Embodied Resource Flows and Product Flows

We develop the absorbing Markov chain (AMC) for describing in detail the network of paths through an industrial system taken by an embodied resource from extraction through intermediate products and, finally, consumer products. We refer to this as a resource‐specific network. This work builds on a recent literature in industrial ecology that uses an AMC to quantify the number of times a resource passes through a recycling sector before ending up in a landfill. Our objective is to incorporate into that analysis an input‐output (IO) table so that the resource paths explicitly take account of the interdependence of sectors through their reliance on intermediate products. This feature makes it possible to track multiple resources simultaneously and consistently and to represent both resources and products in mixed units. Hypothetical scenarios about technological changes and changes in consumer demand are analyzed with an IO model, and model solutions generate the AMC database. A numerical example is provided. We identify the three most critical enhancements to the standard IO model that will be needed for analyzing material cycles: the incorporation of waste‐processing sectors, stock and flow relationships, and international trade. The idea is to implement an AMC after each modeling step for analyses, such as tracking a resource extracted in one region to landfills in other regions and evaluating ways to intensify secondary recovery at key junctures in between.     

Environmental Assessment of Wood‐Based Biofuel Production and Consumption Scenarios in Norway

In Norway, the boreal forest offers a considerable resource base, and emerging technologies may soon make it commercially viable to convert these resources into low‐carbon biofuels. Decision makers are required to make informed decisions about the environmental implications of wood biofuels today that will affect the medium‐ and long‐term development of a wood‐based biofuels industry in Norway. We first assess the national forest‐derived resource base for use in biofuel production. A set of biomass conversion technologies is then chosen and evaluated for scenarios addressing biofuel production and consumption by select industry sectors. We then apply an environmentally extended, mixed‐unit, two‐region input?output model to quantify the global warming mitigation and fossil fuel displacement potentials of two biofuel production and consumption scenarios in Norway up to 2050. We find that a growing resource base, when used to produce advanced biofuels, results in cumulative global warming mitigation potentials of between 58 and 83 megatonnes of carbon dioxide equivalents avoided (Mt‐CO₂‐eq.‐avoided) in Norway, depending on the biofuel scenario. In recent years, however, the domestic pulp and paper industry—due to increasing exposure to international competition, capacity reductions, and increasing production costs—has been in decline. In the face of a declining domestic pulp and paper industry, imported pulp and paper products are required to maintain the demand for these goods and thus the greenhouse gas (GHG) emissions of the exporting region embodied in Norway's pulp and paper imports reduce the systemwide benefit in terms of avoided greenhouse gas emissions by 27%.     

Life cycle sustainability assessment of autonomous heavy‐duty trucks

Connected and automated vehicles (CAVs) are emerging technologies expected to bring important environmental, social, and economic improvements in transportation systems. Given their implications in terms of air quality and sustainable and safer movement of goods, heavy‐duty trucks (HDTs), carrying the majority of U.S. freight, are considered an ideal domain for the application of CAV technology. An input–output (IO) model is developed based on the Eora database—a detailed IO database that consists of national IO tables, covering almost the entire global economy. Using the Eora‐based IO model, this study quantifies and assesses the environmental, economic, and social impacts of automated diesel and battery electric HDTs based on 20 macro‐level indicators. The life cycle sustainability performances of these HDTs are then compared to that of a conventional diesel HDT. The study finds an automated diesel HDT to cause 18% more fatalities than an automated electric HDT. The global warming potential (GWP) of automated diesel HDTs is estimated to be 4.7 thousand metric tons CO₂‐eq. higher than that of automated electric HDTs. The health impact costs resulting from an automated diesel HDT are two times higher than that of an automated electric HDT. Overall, the results also show that automation brings important improvements to the selected sustainability indicators of HDTs such as global warming potential, life cycle cost, GDP, decrease in import, and increase in income. The findings also show that there are significant trade‐offs particularly between mineral and fossil resource losses and environmental gains, which are likely to complicate decision‐making processes regarding the further development and commercialization of the technology.     

