Seb, adding a tax to things people want - income, purchases, gasoline, etc. - is hard enough. Adding a tax to carbon, something few want or need, is a mission doomed to failure. That's probably why the oil and coal industries find them so attractive - they seem so full of potential. But even when enacted (rare), there are unlimited ways to circumvent them.

There is exactly one carbon tax that has proven successful at lowering carbon emissions: the revenue-neutral carbon tax, also known as fee-and-dividend. Here's how it works:

1) A low tax is levied on all hydrocarbon-based fuels entering a jurisdiction: gasoline, oil, coal, kerosene, etc., whether at the border, the wellhead, or the mineshaft.
2) Each month, after deduction of administrative costs, the entire collected sum is divided into equal parts and distributed to every taxpayer in the jurisdiction.
3) Gradually the tax is raised.

Though everyone pays more for fuels that emit carbon, everyone gets a check, whether they've used hydrocarbon fuels or not. If you use less than the average person uses, you actually make money. If you use more than the average, you pay. In this way everyone is either rewarded or punished in exact proportion to the amount of carbon they use.

In British Columbia, this "carrot/stick" approach has reduced gasoline consumption by more than 20%, and remains overwhelmingly popular. Because it's so successful, however, fossil-fuel interests have lobbied heavily against it. That, of course, was expected.