International Trade Drives Global Resource Use: A Structural Decomposition Analysis of Raw Material Consumption from 1990-2010

Water-land-energy efficiency and nexus within global agricultural trade during 1995-2019

Agricultural product demand driven by population and economic growth poses challenges to water, land, and energy utilization, and this increasing local demand is largely met through trade. However, the efficiency and nexus pattern of the water, land, and energy embodied in agricultural trade are not well understood. This study uses the multi-regional input-output framework to analyze agricultural water, land, and energy utilization efficiency of resource footprints per unit economic output as well as their transfer and nexus pattern in global agricultural trade for 1995-2019. The results show that many international agricultural trade paths are inefficient in the water, land, and energy resource use because the agricultural products in these paths are exported from relatively low- to high-efficiency economies/regions. However, these inefficient transfer paths show an increasing trend over the study period. Regarding the water-land-energy nexus, conflicts are prevalent in land-energy and water-energy couplings. Most trade paths are conducted to alleviate the pressure on a specific resource, inadvertently increasing the pressure on other resources. Although agricultural trade is important for meeting global food demands, it is not consistently beneficial to the local environment when considering agricultural resources use efficiency. This study is expected to improve our understanding of agricultural trade impacts to the agricultural resources and support the sustainable development of global agriculture.

Factors influencing the material footprint in the USA

Using novel approaches, namely Fourier autoregressive distributive lag (F-ADL) cointegration and nonlinear autoregressive distributed lag (N-ARDL), this article analyzes how infrastructure investment and environmental R&D affected the material footprint from 1995Q1 to 2019Q4 in the USA while controlling financial development and economic growth. The outcomes reveal that (i) a reduction in the material footprint can be achieved through increasing environmentally related R&D; (ii) by increasing the environmental R&D, material consumption can be used more effectively; (iii) an increase in financial development leads to an increase in the material footprint; and (iv) the slowdown of the economy contributes to efficient material consumption. Integr Environ Assess Manag 2024;20:1217-1224. © 2024 SETAC.

Towards energy sustainability: Exploring the nexus between global value chain participation and energy security in developing and developed countries

International trade has a significant impact on global environmental quality and sustainable economic development. Global value chains (GVCs) have become a crucial component of international trade and development policy. The global production structure has become more complicated with the inclusion of domestic markets in GVC, putting significant pressure on world energy resources and environmental sustainability. Therefore, traditional trade measures no longer accurately reflect how global trade affects the energy security of developing and developed countries. Thus, this study is the first to use a panel-corrected standard error method to look at the relationship between GVC participation and energy security by using a global sample of 35 developed and 27 developing nations from 1995 to 2018. A feasible generalized least squares model was also applied to confirm the robustness of the model. Six indicators-foreign direct investment, industrialization level, capital formation, human capital index, political stability, and GVC-were used in this research to look at their impact on the four fundamental pillars of energy security (availability, applicability, sustainability, and affordability) for sustainable economic development. For developed countries, it was confirmed that there is a non-linear relationship between GVC participation and energy intensity, renewable energy consumption, and non-fossil fuel use. In the case of developing countries, the non-linear relationship in terms of all aspects of energy security was also confirmed. The findings also indicated that GVC's involvement benefits all four dimensions of energy security in both developing and developed countries once it reaches a certain threshold. Our findings further support the impacts of long-term cointegration between GVC and energy security for sustainable economic development. Therefore, the nations must promote technology transfer and capacity building within GVCs for inclusive energy security. Similarly, they may foster sustainable practices through collaborative governance for a stable global energy network by acknowledging the positive impact of income levels on energy security.

