Several definitions of the environmental dimension of the sustainable development exist, but they are usually quite vague, global. In addition, most of the environmental assessments do not take into account properly the variety of the environmental impacts, or are using tools which do not represent the impacts. A correct representation of the whole range of impacts is necessary to ensure that sustainability takes into account environmental issues to a satisfactory degree and in a transparent way. What are the impacts on environment? What are their characteristics or typical features? We answer to these questions by using the concept of chain of causalities, describing the process between a source and a final impact. The parameters of the chain of causalities are: the type of source, the process itself through the main scientific disciplines involved, the time and distance scales between the source and the final impact, the type of final target (nature: resources and ecosystems; humans: human health in a restricted meaning and human well-being; man-made heritage; earth covering all the targets). This analysis allows us to define 50 chains of causalities, corresponding to various public concerns. They are independent and cover all the impacts. They can be merged in different ways, but it appears that the classifications usual in economy according to quality of life / natural heritage, or present / future generations are hardly pertinent. Indeed, if the chains of causalities and the environmental impacts can be described according these axes, they are rather continuous axes than discrete or binary ones.