Review of methods addressing freshwater use in life cycle inventory and impact assessment

Purpose: In recent years, several methods have been developed which propose different freshwater use inventory schemes and impact assessment characterization models considering various cause-effect chain relationships. This work reviewed a multitude of methods and indicators for freshwater use potentially applicable in life cycle assessment (LCA). This review is used as a basis to identify the key elements to build a scientific consensus for operational characterization methods for LCA. Methods: This evaluation builds on the criteria and procedure developed within the International Reference Life Cycle Data System Handbook and has been adapted for the purpose of this project. It therefore includes (1) description of relevant cause-effect chains, (2) definition of criteria to evaluate the existing methods, (3) development of sub-criteria specific to freshwater use, and (4) description and review of existing methods addressing freshwater in LCA. Results and discussion: No single method is available which comprehensively describes all potential impacts derived from freshwater use. However, this review highlights several key findings to design a characterization method encompassing all the impact pathways of the assessment of freshwater use and consumption in life cycle assessment framework as the following: (1) in most of databases and methods, consistent freshwater balances are not reported either because output is not considered or because polluted freshwater is recalculated based on a critical dilution approach; (2) at the midpoint level, most methods are related to water scarcity index and correspond to the methodological choice of an indicator simplified in terms of the number of parameters (scarcity) and freshwater uses (freshwater consumption or freshwater withdrawal) considered. More comprehensive scarcity indices distinguish different freshwater types and functionalities. (3) At the endpoint level, several methods already exist which report results in units compatible with traditional human health and ecosystem quality damage and cover various cause-effect chains, e.g., the decrease of terrestrial biodiversity due to freshwater consumption. (4) Midpoint and endpoint indicators have various levels of spatial differentiation, i.e., generic factors with no differentiation at all, or country, watershed, and grid cell differentiation. Conclusions: Existing databases should be (1) completed with input and output freshwater flow differentiated according to water types based on its origin (surface water, groundwater, and precipitation water stored as soil moisture), (2) regionalized, and (3) if possible, characterized with a set of quality parameters. The assessment of impacts related to freshwater use is possible by assembling methods in a comprehensive methodology to characterize each use adequatel

Integration of environment and nutrition in life cycle assessment of food items: opportunities and challenges

This report is the outcome of a consensus-building project to agree on best practices for environmental and nutritional Life Cycle Assessment (nLCA) methodology, and identify future research needs. The project involved 30 nutritional and environmental LCA researchers from 18 countries. It focused on the assessment of food items (as opposed to meals or diets).Best practice recommendations were developed to address the intended purpose of an LCA study and related modeling approach, choice of an appropriate functional unit, assessment of nutritional value, and reporting nLCA results. An nLCA study should report the quantities of as many essential nutrients as possible and aim to provide information on the nutritional quality and/or health impacts in addition to nutrient quantities. Outstanding issues requiring further research attention include: defining a minimum number of nutrients to be considered in an nLCA study; treatment of nutrients to limit; use of nutrient indexes; further development of Impact Assessment methods; representation of nutritional changes that may occur during subsequent distribution and food preparation in cradle-to-gate nLCA studies; and communication of data uncertainty and variability. More data are required for different regions (particularly developing countries); for the processing, distribution, retail, and consumption life cycle stages; and for food loss and waste. Finally, there is a need to extend nLCA methodology for the assessment of meals and diets, to consider further how to account for the multi-functionality of food in a sustainability framework, and to set nLCA studies within the context of environmental limits.These results provide a robust basis for improving nLCA methodology and applying it to identify solutions that minimize the trade-offs between nourishing populations and safeguarding the environment

