Background, Aim and Scope:
Life cycle assessment (LCA) stands as the preeminent tool for estimating environmental effects caused by products and processes from “cradle to grave” or “cradle to cradle.” It exists in multiple forms, claims a growing list of practitioners and remains a focus of continuing research. Despite its popularity and codification by organizations such as ISO and SETAC, life cycle assessment is a tool in need of improvement. Multiple authors have written about its individual problems, but a unified treatment of the subject is lacking. The following literature survey gathers and explains issues and problems currently limiting LCA.
Main Features:
The review identifies fourteen major problem areas and organizes them by the LCA phases in which each appears. This part of the review is meant as a concise summary for practitioners interested in methodological limitations which might degrade the accuracy of their assessments. For new researchers, it provides an overview of pertinent problem areas toward which they might wish to direct their research efforts. Having identified and discussed LCA’s major problems, closing sections highlight the most critical problems and briefly propose research agendas meant to improve them.
Results:
Multiple problems occur in each of LCA’s four phases and reduce the accuracy of this tool. Considering problem severity and the adequacy of current solutions, six of the fourteen discussed problem are of paramount importance. Functional unit definition, boundary selection, allocation, spatial variation, local environmental uniqueness and data availability / quality are critical problems requiring particular attention.
Discussion:
Problems encountered during goal and scope definition arise from decisions about inclusion and exclusion. Failure to select a representative functional unit or properly define a study’s boundaries can reduce an LCA to a misdirected and expensive exercise in data acquisition. Inventory analysis problems involve flows and transformations. Allocation failures effectively bias all downstream results with an artifact of the analysis. Truncations and assumptions about global homogeneity and steady-state conditions introduce the most severe errors in impact assessment. Order of magnitude errors can result when spatial differences and local environmental uniqueness are ignored. Aggregation is the overarching problem in interpretation.
Conclusions:
Observing that significant efforts by multiple researchers have not resulted in a single, agreed upon approach for the first three critical problems, development of LCA archetypes for functional unit definition, boundary selection and allocation is proposed. Further development of spatially explicit, dynamic modeling is recommended to ameliorate the problems of spatial variation and local environmental uniqueness. Finally, this paper echoes calls for peer-reviewed, standardized LCA inventory and impact databases, and it suggests the development of model-bases. Both of these efforts would help alleviate persistent problems with data availability and quality.
Perspectives:
In its current state, LCA provides relative and directional information to those working in environmental assessment, policy, design and allied fields. If one accepts sustainability as the ultimate goal, the importance of improving LCA to the point where it offers more than ambiguous directional information is clear. Guided by LCA’s current outputs, it is unlikely that one could avoid local minima of environmental damage that fall short of sustainability. Solving the discussed problems would improve LCA in this regard. A superior description of the complex environmental performance space for product systems might give those involved in numerous and varied decision processes the capacity to navigate society toward a more sustainable state.
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