Back of the envelope carbon emissions calculation
The US Gross Domestic Product is $13.2 trillion for 2006 [source]
The estimated greenhouse gas emissions for the US for the same year are: 7,075.6 trillion grams [source].
7075.6 trillion/13.2 trillion = 536 grams per dollar.
This means that on average, for every dollar Americans spend, we release 536 grams of carbon dioxide into the air (ignoring for the moment that GDP is how much we’ve earned, not spent, and that greenhouse gasses include things other than carbon dioxide).
A gallon of gas is 3785 mL, and the density is 0.784 g/mL. So a gallon of gas is 2967 g. We assume that gas is mostly octane, which has a molecular mass of 114.2 g/mol. 1 gallon is therefore 2967/114.2 = 25.98 mol.
Octane has 8 carbons (get it, octane), and thus if completely combusted, will produce 8 moles of carbon dioxide for every mole of octane, or 207.84 moles. Carbon dioxide has a mass of 44.01 g/mol, so each gallon of gas produces 207.84*44.01 = 9147 g of carbon dioxide.
With gasoline at $4 per gallon, this means that every dollar you spend on gas releases 9147/4 = 2286 grams per dollar.
Nearly 4x the “average” emissions.
