In 1968 Garret Hardin published his now famous essay, The Tragedy of the Commons, in which he demonstrated that the inevitable result of unconstrained growth on a commonly held pasture was a "tragedy" of consumption.
Hardin used a metaphor of a common pasture open to all to illustrate how each herdsman, acting in his own rational self-interest, would seek to maximize his personal benefit by putting as many cattle as possible on the pasture, even though it would reduce the quality of the pasture over time.
He employed the term "tragedy" in the sense that philosopher and mathematician Alfred Whitehead used it, "The essence of dramatic tragedy is not unhappiness. It resides in the solemnity of the remorseless working of things."
The remorseless working of things. In the wake of the complete failure of the Rio+20 Conference those words have sobering weight.
With full knowledge that the world is perched on the edge of an ecological abyss, our leaders punted.
Their justification? The economy, specifically economic growth.
Yet Hardin showed that a growth maximizing economy in a world with finite resources would simply annihilate the natural stocks on which it depended for growth, even while each individual was acting in a rational manner. It gives lie to the perversion of Adman Smith's Invisible Hand that conservatives use to justify unconstrained capitalism.
The Tragedy of the Commons is a tragedy of this time and this place. Pastures, resources, clean air, a living climate - each is consumed by our current actions, and the consequences take place in the near term.
But it might be useful to think of the more distant future as a commons - to see this tragedy as a "remorseless" consumption of our progenies' birthright.
Viewed from this perspective, our current lifestyle is revealed as a kind of debt- fueled orgy being conducted at the expense of our children. We are literally robbing them blind.
What would a sustainable economy - a less remorselessly tragic economy that did not treat the future as a commons - look like?
Think of our stock of resources and natural life support systems as a trust fund left by a rich uncle to provide for us in perpetuity. Living off the amount of resources which can be renewed or recycled would be the equivalent of living off the interest from the trust. Dipping into the principal would define an unsustainable economy. When we deplete resources faster than they can be renewed, we are dipping into principal. When we compromise the natural systems that make life possible, we are dipping into principal.
So, how are we doing with our children's trust fund?
Pretty badly. It takes 1.5 Earths to maintain our current economy. By 2050, assuming only moderate growth, it will take nearly 3 Earths worth of resources to sustain the economy.
But of course, we only have one planet.
Those extra worlds we consume represents debt - assets taken from our children. In ecologic terms, it is called "overshoot."
And living systems cannot long survive in overshoot mode.
A classic example of overshoot occurred on St. Mathew Island when the US Coast Guard released 29 Reindeer - 24 females and 5 males--in 1944. By the summer of 1963, the population had exploded to over 6,000 animals. By the end of that year, the population plummeted to fewer than 50 starving animals.
In an ecologic sense, our global economy is very much like the Reindeers at 6,000. We are poised at the top of a dizzying growth jag, but we are seeing the first signs of trouble.
We're having to scrape the bottom of the barrel for oil, exploiting poor quality resources such as the Canadian tar sands, or ultra-deep offshore oil deposits. We're having to literally crack the rock beneath our feet to free up natural gas. Our mines are deeper, our ore bodies less concentrated. We are rapidly depleting our non-renewable resources and failing to replace them with renewables.
Just as in that last year, those reindeer were forced to paw desperately for the lichens and moss that once seemed so plentiful, we are staring into a future of scarcity, want, hunger and death.
It doesn't have to be this way.
The National Renewable Energy Laboratory recently found that the US could provide as much as 80% of its energy needs by 2050 using renewable energy technologies available today, at modest cost. Improvements in technology could reduce even these low costs.
Ultimately, however, living sustainably is neither an economic issue nor a technological challenge, it is a moral one.
The question we must ask ourselves is: Do we want to continue to rob from children not yet born so that we can add a few inches to our already obscenely large TVs; a few horsepower to our crudely over-powered cars; or another 1000 square feet to our self-indulgent McMansions?
And if the answer to those questions is no, then we must vote with our pocket books and wallets as well as in our voting booths.
Quite simply, we can no longer purchase from companies who treat the future as a dump . We can no longer vote for candidates who say they are concerned about the deficit while they run up irrevocable deficits on the only wealth that really matters - natural capital. And most especially we can no longer vote for candidates and incumbents who say they are concerned about our future every four years, and then run the country by the same crooked rules that treat the future as a commons, charting our way remorselessly toward the mother of all tragedies in the intervening years.