According to the authors of "Useless Arithmetic", the mathematical models that policy makers and government administrators use to form environmental policy are seriously flawed. They are often based on unrealistic and sometimes false assumptions and yield answers that support unwise policy. Using examples from the environmental sciences, the authors show how unquestioned faith in mathematical models can blind us to the hard data and sound judgment of experienced scientific fieldwork. The first chapter is a riveting account of how the over reliance on so-called expert models hastened the extinction of the North Atlantic cod on the Grand Banks of Canada. The second chapter presents a general discussion of the limitations of many models used in the environmental sciences. The book, then, presents fascinating case studies of how the seductiveness of quantitative models has led us down a perilous road to unmanageable nuclear-waste-disposal practices, poisoned mining sites, unjustifiable faith in predicted sea-level-rise rates, bad predictions of future shoreline-erosion rates, overoptimistic cost estimates of artificial beaches, and a host of other thorny problems. Useless Arithmetic is a timely and urgent book written in an eloquent and accessible style, evaluating for the general (nonmathematician) reader the assumptions behind models, the nature of the field data, and the dialogue between modelers and their "customers."