[pzone]

Suppose we want a tax of $50 / ton of co2 emitted. Then we do some chemistry and figure that burning 5 barrels of oil emits a ton of co2 into the air. Then the government adds a tax of $10 per barrel. Every producer who buys from the gasoline refiner has to pay the tax.

Individual gas stations and consumers wouldn't have to think about it, since they aren't purchasing from refineries directly. But the prices they pay would increase indirectly.

[alerkay]

That seems pragmatic enough to me, and also quite effective. I live in France and, unless I'm wrong, the highest of the oil-related taxes here apply to the consumers, when you're getting gas at the gas station. Instead, your proposition - to apply a $10 tax on the barrel - would apply the same taxation on any fossil fuel usage, be it plastic fabrication, air transportation, electricity generation, etc... That makes a lot more sense environmentally-speaking.