Exploring the Global Journey of Nickel with Markov Chain Models

Markov chain (MC) modeling is a versatile tool in policy analysis and has been applied in several forms to analyze resource flows. This article builds on previous discussions of the relationship among absorbing Markov chains (AMCs), material flow analysis (MFA), and input‐output (IO) analysis, and presents a full‐scale application of MC modeling for a particular globally relevant, nonrenewable resource, namely nickel. The MC model presented here is built on comprehensive, recently compiled nickel flow data for 52 geographic regions. Considering all possible cycles of recycling and reuse, nickel extracted in 2005 is estimated to have a technological lifetime of 73 ± 7 years. During its global journey, nickel enters use, for some application somewhere in the world, an average of three times, the largest share of which occurs in China. Nickel entering fabrication in 2005 is estimated to enter use approximately four times. Over time, nickel is lost to the environment and as a tramp element in carbon steel; the final distribution of nickel among these absorbing states is 78% and 22%, respectively. Of all the nickel in ore extracted in 2005, fully 28% will eventually end up in the tailings, slag, and landfills of China. MC results are also combined with geographically specific life cycle inventory data to determine the overall energy invested in nickel during its many cycles of use. MCs provide a powerful tool for tracking resources through the network of global production, use, and waste management, and opportunities for further integration with other modeling efforts are also discussed.     

Environmental Impacts of Capital Formation

The investment in capital goods is a well‐known driver of economic activity, associated resource use, and environmental impact. In national accounting, gross fixed capital formation (GFCF) constitutes a substantial share of the total final demand of goods and services, both in terms of monetary turnover and embodied resources. In this article, we study the structure of GFCF and the environmental impacts associated with it on a global scale, and link it to measures of development. We find that the share of GFCF as part of the total carbon footprint (CF) varies more across countries than GFCF as a share of gross domestic product (GDP). Countries in early phases of development generally tend to invest in resource‐intensive assets, primarily infrastructure and machinery, whereas wealthier countries invest in less resource‐intensive assets, such as computers, software, and services. By performing a structural decomposition analysis, we assess the relative importance of investment structure and input‐output multipliers for the difference in carbon intensity of capital assets, and find that the structure of investments plays a larger role for less‐developed countries than for developed countries. We find a relative decoupling of the CF of GFCF from GDP, but we can neither confirm nor rule out the possibility of an absolute decoupling.     

Effects of Using Heterogeneous Prices on the Allocation of Impacts from Electricity Use: A Mixed‐Unit Input‐Output Approach

Economic input‐output life cycle assessment (IO‐LCA) models allow for quick estimation of economy‐wide greenhouse gas (GHG) emissions associated with goods and services. IO‐LCA models are usually built using economic accounts and differ from most process‐based models in their use of economic transactions, rather than physical flows, as the drivers of supply‐chain GHG emissions. GHG emissions estimates associated with input supply chains are influenced by the price paid by consumers when the relative prices between individual consumers are different. We investigate the significance of the allocation of GHG emissions based on monetary versus physical units by carrying out a case study of the U.S. electricity sector. We create parallel monetary and mixed‐unit IO‐LCA models using the 2007 Benchmark Accounts of the U.S. economy and sector specific prices for different end users of electricity. This approach is well suited for electricity generation because electricity consumption contributes a significant share of emissions for most processes, and the range of prices paid by electricity consumers allows us to explore the effects of price on allocation of emissions. We find that, in general, monetary input‐output models assign fewer emissions per kilowatt to electricity used by industrial sectors than to electricity used by households and service sectors, attributable to the relatively higher prices paid by households and service sectors. This fact introduces a challenging question of what is the best basis for allocating the emissions from electricity generation given the different uses of electricity by consumers and the wide variability of electricity pricing.     

