If recycling your glass bottle could save a quarter-pound of CO2, and if your car spews a pound of carbon per mile, how many bottles could you cart how far in order to capture the maximum recycling benefits?
These "routine calculations" reflect the "necessary resource literacy" we'll need to "embed balanced thinking in everyday life", says Craig Simmons (via bestfootforward).
Same goes for your "local, organic" food purchases. Recall that the Seattle food project found that if you drove more than 4 miles to get your "green" plate, you'd blow the whole advantage over the "standard supermarket" plate.
According to Simmons, we all need to learn to balance both sets of the '3 Rs': reduce/reuse/recycle together with readin'/'ritin'/'rithmetic.
"If we are to conserve natural resources, and decarbonise our economy, the waste hierarchy also needs to be considered in the cold light of some robust 'rithmetic."
...Which reminds me to mention that our island's solid waste plan omits any calculations of emissions, except in the analysis of waste-to-energy. That's right: no metrics on the emissions associated with getting our "trash" to the landfill. So it goes.
BTW, the BFF calculations of emissions per bottle are contained in their study of the UK's wine industry.