Climate change is an urgent global challenge, and greenhouse gas (GHG) emissions from metal production contribute to a substantial part of total emissions. Metals play an essential role in human ...life, and their demand will increase with global population and economic growth. Therefore, projecting future GHG emissions associated with metal production and exploring effective measures to alleviate GHG emissions are essential for achieving climate goals. This study projects the future GHG emissions associated with the primary and secondary production of six metals (aluminum, copper, iron, lead, nickel, and zinc) by considering the detailed metal cycles according to the shared socio-economic pathways (SSPs). Additionally, influential factors for GHG emissions in metal cycles are explored using decomposition and sensitivity analyses to reduce future GHG emissions. We show that future GHG emissions from metal production cannot be in line with the climate goal required to maintain the temperature change below 2 °C under any SSP, even though the trends for GHG emissions from metal production are significantly different among the SSPs. Therefore, substantial efforts to reduce GHG emissions are required in addition to the transition to the sustainable socio-economic pathway. From a short-term perspective, lowering the per capita in-use metal stock level and GHG emission intensity of metal production is crucial, especially in middle income groups. From a long-term perspective, improving the recycling rate is a possible step after sufficient in-use metal stocks are accumulated for recycling. To achieve the climate goals for both short- and long-term GHG reductions in metal cycles, a combination of actions on these influential factors without delay is essential.
The projected GHG emissions cannot reach the climate goal under any SSP. Further efforts on lowering per capita in-use metal stocks and GHG emission intensity of metal production and promoting recycling are the key to achieve the climate goal.
Sustainable freshwater management is an essential target for sustainability. The concept of planetary boundaries evaluates whether the environmental loads from humans are within the carrying capacity ...of the environment at a global level, while the region-specific assessment of carrying capacities of freshwater consumption can complement the global-scale sustainability assessment by shedding light on regional sustainability. We show that 24% of the total freshwater consumption exceeds the regional carrying capacities based on spatially and temporally explicit analysis (monthly data for around 11 000 watersheds). Although 19% of the current total freshwater consumption is determined as “luxury consumption” beyond basic needs, approximately 60% of the exceedance is attributed to basic needs of freshwater for sustaining human life. International trade alleviates the overall pressure on carrying capacity by approximately 4.8% (18.9 billion m3) at a global level through virtual water trade; however, several producer countries demonstrate additional overconsumption beyond the regional carrying capacities, while importer countries that can do so mitigate overconsumption. Appropriate irrigation water management and the location of crop production are the keys to maintain our freshwater consumption levels within the regional carrying capacities on a global scale. However, measures that necessitate the consideration of watershed-specific environmental and economic conditions are desirable.
Purpose
The safeguard subject of the Area of Protection “natural Resources,” particularly regarding mineral resources, has long been debated. Consequently, a variety of life cycle impact assessment ...methods based on different concepts are available. The Life Cycle Initiative, hosted by the UN Environment, established an expert task force on “Mineral Resources” to review existing methods (this article) and provide guidance for application-dependent use of the methods and recommendations for further methodological development (Berger et al. in Int J Life Cycle Assess,
2020
).
Methods
Starting in 2017, the task force developed a white paper, which served as its main input to a SETAC Pellston Workshop® in June 2018, in which a sub-group of the task force members developed recommendations for assessing impacts of mineral resource use in LCA. This article, based mainly on the white paper and pre-workshop discussions, presents a thorough review of 27 different life cycle impact assessment methods for mineral resource use in the “natural resources” area of protection. The methods are categorized according to their basic impact mechanisms, described and compared, and assessed against a comprehensive set of criteria.
Results and discussion
Four method categories have been identified and their underlying concepts are described based on existing literature: depletion methods, future efforts methods, thermodynamic accounting methods, and supply risk methods. While we consider depletion and future efforts methods more “traditional” life cycle impact assessment methods, thermodynamic accounting and supply risk methods are rather providing complementary information. Within each method category, differences between methods are discussed in detail, which allows for further sub-categorization and better understanding of what the methods actually assess.
Conclusions
We provide a thorough review of existing life cycle impact assessment methods addressing impacts of mineral resource use, covering a broad overview of basic impact mechanisms to a detailed discussion of method-specific modeling. This supports a better understanding of what the methods actually assess and highlights their strengths and limitations. Building on these insights, Berger et al. (Int J Life Cycle Assess,
2020
) provide recommendations for application-dependent use of the methods, along with recommendations for further methodological development.
Purpose
Life cycle assessment (LCA) has been used to assess freshwater-related impacts according to a new water footprint framework formalized in the ISO 14046 standard. To date, no consensus-based ...approach exists for applying this standard and results are not always comparable when different scarcity or stress indicators are used for characterization of impacts. This paper presents the outcome of a 2-year consensus building process by the Water Use in Life Cycle Assessment (WULCA), a working group of the UNEP-SETAC Life Cycle Initiative, on a water scarcity midpoint method for use in LCA and for water scarcity footprint assessments.
