[NeilBlanchard]

Well, they apparently do not add in a portion of the military costs, or other things that they could have.

Well, there are many hidden costs such as:

Health effects due to gasoline related pollution. In 2008, CSU Fullerton's Institute for Economic and Environmental Studies released a report showing that the cost of air pollution for the greater Los Angeles area adds up to more than $1,250 per person per year, and is more than $1,600 per person in California's Central Valley. In addition to all the medical costs of asthma, and other respiratory illnesses, there are lost workdays, and missing school days that factor in.

Reduced crop yields due to air pollution. The U.S. Global Change Research Program released a report in 2009 that showed greenhouse gases can reduce crop yields for "soybeans, wheat, oats, green beans, peppers and some types of cotton."

Cleaning up oil spills and leaking gasoline storage tanks. While this one is harder to quantify, some estimates on the Gulf spill cleanup are upwards of $20 billion, although we would hope BP is footing the bill for that one. But besides the large oil spills there are thousands of leaking gasoline storage tanks that the EPA cleans up (they've already cleaned up over 400,000 in the last 30 years).

How much is a clean environment worth?