Thursday, January 03, 2008

"Overshoot" and "Unsustainability"

I've noticed that "overshoot" is used very sloppily when referring to humanity's presence in the world. It's almost impossible to tell what a given author means precisely by it. I believe that many authors don't mean anything precisely by it.

Using "overshoot" as a precise metaphor for the approach of an underdamped system to equilibrium, as originally intended by those who introduced the metaphor, would mean that if a variable were in overshoot it would certainly return to a lower value. As with many terms that become popular, the precise metaphor has been forgotten, to the impoverishment of the language.

In a precise use of the metaphor, to say the human population was in overshoot would be to mean that the human population was fated to have its numbers reduced, one way or another, with humanity having only the options of arranging that reduction or allowing nature to do so. The system state of humanity that is named by this use of "overshoot" is an important one. It is unfortunate that we are losing the ability to name this state unambiguously.

Some authors now say "humanity is in overshoot" when they mean simply that "humanity is living unsustainably". This conflation destroys a useful distinction in language by making the only term we have for overshoot, namely "overshoot", into an impressive sounding synonym for a perfectly adequate term that does not need a synomym, "living unsustainably". Simply put, to live unsustainably is to risk entering overshoot, and to be fated to enter overshoot unless a suitable lifestyle change is instituted. To be in overshoot is to be living unsustainably and to have lost any possibility of returning to sustainability without reducing the number of living people. I have found that many people who claim to be interested in the ecological fate of humanity do not even understand that there is a difference between living unsustainably and being in overshoot, because it has never crossed their mind that a state of overshoot, in its original meaning, is possible.

The most interesting thing about the state of overshoot of the human population is that it is impossible to know if we are in that state or even whether whether we are close to being in it. The impossibility of detecting overshoot is due to our inability to distinguish the difference between the consuming the fruits of natural capital and consuming the natural capital itself. I have argued elsewhere ( that this attribute of overshoot, in combination with attributes of current global culture, dooms humanity to enter overshoot. I believe the argument is compelling. I also believe that we are already in overshoot, although the argument just mentioned indicates that a compelling argument for being in overshoot is unlikely until an ongoing compression of humanity's numbers is manifest.