Methods
In the previous work, the question to be answered was identified and different expert workshops around the world led to three different proposals. After eliminating one proposal showing low relevance for the question to be answered, the remaining two were evaluated against four criteria: stakeholder acceptance, robustness with closed basins, main normative choice, and physical meaning.
Results and discussion
The recommended method, AWARE, is based on the quantification of the relative available water remaining per area once the demand of humans and aquatic ecosystems has been met, answering the question “What is the potential to deprive another user (human or ecosystem) when consuming water in this area?” The resulting characterization factor (CF) ranges between 0.1 and 100 and can be used to calculate water scarcity footprints as defined in the ISO standard.
Conclusions
After 8 years of development on water use impact assessment methods, and 2 years of consensus building, this method represents the state of the art of the current knowledge on how to assess potential impacts from water use in LCA, assessing both human and ecosystem users’ potential deprivation, at the midpoint level, and provides a consensus-based methodology for the calculation of a water scarcity footprint as per ISO 14046.
•We introduce a scarcity in mining capacity indicator to represent the degree of pressure on the continuity of mining activity.•Scarcity in mining capacity of metals is assessed using an indicator ...reflecting country-specific mine production and availability.•Country-specific scarcity of a given metal varies by approximately 1-3 orders of magnitude.•The proposed indicator of concentrated production in high-scarcity countries (WS/GS) can complement current criticality assessment in terms of local sustainability.•Assessment of the severity of mining gives metal users clues to improve their responsibility for sustainability in mining.
The sustainability of metal use is threatened by increasing global demand. The concept of scarcity in mining capacity is of particular relevance to the sustainability of metals; it represents an imbalance between availability and mine production and is determined by socio-economic conditions. Although socio-economic conditions vary by region or country, few studies have assessed the scarcity in mining capacity of metals on such regional scales, which fails to assess potential risks for local sustainability. Here, we propose a country-specific indicator for the assessment of scarcity in mining capacity of metals that reflects differences in national conditions. We apply our methodology to 16 representative metals for 2000, 2010 and 2017. The results demonstrate our indicator of country-specific scarcity varies by 1-3 orders of magnitude for the metals considered, depending on reserves and mine production in producing countries. Furthermore, an indicator that represents the degree of concentrated production in high-scarcity countries is introduced, which reveals the dependency on high-scarcity countries for Al, REE, Li, and Sn. For the assessment of the effects of specific demand on the potential risks of threatening local sustainability, we define the severity of mine production that represents the magnitude of the potential risks determined by both country-specific mine production and scarcity. Analysis of metal scarcity considering country-specific conditions can reveal the potential risks for local sustainability associated with metal production and support metal users to seek effective solutions to reduce the potential risks, which is not considered in existing criticality assessments.
Different LCA methods based on monetization of environmental impacts are available. Therefore, relevant monetization methods, namely Ecovalue12, Stepwise2006, LIME3, Ecotax, EVR, EPS, the ...Environmental Prices Handbook, Trucost and the MMG-Method were compared quantitatively and qualitatively, yielding results for 18 impact categories. Monetary factors for the same impact category range mostly between two orders of magnitude for the assessed methods, with some exceptions (e.g., mineral resources with five orders of magnitude). Among the qualitative criteria, per capita income, and thus the geographical reference, has the biggest influence on the obtained monetary factors. When the monetization methods were applied to the domestic yearly environmental damages of an average EU citizen, their monetary values ranged between 7941.13 €/capita (Ecotax) and 224.06 €/capita (LIME3). The prioritization of impact categories varies: Stepwise and Ecovalue assign over 50% of the per capita damages to climate change, while EPS and LIME3 assign around 50% to mineral and fossil resource use. Choices regarding the geographical reference, the Areas of Protection included, cost perspectives and the approach to discounting strongly affect the magnitude of the monetary factors. Therefore, practitioners should choose monetization methods with care and potentially apply varying methods to assess the robustness of their results.
Mining is environmentally disruptive which requires tons of earth materials to be removed and causes modification in original land cover. The processing of materials also requires huge amount of ...energy. In this study, we calculated the Ecological Footprint (EF) of built-up and carbon absorption land for global mining activities with a dataset provided by Werner and colleagues. We first corrected the yield factor and equivalence factor of built-up land. The life cycle inventory to calculate the EF of carbon absorption land was obtained from literatures. According to the findings, tailings storage facility, waste rock dump and riverine tailings disposal had higher EF of built-up land. EF of carbon absorption land was significantly huge, and underground mines had generally higher values than surface mines whereas surface mines had higher EF of built-up land. We also discussed some mechanisms regarding how to reduce the EF of carbon absorption land.
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Purpose
Assessing the potential impacts (characterization) of mineral resource use in life cycle impact assessment (LCIA) has long been debated. One of the most crucial challenges in the ...characterization models for mineral resource use is the consideration of the changing demand and availability of in-use stocks in the future, which is relevant to the global population and economy growth as well as the increasing low-carbon technologies. We propose an extended characterization model to assess the potential impacts for arbitrary time horizons, considering future demand changes and the availability of in-use stock: temporally explicit abiotic depletion potential (TADP).