A 2 °C warmer world is not safe for ecosystem services in the European Alps

Limiting the increase in global average temperature to 2 °C is the objective of international efforts aimed at avoiding dangerous climate impacts. However, the regional response of terrestrial ecosystems and the services that they provide under such a scenario are largely unknown. We focus on mountain forests in the European Alps and evaluate how a range of ecosystem services (ES) are projected to be impacted in a 2 °C warmer world, using four novel regional climate scenarios. We employ three complementary forest models to assess a wide range of ES in two climatically contrasting case study regions. Within each climate scenario we evaluate if and when ES will deviate beyond status quo boundaries that are based on current system variability. Our results suggest that the sensitivity of mountain forest ES to a 2 °C warmer world depends heavily on the current climatic conditions of a region, the strong elevation gradients within a region, and the specific ES in question. Our simulations project that large negative impacts will occur at low and intermediate elevations in initially warm‐dry regions, where relatively small climatic shifts result in negative drought‐related impacts on forest ES. In contrast, at higher elevations, and in regions that are initially cool‐wet, forest ES will be comparatively resistant to a 2 °C warmer world. We also found considerable variation in the vulnerability of forest ES to climate change, with some services such as protection against rockfall and avalanches being sensitive to 2 °C global climate change, but other services such as carbon storage being reasonably resistant. Although our results indicate a heterogeneous response of mountain forest ES to climate change, the projected substantial reduction of some forest ES in dry regions suggests that a 2 °C increase in global mean temperature cannot be seen as a universally ‘safe’ boundary for the maintenance of mountain forest ES.     

Closing the TIMES Integrated Assessment Model (TIAM‐FR) Raw Materials Gap with Life Cycle Inventories

Integrated assessment models are in general not constrained by mineral resource supply. In this paper, we introduce a material accounting method as a first step toward addressing the raw materials gap in the TIMES integrated assessment model (TIAM‐FR version). The method consists of attributing process‐based life cycle inventories (LCIs) taken from the ecoinvent 3.3 database to the TIAM‐FR technology processes constituting the global energy system. We demonstrate the method performing a prospective exercise on the electricity‐generating sector in a second shared socioeconomic pathway (SSP2) baseline scenario on the 2010–2100 time horizon. We start by disaggregating the LCIs into three separate life phases (construction, operation, and decommissioning) and coupling them to their respective TIAM‐FR electric outputs (new capacities, electricity production, and end‐of‐life capacities) in order to estimate the annual mineral resource requirements. Prospective uses of fossil fuels and metallic and nonmetallic mineral resources are quantified dynamically at the life phase and regional levels (15 world regions). The construction of hydropower, solar power, and wind power plants generate increasing use of metallic and nonmetallic mineral resources in successive peak and valley periods. However, the use of fossil fuels is much higher than the use of mineral resources all along the horizon. Finally, we evaluate how sensitive the global material use is to the allocation of a share of infrastructure activities to the decommissioning phase. This approach could be extended to other integrated assessment models and possibly other energy sectors.     

The Energy Structure of the Canadian Economy

We developed a model of a national economy in which the phenomena of supply, demand, economic growth, and international trade are represented in terms of energy flows. In examining the structure of the economy, we distinguish between the energy embodied in capital assets used in the production and distribution of energy and that embodied in capital assets and goods that consume energy. Sources used to quantify the energy flows include: end‐use energy data by economic sector; International Energy Agency–style national energy balances, and national input‐output tables. As an example, the Canadian economy for 2008 produced 16.97 exajoules (EJ) of energy, which after net export of 6.16 EJ and other adjustments left a total primary energy consumption of 10.61 EJ. The energy supply and distribution sectors used close to 32% (3.36 EJ) of total primary consumption. Analysis of primary energy consumption shows that 25.14% was embodied in household consumption, 22.85% was consumed directly by households, 7.88% was embodied in government services, and 34.07% was embodied in exports. Of significance to economic growth, 7.14% was embodied in capital in energy demanding sectors, 1.25% in energy consuming personal assets, and 1.52% in supply sector capital. The energy return on energy investment was relatively constant, averaging 5.14 between 1990 and 2008. Capital investments required to decouple the Canadian economy from its dependence on fossil fuels are discerned.     