Supply Chain Factors Contributing to Improved Material Flow Indicators but Increased Carbon Footprint

Improvements in four material flow indicators (MFIs) have helped facilitate Japan's transition to a sound material-cycle society. However, the economic and technological factors that have affected these MFIs have not been identified previously. Moreover, it is unclear whether the improvements in the MFIs have contributed to Japan's progress toward carbon mitigation. In this study, we quantified the contribution of the factors in the capital-embodied supply chain to changes in the MFIs at the national and sector levels. We also examined the consistency of MFI improvements with carbon footprint reduction. Our results show that, in many sectors, structural changes in the supply chain improved two of the MFIs (resource productivity and material circularity) but increased the carbon footprint of the sector. To address this conflict, producers need to manage their supply chains based on an understanding of the nexus between material consumption and carbon emissions, paying particular attention to supply chains associated with capital formation.

Understanding material and energy use in the processes of decoupling CO2 emissions from economic growth

The share of emissions from materials has dramatically increased over the last decades and is projected to rise in the coming years. Therefore, understanding the environmental effect of materials becomes highly crucial, especially from the climate mitigation perspective. However, its effect on emissions is often overlooked and more attention is heavily paid to the energy-related policies. In this study, to address this shortcoming, we investigate the role of materials on the decoupling of carbon-dioxide emissions (CO2) from economic growth and compare it with the role of energy use in the world's top-19 emitting countries for the 1990-2019 period. Methodologically, using the logarithmic mean divisia index (LMDI) approach, we first decompose CO2 emissions into four effects based on the two different model specifications (materials and energy models). We secondly determine the impact decoupling status and efforts of countries with two different approaches: Tapio-based decoupling elasticity (TAPIO) and decoupling effort index (DEI). Our LMDI and TAPIO results show that material and energy-related efficiency effects have an inhibitory factor. However, the carbon intensity of materials has not contributed to CO2 emissions reduction and impact decoupling as much as the carbon intensity of energy has. DEI results indicate that while developed countries make relatively good progress towards decoupling, particularly after the Paris Agreement, developing countries need to further improve their mitigation efforts. Designing and implementing some policies only centering energy/material intensity or carbon intensity of energy might not be sufficient to achieve the decoupling. Both energy- and material-related strategies should be considered in harmony.

Decomposition Analysis of the Carbon Footprint of Primary Metals

This study investigates how different technological and socioeconomic drivers have impacted the carbon footprint of primary metals. It analyzes the historical evidence from 1995 to 2018 using new metal production, energy use, and greenhouse gas (GHG) emission extensions made for the multiregional input-output model EXIOBASE. A combination of established input-output methods (index decomposition analysis, hypothetical extraction method, and footprint analysis) is used to dissect the drivers of the change in the upstream emissions occurring due to the production of metals demanded by other (downstream) economic activities. On a global level, GHG emissions from metal production have increased at a similar pace as the GDP but have decreased in high-income countries in the most recent 6 year period studied. This absolute decoupling in industrialized countries is mainly driven by reduced metal consumption intensity and improved energy efficiency. However, in emerging economies increasing metal consumption intensity and affluency have driven up emissions, more than offsetting any reductions due to improved energy efficiency.

How can Chinese metropolises drive global carbon emissions? Based on a nested multi-regional input-output model for China

Given metropolises' participation in complex regional and global trade networks, they have huge demands for vast carbon-embodied intermediate and final goods. To clarify embodied carbon transfers of metropolises in regional and international trade, a metropolis-centered model was constructed by nesting the World's multi-regional input-output table and China's multi-regional input-output (CMRIO) table. Based on this model, we analyzed the multi-scale impact of two typical Chinese metropolises, namely Beijing and Shanghai, on global carbon emissions. Structural decomposition analysis and social network analysis (SNA) were used to explore the driving factors of consumption-based carbon (CBC) and the roles of metropolises in the carbon networks. Results showed that both Beijing and Shanghai are net embodied carbon consumers, which respectively drove 231.19 and 219.52 Mt global carbon emissions in 2017. These figures were underestimated by 12.54 % and 15.41 % when using the CMRIO. After China's economy entered a new normal, instead of technological progress, structural adjustment became the prominent factor driving the CBC reduction of metropolises. During 2012-2017, the consumption structure optimization reduced 18.87 and 32.48 Mt CBC in Beijing and Shanghai, respectively. Compared with other domestic regions, the CBC of Beijing has continued to increase, whereas that of Shanghai has declined. At the international scale, the combined net carbon emission imported by the two metropolises was 88.43 Mt in 2017, equivalent to 18.09 % of China's total carbon deficit. This indicates that metropolises have become pioneering regions for China to alleviate the carbon deficit in international trade. By using SNA, we further found that both metropolises are crucial carbon consumers in the global carbon network, with strong stability and obvious hub roles. Furthermore, various urban functions and geographical locations form the heterogeneous structural characteristics of CBC in the two metropolises, highlighting the need for different strategies for embodied carbon mitigation in these metropolises.