Methods
The TADP was developed based on abiotic depletion potential (ADP), which is a widely used characterization model for mineral resource use. While the ADP assesses the potential impacts of mineral resource use based on a natural stock estimate and the current extraction rate, the TADP adopts an average extraction rate for arbitrary time horizons. The average extraction rate was estimated using material flow analysis considering future demand changes and recycling under the five shared socioeconomic pathways (SSPs). TADPs were calculated for six common metals: aluminum, copper, iron, lead, nickel, and zinc.
Results and discussion
As a result of calculating TADPs for the term by 2050 (TADP
2050
), compared to iron, all other metals showed larger values of characterization factors for all SSPs than the original ADPs. The TADP
2050
of copper exhibited the largest difference with ADP among the six metals (approximately 1.9 times), which is mainly attributed to future demand growth. On the other hand, for the longer time perspective, the TADP
2100
of lead and zinc exhibited larger differences with ADP than copper (approximately 2.8 times for zinc), which is mainly due to a relatively shorter lifetime for lead and a lower recycling rate for zinc. This suggests that the relative significance of the characterization factors of metals varies depending on the temporal perspective.
Conclusions
With the proposed characterization model, the potential impacts of mineral resource use can be assessed reflecting future situations for the selected time horizons. The results demonstrate that the consideration of future situations greatly influences the relative significance of the potential impacts of using different mineral resources in the results of LCIA studies. By expanding the coverage of mineral resources and future scenario analysis to other relevant factors, the TADP model can improve the robustness of the assessment and further support decision-making towards sustainable resource management.
Purpose
Guidance is needed on best-suited indicators to quantify and monitor the man-made impacts on human health, biodiversity and resources. Therefore, the UNEP-SETAC Life Cycle Initiative ...initiated a global consensus process to agree on an updated overall life cycle impact assessment (LCIA) framework and to recommend a non-comprehensive list of environmental indicators and LCIA characterization factors for (1) climate change, (2) fine particulate matter impacts on human health, (3) water consumption impacts (both scarcity and human health) and 4) land use impacts on biodiversity.
Methods
The consensus building process involved more than 100 world-leading scientists in task forces via multiple workshops. Results were consolidated during a 1-week Pellston Workshop™ in January 2016 leading to the following recommendations.
Results and discussion
LCIA framework: The updated LCIA framework now distinguishes between intrinsic, instrumental and cultural values, with disability-adjusted life years (DALY) to characterize damages on human health and with measures of vulnerability included to assess biodiversity loss. Climate change impacts: Two complementary climate change impact categories are recommended: (a) The global warming potential 100 years (GWP 100) represents shorter term impacts associated with rate of change and adaptation capacity, and (b) the global temperature change potential 100 years (GTP 100) characterizes the century-scale long term impacts, both including climate-carbon cycle feedbacks for all climate forcers. Fine particulate matter (PM
2.5
) health impacts: Recommended characterization factors (CFs) for primary and secondary (interim) PM
2.5
are established, distinguishing between indoor, urban and rural archetypes. Water consumption impacts: CFs are recommended, preferably on monthly and watershed levels, for two categories: (a) The water scarcity indicator “AWARE” characterizes the potential to deprive human and ecosystems users and quantifies the relative Available WAter REmaining per area once the demand of humans and aquatic ecosystems has been met, and (b) the impact of water consumption on human health assesses the DALYs from malnutrition caused by lack of water for irrigated food production. Land use impacts: CFs representing global potential species loss from land use are proposed as interim recommendation suitable to assess biodiversity loss due to land use and land use change in LCA hotspot analyses.
Conclusions
The recommended environmental indicators may be used to support the UN Sustainable Development Goals in order to quantify and monitor progress towards sustainable production and consumption. These indicators will be periodically updated, establishing a process for their stewardship.
Information disclosure associated with carbon dioxide emissions of goods or services may be useful for stimulating consumers to make choices to reduce carbon dioxide emissions. The scope of this ...study was to analyze the potential impact of information disclosure on consumer choices of daily shopping method through an internet survey of Japanese residents (2630 subjects). Japanese consumers were shown to have a preference for low carbon dioxide emissions in their choice of daily shopping method. Awareness of responsibility and intention to act were identified as crucial influences on consumer willingness to reduce carbon dioxide. Supporting information such as comparative presentation of the impacts of well-known everyday carbon dioxide reducing activities effectively made consumers more receptive and sensitive to the meanings and consequences of their choices. The provision of quantitative information on the carbon dioxide emissions associated with different shopping methods may prompt consumers to alter their current choices by comparing the benefits of carbon dioxide reductions and time savings with their preferences for certain shopping methods.
•Japanese consumers favor choices in daily shopping that minimize CO2 emissions.•Awareness of responsibility and intention to act influence consumer CO2 reductions.•Familiarity with reducing CO2 promotes consumers' understanding of its importance.•Consumers will shop more from home if CO2 reduction information is more available.
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