“Why not just put a tax on carbon?”, asked my Dad last Sunday. It was Father’s Day. We had organized a family video call, and somehow ended up talking about climate.
Economists believe pricing schemes are an important tool to fight climate change. They advocate for the use of market mechanisms which reduce emissions by pricing the costs of those emissions at the source. In other words, polluters should pay for the negative impact their emissions have on the planet.
According to the World Bank, at the start of 2021, globally there were 61 carbon pricing schemes in operation or planned. The largest planned is in China, which will come online fully in December of this year. As you might expect, the sheer number of schemes means there are many variations.
Carbon Pricing Approaches
There are two broad approaches to pricing carbon that are in common use today. These are carbon taxes, and emissions trading systems.
Carbon taxes are consumption taxation models. They encourage consumers to choose products that are more emissions efficient by levying a tax on those that aren’t. Need a litre of fuel? Maybe it will cost an additional 15% in tax. The taxing jurisdiction promises to put that money back into energy efficient or climate transition projects, further accelerating the transition to a decarbonized economy. In some jurisdictions (British Columbia, Canada for example) the carbon tax collected is offset by a reduction in other taxes. The promise is that the carbon tax will be revenue neutral, which satisfies at least some of the folks who object to new taxes.
Emissions trading systems (sometimes called “Cap and Trade” systems) use a different approach to driving emissions reductions. Emissions trading systems price the emissions directly. The government sets a cap on the total emissions permissible in a given period, and then allocates emissions quotas to companies that need them. Stiff penalties are imposed for exceeding the quota. Companies can then choose to become more emissions efficient, or continue to emit. If they continue to emit, they can purchase unused quota from another emitter who may be more efficient or pay the penalty. Over time, the government reduces the cap which creates pressure to be more efficient.
Sometimes emissions trading systems are also connected with an auction, as I wrote about Nova Scotia last week. When an auction is used, the quota allocation is done via auction rather than through some other scheme, which should lead to more optimal outcomes. An auction also has the benefit that it raises money for the government to spend on climate transition or energy efficiency projects, just as a carbon tax does.
Which is better?
So why choose one over the other? There are some major differences.
- Carbon taxes are easy, broad, blunt tools. If you’re buying fuel, they make a lot of sense. But how do you tax the carbon content of a new home, a car, a pair of jeans, or even a carrot? Each will have differing Scope 1,2, and 3 emissions depending on the efficiency of the producers supply chain. To tax the carbon content of a consumer product accurately, you need to know the contributions at each stage of the manufacturing process. We can’t do that accurately today. Emissions trading systems overcome that limitation. Each company in the supply chain has a quota for emissions, and has to live within the quota. (note: in today’s early stage emission trading systems it’s common to only make the largest emitters comply. Hopefully that will change.)
- Carbon taxes may also not be an accurate reflection of the true carbon emissions cost of a given product or service. They are simply implemented as a percentage of the end retail price. An emissions trading scheme allows the market to set the price. To return to the Nova Scotia example from last week, the government set a reserve price of $21 per ton, but the actual price paid was 74% higher, reflecting market demand.
- Carbon taxes are also impractical to implement across borders. How should we tax two vehicles, one made in China in a factory powered by coal/electric, and the other made in Detroit? One of China’s competitive advantages has been their willingness to use cheap, and dirty, coal power to power industry. Again, emissions trading schemes make this easier, since they target the emitters directly.
- And finally, carbon taxes do not create direct incentives to reduce emissions because there is no cap on emissions. With a carbon tax, you could conceivably have a rapidly growing economy with growing emissions. So long as the rate of growth is high enough, then the emissions tax is simply another tax. In a cap and trade emissions market, the government sets the amount of carbon allowed, and reduces that allowance each year, which creates incentives for companies to emit less.
For those reasons, emissions trading systems are preferable to carbon tax systems. Your thoughts?