Have you heard that we’re getting new neighbors? Demographers expect that the number of people living on earth—now about 6.8 billion—will grow to between 8 and 11 billion by 2050.

Whether population tops out at the high or the low end of those projections will have a huge impact on climate change. So population control is again claiming a place on the environmental agenda.

Nairobi slums

Oops! Did I say “population control”? I should have said “addressing population growth” or “assuring reproductive rights for women” or even “securing population justice” — because some people get very nervous when environmentalists start talking about population, and for good reason.

Yet the conversation is worth having, which is why I went to a discussion today at the Center for American Progress in Washington featuring Laurie Mazur, the editor of a new book called A Pivotal Moment: Population, Justice & The Environmental Challenge (Island Press, $30).

Mazur argues that we are at a pivotal moment, not just environmentally, because of the lethal overheating of the planet, but demographically, because, as she writes,

the ultimate size of the human population will be decided in the next decade or so.

That’s because right now the largest generation of young people in human history is coming of age. Nearly half the world’s population—some 3 billion people—is under the age of twenty-five. Those young people will, quite literally, shape the future. (more…)