In their article, Daily and Ehrlich have discussed a number of important recent trends associated with development and global change that appear to be reducing health security. Besides their immediate epidemiological implications, most issues raised in the paper have economic implications. However, from the point of view of the methodology of economics, despite the paper's being illuminating on the issues discussed, the immediate notable aspect is the lack of a model or framework with/within which those issues are being analysed. Indeed, it is very hard to think of a single framework which would be all-encompassing enough to be applicable to the analysis of all the issues raised in the paper. But I submit that these issues can be adequately addressed and analysed using the rather simplistic model of production and consumption,1 which is the core of all economic analysis. In what follows, I will pick only a few of the issues raised in the paper and put them within the context of this basic economic model, so as to examine their economic implications.

Our environment is complex, but it is understandable through rational investigation, and it is not to be feared. So wrote Titus Lucretius Carus of the nature of things some thirty human lifetimes ago—not so long, really. About species evolution Lucretius thought much, guessed well, and worried little. About microparasitic evolution he knew nothing. Would he have feared it? Should we fear it now?

William Nordhaus has gone further than any economist to date at building a dynamic integrated model of the world’s climate and economic systems, with some one-way linkages to agricultural systems and ecosystems. Managing the Commons is an admirably readable description of this effort which, in his words, ‘balances the costs of emissions controls in energy policies and other areas against the impacts to agriculture, coastlines, and ecosystem values’. In addition to a detailed description of the Dynamic Integrated Climate and the Economy (DICE) model and several scenarios produced by the model, the book includes large sections on sensitivity analysis of the model’s parameter uncertainty and an analysis of the value of information gained at various times in the future to the decision process.