Endogenous Emission Caps Always Produce a Green Paradox

Résumé

For any emission trading system (ETS) with quantity-based endogenous supply of allowances, there exists an allowances-demand reducing policy that increases aggregate supply and thus cumulative emissions. We establish this green paradox in a general model and apply the insights to the Market Stability Reserve (MSR) in the EU ETS, implemented in 2018. We show that demand-reducing policies announced in early periods but realized in the future, such as decisions to phase out coal power, can be inverted by the new rules: they may increase cumulative emissions. We provide quantitative evidence of our result for a model disciplined on the price rise in the EU ETS that followed the introduction of the MSR. Our results point to the need for better coordination between dierent policies in the `European Green Deal' proposed by the European Commission late 2019.