Footprints, Footsteps

The news today is full of stories and examples of carbon footprints. How much carbon dioxide does an action create? I read it may be cheaper (by carbon) to drive your car to the store than walk. Walking will burn calories that you will replace with carbon footprints whose sum will exceed the quantity released by the burning of the gas your trip consumed. Probably untrue but a bit humorous.
Carbon footprint is a fad - an early 21st century fad. The measure that will worry the world this century is water footprint. Unlike CO2 which is released by mother nature in levels that make your trip to the store inconsequential by 8 orders of magnitude, water is a finite resource. Global warming will change water distribution in ways we don't understand and in ways that will be difficult to react to. Los Angeles can't move 1000 miles to the south, but the water could.