Looking at the environmental platforms of the remaining major-party candidates, one thing you'll see (and occasionally hear) is a policy called a "cap-and-trade system." Candidates, when faced with questions about global warming and reducing ecological impact, will trot out this idea, which sounds pretty good from the start. When the Clean Air Act was adopted in 1990, the amount of sulphur dioxide, which causes acid rain, was drastically reduced under the first large-scale cap-and-trade system.

[Hillary Clinton] [John McCain] [Barack Obama]

Here's how it works: A governing agency analyzes a certain chemical being emitted into the environment, like a greenhouse gas, and decides how much can be safely released each year. Depending on the plan, companies or corporations that emit this chemical buy or receive "permits," "allowances" or "credits" giving them the right to emit a certain amount of it. Those holding permits are encouraged to become more efficient so they release less than their annual allowance. If they do so, they can sell their permits to another company that hasn't made greener developments.

You can find very useful explanations and charts here, here and here. However, the experts I talked to this week mentioned two important problems with enacting a cap-and-trade system here in the United States: Because CO2 and other greenhouse gases rise into the atmosphere and aren't bound by tidy geopolitical boundaries, this has to be a global system. One country enacting one can make a slight impact -- not a significant difference. If the United States adopts one and China doesn't, the problem won't be solved. Sulphur dioxide was drastically reduced under a cap-and-trade system because the technology for capturing the toxin was readily available and inexpensive to utilize in retro-fitting processes. Similar technology to capture carbon-based compounds is not. This makes becoming more efficient -- and creating a competitive market for trading and selling permits -- very difficult. You won't see companies selling off allowances for more than a decade.

One alternate idea posed to me by Mark Jeantheau at Grinning Planet was a carbon tax, something he said members of Congress are proposing. Instead of a cap-and-trade system, which right now is difficult to enact, the carbon tax would include a tax shift. Income tax would be reduced, but taxes on consumers goods with a deep carbon footprint would increase. The idea is that individuals -- not corporations -- are encouraged to buy more efficient appliances, drive less and do other things to reduce the amount of CO2 produced.

What do you think?

(Top photo from the Dispatch archives)