Tuesday, January 5, 2010
The Economic Equivalence of Cap and Trade and a Carbon Tax
Debate pops up from time-to-time in the media about the relative virtues of a carbon tax and a carbon cap and trade system. Some argue for a tax because of its simplicity, while others argue for cap and trade primarily because it is not a tax. In practice, the two approaches are economically equivalent as long as we have accurate projections on the relationship between a carbon tax and resulting emission reductions.
Under cap and trade, a cap on emissions is set and marketable emissions allowances are created by the government equal in number to the tons of carbon emission equivalents allowed within the cap. These allowances are then either auctioned off or given away. An emitter of greenhouse gases would be required by law to obtain allowances for each ton of carbon equivalents released into the atmosphere. The interplay of demand and supply for such allowances would establish their actual price.
Under a carbon tax, the government directly sets the price for carbon and the volume of carbon emissions emerges as the result of market forces. A higher tax encourages greater reductions in emissions by stimulating a more substantial shift to clean energy and more energy conservation. Gasoline at 4 dollars a gallon because of a higher carbon tax will lead to more fuel efficient hybrid cars on the road than, say, 3 dollar gas. If the tax equals the carbon allowance price that would occur under cap and trade, then the two approaches to limiting emissions would be equivalent. Each would yield the same prices for gasoline and other fuels. If the government knew ahead of time the exact response of all carbon emitters, then the tax could be selected to limit emissions to a specified amount (or cap). In its most recent report, the Intergovernmental Panel on Climate Change suggests that a carbon tax (or price) of roughly $100 per metric ton by 2030 will put us on a path to limiting global temperature changes to about a 2 degree Celsius average. Either a $100 tax or a cap yielding a $100 carbon price will lead to the same result. Under either regime, the incentives to get unhooked from carbon emitting fuels will be the same. Cap and trade and carbon tax would be economically equivalent.
The problem is, no one can know ahead of time exactly what the tax should be to obtain a certain limit on emissions. Maybe the IPCC will be right in its prediction that a $100 a ton will bring about the desired amount of emissions reduction, but then again maybe it won’t. If the tax turns out to be set at too low a level, emissions will be excessive. Of course the tax could be raised, but this might turn out to be politically challenging. A tax increase would incur the wrath of the fossil fuel lobby and would be tough to pull off. If the tax is initially too high, environmentalists will be happy, but industry would be livid and lobby intensively to push it down, opening up the potential for a downward tax adjustment getting out of hand. Altering a tax once it is set would be politically messy.
Cap and trade has its own unfortunate political realities. If the U.S. Clean Energy Act now before the Senate passes and becomes law with cap and trade in place, many carbon allowances will be given away. Environmentalists hate the idea of coal-fired utilities getting free allowances. I suspect that if Congress were currently negotiating a carbon tax instead of a cap, huge giveaways of tax revenues to utilities and others would occur just as it has for carbon allowances. It’s ugly, but to get unhooked from fossil fuels and to move to a clean energy path under a democracy will require buying the political support of entrenched interests. This is the truth of interest group politics in a democracy. In essence, the fossil fuel industry will have to be bribed to go away no matter whether we adopt a carbon tax or cap and trade.
The biggest political advantage of cap and trade is that it is not a tax in the ordinary sense of the term. Taxes in this country are politically a tough sell. Cap and trade indeed results in a price being placed on carbon much in the same way a tax would—the right wing critics of cap and trade are right about this—but it is a price, not a tax. The real economic virtue of cap and trade is that we know we are getting a specific cap on emissions. We don’t know exactly what we would get from a tax. With caps in place, the political struggle will be done with. Establishing an adjustable tax could be just the beginning of a never-ending battle over its magnitude.
Perhaps our attitude toward taxes will change in the future. We could fund our government and reduce government deficits by taxing bad things, such as carbon emissions, instead of good things, such as earning income from work. The French government recently signed a carbon tax into law, but ran afoul of constitutional problems over exemptions of polluting industries. French President Sarkozy believes that his government will ultimately approve a revised carbon tax law that will pass constitutional muster. Unlike the U.S., the French get most of their electricity from carbon-free nuclear plants, eliminating a significant source of political opposition to a carbon tax.