We present a quantitative analysis of global and regional food supply to reveal the flows of calories, protein and the micro-nutrients vitamin A, iron and zinc, from production through to human consumption and other end points. We quantify the extent to which reductions in the amount of human-edible crops fed to animals and, less importantly, reductions in waste, could increase food supply. The current production of crops is sufficient to provide enough food for the projected global population of 9.7 billion in 2050, although very significant changes to the socio-economic conditions of many (ensuring access to the global food supply) and radical changes to the dietary choices of most (replacing most meat and dairy with plant-based alternatives, and greater acceptance of human-edible crops currently fed to animals, especially maize, as directly-consumed human food) would be required. Under all scenarios, the scope for biofuel production is limited. Our analysis finds no nutritional case for feeding human-edible crops to animals, which reduces calorie and protein supplies. If society continues on a 'business-as-usual' dietary trajectory, a 119% increase in edible crops grown will be required by 2050.

This paper examines the US military's impact on climate by analysing the geopolitical ecology of its global logistical supply chains. Our geopolitical ecology framework interrogates the material‐ecological metabolic flows (hydrocarbon‐based fuels, water, sand, concrete) that shape geopolitical and geoeconomic power relations. We argue that to account for the US military as a major climate actor, one must understand the logistical supply chain that makes its acquisition and consumption of hydrocarbon‐based fuels possible. Our paper focuses on the US Defense Logistics Agency – Energy (DLA‐E), a large yet virtually unresearched sub‐agency within the US Department of Defense. The DLA‐E is the primary purchase‐point for hydrocarbon‐based fuels for the US military, as well as a powerful actor in the global oil market. After outlining our geopolitical ecology approach, we detail the scope of the DLA‐E's operations, its supply chain, bureaucratic practices, and the physical infrastructure that facilitates the US military's consumption of hydro‐based carbons on a global scale. We show several “path dependencies” – warfighting paradigms, weapons systems, bureaucratic requirements, and waste – that are put in place by military supply chains and undergird a heavy reliance on carbon‐based fuels by the US military for years to come. The paper, based on comprehensive records of bulk fuel purchases we have gathered from DLA‐E through Freedom of Information Act requests, represents a partial yet robust picture of the geopolitical ecology of American imperialism.

19In order to meet internationally agreed targets for avoiding dangerous 20 anthropogenic climate change, an absolute priority for global society is to rapidly 21 stabilise and then reduce carbon dioxide emissions into the atmosphere. Any entity, 22 be it individual, company, or nation state, is more able to reduce its carbon dioxide 23 (and other greenhouse gas) emissions if these can be quantified and attributed and 24 the effects of interventions estimated. The current state of product and supply chain 25 carbon accounting methods does not consistently meet the standards required to 26 tackle this global challenge. This study therefore aims to identify key methodological 27 practices affecting the accuracy of carbon accounting models and in particular to 28 assess the effects of the system boundaries they employ. Models currently available 29 for estimating carbon emissions are either input-output based (using macro-30 economic analysis), process-based (using specific carbon emissions attributes 31 through the life-cycle of a product, service or event), or a hybrid of the two. Here, a 32 detailed comparison has been made between various input-output and process-33 based models and the results compared with those from a hybrid model that was 34 taken to represent 'best practice' in carbon accounting. Key factors affecting 35 accuracy were found to lie in: the detail of methodological decisions for input-output 36 models, the economic region or regions upon which the model is based, and the 37 quality, disaggregation and, especially for price-volatile products, the temporal 38 alignment of the data. The relative significance of these factors is explored. For 39 copper wire, a system boundary gap analysis was conducted on an industry-leading 40 process-based model (GREET.net) compared with a complete system as described by 41 the best performing input-output model. GREET.net was found to suffer a 60% 42 truncation error. The copper wire example demonstrates the practicality of 43 substituting process-based analysis into input-output based supply chain emissions 44 assessments. 45 46 Key words 47 Carbon accounting; embodied carbon; input-output models; life cycle analysis; 48 process-based analysis 49 50 M

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