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Reducing food losses and waste is crucial to making our food system more efficient and sustainable. This is the first paper that quantifies the environmental impacts of food waste by distinguishing the various stages of the food value chain, 33 food categories that represent the whole food basket in Switzerland, and including food waste treatment. Environmental impacts are expressed in terms of climate change and biodiversity impacts due to water and land use. Climate change impacts of food waste are highest for fresh vegetables, due to the large amounts wasted, while the specific impact per kg is largest for beef. Biodiversity impacts are mainly caused by cocoa and coffee (16% of total) and by beef (12%). Food waste at the end of the food value chain (households and food services) causes almost 60% of the total climate impacts of food waste, because of the large quantities lost at this stage and the higher accumulated impacts per kg of product. The net environmental benefits from food waste treatment are only 5-10% of the impacts from production and supply of the wasted food. Thus, avoiding food waste should be a first-line priority, while optimizing the method of treatment is less relevant.

Background, aim and scope Electricity use or substitution is one of the key parameters with regard to life cycle assessment (LCA) results. At the same time, it is often used as an illustrative example to highlight the modelling differences between decision-oriented and descriptive LCA. Three basically different models exist in life cycle inventory analysis: the attributional, the consequential and the decisional model. This paper proposes criteria that help to classify typical LCA questions regarding real business cases and find the most appropriate life cycle inventory (LCI) model. The framework is applied to a case study of an LCA of electricity use and supply within the international operations of an environmental service company with headquarters in France. Main features Individual decision with comparatively small consequences can be modelled under ceteris paribus (other things being equal) conditions. Decision situations with medium to large potential consequences should be modelled under the conditions of mutatis mutandis (the necessary changes being made). The key question is how to distinguish between small, medium and large consequences. We recommend using the relative economic size to classify objects of investigation and the LCA goals related to them into three groups to which the most appropriate LCI models are assigned. Results and discussion The attributional approach is sensible for environmental reporting and product labelling and declaration where the relative economic size of the object of investigation is small. The decisional approach is sensible for LCAs of product and process development, as well as site and supplier evaluation carried out by private companies in case the relative economic size of the object of investigation is medium. The consequential approach is of relevance for policy support of governments and international organisations as well as for strategic decisions of companies, where the relative economic size of the object of investigation is large. The consequential approach is also sensible in product or service comparisons by companies, if they offer products or services that are in line or help to comply with large-scale government policy measures (like for instance promoting renewable fuels). The French attributional and decisional electricity supply mix causes greenhouse gas emissions of 98 and 225 gCO 2 -eq./kWh, respectively, whereas the European attributional and decisional electricity supply mix causes greenhouse gas emissions of 554 and 473 gCO 2 -eq./kWh, respectively. The volumes of high radioactive waste generated with the French and EU-27 electricity mixes amount to 11 and 3.5 mm 3 /kWh for the attributional mixes as well as 3.8 and 0.034 mm 3 / kWh for the decisional mixes. Conclusions The criterion "relative economic size" helps to better decide on the appropriate LCI model to be applied in specific LCA case studies supporting any kind of decisions. Being quantitative, the "relative economic size" criterion is comparable to the criteria used to delimitate the ...

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