## Friday, September 19, 2008

### Desirable vs. Achievable Consumption

Using the Third Law of Consumption, we can determine the amount that the average world citizen could consume (where the world is considered an “isolated population”) based on life expectancy.

With the number of years between generations (the “generation interval”) at 21 years and the minimum life expectancy at 40 years, a life expectancy of 65 years corresponds to a per capita consumption that is 15 times the amount for someone expecting to live 40 years. For a life expectancy of 70 years, the consumption ratio jumps from 15 to 27. If everyone lived to an average of 100 years, the ratio would be 720.

From the First Law of Consumption, we can estimate the average speed required to achieve different life expectancies for a given population size. A life expectancy of 40 for 6.9 billion people (roughly the current world population) years corresponds to 16 mph; a life expectancy of 65 years requires a speed of 250 mph; for 70 years, the speed is 430 mph; and for 100 years, we would need to be able to move resources at more than 11,000 mph.

The Second Law of Consumption tells us that even with the technology to move resources we will be severely limited by the amount of available resources, a fact which our population growth is already reflecting. According to my model, the depletion-related decrease in population is being absorbed by consumption, which in addition to growth is increasing the amount of depletion.

Adding life expectancy arbitrarily will only exacerbate the situation by drawing down resources even faster. If we consumed just enough resources to keep the population constant, we would have 65 years remaining at the current estimated life expectancy of 69 years, which would effectively only apply to a few (if any) survivors. It turns out that this strategy – keeping population constant by maintaining consumption – would only work for a life expectancy of 68 years, a point we probably passed in 2006. Unless we increase the overall supply of resources, a growing number of us are doomed to die sooner than we should.