Comparative analysis of life cycle water accounting of the Lurgi low-pressure methanol production process with biomass or coal as raw materials

Water and energy are both essential for methanol production. This study focuses on the two processes of coal to methanol and biomass to methanol, and analyzes the water footprint of the methanol production process in the life cycle. The results indicate that the water footprint of biomass to methanol is 1707.54 L/MJ, and the dominant factor was the water consumption in the growth stage of biomass, accounting for over 95 % of the total water consumption. The water footprint of the coal to methanol process is 161.40 L/MJ. The main contributor to this process was the methanol stage, which accounted for 99.75 % of the total water footprint. However, the water consumption of the biomass to the methanol stage accounted for only 51.6 % of that of the coal to methanol stage. Based on the power situation of 30 provinces, the indirect water consumption caused by power generation in different regions was calculated, resulting in greater changes in the total water footprint of the biomass to methanol process. Through a sensitivity analysis, the effects of 24 influencing factors and main inputs on the total water consumption were investigated. This study provides the relevant water consumption of the two methanol production processes within the standard range, and the results emphasize the importance of biomass utilization and water conservation.

Relocating Industrial Plants Delivers Win-Win Emission Reduction Benefits to Origin and Destination Regions

Relocating pollution-intensive factories is one of the most effective measures to meet mandatory environmental regulations in developed cities while simultaneously imposing environmental pressure on the receiving cities. Existing studies often assume that relocated plants produce the same or higher emissions when relocated. However, the current pollution mitigation policies enforce even higher emission standards in the destination after plant relocation. We employ a bottom-up pollution accounting approach to assess the impact of intraregional or interregional relocation of iron and steel plants in China's Beijing-Tianjin-Hebei (BTH) area on various air pollutants; specifically, seven policy scenarios are modeled, based on stringency, implementation scope, and production technologies. We find that relocation combined with emission standards enforcement and shifts from BOF (basic oxygen furnace) to EAF (electric arc furnace) production technology may significantly reduce emissions within and outside BTH areas by as much as 28.8% compared to business as usual. The observed reduction is mainly due to the requirement of meeting ultralow emission standards directly or indirectly after relocation. Both origin and destination cities benefit from the relocation, with limited emission spillovers (+9.1%) for destinations outside BTH and even a net reduction (9.4%) in Tangshan. We conclude that combining factory relocation with stricter emission standards and production technological innovation could circumvent the Pollution Haven Hypothesis and deliver win-win air pollution reduction benefits for both origins and destinations.

Risk Transmission of Trade Price Fluctuations from a Nickel Chain Perspective: Based on Systematic Risk Entropy and Granger Causality Networks

Nickel is a strategic mineral resource, with 65% of nickel being used in stainless steel. The situation in Ukraine starting in February 2022 has led to significant fluctuations in nickel prices, with prices of nickel products along the same chain affecting and passing through each other. Using systematic risk entropy and granger causality networks, we measure the volatility risk of trade prices of nickel products using the nickel industry chain trade data from 2000-2019 and explore the transmission patterns of different volatility risk prices from the industry chain perspective. The findings show that: (1) Nickel ore has the highest risk of import trade price volatility and a strong influence, but low risk transmission. Stainless steel has the highest trade price impact but is also subject to the strongest passive influence. (2) The Americas have a higher risk of trade price volatility but a weaker influence. The influence and sensitivity of trade prices is stronger in Asia and Europe. (3) Indonesia's stainless steel export prices have a high rate of transmission and strong influence. Germany's ferronickel export prices are highly susceptible to external influences and can continue to spread loudly. Russian nickel ore export prices are able to quickly spread their impact to other regions.

