Conducting Environmental Impact Assessment in Developing Countries (United Nations University, 1999, 375 p.): 9. Emerging developments in EIA: 9.2 Cumulative effects assessment: 9.2.3 Conclusion

Conducting Environmental Impact Assessment in Developing Countries (United Nations University, 1999, 375 p.)

9. Emerging developments in EIA

9.2 Cumulative effects assessment

		(introduction...)
		9.2.1 Concepts and principles relevant to CEA
		9.2.2 Conceptual framework
		9.2.3 Conclusion

9.2.3 Conclusion

Cumulative environmental problems can be desegregated by distinguishing their sources, pathways, and effects. Application of the typology specific to each component provides a basis for identifying and analysing perturbations, mechanisms of accumulation, and temporally and spatially differentiated effects. The framework can provide guidance to conventional CEA practice characterized by multiple projects bound in time and space, as well as to innovative CEAs of temporally repetitive and spatially dispersed human actions of a non-project nature. Such CEAs can generate new information and insights about environmental changes too frequently deemed insignificant.

Table 9.4 Characterizing cumulative effects

Characteristics		Examples
Sources
	Action quantity	Single, multiple, global, cause unknown
	Action type	Similar or different, common or uncommon, human or natural, additions to or removal from environment
	Temporal characteristics	Historical, existing, or future; short, medium, or long term; low, moderate, or high frequency; continuity of actions over time
	Spatial characteristics	Local, regional or global; small or large scale; continuity of actions over space
	Proponents	Single or multiple; public or private
	Source connections	Connected, unconnected, uncertain connections
Pathways to the environment
	Environmental media	Groundwater, surface water, air, energy
	Degree of concentration	Concentrated or dispersed over time and space
	Degree of continuity	Continuous or discontinuous over time or space (e.g., time or space lags)
	Pathway connections	Connected pathways, unconnected pathways, uncertain connections across pathways
Environment
	System type	Number, type, components, structure, and function of ecological, social, economic, institutional and political systems
	Resources	Number, type and significance
	Significance	Number and type of valuable ecosystem and other ecological components
	State of environment	Healthy, impaired, or collapsed; stable or unstable; resilient or not resilient
	Environmental connections	Connected components, unconnected components, uncertain connections
Interactions
	Connection to sources	Connected, not connected, connections uncertain
	Strength of connections	Strongly connected, weakly connected
	Direction of connection	Direct, indirect, feedback
	Temporal distribution	Concentrated or dispersed; continuous or discontinuous distribution of effects
	Special distribution	Concentrated or dispersed; continuous or discontinuous distribution of effects
	Nature of connections	Additive or interactive, reversible or irreversible
	Significance of connections	Significant, insignificant, uncertain significance

There remain challenges to conduct a CEA focused on sources, pathways, and effects. Sources of cumulative environmental change that are non-project in nature are likely to involve numerous "proponents'', if they can even be identified.

The least understood of the three components of the framework is pathways of accumulation. The complexity of these pathways is evident in multiple routes, feedback loops, and processes that are interactive, synergistic, or involve compounding. Theoretical understanding and tools to identify, monitor, and analyse these pathways are not readily available.

Finally, while cumulative effects can be analysed using available information sources, empirical evidence is often scanty, and quantitative analyses of effects are hindered by insufficient data. CEA requires a temporal scan of long duration and geographic representation at various scales. The limited time span and local focus of many existing databases impede analyses at broader temporal and spatial scales. Rigorous analysis of cumulative effects requires building up the empirical base.

The field of CEA is still in its infancy, so there are few cases where CEAs for major projects have been completed. In general, thus, there is more agreement on the concept of CEA than there is on practical methodologies and techniques.