the General Sustainability Formula

..applied to human ecology.

S=E/PC, sustainable if S is larger than one.

S is Sustainability
E is Ecosystem vigor
P is Population
C is per capita ConsumptionWaste stream

An ecosystem or species is Sustainable if E divided by (P times C) is larger than one.   The advantage of the formula as a heuristic tool are several, including its simplicity, its lack of political overtones, and because rather that pointing to degradation (doom and gloom, or Impact), it points to possibly increasing sustainability while (possibly) increasing per capita wealth. The formula is often quickly grasped, and seen as a self-evident truth.  

In nature, animals tend to drive S to equal one.  
Its workings can be easily demonstrated with a stable deer herd of 10,000 animals as:
S = 10,000 / (10,000 * 1) so yes; S equals one.

The formula's weakness is that in nature the variables most often can not be quantified with enough accuracy to produce precision predictions in say; wildlife management.   However, any population management model that ignores any one variable is in danger of being irrelevant or worse.  

Humans are assumed to be the P for the remainder of this page. Also for simplicity, the consumption end of the ConsumptionWaste stream is emphasized.

from an e-mail discussion:

   Looking to a human S, pure nature might look like: S=40 billion/0*0.   
   So S is infinite.    Nearly anything else is a matter of opinion.
   Remember that E "assumes" the poverty consumption level of one.
   Humans need not do that, but it is a natural tendency.   
   
   The good news is; the haze blanket is not sustainable.    Getting
   sustainable will clear up most environmental problems.

   A necessary goal but not a sufficient one?  Perhaps science must 
   put its foot down and squash non-sustainable behavior?  Beyond 
   that it may be for politics (the people) to decide.

   A danger lies in getting diverted with the impossibilities of  
   calculating human wants and forgetting about the necessary.

 

Like Ohm's Law in electronics, in a system under load, (most functioning systems,) changing any one value tends to affect the others.

There have been suggestions that a region's Ecosystem vigor can often be roughly estimated using soil type, biofunctional diversity, and net primary production (NPP).   Ecosystem vigor is the system's ability to resist or absorb consumption or insult.   For example, sustainable behavior in Kansas may not be sustainable on arctic tundra, nor a rainforest.

The PC value of a particular behavior in a particular E could be determined by the time it takes the system to replenish or repair that behaviour.   For this reason, consuming renewable resources may have a very different ConsumptionWaste value than non-renewables.

Unlike some Impact formulas, neither the controversial and complicated effects of Affluence nor Technology are directly measured; only the end effects are of concern.  

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Douglas Bashford - bashford@psnw.com

http://www.psnw.com/~bashford/e-sust-f.html