Interprovincial Metal and GHG Transfers Embodied in Electricity Transmission across China: Trends and Driving Factors

With the increasing proportion of low-carbon power in electricity generation mix, power generation will be transformed from carbon-intensive to metal-intensive. In this context, metal and GHG transfers embodied in electricity transmission of China from 2015 to 2019 are quantified by the Quasi-Input-Output model. Combined with complex network theory, we have distinguished whether metal and GHG transfers show different trends as electricity trade changes. Driving factors contributing to forming the metal and GHG transfers are also explored based on the Quadratic Assignment Procedure. The results show that the electricity trade change has strengthened the metal transfer network significantly, while several key links in the GHG transfer network have weakened. Moreover, we find provincial differences in low-carbon electricity investment contributing to the metal transfer while affecting the GHG transfer little. The above facts imply an expanding embodied metal transfer in the future and shed light on policy making for power system decarbonization.

The misinterpretation of structure effects of the LMDI and an alternative index decomposition

Changing the structure of the economy is often considered an option to reduce environmental impacts – for example, by changing the mix of sectors in the economy, the energy mix of production, or the mix of origin countries for imported products. To study the effect of such structure (or mix) effects, researchers often use index decomposition analysis (IDA). This study uses experimental data to show that most existing IDA methods, especially the widely used LMDI (logarithmic mean divisia index), yield results that are difficult to understand and easily misinterpreted. We use formal proof to demonstrate that:•

The LMDI interpretation problem is due to the use of shares to describe the considered mix.

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We developed an alternative method, the Marshall-Edgeworth with Structure Effects (MESE).

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The MESE defines structure effects by comparing each observation to a hypothetical average, which better reflects the common understanding of structure effects.

We compared empirical data on the LMDI and the MESE, analysing the effect of the changing sector mix on energy use in the USA from 1995 to 2016, and found that results from the two tools differed significantly. We therefore recommend using the MESE when structure effects are included in IDA.

Economic policy uncertainty and energy production in China

Owing to economics are usually linked with energy production, economic policy may have an instantaneous adjustment according to the current monetary, financial, cultural circumstances. This research thus investigates the dynamic co-movement as well as cointegration relationships between economic policy uncertainty (EPU) and disparate energy productions, i.e., Chinese coal, natural gas, crude oil, electricity as well as renewable energy, during the period from January 1995 to October 2019 in China. We compare the two EPU indices and make empirical and robust analysis to get more evidence for the time-varying co-movement between energy production and EPU. The empirical results show that there are stationary properties and cointegration relationships between energy production and EPU. By utilizing wavelet co-movement analysis in the time-frequency domain, our results show a significant positive co-movement among disparate energy productions and EPU at high frequencies, i.e., in the short term, but weaker co-movement at low frequencies, i.e., in the long term. Hence, the phase-difference series are mostly around the zero line, implying the variables behave to the dynamics of the co-movement with positive causality. Policy recommendations are offered in accordance with our finding.

Development of the Concept of Circular Supply Chain Management—A Systematic Review

This systematic review presents the most important characteristics and trends of research in circular supply chain management (CSCM), taking into account the impact of COVID. In addition, the similarities and differences between the basic concepts often used as synonyms for sustainability are also presented. First, the sample database (39,000 records) was based on a search containing publications’ titles regarding supply chain management (SCM). After narrowing the topic from SCM towards CSCM, the considered paper characteristics were expanded, including abstract and author keywords, to get a manageable number of samples for the systematic analysis (6095 documents) and the most accurate results possible. The analysis’ base sample was divided into two periods (before and after 2012) due to a significant increase and change in the number of publications, their subject, characteristic journals and geographical location. Sustainability has emerged since 2012, while a circular approach emerged after 2017 with a significant share of research, mainly thanks to relevant EU policies. Although the role of the US has been decisive in the field, the European research bases of previous years have increasingly been replaced by Far Eastern dominance. Currently, CSCM’s most important journal is the International Journal of Supply Chain Management (Elsevier), but most articles on the impact of COVID have been published in Sustainability (MDPI). More effective policy implementation and the fight against COVID in the development of supply chains are also likely to spread the circular economic model in the future.

