readily quantifiable, there would still be the matter of selecting the most effective, least costly response strategies. Here economic concepts are central. Proposed responses to greenhouse warming include ideas that would affect national economies, international trade, and the life-styles of people in both developing and industrialized societies. Moreover, selecting some of these alternatives would mean that other highly valued objectivessuch as improving economic status or national securitywould have to be altered. Making choices in the face of scarcitythe problem at the heart of economic scienceis inescapable.
Much of this chapter is devoted to explaining the difficulties of carrying out a conceptually straightforward approach. There are three critical problems: (1) markets are imperfectthat is, neither the prices observed nor the responses of markets are the simple result of demand and supply operating unimpeded; (2) uncertainties abound in the technical realm, in social responses to policy instruments, in environmental changes due to changing climate, and in markets; and (3) consideration of most alternatives requires comparing costs and benefits at different times, paid for or enjoyed by different people.
Although it has been possible to assemble an overview of the options for mitigating greenhouse warming, the panel urges readers to bear in mind the formidable problems of theory and practice limiting the precision of the estimates that can be provided at this time and even the qualitative accuracy of the picture that can be presented.
Greenhouse warming is a phenomenon of the atmosphere, taking place in a global "commons." Similar emissions of greenhouse gases have similar potential to affect global climate, regardless of their country of origin. Thus mitigation strategies must be global in scope, at least implicitly involving both developed and developing countries. Indeed, many of the lowest-cost mitigation options may be found at first in some of the poorest developing countries. For example, the efficiency of wood-burning cookstoves can potentially be raised at very low cost (Reid, 1989). Because these countries may be unwilling or unable to afford such policies, the developed countries may choose to underwirte such efforts. This targeted redistribution of economic resources could be efficient and less costly to the developed countries than mitigation strategies directed solely toward their domestic economies.
Because of the limited availability of information on a global basis, however, and the scope of the panel's responsibilities, the analysis of mitigation options in the chapters that follow is devoted largely to the United States. With a few exceptions, information on mitigation costs and estimates of