I further refined my stress model, adding the measurement of total “distance” traveled by the population. (For a graph of this and other variables over time, see my Web site.)
I’m hoping to correlate distance to energy use, and thereby consumption, thus tying this model to my consumption model. Annual values of distance (compensated for population size) are not correlated with U.S. energy use, but a plot of cumulative distance versus cumulative energy use looks well behaved; though most attempts at reasonable curve fits show energy climbing at an increasing rate as cumulative distance increases. This implies that we would need to reduce our annual per capita distance traveled much lower than my model implies is possible (that is, below 33 percent of the maximum) to level off our consumption with our current energy portfolio.