Environmental Impact of the Shadow Economy, Globalisation, Trade and Market Size: Evidence Using Linear and Non-Linear Methods

The achievement of the Sustainable Development Goals (SDG) related to the environment requires identifying new sources of environmental degradation. In this research, we examine the impact of the underground economy on polluting gas emissions. This relationship was estimated, including the role of globalization, trade, and market size. Using annual data from the World Bank and the International Monetary Fund, we found that, in the short term, the underground economy had a negative effect on global environmental pollution and a long-term negative impact. In the long term, the cointegration results indicate a long-term relationship between the series included in the investigation. The existence of a long-term relationship between the variables implies that as the underground economy increases, the emissions of polluting gases also change. In the long term, policymakers can use the black economy as an instrument to influence environmental pollution. Likewise, we found a threshold effect in the index of globalization, trade, and market size. The existence of a threshold effect implies that from a threshold, the impact of globalization, trade, and the size of the market on polluting emissions is more significant. Therefore, the environmental policy must consider these aspects to achieve greater effectiveness of regulation in favor of the environment. The results were stable, including the dependence of the cross-sections and the heterogeneity in the slope of the panel. Actions to mitigate polluting gas emissions should regulate informal and clandestine activities and take advantage of globalization and trade to improve the practices of companies and individuals.

Quantifying economic-social-environmental trade-offs and synergies of water-supply constraints: An application to the capital region of China

Sustainable water management is one of the sustainable development goals (SDGs) and is characterized by a high level of interdependencies with other SDGs from regional to global scales. Many water assessment studies are restricted to silo thinking, mostly focusing on water-related consequences, while lacking a quantification of trade-offs and synergies of economic, social, and environmental dimensions. To fill this knowledge gap, we propose a "nexus" approach that integrates a water supply constrained multi-regional input-output (mixed MRIO) model, scenario analysis, and multi-criteria decision analysis (MCDA) to quantify the trade-offs and synergies at the sectoral level for the capital region of China, i.e. the Beijing-Tianjin-Hebei urban agglomeration. A total of 120 industrial transition scenarios including nine major industries with high water-intensities and water consumption under current development pathways were developed to facilitate the trade-off and synergy analysis between economic loss, social goals (here, the number of jobs) and environmental protection (with grey water footprint representing water pollution) triggered by water conservation measures. Our simulation results show that an imposition of a tolerable water constraint (a necessary water consumption reduction for regional water stress level to move from severe to moderate) in the region would result in an average economic loss of 68.4 (± 16.0) billion Yuan (1 yuan ≈ 0.158 USD$ in 2012), or 1.3 % of regional GDP, a loss of 1.94 (± 0.18) million jobs (i.e. 3.5 % of the work force) and a reduction of 1.27 (± 0.40) billion m³ or about 2.2% of the regional grey water footprint. A tolerable water rationing in water-intensive sectors such as Agriculture, Food and tobacco processing, Electricity and heating power production and Chemicals would result in the lowest economic and job losses and the largest environmental benefits. Based on MCDA, we selected the 10 best scenarios with regard to their economic, social and environmental performances as references for guiding future water management and suggested industrial transition policies. This integrated approach could be a powerful policy support tool for 1) assessing trade-offs and synergies among multiple criteria and across multiple region-sectors under resource constraints; 2) quantifying the short-term supply-chain effects of different containment measures, and 3) facilitating more insightful evaluation of SDGs at the regional level so as to determine priorities for local governments and practitioners to achieve SDGs.

