Optimal Emission Prices Over the Business Cycles
研究证明最优排放价格在经济周期中呈顺周期性，即衰退期应降低碳价，且碳价波动幅度应较小，气候政策应聚焦于长期增长路径而非短期波动。
Abstract We prove that under the most typical circumstances optimal emission prices are procyclical, i.e., prices should be lower during recessions. The procyclicality is more likely when emissions propagate very slowly into environmental damage. A prime example of such process is $$\hbox {CO}_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CO</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math> emissions. We show that carbon prices should be closely linked to the fluctuations of the marginal utility of consumption, which implies relatively modest magnitude of carbon price fluctuations. Our findings imply that climate policies should focus on setting the carbon price to the optimal growth path level and give carbon price fluctuations only a secondary role. Opposite to the carbon price, the cyclicality of optimal emissions depends on the production technology in the energy sector, and may become countercyclical in future if the technology mix becomes less fossil dependent.