"Big Foot" (NEW YORKER, 2/25/08) by Michael Specter, describes the complexities of calculating the "carbon footprint" (climate impact) of various food products. Specter also described the similarly complex "cap and trade" system often discussed as a way to reduce greenhouse gas emissions.
My response, published 3/24/08:
Specter notes that we need price incentives to reduce greenhouse-gas emissions. But there’s a simpler alternative to cap and trade, which is a complex (and volatile) system. A carbon tax levied on fossil fuels as they enter the economy (through importation or extraction from the earth) would allow the prices of goods and services to reflect their carbon footprint; and a Congressional Budget Office study concluded that the net benefits of a tax could be roughly five times as high as the net benefits of an inflexible cap. Simple, fair, direct, and, perhaps most important, predictable.