Employing droughts and floods to proxy for changes in precipitation, this paper shows nomadic incursions into settled Han Chinese regions over a period of more than two thousand years—the most enduring clash of civilizations in history—to be positively correlated with less rainfall and negatively correlated with more rainfall. Consistent with findings that economic shocks are positively correlated with conflicts in modern sub-Saharan Africa when instrumented by rainfall, our reduced-form results extend this relationship to a very different temporal and geographical context, the Asian continent, and long historical period.

With a focus on two sorts of regulation—renewable electricity and clean energy standards, and automobile fuel-economy standards—we analyze problematic interactions that arise when state policies are nested within the domain of Federal policy. Here state efforts may fail to reduce greenhouse gas emissions nationally, and may compromise cost-effectiveness. Difficulties from overlapping regulations are avoidable through price- (as opposed to quantity-) based Federal policy. We identify some potentially positive interactions between state and Federal policies, and identify rationales for state action when Federal and state policies do not overlap.

This paper analyzes 19th and 20th century data from a well-known château in Bordeaux. The dataset includes information on weather conditions, starting dates of three phenological stages of grapevine, prices, and yields. We discuss how these variables have evolved over the last two centuries. We also study to what extent the impact of climate on yields and prices has changed over time. Our regression analysis suggests that the effect of temperature on yields has become weaker since the 19th century. The influence on prices has, on the contrary, become stronger.

We review the proposed measures for addressing competitiveness and carbon leakage concerns in recent US climate policy legislation. For eligible energy-intensive, trade-exposed sectors, output-based rebates would initially dampen cost increases; later, border adjustments would ensure that imports face comparable cost burdens. Both measures can in theory enhance the economic efficiency of carbon reduction efforts, but both pose some interesting economic and practical trade-offs. This paper discusses our recent research into the welfare and carbon leakage effects of using output-based allocation and trade measures in conjunction with climate policies.

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.