Life cycle assessment (LCA) is a commonly used tool to quantify life cycle environmental footprints of products. Uncertainty in LCA modeling, particularly from uncertainty in production practices (represented through input parameter arguments), can lead to incorrect conclusions and hamper decision‐making. Characterization of uncertainty through stochastic means and sensitivity analysis is utilized in a small fraction of LCA case studies, and the majority of studies default to scenario analysis due to its lower barrier to implementation and its results are easier to interpret. In this article, we introduce a sensitivity metric, relative sensitivity value (RSV), which allows LCA practitioners to gauge the relative influence of production practices on life cycle impacts in multiple phases and impact categories. Relative sensitivity value bridges the gap between scenario analysis and global sensitivity analysis, and it allows an LCA practitioner to provide an easy‐to‐interpret metric for quantifying the degree to which incremental changes in production practices influences the life cycle environmental footprint. We present the methodology used to calculate RSV and provide programming code, which can be readily used by an LCA practitioner to calculate RSV for their LCA model. We demonstrate the usage of RSV through a livestock husbandry LCA case study, in which we show how RSV results may be presented and interpreted, and how conclusions regarding production practices may be drawn. Integr Environ Assess Manag 2023;19:547–555. © 2022 SETAC

Sheep sector in Canada is growing, and producers have ranked their desire to estimate the environmental performance of sheep farming (for benchmarking and marketability) high. Life cycle assessment (LCA) studies on the Canadian sheep sector are underrepresented, however, and record on feeding options and pasture management on sheep farms is difficult to find. This study aims to address this knowledge gap by conducting a cradle-to-gate LCA on sheep production using Ontario-specific primary data. Life cycle implications of Ontario’s sheep meat production in the categories of global warming (GW), non-renewable energy demand (ED), and water depletion (WD) are estimated by considering the impacts of livestock emissions, feed production, manure management, and farming infrastructure/operations up to the point where the animal leaves the farm for slaughter (i.e., cradle-to-farmgate system boundary). Data on sheep farming practices from 23 farms in Ontario is gathered (primarily through surveys), parametrized, and inputted into the LCA model to estimate Ontario-specific impacts. Allocation of impacts to sheep meat is done through protein mass allocation (PMA), and impact scores are normalized using a functional unit of kilogram liveweight (kg LW). The LCA model code is made available under General Public License (GPL) for further application and improvement. Life cycle impacts per kg LW meat for over 90

Life cycle assessment (LCA) is increasingly being used as a tool to estimate environmental impacts in the sheep sector. Policymakers have been keener on developing policies and recommending best management practices from a life cycle perspective. This paper reviews the key LCA studies of the sheep sector within the last fifteen years to assess the state of the art of the environmental impacts of the sheep supply chain. Peer-reviewed LCAs as well as global, organizational efforts on the subject have also been reviewed and discussed. Discussions are categorized by products, hotspots, methodologies and system boundaries, and impacts of interest. The vast majority of studies have utilized a "cradle-to-farmgate" system boundary, where impacts associated with production of major farm inputs, management/applications of inputs and direct emissions from livestock are included. The sole focus of the majority of studies in terms of the category of impact has been climate change, quantified through greenhouse gas (GHG) emissions. The impact results are difficult to generalize due to wide discrepancies in farming practices, production efficiencies, product allocation and emission modeling methods. The GHG emissions, however, associated with sheep meat, milk and wool fall in the range of 3.5-25 kg CO2-eq/kg live weight, 2-5 kg CO2-eq/kg fat and protein corrected milk (FPCM), and 20-60 kg CO2-eq/kg greasy wool, respectively. The overwhelming consensus is that the single largest contributor to GHG emissions is direct methanic emission from livestock, generally contributing to 50%-75% of overall GHG emissions. More research needs to be conducted on determining impacts of "post-farm" activities such as processing of sheep products before it reaches the consumers, inclusion of the benefits of carbon sequestration, and consideration of environmental impacts other than climate change. (C) 2021 Elsevier Ltd. All rights reserved.

A comparative cradle-to-grave life cycle assessment (LCA) of a low-impact-development (LID) parking lot test-site is performed to quantify the environmental costs of the manufacturing, construction, transportation, operation, maintenance and decommissioning of three bioretention cells and three permeable pavement systems (PPS) located in Mississauga, Ontario, as well as a hypothetical stormwater management pond. The LIDs' influent and effluent water quality and volume data is used to quantify the environmental benefits offered by the LIDs. Ecoinvent v3 LCA database is utilized to create an inventory of the materials and energy used during the life cycle of the LIDs. Using TRACI 2.1 impact assessment method, an LCA is conducted to simulate impacts on ten midpoint categories using a functional unit of “1 m2 of impervious area treated”. It has been found that manufacturing of raw materials has the largest impact (∼50%) on ozone depletion, global warming, smog potential, acidification, carcinogenic emissions, respiratory effects and fossil fuel depletion. The LIDs offer a significant avoidance of eutrophication potential, non-carcinogenic emissions and ecotoxicity, which are all mostly associated with the water quality benefits offered by the LIDs. The bioretention impacts are ∼90% lower than the PPS′ on a “per 1 m2 of impervious area treated” basis due to its larger impervious area treatment relative to its size compared to the PPS. The benefits offered by bioretention are significantly higher on “per 1 m2 LID area” basis (∼12x), but comparable on “per 1 m2 impervious area treated” basis. The impacts normalized by per-capita emissions in Canada in the year 2005 show that the negative impacts of the LIDs are insignificant compared to the benefits they provide. A comparison of the LIDs to a traditional pipe-and-pond infrastructure of an equivalent treatment capacity reveals that the cradle-to-grave impacts of LIDs are ∼20% lower compared to the detention pond's, and the benefits accrued by the LIDs are ∼300% higher compared to the detention pond, making a strong case for the selection of LIDs over traditional stormwater management practices.