ABSTRACT
Cumulative effects can result from multiple effects from the same project or the combined effect of multiple developments giving rise to multiple effects. In the United States, cumulative effects should be addressed in all environmental impact statements prepared under the National Environmental Policy Act. The international finance corporation (IFC) guidance is directed to private projects in emerging markets but it also provides a useful approach to cumulative effects assessment (CEA) in any country. The purpose of CEA in environmental and social impact assessment (ESIA) is to consider the incremental contribution of the project together with effects from other past, present and reasonably foreseeable future activities. From the review of the literature, it is clear that CEA practitioners have a consistent understanding of the term synergistic in ESIA. CEA for additive effects is conceptually simple: it is the sum of the magnitudes of the same effect and the combined effect is assessed as if resulting from a single project.
