Robert Mendelsohn of Yale School of the Environment, Department of Economics, and Yale School of Management reviews “Climate Future: Averting and Adapting to Climate Change” by Robert S. Pindyck. The Econlit abstract of this book begins: “Explores the extent and nature of the uncertainty of climate change's impact on the economy and society, promoting the argument that climate policy should focus on adaptation in preparation for the unlikelihood of sufficiently reducing greenhouse gas emissions.”

This paper provides (for the nonspecialist) a highly streamlined discussion of the main issues, and controversies, in the design of climate mitigation policy. The first part of the paper discusses how much action to reduce greenhouse gas emissions at the global level is efficient under both the cost-effectiveness and welfare-maximizing paradigms. We then discuss various issues in the implementation of domestic emissions control policy, instrument choice, and incentives for technological innovation. Finally, we discuss alternative policy architectures at the international level.

I review the economic characteristics of the climate problem, focusing on the choice of discount rates in the presence of a stock externality, risk and uncertainty/ambiguity, and the role of integrated assessment models (IAMs) in analyzing policy choices. I suggest that IAMs can play a role in providing qualitative understanding of how complex systems behave, but are not accurate enough to provide quantitative insights. Arguments in favor of action on climate issues have to be based on aversion to risk and ambiguity and the need to avoid a small but positive risk of a disastrous outcome.

The problem of global climate change presents overwhelming factual, analytical, and normative challenges. Nordhaus surveys this terrain bravely and mostly successfully. He explains the scientific/economic consensus that the planet is warming, that people are responsible, that the consequences are bad, and that immediate action is benefit/ cost justified. He also discusses the efficient policy response, and the challenges of achieving coordinated global action. His approach is mostly that of standard neoclassical economics, and some of the limitations of that paradigm in this context are not addressed. But overall, The Climate Casino provides an excellent self-contained introduction to the subject.

Very little. A plethora of integrated assessment models (IAMs) have been constructed and used to estimate the social cost of carbon (SCC) and evaluate alternative abatement policies. These models have crucial flaws that make them close to useless as tools for policy analysis: certain inputs (e.g., the discount rate) are arbitrary, but have huge effects on the SCC estimates the models produce; the models' descriptions of the impact of climate change are completely ad hoc, with no theoretical or empirical foundation; and the models can tell us nothing about the most important driver of the SCC, the possibility of a catastrophic climate outcome. IAM-based analyses of climate policy create a perception of knowledge and precision, but that perception is illusory and misleading.

A rapidly growing body of research applies panel methods to examine how temperature, precipitation, and windstorms influence economic outcomes. These studies focus on changes in weather realizations over time within a given spatial area and demonstrate impacts on agricultural output, industrial output, labor productivity, energy demand, health, conflict, and economic growth, among other outcomes. By harnessing exogenous variation over time within a given spatial unit, these studies help credibly identify (i) the breadth of channels linking weather and the economy, (ii) heterogeneous treatment effects across different types of locations, and (iii) nonlinear effects of weather variables. This paper reviews the new literature with two purposes. First, we summarize recent work, providing a guide to its methodologies, datasets, and findings. Second, we consider applications of the new literature, including insights for the “damage function” within models that seek to assess the potential economic effects of future climate change.

How much and how fast should we react to the threat of global warming? The Stern Review argues that the damages from climate change are large, and that nations should undertake sharp and immediate reductions in greenhouse gas emissions. An examination of the Review's radical revision of the economics of climate change finds, however, that it depends decisively on the assumption of a near-zero time discount rate combined with a specific utility function. The Review's unambiguous conclusions about the need for extreme immediate action will not survive the substitution of assumptions that are consistent with today's marketplace real interest rates and savings rates.

The Stern Review calls for immediate decisive action to stabilize greenhouse gases because “the benefits of strong, early action on climate change outweighs the costs.” The economic analysis supporting this conclusion consists mostly of two basic strands. The first strand is a formal aggregative model that relies for its conclusions primarily upon imposing a very low discount rate. Concerning this discount-rate aspect, I am skeptical of the Review's formal analysis, but this essay points out that we are actually a lot less sure about what interest rate should be used for discounting climate change than is commonly acknowledged. The Review's second basic strand is a more intuitive argument that it might be very important to avoid possibly large uncertainties that are difficult to quantify. Concerning this uncertainty aspect, I argue that it might be recast into sound analytical reasoning that might justify some of the Review's conclusions. The basic issue here is that spending money to slow global warming should perhaps not be conceptualized primarily as being about consumption smoothing as much as being about how much insurance to buy to offset the small change of a ruinous catastrophe that is difficult to compensate by ordinary savings.

What are the ethical implications of our contributions to global warming on an individual level? In his extended essay, John Broome analyzes the moral implications of our imposing damages on future generations through our greenhouse-gas emissions. He argues that we as individuals owe restitution to those who are in the future damaged by these unjust acts. He suggests that restitution can be accomplished by completely offsetting emissions and thereby having a zero carbon footprint. This review examines the force of his arguments and suggests that offsetting emissions on an individual basis is an imperfect substitute for collective action or more encompassing contributions to those hurt by our externalities.