Those not satisfied that price signals prompt efficient actions (and who do not expect policy makers to modify selected prices accurately or soon) evoke footprints. Trouble is that there are many plausible footprints (water footprints, carbon, footprints, air pollution footprints, etc.).
We are back to the calculation debates. Can the giant calculation machine that markets serve as be replaced by mere mortals (let alone polticians)?
The Real Estate Research Corporation famously published its "Costs of Sprawl" in 1974, calculating what could be saved via compact urban development. Critics quickly found the flaws in this approach.
Today's LA Times includes Ed Glaeser's "Growing greener ... California should build more, not less to help the environment." The least carbon footprint-demanding development is in the most benign climates.
Along the same lines, The Economist (Feb 28-March 6) reports information on water footprints ("Excess liquidity"). It requires 140 liters of water to brew one cup of coffee -- includes growing the coffee beans.
Who knew? And that's the point.