Agent-based modeling and simulation for the circular economy: Lessons learned and path forward

Circular economy aims at decoupling human activities from resource use and creating wealth. However, many have questioned the link between increased circularity and sustainability, resulting in several methodological approaches being developed to answer that question. This article analyzes and discusses the insights gained from applying agent-based modeling and simulation to study the techno-economic and social conditions promoting circularity and sustainability. This article analyzes the benefits and limitations of this technology and discusses future methodology developments within the circular economy context. Moreover, six limits of the circular economy concept are used to interpret insights from the literature: thermodynamic limits, system boundary limits, limits posed by the physical scale of the economy, limits posed by path dependencies and lock-in, limits of governance and management, and limits of social and cultural definitions. Promising research avenues are to use this methodology with machine learning, industrial ecology methods, and detailed geographic information.     

Renewable Energy and Carbon Management in the Cradle‐to‐Cradle Certification: Limitations and Opportunities

As part of the Cradle to Cradle^® (C2C) certification program, the C2C certification criterion, Renewable Energy and Carbon Management (RE&CM), focuses on use of electricity from renewable energy (RE) and direct greenhouse gas offsets in the manufacturing stage and, to a limited extent, on the cradle to gate only at the highest level of certification. The aim of this study is to provide decision makers with a quantified overview of possible limitations of that C2C certification requirement and potential gains by introducing a full life cycle assessment (LCA) perspective to the scheme. Scenario analysis was used to perform an LCA of an aluminum can system representing different levels of the C2C certification criterion, RE&CM, considering different strategies to achieve 100% RE in the manufacturing stage. The adoption of a broader life cycle RE perspective was considered through the implementation of electricity from renewable sources from cradle to grave. Our results show that compliance with the current RE&CM certification framework offers limited benefits, that is, significant reduction for climate change, but negligible reductions for other environmental impacts (e.g., particulate matter and acidification). However, increasing the share of RE in the primary aluminum production from a full life cycle perspective can greatly increase the environmental benefits brought up by the C2C certification not only for climate change, but also for the broader range of impact categories. In our striving toward environmental sustainability, which often cannot be approximated by climate‐change impacts alone, we therefore recommend decision makers in industries to combine the C2C certification with LCA when they define strategies for the selection of RE and raw materials suppliers.     

Escaping from prison: an economic reassessment of Rutland Water

Recently in the water industry interest has been growing in solutions to widening demand-supply gaps. These include demand-management elements. The paper examines the 1970 decision by Parliament to build Rutland Water and concludes that, despite over-predictions of water demands, the very few hard facts then available concerning water economy measures would probably not have prevented the reservoir being authorised, had they been taken into account. By 1981, however, dramatic reductions in expected population and per capita public water supply growth had occurred, with much more evidence available concerning the scope of demand-management. It is suggested a similar decision on economic grounds would probably have been a negative one.     

Locomotor energetics and hominid evolution

The presence of a bipedal gait in fossil apes is now recognized as the earliest paleontological evidence of the beginnings of the human lineage. Thus, the search for the selective pressure that led to the adoption of bipedal posture and gait is the search for the origins of the human adaptation. One of the most popular candidates for the origin of erect posture is its purported energetic advantage.^1–4 This argument is reevaluated in light of data on the energetic cost of locomotion in mammals and, particularly, data on the effect of bipedalism on cost. I go on to discuss what morphological traces we might expect to see of changes in the locomotor economy of our ancestors once bipedalism became established.     

Quantity,Components, and Value of Waste Materials Landfilled in the United States

The current system of production and consumption needs end‐of‐life disposal to function, but the linkage between upstream production‐consumption with the downstream landfill as terminus is, at best, a tenuous, one‐way relationship, suggesting a partial system failure. A starting point to fix this link is to confront, systematically, the messy “black box” that is mixed waste landfilling, interrogate its contents locally, and determine a baseline that can be used to scale up results. Here, we develop a detailed model characterizing landfilled municipal solid waste (MSW) in the United States across the dimensions of material quantity, quality, location, and time. The model triangulates measurements spanning 1,161 landfills (representing up to 95% of landfilled MSW) and 15,169 solid waste samples collected and analyzed at 222 sites across the United States. We confirm that landfilled quantities of paper (63 million megagrams [Mg]), food waste (35 million Mg), plastic (32 million Mg, textiles (10 million Mg), and electronic waste (3.5 million Mg) are far larger than computed by previous top‐down U.S. government estimates. We estimate the cost of MSW landfill disposal in 2015 (10.7 billion U.S. dollars [USD]) and gross lost commodity value of recyclable material (1.4 billion USD). Further, we estimate landfill methane emissions to be up to 14% greater (mass basis) than the 2015 U.S. inventory. By principally relying on measurements of waste quantity and type that are recorded annually, the model can inform more effective, targeted interventions to divert waste materials from landfill disposal, improve local, regional, and national emission estimates, enhance dissipative loss estimates in material flow analyses, and illuminate the dynamics linking material, energy, and economic dimensions to production, consumption, and disposal cycles.     