Mainstreaming life cycle thinking through a consistent approach to footprints

Over recent years, footprints have emerged as an important means of reporting environmental performance. Some individual footprints have become quite sophisticated in their calculation procedures. However, as an overallclass of environmental metrics they have been poorly defined, having a variety of conceptual foundations and an unclear relationship to LCA. The variety and sometimes contradictory approaches to quantification have also led to confusing and contradictory messages in the marketplace which have undermined their acceptance by industry and governments.In response, a task force operating under the auspices of the UNEP/SETAC Life Cycle Initiative project on environmental Life Cycle Impact Assessment has been working to develop generic guidance for developers of footprint metrics. The initial work involved forming a consensual position on the difference between footprints and existing LCA impact category indicators. In short, footprints are deemed to have a primary orientation toward society and nontechnical stakeholders and report only on selected topics of concern. On the other hand, LCA impact category indicators have a primary orientation toward technical stakeholders and report in relation to a larger framework designed for comprehensive evaluation of environmental performance and trade-offs. The task force has also developed a universal footprint definition. In parallel to Area of Protection, we introduce Area of Concern. In the same way that LCA uses impact category indicators to assess impacts that follow a common cause-effect pathway toward Areas of rotection, ootprint metrics address Areas of Concern. The critical difference is that Areas of Concern are defined by the interests of stakeholders in society rather than the LCA community. In addition, Areas of Concern are stand-alone and not part of a framework intended for comprehensive environmental performance assessment. Accordingly, footprints are universally defined as metrics used to report life cycle assessment results addressing an Area of Concern

Global guidance on environmental life cycle impact assessment indicators: Progress and case study

International audiencePurpose: The life cycle impact assessment (LCIA) guidance flagship project of the United Nations Environment Programme (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative aims at providing global guidance and building scientific consensus on environmental LCIA indicators. This paper presents the progress made since 2013, preliminary results obtained for each impact category and the description of a rice life cycle assessment (LCA) case study designed to test and compare LCIA indicators. Methods: The effort has been focused in a first stage on impacts of global warming, fine particulate matter emissions, water use and land use, plus cross-cutting issues and LCA-based footprints. The paper reports the process and progress and specific results obtained in the different task forces (TFs). Additionally, a rice LCA case study common to all TF has been developed. Three distinctly different scenarios of producing and cooking rice have been defined and underlined with life cycle inventory data. These LCAs help testing impact category indicators which are being developed and/or selected in the harmonisation process. The rice LCA case study further helps to ensure the practicality of the finally recommended impact category indicators. Results and discussion: The global warming TF concludes that analysts should explore the sensitivity of LCA results to metrics other than GWP. The particulate matter TF attained initial guidance of how to include health effects from PM2.5 exposures consistently into LCIA. The biodiversity impacts of land use TF suggests to consider complementary metrics besides species richness for assessing biodiversity loss. The water use TF is evaluating two stress-based metrics, AWaRe and an alternative indicator by a stakeholder consultation. The cross-cutting issues TF agreed upon maintaining disability-adjusted life years (DALY) as endpoint unit for the safeguard subject 'human health'. The footprint TF defined main attributes that should characterise all footprint indicators. 'Rice cultivation' and 'cooking' stages of the rice LCA case study contribute most to the environmental impacts assessed. Conclusions: The results of the TF will be documented in white papers and some published in scientific journals. These white papers represent the input for the Pellston workshop', taking place in Valencia, Spain, from 24 to 29 January 2016, where best practice, harmonised LCIA indicators and an update on the general LCIA framework will be discussed and agreed on. With the diversity in results and the multi-tier supply chains, the rice LCA case study is well suited to test candidate recommended indicators and to ensure their applicability in common LCA case studies

Quantifying Earth system interactions for sustainable food production via expert elicitation

Several safe boundaries of critical Earth system processes have already been crossed due to human perturbations; not accounting for their interactions may further narrow the safe operating space for humanity. Using expert knowledge elicitation, we explored interactions among seven variables representing Earth system processes relevant to food production, identifying many interactions little explored in Earth system literature. We found that green water and land system change affect other Earth system processes strongly, while land, freshwater and ocean components of biosphere integrity are the most impacted by other Earth system processes, most notably blue water and biogeochemical flows. We also mapped a complex network of mechanisms mediating these interactions and created a future research prioritization scheme based on interaction strengths and existing knowledge gaps. Our study improves the understanding of Earth system interactions, with sustainability implications including improved Earth system modelling and more explicit biophysical limits for future food production

Potential impact of dietary choices on phosphorus recycling and global phosphorus footprints: the case of the average Australian city

