Human fertility crowds out Earth's other inhabitants

Chicago's National Public Radio station seems to be playing Cupid. WBEZ just launched a cute ad campaign urging listeners to go make babies today so the 2032 fund drive can be successful. Hey -- loyal NPR listeners make more loyal NPR listeners, right?

Well, let's hope Fox News doesn't follow suit. Ha ha.

Sure, I get that this is a tongue-in-cheek spot -- and it's clever enough -- but really? There are already more than 300 million people in the United States, and worldwide we passed the 7 billion mark in 2011.

Every day 200,000 more people crowd onto our planet. Left unchecked, the world population could hit 10 billion by 2050 and the U.S. population could reach 450 million.

Problem is, the cost of all those new NPR listeners, and their Fox News counterparts, may be a tad steep. They'll need to gobble up land and water, pollute the air, accelerate the extinction of animals and push our climate perilously close to disaster.

Look what we've already done with 7 billion people:

• Scientists agree the world is experiencing the planet's sixth mass extinction crisis. Animals and plants are disappearing at 1,000 times the natural rate.

• 1985 was the last year our planet experienced an average-temperature month as climate change has ushered in epic droughts, staggering melting of Acrtic sea ice.

• In Florida, where the population is expected to hit 36 million by 2050, hydrologists warn that overpumping is making the state's biggest aquifer salty .

• The Department of the Interior reported that the Colorado River -- which already supplies water to 36 million people -- will be unable to meet future demands due to population growth.

• The National Marine Fisheries Service recommended adding 66 species of corals to the Endangered Species list because population growth is driving them to extinction.

• The U.S. Forest Service projects 36 million acres of American forests will be lost to sprawl by 2050.

So, yeah, we can joke coyly about adding people to the planet and watch the effects of growth boosterism cascade around us -- or we can start having a real conversation about runaway population growth, overconsumption and the pressing need to create a sustainable world.

The trouble is getting the conversation started. Ask Bindi Irwin, 14-year-old daughter of the late "crocodile hunter" Steve Irwin. Bindi was asked by the U.S. State Department to write an essay for Go Wild, a State Department publication. Bindi's essay argued that population growth is driving our planet's species to the brink. She explained how population growth, and overconsumption of resources, creates a situation unsuitable for our planet's wildlife. The State Department edited her essay and removed all references to population growth, gutting her essay's heart and soul.

Not everyone is so reluctant: Scientists are increasingly raising concerns about how the growing human population is affecting plants and animals.

The Center for Biological Diversity, where I work, handed out 50,000 free Endangered Species Condoms at the end of 2012. Each package features an animal threatened by population growth, from polar bears to Florida panthers to the mighty Ozark hellbender.

The condoms are a great way to talk population and the importance of common-sense ways to begin slowing our growth.

It's not rocket science: The more people we crowd onto the planet, the less room there is for animals and the wild places we love. And the less room there is for human quality of life.

WBEZ's ad campaign isn't all bad; it gives us reason to talk about the advisability of making babies willy-nilly. And about just how clever and funny that is -- or isn't.

• Jerry Karnas was climate and energy adviser to former Florida Gov. Charlie Crist and is the National Population Campaign director for the Center for Biological Diversity.