Suppose we want a tax of $50 &#x2F; 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.<p>Individual gas stations and consumers wouldn&#x27;t have to think about it, since they aren&#x27;t purchasing from refineries directly. But the prices they pay would increase indirectly.