The societal roots of the environmental discussion are discussed. Attention focusses on the roles played by the nature conservation, environmental, consumer and anti-nuclear movements, popular and popularized science, the media and the development of environmental policy and regulation.The scientific approach and the societal background enable us to understand the concept of the “environmental crisis”, which itself provides the most important contextual background to environmental ethics. To illustrate contemporary thinking, an analysis of Agenda 21 shows how environmental problems are currently seen (...) as the result of poverty, consumption and production patterns and demographic and decision making issues.Using this environmental knowledge background as a reference, the main lines of thinking in environmental ethics are overviewed. The overview begins by looking at approaches which value the environment because it is or might be of value to man. It continues by considering approaches which are intermediate between the anthropocentric and deep ecological viewpoints. In particular, Leopold's”Land Ethic” and Singer's”Animal Liberation” ideas are discussed.Deep ecology is based on the idea that nature as a whole has moral value. Reference is made to the work of the Norwegian philosopher Naess and to the more scientifically-rooted “deep green theory” of Sylvan and Plumwood.In addition to these different lines of theorising within environmental ethics, the ethical aspects of such anchorpoints in the environmental discussion as sustainable development and the Gaia theory, are also discussed. (shrink)