I offer a selective review of discounting and climate policy. Analytic and numerical models show that different assumptions greatly change the degree to which decisions about climate policy depend on the discount rate. I discuss a claim that standard models exaggerate the current generation's...

We introduce a “smart” cap and trade system that eliminates the welfare costs of asymmetric information (“uncertainty”). This cap responds endogenously to technology or macroeconomic shocks, relying on the market price of certificates to aggregate information. It allows policy makers to...

Intergenerational altruism and contemporaneous cooperation are both important to the provision of long-lived public goods. Equilibrium climate protection may depend more sensitively on either of these considerations, depending on the type of policy rule one examines. This conclusion is based on...

“Prices versus quantities” (Weitzman 1974), a hugely influential paper, is widely cited (and taught) in current debates about the best policy to reduce greenhouse gas emissions. The paper’s criterion for ranking policies suggests that technological uncertainty favors taxes over cap and...

We compare the instantaneous and the long run effects of environmental reform in closed and open economies. Harmonization upward (decreasing distortions where they are most severe) or harmonization downward (increasing distortions where they are less severe), both tend to increase instantaneous...

The amount of cooperation needed to improve the welfare of signatories of International Environmental Agreements (IEAs), in the presence of market imperfections, depends on the characteristics of pollution. In a dynamic model, the conventional wisdom on the effect of free-riding needs to be...

We compare the effects of taxes and quotas for an environmental problem in which the regulator and polluter have asymmetric information about abatement costs, and the environmental damage depends on the stock of pollution. We thus extend to a dynamic framework previous studies in which...

We compare taxes and quotas when firms and the regulator have asymmetric information about abatement costs. Damages are caused by a stock pollutant. Uncertainty enters multiplicatively, i.e. it affects the slope rather than the intercept of abatement costs. We calibrate the model using cost and...

We estimate a structural model of OECD countries in which GDP and CO2 emissions are endogenous. We use the estimated model to simulate the price of tradable CO2 permits and the efficiency gains from trade. Our estimated prices are high, relative to previous estimates, and the efficiency gains...

Increased population pressure and political decisions have led to more intensive agricultural practices in China. As in other regions of the world, these practices can damage natural capital. We use the Kalman filter and Chinese panel data to estimate an index of environmental productivity...