Purpose Assessing impacts of abiotic resource use has been a topic of persistent debate among life cycle impact assessment (LCIA) method developers and a source of confusion for life cycle assessment (LCA) practitioners considering the different interpretations of the safeguard subject for mineral resources and the resulting variety of LCIA methods to choose from. Based on the review and assessment of 27 existing LCIA methods, accomplished in the first part of this paper series (Sonderegger et al. 2020 ), this paper provides recommendations regarding the application-dependent use of existing methods and areas for future method development. Method Within the “global guidance for LCIA indicators and methods” project of the Life Cycle Initiative hosted by UN Environment, 62 members of the “task force mineral resources” representing different stakeholders discussed the strengths and limitations of existing LCIA methods and developed initial conclusions. These were used by a subgroup of eight members at the Pellston Workshop® held in Valencia, Spain, to derive recommendations on the application-dependent use and future development of impact assessment methods. Results and discussion First, the safeguard subject for mineral resources within the area of protection (AoP) natural resources was defined. Subsequently, seven key questions regarding the consequences of mineral resource use were formulated, grouped into “inside-out” related questions (i.e., current resource use leading to changes in opportunities for future users to use resources) and “outside-in” related questions (i.e., potential restrictions of resource availability for current resource users). Existing LCIA methods were assigned to these questions, and seven methods (ADP ultimate reserves , SOP URR , LIME2 endpoint , CEENE, ADP economic reserves , ESSENZ, and GeoPolRisk) are recommended for use in current LCA studies at different levels of recommendation. All 27 identified LCIA methods were tested on an LCA case study of an electric vehicle, and yielded divergent results due to their modeling of impact mechanisms that address different questions related to mineral resource use. Besides method-specific recommendations, we recommend that all methods increase the number of minerals covered, regularly update their characterization factors, and consider the inclusion of secondary resources and anthropogenic stocks. Furthermore, the concept of dissipative resource use should be defined and integrated in future method developments. Conclusion In an international consensus-finding process, the current challenges of assessing impacts of resource use in LCA have been addressed by defining the safeguard subject for mineral resources, formulating key questions related to this safeguard subject, recommending existing LCIA methods in relation to these questions, and highlighting areas for future method development.

中文翻译：

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生命周期影响评估中的矿产资源：第二部分 – 关于现有方法的应用相关使用和未来方法开发需求的建议

目的 评估非生物资源使用的影响一直是生命周期影响评估 (LCIA) 方法开发者之间持续争论的话题，也是生命周期评估 (LCA) 从业者考虑到对矿产资源保护主题的不同解释和由此产生了多种 LCIA 方法可供选择。基于在本系列论文的第一部分（Sonderegger 等人，2020 年）中完成的 27 种现有 LCIA 方法的审查和评估，本文提供了关于现有方法的应用相关使用和未来方法开发领域的建议。方法 在联合国环境署主办的生命周期倡议的“LCIA 指标和方法全球指南”项目中，代表不同利益相关者的“矿产资源工作组”的 62 名成员讨论了现有 LCIA 方法的优势和局限性，并得出了初步结论。在西班牙巴伦西亚举行的 Pellston Workshop® 上，一个由八名成员组成的小组使用这些方法来得出关于影响评估方法的应用依赖使用和未来发展的建议。结果与讨论 首先，界定了自然资源保护区（AoP）内矿产资源的保障主体。随后，制定了关于矿产资源使用后果的七个关键问题，分为“由内而外”相关问题（即当前资源使用导致未来用户使用资源的机会发生变化）和“由外而内”相关问题（IE，当前资源用户的资源可用性的潜在限制）。将现有的 LCIA 方法分配给这些问题，并推荐在当前不同推荐级别的 LCA 研究中使用七种方法（ADP 最终储量、SOP URR、LIME2 终点、CEENE、ADP 经济储量、ESSENZ 和 GeoPolRisk）。所有 27 种确定的 LCIA 方法都在电动汽车的 LCA 案例研究中进行了测试，由于它们对影响机制的建模解决了与矿产资源使用相关的不同问题，因此产生了不同的结果。除了特定方法的建议外，我们建议所有方法都增加涵盖的矿物数量，定期更新其特征因子，并考虑将次生资源和人为储量包括在内。此外，耗散资源使用的概念应在未来的方法开发中加以定义和整合。结论 在国际共识发现过程中，通过定义矿产资源的保障主体、制定与该保障主体相关的关键问题、推荐与这些问题相关的现有 LCIA 方法，解决了当前在 LCA 中评估资源使用影响的挑战，并突出显示未来方法开发的领域。