WaPo editorial board: 'This policy is a steadily rising carbon tax. A carbon tax would put a lower ceiling on national gasoline use without more aggressive regulatory interventions. It would also encourage every other piece of the economy to green up over time, starting with those for whom doing so is cheapest. This is why it is also the least expensive path to lowering the country’s carbon dioxide emissions. But a carbon tax would require Congress to act, which it has serially failed to do.'