Tim Worstall on the ASI Blog looks at the robust economic tools that are available to control externalities. Here I enlarge on a blog comment looking the limits of these tools in combating climate change.

Although economic solutions may be “hugely cheaper than the sort of command and control systems”, that does not mean they are a solution in every circumstance. In the area of climate change mitigation there are four practical areas where such solutions may have higher costs than the original problem.

1. The economic policy is applied too far. The benefit to cost ratios will fall the greater the desired change. A 1% reduction in CO2 can be achieved, ceteris paribus, by economic solutions at a benefit to cost ratio of much greater than 1. The costs will rise exponentially after that, so for a given state of technology, the ratio will quickly reduce to less than one. This is the implication of Richard Tol’s 2010 paper “An Analysis of Mitigation as a Response to Climate Change” (2.5MB pdf). Looking at various scenarios, reducing the total amount spent on climate change mitigation from $2.5 trillion to a twentieth of the size increases the benefit to cost ratio from 1/100 to 3/2. I try to graph this here.
2. Any Cap and trade or Carbon taxes will not be implemented in their purest form. Public Choice theory (or practical examples) will predict that special interest groups will seek to maximize their returns. Those businesses that will be harmed will seek to reduce the effectiveness. Those who can make easy gains (and thus have permits to sell) along with any potential administrators of the scheme will be keen to promote it. There is a long policy chain linking the pure theory and the final outcomes. These various levels of policy formulation and implementation diminish the benefit / cost ratio as I attempt to outline here.
3. Scheme avoidance. For either a carbon tax or a carbon trading scheme, if there is competition from those outside the area of the scheme that is not proportionately shared by all emitters, then those facing the competition will have the gravest effect on their business. For instance both the steel industry and fossil-fuel power stations are huge CO2 emitters. The European steel firm cannot pass on the cost of the permits to its customers, as it is competing with firms in emerging economies with little or no carbon-trading. A British coal or oil power station does not have this competition, and its main competition comes from the more expensive nuclear power stations, the less reliable wind and the finite hydro-power stations. In the short-term it can pass on the costs. Protectionism is not a solution as it imposes extra costs.
4. The more encompassing a cap and trade scheme, the greater the number of participants and the complexity. The greater of severity of the scheme, the greater the potential economic gains and losses. Combine these two areas and you create large potential gains from out-right corruption, or engineering biases through the political system, or having unidentified inefficiencies.

    

   The economic tools might be quite powerful and robust, but put into the hands of inexpert users can create a lot of harm. A bit like a hot-hatch in the hands of 17-year-old trying to impress his mates on a night out.