Regional material flow accounts for China: Examining China's natural resource use at the provincial and national level

Over the last three decades, China has experienced the most dynamic economic development lifting living standards and resulting in fast‐growing use of natural resources. In the past, the focus has been on national MFA accounts which do not do justice to the second largest economy, home to 19% of the world population and having 30% of global material use. In this research, we calculate material extraction for China at the regional level during 1995–2015 using the most recent available statistical data and applying the most up‐to‐date international calculation methods. In particular, we combine a bottom‐up and top‐down approach for constructing the dataset of China's economically used Domestic Extraction (DEU) in an integrated way. This approach also improves the Chinese national material flow accounts and allows us to present a reliable database of DE of materials for China to date. Our new dataset provides the basis for calculating material footprints and environmental impacts of China's regions. The dataset enables us to evaluate regional resource efficiency trends in China. We find that during the past two decades, China's material use has grown strongly from 11.7 billion tonnes in 1995 to 35.4 billion tonnes in 2015. Material use has accelerated between 2000 and 2010 but slowed down between 2010 and 2015 reflecting the economic contraction caused by the Global Financial Crisis which reduced the global demand for China's manufacturing and a reorientation of China's economic policy settings toward quality of growth. Unsurprisingly, different regions play different roles in the supply chain of materials, achieving different economic performances resulting in very diverse material efficiency outcomes. This information is important to allow for a targeted policy approach to increase resource efficiency, reduce environmental impacts of resource use, and grow wellbeing in China with large positive implications for global sustainability. This study provides the basis for the development of relevant resource management policies for different regions in the future.     

The role of forest residues in the accounting for the global warming potential of bioenergy

Bioenergy makes up a significant portion of the global primary energy pie, and its production from modernized technology is foreseen to substantially increase. The climate neutrality of biogenic CO₂ emissions from bioenergy grown from sustainably managed biomass resource pools has recently been questioned. The temporary change caused in atmospheric CO₂ concentration from biogenic carbon fluxes was found to be largely dependent on the length of biomass rotation period. In this work, we also show the importance of accounting for the unutilized biomass that is left to decompose in the resource pool and how the characterization factor for the climate impact of biogenic CO₂ emissions changes whether residues are removed for bioenergy or not. With the case of Norwegian Spruce biomass grown in Norway, we found that significantly more biogenic CO₂ emissions should be accounted towards contributing to global warming potential when residues are left in the forest. For a 100‐year time horizon, the global warming potential bio factors suggest that between 44 and 62% of carbon‐flux, neutral biogenic CO₂ emissions at the energy conversion plant should be attributed to causing equivalent climate change potential as fossil‐based CO₂ emissions. For a given forest residue extraction scenario, the same factor should be applied to the combustion of any combination of stem and forest residues. Life cycle analysis practitioners should take these impacts into account and similar region/species specific factors should be developed.     

北京市水足迹及农业用水结构变化特征

运用水足迹的理论和方法计算评价了1990—2005年北京市水足迹及水资源利用的可持续性,在此基础上进一步分析了北京市农业用水结构的变化特征。结果表明:(1)北京市水足迹从1990年的81.5亿m3上升至2005年的168.6亿m3,人均水足迹由750.1m3上升为1096.0m3;(2)北京市水资源匮乏度不断升高,1995年以来水资源自给率呈下降趋势,与之相对应的水资源依赖度越来越高;(3)农业部门用水量在本地用水量中的比例平均每年为55.1%,虚拟水净输入量在虚拟水净输入总量中的比例平均每年达到89.1%;(4)高耗水型作物产品生产用水比例升高加大了农业用水压力,动物产品生产用水量呈增加趋势,2001—2005年动物产品生产引入的虚拟水占到其虚拟水总量的81.3%。北京市水资源利用呈不可持续状态,通过农业系统内部结构的优化调整,实现农业部门水资源的高效利用是缓解北京市水资源紧缺问题的关键。     

