Like all other species, humans impact their environment. The scale of human impacts has grown as a result of population growth and increased consumption of goods and services. At the same time, our understanding of the environmental consequences of human activities has improved.
Decades ago, attention focused mainly on clear-cut, obvious environmental insults: deadly chemical fogs, burning rivers, and eutrophic lakes. Today, scientists and the public are paying more attention to less apparent impacts such as stratospheric ozone depletion, greenhouse gas emissions, bioaccumulation of toxic chemicals, and the disappearance of unfamiliar or even unknown species.
This broadening appreciation for less obvious but still significant environmental impacts has elevated the importance of methods for detecting and measuring substances known to affect the health of the environment. Currently, dozens of measurement techniques are in relatively early stages of development or adoption. Some are intended to help study the condition of an ecosystem; others are designed for comparing the impact of alternative human activities.
The two categories of metrics have been developed by two cadres of professionals: those focused on assessing the condition of ecosystems and those interested in assessing environmental impacts associated with particular activities or products. Although these two groups play complementary, closely related roles, they have traditionally had little interaction.
The papers in this volume are the product of a 1994 National Academy of Engineering (NAE) workshop. The workshop was intended to promote interaction, coordination, and cross-fertilization between those who assess and manage the condition of ecosystems and those who assess and manage the environmental performance of institutions. The papers were contributed by engineers, ecolo-