even military officers are breaking down climate change’s impacts into what they hope are more manageable topics for examination. The migration that climate change could cause is one such topic. For instance, the Center for American Progress recently posted a piece entitled “Climate Refugees: Global Warming will Spur Migration.” The International Peace Academy analyzed “Climate Change and Conflict: The Migration Link” in a May 2007 Coping With Crisis working paper. Climate change-induced migration also figured prominently in the security perspective offered by the CNA Corporation’s Military Advisory Board in its “National Security and the Threat of Climate Change.”

Next year, for the first time in history, more than half of the world’s population will live in cities. This urban growth is inevitable, says a new United Nations Population Fund (UNFPA) report. Although cities are sometimes thought of as synonymous with poverty and large ecological footprints, the report, entitled State of World Population 2007: Unleashing the Potential of Urban Growth, describes the unprecedented urbanization as an opportunity. Lead author George Martine discusses the misconceptions surrounding urbanization and the ways in which policymakers can maximize the benefits of urban growth.