Resource Use in Small Island States

Iceland and Trinidad and Tobago are small open, high‐income island economies with very specific resource‐use patterns. This article presents a material flow analysis (MFA) for the two countries covering a time period of nearly five decades. Both countries have a narrow domestic resource base, their economy being largely based on the exploitation of one or two key resources for export production. In the case of Trinidad and Tobago, the physical economy is dominated by oil and natural gas extraction and petrochemical industries, whereas Iceland's economy for centuries has been based on fisheries. More recently, abundant hydropower and geothermal heat were the basis for the establishment of large export‐oriented metal processing industries, which fully depend on imported raw materials and make use of domestic renewable electricity. Both countries are highly dependent on these natural resources and vulnerable to overexploitation and price developments. We show how the export‐oriented industries lead to high and growing levels of per capita material and energy use and carbon dioxide emissions resulting from large amounts of processing wastes and energy consumption in production processes. The example of small open economies with an industrial production system focused on few, but abundant, key resources and of comparatively low complexity provides interesting insights of how resource endowment paired with availability or absence of infrastructure and specific institutional arrangements drives domestic resource‐use patterns. This also contributes to a better understanding and interpretation of MFA indicators, such as domestic material consumption.     

Vegetation cover—another dominant factor in determining global water resources in forested regions

Forested catchments provide critically important water resources. Due to dramatic global forest change over the past decades, the importance of including forest or vegetation change in the assessment of water resources under climate change has been highly recognized by Intergovernmental Panel on Climate Change (IPCC); however, this importance has not yet been examined quantitatively across the globe. Here, we used four remote sensing‐based indices to represent changes in vegetation cover in forest‐dominated regions, and then applied them to widely used models: the Fuh model and the Choudhury‐Yang model to assess relative contributions of vegetation and climate change to annual runoff variations from 2000 to 2011 in forested landscape (forest coverage >30%) across the globe. Our simulations show that the global average variation in annual runoff due to change in vegetation cover is 30.7% ± 22.5% with the rest attributed to climate change. Large annual runoff variation in response to vegetation change is found in tropical and boreal forests due to greater forest losses. Our simulations also demonstrate both offsetting and additive effects of vegetation cover and climate in determining water resource change. We conclude that vegetation cover change must be included in any global models for assessing global water resource change under climate change in forest‐dominant areas.     

Shifting Trade Patterns as a Means of Reducing Global Carbon Dioxide Emissions

This article extends and applies the world trade model with bilateral trade (WTMBT), a linear program with any number of goods, factors, and regional trade partners that determines regional production, bilateral trade patterns, and region-specific prices on the basis of comparative advantage by minimizing factor use. The model provides a consistent analysis of the global production system, representing geographical location at a regional level, region-specific technologies at a sector level, emissions from production, and resource constraints and costs. An illustrative analysis investigates how changes in the geographic distribution of production could contribute to reducing global carbon dioxide (CO₂) emissions and at what cost. The model provides a bridge between global objectives and their determinants and consequences in specific sectors in individual regions. Multi-objective analysis is used to construct a trade-off curve between global factor costs and CO₂ emissions. The relevance of both primal and dual solution variables is demonstrated. In particular, changes in goods prices and emissions are investigated. We conclude that the main impact of tightening carbon constraints is a substantial reduction in international trade accompanied by a shift away from regions most reliant on the combustion of coal. In addition to the analysis of the overall global trends, including the impact on prices, the implications of the global carbon constraint for one specific industry are investigated.     

Land cover change or land‐use intensification: simulating land system change with a global‐scale land change model

Land‐use change is both a cause and consequence of many biophysical and socioeconomic changes. The CLUMondo model provides an innovative approach for global land‐use change modeling to support integrated assessments. Demands for goods and services are, in the model, supplied by a variety of land systems that are characterized by their land cover mosaic, the agricultural management intensity, and livestock. Land system changes are simulated by the model, driven by regional demand for goods and influenced by local factors that either constrain or promote land system conversion. A characteristic of the new model is the endogenous simulation of intensification of agricultural management versus expansion of arable land, and urban versus rural settlements expansion based on land availability in the neighborhood of the location. Model results for the OECD Environmental Outlook scenario show that allocation of increased agricultural production by either management intensification or area expansion varies both among and within world regions, providing useful insight into the land sparing versus land sharing debate. The land system approach allows the inclusion of different types of demand for goods and services from the land system as a driving factor of land system change. Simulation results are compared to observed changes over the 1970–2000 period and projections of other global and regional land change models.     

