Common views hold that the efficient way to limit warming to a chosen level is to price carbon emissions at a rate that increases exponentially. We show that this Hotelling tax on carbon emissions is actually inefficient. The least-cost policy path takes advantage of the climate system's inertia to delay reducing emissions and allow greater cumulative emissions. The efficient carbon tax follows an inverse-U-shaped path and grows more slowly than the Hotelling tax. Economic models that assume exponentially increasing carbon taxes are overestimating the cost of limiting warming, overestimating the efficient near-term carbon tax, and overvaluing technologies that mature sooner.

Using an international sample of 38 countries, we find that firms located in countries experiencing greater socioeconomic damage from extreme climate events have higher implied costs of equity capital. This finding is attributed to heightened operational uncertainty, greater information asymmetry, and intensified agency conflicts that arise in the wake of extreme climate events. The relation is stronger for firms that derive substantial revenue from domestic markets, operate in climate-vulnerable industries, or are closely held by domestic institutional investors. The effect also varies across countries and is concentrated in markets characterized by low transparency or limited integration into the global financial market. While extreme climate events negatively influence firm performance and valuation, they raise corporate awareness of climate risk.

How does demand uncertainty affect firms' investment decisions? We examine this question in the context of electricity‐producing firms' planned investments in new power plants. We measure uncertainty about future electricity demand using plausibly exogenous variation in temperature projections across scientific climate models. The results show that uncertainty increases investment in power plants with flexible production technologies, while reducing investment in less flexible technologies. Overall, the net effect of uncertainty on investment is positive when firms have access to flexible investment opportunities. These findings are consistent with models in which production flexibility shapes the investment response to demand uncertainty.

Lemoine and Rudik (2017) argues that it is efficient to delay reducing carbon emissions, due to supposed inertia in the climate system’s response to emissions. This conclusion rests upon misunderstanding the relevant earth system modeling: there is no substantial lag between CO 2 emissions and warming. Applying a representation of the earth system that captures the range of responses seen in complex earth system models invalidates the original article’s implications for climate policy. The least-cost policy path that limits warming to 2°C implies that the carbon price starts high and increases at the interest rate. It cannot rely on climate inertia to delay reducing and allow greater cumulative emissions.

Mattauch et al. (2020) claims that the quantitative conclusions in Lemoine and Rudik (2017)—henceforth, LR17—are not robust to using a climate model consistent with recent scientific results. We observe that LR17 in fact analyzes an extension to a more realistic carbon model that generates an efficient emission tax trajectory very similar to that in Mattauch et al. (2020), and we here show that simplifications in the temperature model of LR17 do not qualitatively affect their policy conclusions. Accounting for inertia reduces the initial emission tax by 42 percent and reduces the present value of abatement cost by 39 percent.

Katharine Coman's “Some Unsettled Problems of Irrigation,” published in March 1911 in the first issue of the American Economic Review, addressed issues of water supply, rights, and organization. These same issues have relevance today, in the face of growing concern about the availability of fresh water worldwide. The central point of this article is that appropriative water rights and irrigation districts that emerged in the American West in the late nineteenth and early twentieth centuries in response to aridity to facilitate agricultural water delivery, use, and trade raise the transaction costs today of water markets. These markets are vital for smooth reallocation of water to higher-valued uses elsewhere in the economy and for flexible response to greater hydrological uncertainty. This institutional path dependence illustrates how past arrangements to meet conditions of the time constrain contemporary economic opportunities. They cannot be easily significantly modified or replaced ex post.

This paper evaluates the potential for global reallocation between agricultural and nonagricultural production to contribute to climate change adaptation. Empirical estimates using a global sample of firms suggest that rising temperatures reduce productivity less in nonagriculture than angriculture, implying large potential gains if hot countries could increase food imports and shift labor toward manufacturing. However, model counterfactuals show that subsistence consumption needs and high trade barriers combine to create a “food problem” in which climate change instead intensifies agricultural specialization in especially vulnerable regions. Simulations suggest that reducing trade barriers can significantly reduce climate damages, especially in poor countries.

Houses in cold climates are kept warmer in winter than those in warm climates, des pite the greater cost of heating in colder climates. It is shown that this is not only consistent with, but also implied by, rationality. The contrary intuition is based on a confusion between average and ma rginal cost. The same analysis implies that it is rational to keep th e thermostat setting constant throughout the heating season rather th an changing it with changes in external temperature.

This paper reports the results of an evaluation of partial-equilibrium welfare measures of the effects of large multisector shocks to an economic system. A nine a developed economy was used in the analysis. The findings indicate that the errors in single-sector, partial-equilibrium welfare measures depend on the consistency in the signs and approximate magnitude of indirect price effects. Disparities in either the direction or size of price changes in the indirectly affected markets can lead to large errors in the partial-equilibrium welfare measures.