SummaryIt is increasingly recognized that the growing metabolism of society is approaching limitations both with respect to sources for resource inputs and sinks for waste and emission outflows. The circular economy (CE) is a simple, but convincing, strategy, which aims at reducing both input of virgin materials and output of wastes by closing economic and ecological loops of resource flows. This article applies a sociometabolic approach to assess the circularity of global material flows. All societal material flows globally and in the European Union (EU-27) are traced from extraction to disposal and presented for main material groups for 2005. Our estimate shows that while globally roughly 4 gigatonnes per year (Gt/yr) of waste materials are recycled, this flow is of moderate size compared to 62 Gt/yr of processed materials and outputs of 41 Gt/yr. The low degree of circularity has two main reasons: First, 44% of processed materials are used to provide energy and are thus not available for recycling. Second, socioeconomic stocks are still growing at a high rate with net additions to stocks of 17 Gt/yr. Despite having considerably higher end-of-life recycling rates in the EU, the overall degree of circularity is low for similar reasons. Our results indicate that strategies targeting the output side (end of pipe) are limited given present proportions of flows, whereas a shift to renewable energy, a significant reduction of societal stock growth, and decisive eco-design are required to advance toward a CE.

Human-made material stocks accumulating in buildings, infrastructure, and machinery play a crucial but underappreciated role in shaping the use of material and energy resources. Building, maintaining, and in particular operating in-use stocks of materials require raw materials and energy. Material stocks create long-term pathdependencies because of their longevity. Fostering a transition toward environmentally sustainable patterns of resource use requires a more complete understanding of stock-flow relations. Here we show that about half of all materials extracted globally by humans each year are used to build up or renew in-use stocks of materials. Based on a dynamic stock-flow model, we analyze stocks, inflows, and outflows of all materials and their relation to economic growth, energy use, and CO 2 emissions from 1900 to 2010. Over this period, global material stocks increased 23-fold, reaching 792 Pg (±5%) in 2010. Despite efforts to improve recycling rates, continuous stock growth precludes closing material loops; recycling still only contributes 12% of inflows to stocks. Stocks are likely to continue to grow, driven by large infrastructure and building requirements in emerging economies. A convergence of material stocks at the level of industrial countries would lead to a fourfold increase in global stocks, and CO 2 emissions exceeding climate change goals. Reducing expected future increases of material and energy demand and greenhouse gas emissions will require decoupling of services from the stocks and flows of materials through, for example, more intensive utilization of existing stocks, longer service lifetimes, and more efficient design. material flow accounting | socioeconomic metabolism | circular economy | carbon emission intensity | manufactured capital T he growing extraction of natural resources, and the waste and emissions resulting from their use, are directly or indirectly responsible for humanity approaching or even surpassing critical planetary boundaries (1). Both decoupling of resource use from economic development and absolute reductions in the use of certain materials and energy sources are imperative for sustainable development (2). The demand for materials and energy is to a large extent driven by constructing, maintaining, and operating inuse stocks of materials (hereafter "material stocks"), or what economists call manufactured capital (buildings, infrastructure, artifacts). These stocks transform material and energy flows into services, such as shelter or mobility (3, 4). The significance of longlived stocks of infrastructure and buildings for determining and potentially reducing future material and energy use and greenhouse gas emissions is increasingly recognized (5, 6). This study investigates the dynamics of global stocks and flows of materials by using and expanding a material flow accounting (MFA) approach. MFA is used in industrial ecology to study the biophysical domain of society, comprising in-use stocks and the processes and flows that maintain and operate these stocks, ...

