There is always an aura of unreality that surrounds “reality shows,” but nowhere is that more apparent than on TLC’s expanding cable network, which features shows such as “Jon and Kate Plus 8” and “18 Kids and Counting.”

The world is careening toward a climate disaster; an international food crisis looms on the horizon; and scarcity of fresh water, oil, and other resources are dampening future economic growth prospects, but Jim Bob and Michelle Duggar and their 18 children are doing just fine, thank you.

TLC ought to know better. The producers of its Discovery Health channel go out of their way to showcase their environmental concerns. Several episodes of “Jon and Kate Plus 8,” in fact, are dedicated to showing how the Gosselins transform their home into an “eco-savvy” home, complete with solar panels and environmentally-friendly light bulbs.

The “unreal” message behind all these reality shows is that there is nothing unsustainable about having super-large families. If the average American family had eight kids, let alone 18, the world as we have known it would almost certainly be doomed, no matter how environmentally conscious we are.

That’s because the American lifestyle, even in its greenest shades, is simply not sustainable on a global level, and certainly not at the levels of material comfort enjoyed by the Gosselins and the Duggars. If the average American family had eight children, our population would more than quadruple by mid-century, and so would our claim on the world’s resources.

Despite all the concern about a “birth dearth,” America’s population is still growing. Thanks to immigration and a recent uptick in birth rates, U.S. population is expected to jump from 307 million today to 438 million over the next 41 years. We don’t need to “super-size” our families.

We may only have 5 percent of the world’s population, but for the past several decades, the U.S. has been accounting for about 25 percent of the world’s resource consumption and, even worse, about 25 percent of its greenhouse gas emissions. Children born in the U.S., particularly those born in an affluent home, will have a far bigger environmental impact than children born in developing countries.

A real “reality program” would show that rising population and standards of living are already imperiling the planet’s future. The World Wildlife Fund estimates that “humanity’s demand on the planet’s living resources, its Ecological Footprint, now exceeds the planet’s regenerative capacity by about 30 percent.”

According to WWF, our collective human footprint has more than doubled over the past 45 years. And it keeps on growing. Global population, now 6.8 billion, is on track to reach 9.2 billion or higher by mid-century, and despite a severe global recession, our per capita consumption of resources is likely to begin climbing again sometime next year.

A rapidly rising middle class in China, India and other parts of Asia is fueling a global and increasingly insatiable appetite for diminishing resources. The world, in fact, is filled with people who aspire to live an affluent American lifestyle, and who are we to fault them?

But if the world cannot sustain seven billion people living an American lifestyle, and we’re not prepared to make major changes in our own lifestyles, why does a cable television network glorify an American family with 18 children?

Good question. Earlier this year, when Nadya Suleman had her octuplets, popular opinion came down hard on her because she didn’t have the resources to raise that many children. But, thanks to TLC, the Gosselins and the Duggars have achieved celebrity status, even though the world may not be able to support an ever expanding humanity.

TLC needs a reality check. Stories about super-sized families may boost ratings, but they’re damaging to the planet.

Robert J. Walker is executive vice president of The Population Institute, a nonprofit organization working to achieve a world population that can live in harmony with the planet.