Depletion Index

Depletion Index (DI) depends on the amount of resources removed from the environment and not returned. However, to reflect the abundance of certain resources, and scarcity of others, we will also include the known reserves of the resource in the index. The Depletion index can be thus expressed as:

DI = (amount used)/(known reserves) * scaling factor * relative importance

Right now we consider all the resources to be of the same importance, thus the last factor in the DI will be set to 1 for all resources.

Scaling factor is the same for all resources, and set to the value of 19e16. That makes 1 pound of coal having DI of 100 (as the world reserves of coal are estimated to be 19e14 pounds).

Resources can be of any kind here: the most popular are of course minerals, but also timber, plants, animals, even land or habitat. Some of them, like oil or coal, have pretty well know estimates as to the reserves; others we will need to estimate ourselves.