Cumulative Effects Assessment Management (CEAM) began in the early 1970s when it was realized that proposed projects needed to be analyzed in relation to their location and surrounding land uses. Further, agencies that processed multiple concurrent permit approvals for similar types of projects also realized that such approvals needed to incorporate consideration of all applications in close spatial and temporal proximity to each other, as such actions often contribute to cumulative effects.
In the practice of EIA in the USA, the term “cumulative effects†was first mentioned in guidelines of the Council on Environmental Quality (CEQ) in 1973. In mid-1979, CEQ’s first EIA-related regulations defined a cumulative impact (effect) as the:
“impact on the environment which results from the incremental impact of the action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (federal or non-federal) or person undertake such other actions. Cumulative impacts can result from individually minor, but collectively significant, actions taking place over a period of timeâ€.
In the 20-year period encompassing the 1980s and 1990s, environmental impact studies in both the USA and Canada began to routinely incorporate cumulative effects considerations in study documents. Further, other definitions appeared. For example, the Canadian Environmental Assessment Agency (CEAA) has suggested a simple definition:
“cumulative effects are changes to the environment that are caused by an action in combination with other past, present, and future human actions.â€
During the latter part of the 1990s, the Annual Meetings of the International Association for Impact Assessment (IAIA) began to include papers and topical sessions on CEAM, and resultant and related papers have been published in Project Appraisal, Impact Assessment and Project Appraisal, Environmental Impact Assessment Review, Environmental Practice, and Environmental Assessment Policy and Management. Litigation related to the adequacy of CEAM within impact study documents also began to appear in the USA in both the 1980s and 1990s. The absence of acceptable frameworks or multi-step processes for addressing CEAM seemed to be fundamental to many plaintiffs’ challenges. As a result, in the late 1990s, both the CEQ in the USA and CEAA in Canada published practitioner guidance. Both processes were conceptually similar, and they both included 11 steps which were generally matchable. These steps are consistent with the six step process described below.
The first decade in the 21st century has experienced continuing improvements in CEAM practice, particularly as related to proposed projects. Strategic environmental assessments (SEAs), also referred to as Programmatic EISs in the USA, also have given greater attention to cumulative effects issues. In fact, CEAM should be a central feature of these strategic studies. Further, methods and tools used in EIA practice began to be modified to incorporate consideration of the combined effects of multiple actions on selected VECs (Valued Ecosystem Components). New topics such as environmental sustainability have also been recognized as integrators of concerns related to cumulative effects. Finally, the potential benefits of cumulative effects thinking relative to global issues such as climate change are being explored along with the development of appropriate procedures for such evaluations.
As noted above, CEAM frameworks have been promulgated in the USA and Canada. Further, such frameworks (step-wise processes or procedures) have also been developed for usage in the European Union countries, Australia, New Zealand, and elsewhere. The frameworks can generally be condensed into the following six steps:
The first decade of EIA practice occurred in the 1970s, and one topic which received considerable attention was related to appropriate methods and tools which could be used by practitioners. Over the ensuing three decades, the types of EIA-related methods and tools have continued to expand. Since the practice of CEA is now into its second decade, interest is continuing on appropriate methods and tools which could be used to improve professional practice. Based upon the review of various CEA informational sources, it can be concluded that many of the current and developing methods and tools are similar to those used for EIA practice. The primary difference is related to the need to incorporate other actions and their contributions to cumulative effects on specific VECs. Such incorporation is often done by simple modifications to existing EIA methods and tools. Brief examples of such modifications include:
(1) adding “other actions†questions to questionnaire checklists focused on identifying direct and indirects of proposed actions;
(2) modifying interaction matrices to include columns related to past, present, and future actions; and
(3) modifying network diagrams to include other actions.
Special thanks to Larry Canter and William Ross for providing initial content for this IAIA Wiki topic.
