I agree.  The one positive thing I'll say about a gas tax is that, in theory, it would increase demand for more fuel-efficient cars since, as you say, demand for gas is relatively price-inelastic.

On the other hand...a gas tax is an incredibly regressive tax which will make lots of regular folks hopping mad, thereby creating undying enmity for the environmental movement among all sorts of people.  It's a big political loser that could kill public support for all kinds of other important environmental measures, like renewable energy.

Carbon tax, yes, for all the reasons you say.  Or carbon-trading with auctioned permits, if that's more politically realistic.

I certainly wouldn't want just a gas tax increase to be proposed (note: I'm pretty sure all the states have a gas tax already, so it's not something new).

I mentioned here before that I think one idea (I don't know about political possibility here) would be a C&T scheme for the electric industry (we could expand it later) and a gas tax to address transportation.

I haven't given it much thought since then, but there might be some reasons not to totally throw away the gas tax.  Maybe, Jason Scorse could give some input?

It levies the prices directly on the consumable goods, and could potentially have a greater behavior change effect among motorists than an upstream carbon tax would.

relatively hidden costs might not be what we want when talking about transportation

a gas tax would not only affect emissions levels, but might also address other issues like congestion.

Just some thoughts.  I for one don't like to see too many taxes thrown out there.  So for simplicity's sake, I'd say stick with the carbon pricing.

on the regressivity GreenMom.  That right there, pretty much makes the gas tax a political loser.

A carbon tax that doubles the average price of coal would only increase the price of gasoline by $0.06 per gallon.

Right, as sunflower points out, the ratio of hydrogen to carbon makes a big difference in how heavy a carbon tax hits a given fuel.  Coal is typically around 1:1. Gasoline (octane) averages 2.25:1. Methane is the best hydrocarbon, at 4:1.  

-- entropyproduction.blogspot.com

...it is dedicated to tangible, extant alternatives to driving, i.e., a quality, robust mass transit system. People support taxes when there is a proven and direct benefit. A gas tax for its own sake is a loser.

(Please Note: I am not Congressman Kennedy)

A couple of points.

1. A "pure" carbon tax will hit very visible consumer products like gasoline, natural gas and home heating oil.

Prices will rise, be attributed to the new tax (presumably passed a Democratic congress), be highly unpopular and the difference the "pure" carbon tax would have on reducing gasoline consumption and thus greenhouse gas emission reduction is hard to estimate.

A modified carbon tax could make allowances for some consumer commodoties like gasoline and exempt them. Problem is that is a slippery slope. There are thousands of well-connected lobbyists in Washington, DC that have clients who have products they would like exempted too.

The simplicity advantage that a pure carbon tax has is lost. The simplicity advantage of a tax to a "cap & trade" approach begins to erode.

2. Now a few questions. Under a carbon tax, what will be the annual reduction in U.S. greenhouse gas emissions 10 years from the enactment of the tax? 20 years? 30 years?

If a tax does not have the desired effect in terms of reducing emissions, will the congress have to go back and pass a new tax increase every few years? That would be fun.

I guess you could say I am very skeptical of the political viability of a carbon tax.

David, I'm not sure I agree that these are positive attributes, or even true:

That means, when it comes to a well-crafted carbon tax: the costs are (relatively) hidden from voters, and
the benefits are immediately tangible.

One of the reasons why the USA tends to use a sales tax rather than a value-added tax (VAT), the kind of consumption tax used in most other countries, is that U.S. politicians say that they want people to see how much tax they are paying when they pay for their purchases at the till. (Personally, I think this argument has little merit in an educated society: people here in Europe are well aware that 20% of the purchase price of anything they buy is VAT.) Hiding a tax burden should not necessarily be an objective.

In any case, coal and petroleum producers will certainly remind people how much they are paying in tax, especially every time that prices rise -- whether due to the tax or not.

I agree with Patrick Kennedy, also, that it would be naive to think that a carbon tax would be so simple to implement. There would probably be provisions, like with VAT, to credit carbon that is immobilized (e.g., turned into plastic) or captured. And once the principle is established that carbon must be taxed for climate-protection reasons, the fossil-fuels industry will legitimately raise questions as to why other industries that generate non-carbon greenhouse gases (e.g., nitrous oxides, sulfur hexafluoride) are not also taxed.

Finally, it is not clear which benefits of a carbon tax you see would be immediately tangible that are different from what you claim would be the (relatively) hidden benefits of higher gasoline (and presumably diesel) taxes. Surely you are not suggesting -- given the lag between changes in GHG levels in the atmosphere and changes in climate -- that the benefits of a more stable atmosphere would be evident immediately. If a carbon tax were applied in a revenue-neutral way, and taxpayers immediately saw a reduction in income taxes ... well, couldn't they also see such a shift if gasoline (and diesel) taxes were raised?

All that is not to disagree with basic argument -- that a carbon tax would be superior to a gasoline tax. It is just to say that the issues are not so black and white as you present them here.

A modest tax on gas, diesel, and aviation fuels will provide states and municpalities with the revenue to address the major sources of greenhouse gas emisssons - transportation and energy. A gas tax can be implemented quickly relative to a carbon tax assessed against fossil fuel producers. We tried to get a carbon tax on energy producers passed in California last year and it failed! If the measure had passed, it would assuredly have been challenged in the courts robbing us of the few remaining years we have to make real reductions in GHGs.

Over the last 7 years, Californians have consumed nearly 16 billion gallons of gas a year. At $3.25/gallon, all taxes amount to approximately $0.66. If we were to assess an additional $0.25/gallon as a gas tax for the carbon produced (assumes that carbon costs $25/ton), we would have an additional $4 billion annually to fund:
Better and cheaper public transportation that would benefit low and middle income earners;
Increase state subsidies for energy efficiency programs and renewable energy;
Provide incentives for more fuel efficient and lower emission vehicles including those used in agriculture.

The list could go on - you could do much with $4B a year AND you might find that you have the right combination of inducements and disincentives to get people to understand the urgency of the issue we are facing and begin to change their behavior.

Tom Kelly