SummaryMaterial stocks are an important part of the social metabolism. Owing to long service lifetimes of stocks, they not only shape resource flows during construction, but also during use, maintenance, and at the end of their useful lifetime. This makes them an important topic for sustainable development.In this work, a model of stocks and flows for nonmetallic minerals in residential buildings, roads, and railways in the EU25, from 2004 to 2009 is presented. The changing material composition of the stock is modeled using a typology of 72 residential buildings, four road and two railway types, throughout the EU25. This allows for estimating the amounts of materials in in‐use stocks of residential buildings and transportation networks, as well as input and output flows. We compare the magnitude of material demands for expansion versus those for maintenance of existing stock. Then, recycling potentials are quantitatively explored by comparing the magnitude of estimated input, waste, and recycling flows from 2004 to 2009 and in a business‐as‐usual scenario for 2020. Thereby, we assess the potential impacts of the European Waste Framework Directive, which strives for a significant increase in recycling.We find that in the EU25, consisting of highly industrialized countries, a large share of material inputs are directed at maintaining existing stocks. Proper management of existing transportation networks and residential buildings is therefore crucial for the future size of flows of nonmetallic minerals.

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Summary The concept of a circular economy (CE) is gaining increasing attention from policy makers, industry, and academia. There is a rapidly evolving debate on definitions, limitations, the contribution to a wider sustainability agenda, and a need for indicators to assess the effectiveness of circular economy measures at larger scales. Herein, we present a framework for a comprehensive and economy‐wide biophysical assessment of a CE, utilizing and systematically linking official statistics on resource extraction and use and waste flows in a mass‐balanced approach. This framework builds on the widely applied framework of economy‐wide material flow accounting and expands it by integrating waste flows, recycling, and downcycled materials. We propose a comprehensive set of indicators that measure the scale and circularity of total material and waste flows and their socioeconomic and ecological loop closing. We applied this framework in the context of monitoring efforts for a CE in the European Union (EU28) for the year 2014. We found that 7.4 gigatons (Gt) of materials were processed in the EU and only 0.71 Gt of them were secondary materials. The derived input socioeconomic cycling rate of materials was therefore 9.6%. Further, of the 4.8 Gt of interim output flows, 14.8% were recycled or downcycled. Based on these findings and our first efforts in assessing sensitivity of the framework, a number of improvements are deemed necessary: improved reporting of wastes, explicit modeling of societal in‐use stocks, introduction of criteria for ecological cycling, and disaggregated mass‐based indicators to evaluate environmental impacts of different materials and circularity initiatives.

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Meat is an important food for human nutrition, by especially providing high-quality protein and also some essential micronutrients, in front iron, zinc, and vitamin B. However, a high intake of red and processed meat is associated with an increased risk for diseases, especially type 2 diabetes and colorectal cancer, as several epidemiological studies and meta-analyses have shown. This review summarizes meta-analyses of publications studying the association between red and processed meat intake and type 2 diabetes, cardiovascular diseases, colorectal and other cancers, and all-cause mortality. Various potential mechanisms involved in the increased disease risk are discussed. Furthermore, the beneficial effects of healthy alternatives for meat, like fish, nuts, vegetables and fruits, pulses and legumes, whole grains, and dairy products are reviewed by including selected papers and recent meta-analyses.

A case-control study of the car-free model housing project in Vienna was conducted to evaluate whether people living in this settlement have more 'sustainable lifestyles' than people living in comparable buildings in Vienna. Another aim was to identify the lifestyle characteristics and household activities which significantly influence the environmental impact of the residents of the car-free housing project and a control group. The control group, referred to as the reference settlement, was chosen from a nearby building complex, with similar characteristics, but without the car-free feature. Household consumption patterns were estimated based on interviews in combination with data from the Austrian consumer expenditure survey and the national accounts. The evaluation of household environmental impacts uses emissions estimates from the Austrian national accounting matrices including environmental accounts and data from life-cycle assessments.Households from the car-free settlement have substantially lower environmental impacts in the categories of ground transportation and energy use; their CO 2 emissions of these two categories are less than 50% of those living in the reference settlement. The households in the car-free settlement have somewhat higher emissions in the categories air transport, nutrition, and 'other' consumption, reflecting the higher income per-capita. As a result, the CO 2 emissions are only slightly lower than in the reference settlement, but the emissions intensity is 20% lower. Both household groups have significantly lower environmental impacts than the Austrian average reflecting less car use and cleaner heating energy in Vienna.