This article explores dynamic relations governing population growth, resource depletion, and world economics by means of a few simple modeling and simulation exercises. To this end, we start out by exploring the concept of an ecological footprint, representing the amount of land that a person needs to produce everything that he or she consumes: food, clothing, energy, shelter, the tools that are needed to make the clothing, etc. and place it in relation with the human development index, a measure of the quality of life of an individual. We then relate the ecological footprint to the per capita energy consumption. This discussion serves to provide a quantitative understanding of the limited resources that are at our disposal.

On Monday the president gave a speech touting his plan to reduce gas consumption by 20 percent in the next 10 years. He didn't say so explicitly, but it's clear he intends to increase fuel economy standards for cars. Mr. Bush also wants the energy industry to produce more ethanol.

That's an increase of 85 percent, and rural households have been hardest hit because they spend about 20 percent more on gas than urban residents, the Consumer Federation of America and Consumers Union said, citing Labor Department figures.

Here is a quick run down on the possible disaster we face this summer as we head into Memorial Day with the lowest beginning-of-driving-season stocks in US history. It would have been convenient had someone found out exactly what Minimum Operating Levels* really have become. I suspect we will answer this riddle this summer.

Minimum Operating Levels of petroleum inventories are when all cushions have been used up and the system is now starting to “rob Peter to pay Paul." At this stage, the risk of shortages starting to crop up is Red Alert. Sadly, the last serious study of where this invisible line of minimum stocks is was a NPC study done in 1988.