Condoms prevent transmissions of disease, and could be key to population control. Photo: Rampant Gian (flickr)

CIA director Michael Hayden recently identified one of the biggest threats facing the U.S., something that occurs over 215 million times a day — sex.

“Population is the essential multiplier for any number of human ills," Hayden said recently. He said overpopulation in the poorest parts of the world is causing global political instability and extremism, climate change, and the food and fuel crises.

In the 1970s, environmentalists frequently discussed the problems of overpopulation, but in the last 30 years, rigid population control has been condemned.

Robert Engleman, vice-president at the Worldwatch Institute and author of the new book More: Population, Nature and What Women Want, says that after China's controversial one-child policy, "Environmentalists came to realize how complicated and sensitive this issue was.”

As food and fuel prices rise, so do concerns that the planet’s limits are finite. Population growth has slowed in developed countries, but is still rising in much of the developing world. With climate change forcing a fresh look at overpopulation, Engleman’s new book argues that “the key to limiting population growth is to give control over procreation to women.”

What Engleman is suggesting is not feminism, it’s just common sense. He says that even in societies with traditionally large families, when women gain control over family sizes with contraception access, birth rates shrink.

Fifty-year-old Linganni, who earns $2.50 a week sweeping streets in Burkina Faso, would certainly agree that too many children and not enough food is a problem. In an article that discusses how the food crisis is hitting women the hardest, The Washington Post describes how her 25 children share one meal a day. And Linganni always eats last.

In his recent article "What Condoms Have To Do With Climate Change", Time's Bryan Walsh suggests the best policy for the U.S. would be “vigorous foreign aid that helps make contraception safe, reliable and accessible in every country — too often women in the developing world who want to use contraception, can't get it.”

Contraceptive aid from the U.S. may be a difficult sell, considering that Americans are still obsessing over abstinence-only sex education and holding father-daughter purity balls. And around the world, contraception is often taboo, and the decision whether to use it is up to the man.

One solution is to support forms of contraception that give women control and are invisible to men, like the Pill or IUDs. But whatever the approach, women need to have control over the number of kids they have. Population control will only happen, Engleman reminds us, when "women are in charge."