Changes in human diets, population increase, changes in farming practices, and globalized food chains have led to dramatic increases in the demand for phosphorus fertilizers. Long-term food security and water quality are however threatened by such increased phosphorus consumption because the world’s main source, phosphate rock, is an increasingly scarce resource. At the same time losses of phosphorus from farms and cities have caused widespread water pollution. As one of the major factors contributing to increased phosphorus demand, dietary choices can play a key role in changing our resource consumption pathway. Importantly, the effects of dietary choices on phosphorus management are two-fold: First, dietary choices affects a person or region’s ‘phosphorus footprint’ – the magnitude of mined phosphate required to meet food demand. Second, dietary choices affect the magnitude of phosphorus content in human excreta, and hence the recycling- and pollution-potential of phosphorus in sanitation systems. When considering options and impacts of interventions at the city scale (e.g. potential for recycling), dietary changes may be undervalued as a solution towards phosphorus sustainability. In an average Australian city for example, a vegetable-based diet could marginally increase phosphorus in human excreta (8% increase). However such a shift could simultaneously dramatically decrease the mined phosphate required to meet the city resident’s annual food demand by 72%. Taking a multi-scalar perspective is therefore key to fully exploring dietary choices as one of the tools for sustainable phosphorus management

Mapping phosphorus hotspots in Sydney’s organic wastes: a spatially-explicit inventory to facilitate urban phosphorus recycling

Phosphorus is an essential element for food production whose main global sources are becoming scarce and expensive. Furthermore, losses of phosphorus throughout the food production chain can also cause serious aquatic pollution. Recycling urban organic waste resources high in phosphorus could simultaneously address scarcity concerns for agricultural producers who rely on phosphorus fertilisers, and waste managers seeking to divert waste from landfills to decrease environmental burdens. Recycling phosphorus back to agricultural lands however requires careful logistical planning to maximize benefits and minimize costs, including processing and transportation. The first step towards such analyses is quantifying recycling potential in a spatially explicit way. Here we present such inventories and scenarios for the Greater Sydney Basin’s recyclable phosphorus supply and agricultural demand. In 2011, there was 15 times more phosphorus available in organic waste than agricultural demand for phosphorus in Sydney. Hypothetically, if future city residents shifted to a plant-based diet, eliminated edible food waste, and removed animal production in the Greater Sydney Basin, available phosphorus supply would decrease to 7.25 kt of phosphorus per year, even when accounting for population growth by 2031, and demand would also decrease to 0.40 kt of phosphorus per year. Creating a circular phosphorus economy for Sydney, in all scenarios considered, would require effective recycling strategies which include transport outside of the Greater Sydney Basin. These spatially explicit scenarios can be used as a tool to facilitate stakeholders engagement to identify opportunities and barriers for appropriate organic waste recycling strategies

Greenhouse gas implications of peri-urban land use change in a developed city under four future climate scenarios

Present decisions about urbanization of peri-urban (PU) areas may contribute to the capacity of cities to mitigate future climate change. Comprehensive mitigative responses to PU development should require integration of urban form and food production to realise potential trade-offs. Despite this, few studies examine greenhouse gas (GHG) implications of future urban development combined with impacts on PU food production. In this paper, four future scenarios, at 2050 and 2100 time horizons, were developed to evaluate the potential GHG emissions implications of feeding and housing a growing urban population in Sydney, Australia. The scenarios were thematically downscaled from the four relative concentration pathways. Central to the scenarios were differences in population, technology, energy, housing form, transportation, temperature, food production and land use change (LUC). A life cycle assessment approach was used within the scenarios to evaluate differences in GHG impacts. Differences in GHG emissions between scenarios at the 2100 time horizon, per area of PU land transformed, approximated 0.7 Mt CO-e per year. Per additional resident this equated to 0.7 to 6.1 t CO-e per year. Indirect LUC has the potential to be significant. Interventions such as carbon capture and storage technology, renewables and urban form markedly reduced emissions. However, incorporating cross-sectoral energy saving measures within urban planning at the regional scale requires a paradigmatic shift