We empirically show that the short-run elasticity of substitution between capital and labor ($\sigma_t$) is countercyclical. In recessions, capital and labor are more substitutable than in expansions. We explore the effects of the countercyclicality of $\sigma_t$ on aggregate fluctuations in the...

While cap-and-trade policies have been advocated as an efficient market-based approach in regulating greenhouse gas (GHG) emissions from the power sector, a major criticism is that the resulting GHG emissions permit prices may be volatile, adding one more layer of uncertainty to market...