Earth's pop. will top 7 Billion this year

For some, all the world's environmental ills, no matter their varied causes and effects, come down to one thing: Too many people. Earth simply can't sustain all of us, especially not at the consumptive pace U.S. residents have set.

And it's about to intensify.

This month, National Geographic takes an in-depth look at what to expect this year, when the world population is supposed to reach 7 billion.

"And the explosion, though it is slowing, is far from over," writes author Randy Kunzig.  "Not only are people living longer, but so many women across the world are now in their childbearing years—1.8 billion—that the global population will keep growing for another few decades at least, even though each woman is having fewer children than she would have had a generation ago. By 2050 the total number could reach 10.5 billion, or it could stop at eight billion—the difference is about one child per woman. UN demographers consider the middle road their best estimate: They now project that the population may reach nine billion before 2050—in 2045. The eventual tally will depend on the choices individual couples make when they engage in that most intimate of human acts..."

"With the population still growing by about 80 million each year, it's hard not to be alarmed. Right now on Earth, water tables are falling, soil is eroding, glaciers are melting, and fish stocks are vanishing. Close to a billion people go hungry each day. Decades from now, there will likely be two billion more mouths to feed, mostly in poor countries. There will be billions more people wanting and deserving to boost themselves out of poverty. If they follow the path blazed by wealthy countries—clearing forests, burning coal and oil, freely scattering fertilizers and pesticides—they too will be stepping hard on the planet's natural resources. How exactly is this going to work?"

The story is timely and thought-provoking. The glorious photos are by Randy Olson.