I have seen a number of "carbon footprint" calculators, and I have read there are many more. But the ones I have seen are simplistic. I mean, they contain a lot of information, but they all run into the problem that they are not complex enough. The problem is this: what is the carbon footprint of an apple? How does consumption of apples in YOUR daily life affect the atmosphere as compared to MY consumption of apples?
Apples are grown in certain regions of the world. It seems reasonable to assume that all the apples in a region share equally in their production cost. Of course, the first apple of the day that is harvested will be driven around the field all day, whereas the last apple of the day must only be carried to the sorting house. However, we cannot tell these apples apart. We say they all have the same harvesting costs; the same processing and packing costs. We take these costs - the carbon emissions that arise from apple processing - and divide them among the quantity of apples that are consumed. Now, if you live in an apple-growing region and you eat a lot of apples, you might buy apples at the packing plant. Maybe they sell cases? You drive a few miles in your car and you have apples all month. Contrariwise, for me to buy an apple it must be transported by truck cross-country, loaded onto a ship, travel an ocean, be transported to a warehouse, be distributed to a grocery store, and then I have to go to the grocery store to get it and take it home. In some of the transport chain, it may be refrigerated.
Whether we each devote our apple-purchasing trip to only buying apples, or whether we make multiple purchases on the same trip - this affects the carbon footprint of the apples we consume. The accounting would be mind-numbing. So we can't do it that way. We have to somehow develop an estimate of our carbon footprint without having to elucidate our entire life history. And yet, our life history is what makes our carbon footprint bigger or smaller!
I think there can be some simplifying assumptions made. Everyone who uses electricity can be assigned some responsibility for carbon emission based on their particular power supplier's generating method(s). It might not be easy to assign that per-kilowatt-hour carbon footprint to that utility, but once it is done then those customers can each calculate their share of the utility's emissions. Likewise, people in a region can calculate their carbon footprint based on the amount of fuel they burn in cars, once they know the local footprint of the fuel based on distance from the refinery. The carbon footprint of durable goods and commodity items of various sorts can be developed on a regional basis, by similar means.
I thought I would tackle this - try to calculate just MY carbon footprint. Wow, it is almost impossible! I found a calculator on BBC that would tell me the carbon footprint of my groceries. But it is only good for maybe London? I grow avocados - there is no carbon footprint for them here. But for Londoners, the carbon footprint includes a lot of transportation. The calculator doesn't help.
Can there be a universal carbon footprint calculator? Is anybody working on one? What have people seen? Is there interest in determining one's carbon footprint? If you knew that certain of your activities contributed significantly to your total carbon footprint, would you be inclined to change those activities? I'd like to have discussion on this and suggestions!