There is a large consensus among international institutions and national governments to favor urban-containment policies - the compact city - as a way to improve the ecological performance of the urban system. This approach overlooks a fundamental fact: what matters for the ecological outcome of...

This paper examines future energy and emissions scenarios in China generated by the Integrated Assessment Model WITCH. A Business-as-Usual scenario is compared with five scenarios in which Greenhouse Gases emissions are taxed, at different levels. The elasticity of China’s emissions is...

We study the relationship between geography and growth. To do so, we first develop a dynamic spatial growth theory with realistic geography. We characterize the model and its balanced growth path and propose a methodology to analyze equilibria with different levels of migration frictions. We...

What should be the West's top priority for climate-change policy? This article is a revised and updated version of my talk to the Potsdam Global Sustainability Symposium (which drafted the Potsdam Declaration presented to the 2007 UN Climate Change Conference in Bali).

A 'folk theorem' originating, among others, in the work of Stiglitz maintains that competitive equilibria are always or 'generically' inefficient (unless contracts directly specify consumption levels as in Prescott and Townsend, thus bypassing trading in anonymous markets). This paper critically...

This paper studies equilibria for economies characterized by moral hazard (hidden action), in which the set of contracts marketed in equilibrium is determined by the interaction of financial intermediaries. The crucial aspect of the environment that we study is that intermediaries are restricted...

This paper studies fiscal federalism when regions differ in voters’ ability to monitor public officials. We develop a model of political agency in which rent-seeking politicians provide public goods to win support from heterogeneously informed voters. In equilibrium, voter information...

We estimate how random weather fluctuations affected infant mortality across 28 African countries in the past, combining high-resolution data from retrospective fertility surveys (DHS) and climate-model reanalysis (ERA-40). We find that infants were much more likely to die when exposed in utero...

This paper builds a two-country (North, South), two-sector (polluting, nonpolluting) trade model with directed technical change, examining whether unilateral environmental policies can ensure sustainable growth. The polluting good is produced with a clean and a dirty input. I show that a...

Climate change must deal with two market failures, global warming and learning by doing in renewable use. The social optimum requires an aggressive renewables subsidy in the near term and a gradually rising carbon tax which falls in long run. As a result, more renewables are used relative to...