This study deals with issues of environmental change and degradation, with special reference to Southern Africa. Over the last couple of decades this debate has become quite heated. The aim of this paper is to clarify contrasting opinions, and to describe the more far-reaching shifts in scientific thinking. This is done by discussing definitions of the processes involved, the commonly used indicators and ascribed causes of degradation and the importance of time and space, especially in the context of the variability and heterogeneity which characterises the semi-arid environments. The value of interdisciplinarity is highlighted throughout the paper.