Efforts for a Circular Economy in China: A Comprehensive Review of Policies

Circular economy concepts, practices, and policies are increasingly drawing attention as important means for the pursuit of sustainable development. This article uses a conceptual framework to catalogue and investigate policy efforts for the circular economy in China. Based on the framework, policy prototypes and specific examples are identified: resource‐oriented, production‐oriented, waste, and use‐oriented and life cycle policies. A comprehensive review of 280 related policies shows that China has a long history of resource‐oriented policies and implemented production‐oriented policies very quickly after the year 2000. China's policies toward the circular economy became more comprehensive through time, with a broad engagement of government agencies, an extensive and progressive coverage of recycling opportunities, production initiatives across multiple scales, and use of different policy instruments. The continuous progress has been driven by proactive state actors and their learning from the international society. The current policy framework, however, is concerned more with the means rather than the ends of the circular economy, and relies too much on direct subsidies and other financial incentives. Policy making can be improved by more explicit consideration of the whole production life cycle and use of market‐based policy design.     

中国城市生态与经济社会协同性评估

为认识城市经济社会和生态的协同特征,本研究基于城市人均绿地面积、人均GDP和人均期望寿命等构建城市生态与经济社会功能协同性指标评价体系,建立城市生态与经济社会协同性指数评价方法。通过比较中国35个典型城市的协同性指数与功能综合得分,分析了中国城市协同性特征,并按照城市规模、行政区类型分析城市协同性差异和城市功能综合得分差异,对协同水平进行分类。结果表明: 2016年,中国35个城市生态与经济社会平均协同性指数为28.79,协同性最强城市的协同性指数为3.83,最弱的城市为63.04,表明中国城市协同性不高且城市间差异较大。协同性指数、城市经济功能、社会功能与城市人口规模、经济规模呈显著正相关。不同人口规模、经济规模、不同行政职能城市之间协同性指数差异具有显著性。中国城市化总体仍处于功能失衡的发展阶段,城市发展有利于各城市功能性提高但并未有效提升协同性,生态功能的高低显著影响城市协同性,城市生态功能不高是当前中国城市协同性高低的主要制约因素。     

Opposing effects of elevated CO2 and N deposition on Lymantria monacha larvae feeding on spruce trees

The effects of elevated atmospheric CO₂ and increased wet N deposition on leaf quality and insect herbivory were evaluated in nine model ecosystems composed of 7-year-old spruce trees (Picea abies) and three understorey species established on natural forest soil. Each model ecosystem was grown in a simulated montane climate, and was exposed to one of three CO₂ concentrations (280, 420, and 560 μl l⁻¹), and to one of three levels of N deposition (0, 30, and 90 kg ha⁻¹ year⁻¹) for 3 years. In the 3rd year of the experiment second to third instars of the nun moth (Lymantria monacha) were allowed to feed directly on current-year needles of top canopy branches of each tree for 12 days. Specific leaf area (SLA), water content, and N concentration decreased in needles exposed to elevated CO₂, whereas the concentrations of starch, condensed tannins, and total phenolics increased. Increased N deposition had no significant effect on SLA, and water content, but the concentrations of starch, condensed tannins, and total phenolics decreased, and sugar and N concentrations increased. Despite higher relative consumption rates (RCRs) larvae consumed 33% less N per unit larval biomass and per day at the two high CO₂ treatments, compared to those feeding on 280 μl l⁻¹-needles, but they maintained similar N accumulation rates due to increased N utilization efficiencies (NUE). However, over the 12-day experimental period larvae gained less N overall and reached a 35% lower biomass in the two high-CO₂ treatments compared to those at 280 μl l⁻¹. The effects of increased N deposition on needle quality and insect performance were generally opposite to those of CO₂ enrichment, but were lower in magnitude. We conclude that altered needle quality in response to elevated CO₂ will impair the growth and development of L. monacha larvae. Increasing N deposition may mitigate these effects, which could lead to altered insect herbivore distributions depending on regional patterns of N deposition. Received: 8 June 1998 / Accepted: 27 October 1998     

谈中石器时代

谈中石器时代陈淳（ＤｅｐａｒｔｍｅｎｔｏｆＡｎｆｏｒｏｐｏｌｏｇｙ,ＭｃＧｉｌｉＵｎｉｖｅｒｓｉｔｙ,Ｍｏｎｔｒｅａｌ,Ｃａｎａｄａ）１概念与定义中石器时代一度曾是个众说纷纭的概念,现在则是史前研究中的一个重要对象．它涉及旧石器时代向新石器时代的过渡...     

Mineral resources in the age of climate adaptation and resilience

This article discusses issues on resources availability to achieve climate adaptation and resilience for cities and infrastructures. In the age of climate change, there could be cascading failures through a range of infrastructure breakdowns. Direct and indirect damage costs could exceed what had been estimated in traditional risk assessments. This could be exacerbated through abrupt price peaks in international supply chains of minerals, and through events happening in remote parts of the world that affect extraction and vulnerable industries. The core argument made here is one of feedbacks: climate adaptation has significant resource implications, and how resources are being used will have implications on climate strategies. Industrial Ecology has a role to play assessing those interactions and providing a better grasp of the spatial dimension of material flows, partly to track those flows and align them to specific actors, and partly to address interlinkages across different flows and their stocks (‘the resource nexus’). Methodological novelties are needed to better understand the resource base and the socio‐economic dimension, especially on innovations and transitions that can help to cope with the challenges ahead. Altogether this would enable research to establish an evidence base on sustainable materials to deliver parts of the UN Sustainable Development Goals (SDGs) and to reassess infrastructure assets and the mineral resources in the age of climate adaptation and resilience.