The difficulties of calculating “carbon footprint”

I read this article in the New York times a few weeks ago, entitled “How Green Is My Orange?”:

http://www.nytimes.com/2009/01/22/business/22pepsi.htm

It outlines some of the difficulties associated with trying to determine the carbon footprint (or, in fact, any other environmental footprint) of consumer products. One problem is that a lot of that data is hidden or not easily accessible (how many pounds did the truck haul, how many gallons of gas did it use, how many miles out of its way did it go to deliver to your store, etc.). Another problem is to know where to stop: Do we count fuel used by farmers to power their tractors? How about the fuel used to operate tanker trucks to deliver the fuel to the farmers? What about the fuel used to fly an oil company executive to the Middle East to secure a contract for more oil, which was then used to make the gasoline? In what could be described as the reverse corollary to the Butterfly Effect, an unimaginable tree of events transpired to bring any product to any particular storefront. Even the environmental cost of preparing such a report should theoretically be considered in the report itself.

The market is supposed to collapse all of this complexity and history into a single number: the price. But the problem is that, with conflicting moral views and priorities, some consumers inevitably won’t agree with the way in which the complexities were collapsed (e.g. Should pollution be taxed? Should the government subsidize oil drilling?), and will demand more information about the history of their product. But exactly how much information the bulk of consumers want — and are willing to pay for — has not exactly been settled. I fear that catch-all, broad labels such as “organic” and “local” will suffer the same fate as price — just as suppliers often sacrifice the environment or human welfare to drive down price, they could just as easily (and often do) sacrifice the environment or human welfare to satisfy requirements for labeling their products “local” or “organic”. At the same time, metrics complex enough to provide the information necessary to make informed decisions remain elusive. It’s a difficult problem, and one I don’t think is going to be solved quickly or easily.