Water footprint assessment for service sector: A case study of gaming industry in water scarce Macao

Although numerous studies have been carried out to investigate the water footprint of different economies at global, national and regional scales, the research on water footprint of individual economic sector, which is the elementary part of each economy, is still lacking. To fill the gap, this paper for the first time employs a hybrid method to evaluate the water footprint of gaming industry in water scarce Macao, based on the latest statistics and most exhaustive embodied water intensity databases. The results show that direct water use only accounts for extremely small fraction of the gaming industry's water footprint, indicating that the exchange of water embodied in product and service between different sectors is also a useful mean to satisfy individual sector's demand for water resources. As Macao's demand for water is growing, integrated plans including economic instruments and measures like reducing the scale of commission input and promoting efficiency would ease Macao's water pressure. Water footprint assessment in this study brings along new perspectives on gaming industry's water management and encourages wise use of goods, materials and services in a sustainable way.     

Scale‐invariance of niche breadth in fleas parasitic on small mammals

The resource specialization or niche breadth of a species is not fixed across populations, but instead varies over geographical space. A species may be a local specialist but a regional generalist, if it uses locally few resources that are substitutable across locations. In contrast, a species is a local generalist and a regional specialist if it uses locally many resources that cannot be substituted from 1 location to the next. Scale‐dependence can thus be a major factor in estimation of niche breadth. Here, we test for relationships between local and global estimates of host specificity (a measure of niche breadth for parasites) in fleas (Siphonaptera) parasitic on small mammals from 49 different regions within the Holarctic. Across all fleas, we found a strong, positive relationship between the number of host species that a flea uses in 1 locality and the number of different host species that can serve as the flea's principal host (i.e. the one supporting the most fleas in a region) among all regions. Also, we observed a strong positive relationship between the taxonomic distinctness of the host species used in 1 locality and that of all known principal hosts among all localities. These relationships held after correcting for potentially confounding phylogenetic influences. We discuss the implications of scale‐independent host specificity and its association with geographical range size and species‐specific patterns of host use.     

Global Lithium Availability

There is disagreement on whether the supply of lithium is adequate to support a future global fleet of electric vehicles. We report a comprehensive analysis of the global lithium resources and compare it to an assessment of global lithium demand from 2010 to 2100 that assumes rapid and widespread adoption of electric vehicles. Recent estimates of global lithium resources have reached very different conclusions. We compiled data on 103 deposits containing lithium, with an emphasis on the 32 deposits that have a lithium resource of more than 100,000 tonnes each. For each deposit, data were compiled on its location, geologic type, dimensions, and content of lithium as well as current status of production where appropriate. Lithium demand was estimated under the assumption of two different growth scenarios for electric vehicles and other current battery and nonbattery applications. The global lithium resource is estimated to be about 39 Mt (million tonnes), whereas the highest demand scenario does not exceed 20 Mt for the period 2010 to 2100. We conclude that even with a rapid and widespread adoption of electric vehicles powered by lithium‐ion batteries, lithium resources are sufficient to support demand until at least the end of this century.     

Developing Ethical Awareness in Global Health: Four Cases for Medical Educators

In recent years, the growth of interest in global health among medical students and residents has led to an abundance of short‐term training opportunities in low‐resource environments. Given the disparities in resources, needs and expectations between visitors and their hosts, these experiences can raise complex ethical concerns. Recent calls for best practices and ethical guidelines indicate a need for the development of ethical awareness among medical trainees, their sponsoring and host institutions, and supervising faculty. As a teaching tool to promote this awareness, we developed a scenario that captures many common ethical issues from four different perspectives. Each perspective is presented in case format followed by questions. Taken together, the four cases may be used to identify many of the elements of a well‐designed global health training experience.