In a word: health. The health of the planet.

Put simply, a huge gap between the fabulously wealthy and everyone else is bad for the planet. Why? Because such a system is wasteful and costly.

It’s wasteful because it allows some to have way, way more than they need to live well and in doing so to continue raiding the planet for resources. It’s costly because waste is always costly.

At last the American people are waking up to what the statistics have been showing for decades already: the gap between the wealthy and the rest in this country is astounding—and rapidly growing. According to the CIA World Factbook, income distribution in the United States is worse than India, not so bad as Brazil, but significantly worse than European countries. On a par with Mexico—except Mexico is moving toward greater equality while we’re going in the opposite direction.

The ecological economist Josh Farley says such inequality is unsustainable. If we are going to live within the planet’s limits, then we have to come to grips with how its gifts are distributed. Vast inequalities in wealth are expensive and inefficient, he says in this lecture. For example, societies with poor distribution of wealth also suffer poorer health, for not only does poverty increase stress, leading to more health problems, but relative poverty does so as well. Lower-status people have poorer health even when they are well enough off to meet their basic physical needs. He says,

Poverty is not compatible with sustainability. But way more important, the wealthy use the vast majority of resources.

The problem in our present economic system, he says, is that a massive redistribution of wealth is indeed going on, but it’s happening in one direction only. The goods of the Earth, such as access to clean water, to forests, to energy sources and airwaves, are being funneled toward fewer and fewer people. The challenge is to allow these benefits to move in the other direction as well—or, in economic terms, to recapture the income that accrues to the few when they use the benefits of Earth, which belong to all.

Farley quotes former Supreme Court Justice Louis Brandeis:

We can have democracy in this country, or we can have great wealth concentrated in the hands of a few, but we can’t have both.

Farley adds:

Ironically, Americans have two dreams. We want to become fabulously well-to-do, and we want to live in a democracy. And they’re incompatible.

Nothing less than the future of democracy is at stake in this country. Occupy Wall Streeters know this.

But here’s the catch: the problem is even greater between this country and the rest of the world. However large—and growing—the gap between the fabulously wealthy and everyone else in the country, it is peanuts compared to the gap between the fabulously wealthy industrialized nations and everyone else in the world. The United States alone consumes 25 percent of the world’s resources.

Occupy Wall Street is right: we’re going to have to reimagine the very rules of engagement in this society, starting with how we do business and how we think about ownership and how we decide who gets to make political decisions. The benefits of Earth have to flow toward all, not merely the 1 percent.

But that means we’re going to have to reimagine the 99 percent as well, because from the perspective of the rest of the world, the American 99 percent is the world’s 1 percent. And if sharing the wealth is what Occupy Wall Street is calling for, then it applies to the American 99 percent as well.

I am one of the 99 percent in this country. We, the American 99 percent, can’t continue to burn fossil fuels and use up the Earth’s resources and heat the Earth’s atmosphere like we have been doing. We are endangering the health of the planet for everyone else.

Richard Louv came to town this week, inspiring people to connect with nature. The bottom line, he said, because of the enormity of our ecological crises, is that

In the next forty years, everything is going to have to change. Our economics, our ways of using resources, building houses and communities. This is the best news young people have heard in a long time. Everything must change!

I am grateful to the young—and not so young—people occupying New York and Denver and Boulder and Madrid and London and everywhere. I plan to join them myself.

And as Americans go out to occupy the centers of our own towns and cities, let’s keep reminding ourselves: Curbing corporate greed and taking back democratic control in this country are vital to improving the health of the planet.

But surviving on the planet means changing our lives as well. We, the 99 percent of this fabulously wealthy country, will need to learn to share too.