Shi-Ling Hsu


This Article proposes a way of introducing some organization and tractability in climate science, generating more widely credible evaluations of climate science, and imposing some discipline on the processing and interpretation of climate information. I propose a two-part policy instrument consisting of (1) a carbon tax that is indexed to a "basket" of climate outcomes, and (2) a cap-andtrade system of emissions permits that can be redeemed in the future in lieu of paying the carbon tax. The amount of the carbon tax in this proposal (per ton of C0 2) would be set each year on the basis of some objective, non-manipulable climate indices, such as temperature and mean sea level, and also on the number of certain climate events, such as flood events or droughts, that occurred in the previous year (or some moving average of previous years). I refer to these indices and events as climate outcomes. In addition to a carbon tax rate being set each year, an auction would be held each year for tradable permits to emit a ton of carbon dioxide in separate, specific, future years. That is, in the year 2012, a number of permits to emit in 2013 would be auctioned, as well as a number of permits to emit in 2014, in 2015, and so forth. In the year 2013, some more permits to emit in 2014 would be auctioned, as well as more permits to emit in 2015, 2016, and so forth. The permits to emit in the future are essentially unitary exemptions from a future carbon tax: An emitter can either pay the carbon tax or surrender an emissions permit to emit in the specific vintage year. Because of this link between the carbon tax and the permit market, the trading price of the permits should reflect market expectations of what the carbon tax will be in the future and, concomitantly, expectations of future climate outcomes. The idea is to link the price of tradable permits to future climate outcomes, so that a market is created in which accurate and credible information about future climate conditions are important inputs into the price of permits. The market for tradable permits to emit in the future is essentially a prediction market for climate outcomes. And yet, unlike prediction markets that have been operated or proposed thus far, this prediction market for climate outcomes operates against the backdrop of an actual and substantial tax liability. Whereas prediction markets have heretofore largely involved only recreational trading, this prediction market will operate against a regulatory backdrop and thus will provide much stronger incentives for traders to acquire and trade on information.