U.S. author Alan Weisman has travelled around the world to discover why the global population is careening out of control. And he came back with some astonishing stories.

While researching his latest book, Countdown: Our Last Best Hope for a Future on Earth? (Little, Brown and Company), the Massachusetts-based writer discovered that in the landlocked West African country of Niger, women have eight or nine children on average. A mayor of one town bragged to him about fathering 33 kids.

Weisman reports that this explosion of births has fortified a slave trade that comprises 10 percent of that country’s population.

Meanwhile, neighbouring Nigeria’s population is expected to double to 333 million by 2040, making it the fastest-growing country on the planet.

In the Philippines, Weisman learned that the exploding number of people is jeopardizing marine species. That’s because 90 percent of Filipinos’ protein sources come from the sea.

In Uganda, he found out that it’s the other primates that are under siege. He also travelled to Israel and Palestine, where there isn’t enough water to irrigate crops to keep everyone fed. Yet women continue giving birth at an astonishing rate.

Weisman points out in his book that at the current rate of growth, the global population will have risen from seven billion in 2011 to 10.9 billion by 2100. It’s the equivalent of adding Germany’s population to the planet every year.

He’s concluded that nowhere is the situation more perilous than in Pakistan, a nuclear power with poor prospects for controlling population growth. There, he met young men in overcrowded Karachi whose only job opportunity was becoming “hired pistols for the warlords”.

“I went to see a really promising environmental program there to save the mangroves in Karachi harbour,” Weisman tells the Georgia Straight over the phone during a drive through the Arizona desert. “And I got there a day late because the guys I went to interview were found tortured and floating in the lagoon.”

With 185 million people packed into an area the size of Texas, he says, Pakistan’s population is exploding because of a weak central government, a lack of female education, and an astronomical number of young people of childbearing age.

The roots go back to the Green Revolution of the 1960s, when a potentially devastating famine was halted. Weisman explains that farmers’ use of hybrid seeds sharply increased the number of grains on each stalk of wheat or rice, enabling many more people to live long enough to have children. They later had their own kids. It’s one of the reasons why Pakistan’s population is expected to climb to nearly 400 million by the middle of the century.

“One of the most hopeful stories in Countdown is this school system that’s been started by these businessmen who got sick and tired of watching their country going down the tubes,” Weisman says.

In numerous countries, he explains, the advancement of education, particularly for young women, sharply slows the birthrate. It’s even occurred in strongly Catholic countries, such as Italy and Spain.

In these Pakistani schools, students are paired with female mentors who work as teachers, doctors, nurses, and flight attendants.

“They never have to talk about family planning because these girls get it,” Weisman says. “These professional women that they meet only have two children. They can’t afford to have any more and have their job.”

That leads into a discussion about the impact of Malala Yousafzai, the 16-year-old Pakistani educational activist who was shot in the head by the Taliban on October 9, 2012. She has since become a global symbol of female emancipation by continuing to speak out on behalf of girls’ schooling.

“This young woman is an example of how education can turn everything around in that country,” Weisman declares.

One of Countdown’s central points is that if human beings don’t reduce the global fertility rate, Mother Nature will impose her own solution. And it won’t be pretty.

“The reason why I ultimately focused on population was that this is the one thing that we already know how to do,” Weisman says. “We’re not very good at suddenly replacing all of our carbon-based energy with zero-emission energy.”

And there is no shortage of success stories in Countdown. In Iran, for example, a massive educational campaign, including classes for couples planning to get married, sharply drove down that country’s birthrate following the nearly decade-long war with Iraq.

One of the keys was promoting educational opportunities for young women, as well as Ayatollah Ali Khameini’s decision to allow voluntary sterilization. His big fear was that the economy couldn’t absorb a growing population of young people born during the Iran-Iraq war. But recently, Weisman reports, the country has reversed some of these policies and has been trying to encourage couples to have more children. He notes that this may be related to fears of another war.

In Thailand, family-planning campaigner Mechai Viravaidya employed humour to encourage the use of condoms, achieving stunning success in bringing down the birthrate. In 2007, he received the Gates Award for Global Health.

Meanwhile, in the Philippines, where the Catholic Church vehemently opposes family planning, President Benigno Aquino signed a reproductive-health bill into law. (Weisman points out in his book that the legislation faces a court challenge.) And in Japan, married women told the author that they’ve simply stopped having sex with their husbands to avoid becoming pregnant, which is one of many reasons why that country’s birthrate has declined.

China pioneered population control in 1979 with its one-child policy, which required pregnant mothers to go on abortion leave from work. Weisman says it’s unlikely that the rest of the world would ever go along with this type of program because “most people find it loathsome.”

“The way this happens is not through government intervention,” Weisman insists. “The role of government is to make this stuff [contraception] available to people and let them decide for themselves how many kids they want. If you add female education, you’re almost guaranteed that the average number of kids is going to be two or lower.”

When asked if he’s an optimist or pessimist about the prospects for controlling a rising global population, Weisman replies: “Well, I’m more optimistic, actually. I don’t pull any punches in this book. We’re facing some really difficult times in this world right now. The 21st century is going to be a wild ride. We have rejigged atmospheric chemistry and that, in turn, is completely changing the chemistry of the seas. And we just don’t know what is going to happen here.”

He adds the rising sea levels caused by climate change pose a monumental threat to rice harvests in heavily populated countries like China and the Philippines.

“That’s the most important crop on Earth in terms of the number of people who depend on it,” he says. “So much of it is grown at sea level. For just US$8.5 billion a year, which is what the U.S. was spending a month in Afghanistan and Iraq, we could make contraception available throughout the world to every woman who wanted it.”

Countdown is a sprawling, ambitious book full of colourful stories of courageous campaigners trying to tackle rampant population growth. The author quips that if he’d known what he was getting into when he pitched the book to his publisher, he would have had his head examined.

Even though Weisman writes nonfiction books about weighty subjects, including the best-selling The World Without Us, he remains a voracious reader of fiction. He likens novels to “vitamins” because they help him develop a narrative voice. Scientists absorb facts, he says, whereas most other people enjoy stories with well-developed characters.

“Readers will follow other human beings into very difficult or even very serious terrain because they’re fascinated to see how human beings deal with that—how they resolve situations, how they succeed, how they fail,” he says. “So I’ve learned to build all of my writing—all of this stuff I’ve talked about—around human stories.” 

Follow Charlie Smith on Twitter @csmithstraight.