in Hobbs, R. and H. Mooney (eds), Biological Invasions and Global Change, Island Press, 1999 (in press).

Earth Systems: Processes and Issues is the ideal textbook for introductory courses in earth systems science and environmental science. Integrating the principles of the natural sciences, engineering, and economics as they pertain to the global environment, it explains the complex couplings and feedback mechanisms linking the geosphere, biosphere, hydrosphere, and atmosphere. An impressive group of internationally respected researchers and lecturers have brought together a vast wealth of teaching experience to produce this fully integrated environmental textbook. It has been designed for the wide range of courses at the first-year university level which touch upon environmental issues: in earth and atmospheric science, environmental science, biological science, oceanography, geography, civil engineering, and social science. Each chapter includes a reading list of the most important references, and problem sets will encourage students to explore the subject further. This text will favorably influence the future development of environmental studies and earth system science.

This paper explores the significance of policy-induced technological change for the design of carbon-abatement policies. We derive analytical expressions characterizing optimal CO2 abatement and carbon tax profiles under different specifications for the channels through which technological progress occurs. We consider both R&D-based and learning-by-doing-based knowledge accumulation, and examine each specification under both a cost-effectiveness and a benefit-cost policy criterion. We show analytically that the presence of induced technological change (ITC) implies a lower time profile of optimal carbon taxes. The impact of ITC on the optimal abatement path varies. When knowledge is gained through R&D investments, the presence of ITC justifies shifting some abatement from the present to the future. However, when knowledge is generated through learning-by-doing, the impact on the timing of abatement is analytically ambiguous. Illustrative numerical simulations indicate that the impact of ITC upon overall costs and optimal carbon taxes can be quite large in a cost-effectiveness setting but typically is much smaller under a benefit-cost policy criterion. The impact of ITC on the timing of abatement is very weak, and the effect (applicable in the benefit-cost case) on total abatement over time is generally small as well, especially when knowledge is accumulated via R&D.

Nitrogen fertilization is a substantial source of nitrogen-containing trace gases that have both regional and global consequences. In the intensive wheat systems of Mexico, typical fertilization practices lead to extremely high fluxes of nitrous oxide (N2O) and nitric oxide (NO). In experiments, lower rates of nitrogen fertilizer, applied later in the crop cycle, reduced the loss of nitrogen without affecting yield and grain quality. Economic analyses projected this alternative practice to save 12 to 17 percent of after-tax profits. A knowledge-intensive approach to fertilizer management can substitute for higher levels of inputs, saving farmers money and reducing environmental costs.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.