Industrial polycyclic aromatic hydrocarbons (PAHs) emissions embodied in domestic trade in China in 2012

Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) emissions cause non-negligible damage to human health and well-being. Effective regional cooperation is urgently required to mitigate PAHs emissions to maintain satisfactory air quality. This study quantified and tracked China's PAHs emissions flows embodied in interprovincial trade. A production-based emissions inventory of 16 U.S. EPA priority PAHs based on commercial energy consumption in China in 2012 was compiled using the emissions factor approach. Then, a multiregional input-output model was constructed to reveal consumption-based emissions and to track the PAHs emissions embodied in the trade of 27 major sectors across 30 regions in China. Key structural paths were also identified using structural path analysis (SPA). In 2012, the total industrial energy-derived PAHs emissions were estimated to be 47.7 tons of BaP-toxic equivalents (8032.7 tons of mass). Shandong, Hebei, and Hubei accounted for more than 24.0% of the production-side PAHs emissions in the whole country. Approximately 30.8% of China's PAHs emissions were embodied in goods consumed outside of the province in which they were produced. PAHs flow tended to start in the western regions and ended in the eastern regions along the coast. The results of the SPA showed that critical paths, such as from the Metallurgy sector to the Construction sector, embodied a large amount of emissions and had the potential to affect the performance of the entire system. By paying attention to the consumption-based accounting as well as the production-based accounting of emissions and by focusing on vital transfer paths, policymakers can devise effective and targeted environmental protection and sustainable development policies in China.

Do material efficiency improvements backfire?: Insights from an index decomposition analysis about the link between CO2 emissions and material use for Austria

To keep global heating and other negative consequences of socioeconomic activities within manageable boundaries, industrialized countries must undergo substantial decarbonization, requiring the exploitation of synergies with other environmental endeavors. Improving resource efficiency-that is, reducing the resources required to generate a unit of economic output-is a prominent goal pursued across levels of scale. How does resource efficiency relate to decarbonization? Do economies decrease their emissions as they become more efficient? We examine this relationship for Austria from 2000 to 2015 by conducting an index decomposition analysis at the sectoral level by using consumption-based indicators from the multi-regional input-output model Exiobase. Our analysis shows that for Austria, the currently popular pursuit of material efficiency appears to run the risk of coinciding with higher emissions, suggesting that the opportunities to achieve both decarbonization and dematerialization are limited. The Austrian service sectors could contribute to a reduction of the CO2 footprint via material efficiency improvements, but strong economic growth foils this possibility coming to fruition. The Austrian economy would do well to either curb demand for goods and services driving global CO2 emissions or to produce imported goods and services domestically in an environmentally more benign manner.

Improving Subnational Input-Output Analyses Using Regional Trade Data: A Case-Study and Comparison

Environmentally extended input-output analysis (EE-IO) is widely used for evaluating environmental performance (i.e., footprint) at a national level. Many studies have extended their analyses to the subnational level to guide regional policies. One promising method is to embed nationally disaggregated input-output tables, e.g., nesting a provincial level table, into a global multiregional input-output table. However, a widely used approach to environmental assessment generally disaggregates the trade structure at the national level to the provincial level using the same proportions (proportionality assumption). This means that the subnational spatial heterogeneities on international trade are not fully captured. By calculating the Chinese provincial material footprint (MF) based on two approaches-the proportionality assumption and the actual customs statistics-in the same framework, we evaluate the quantitative differences when the proportionality assumption is addressed. By computing MF for 23 aggregated resources across 30 Chinese provinces, our results show for countries with large material flows like China, estimating subnational-level international trade by proportionality assumption may lead to significant differences in material flows at both the disaggregated and aggregated levels. An important follow-up question is whether these differences are also relevant for other footprints.

Environmental-social-economic footprints of consumption and trade in the Asia-Pacific region

Asia-Pacific (APAC) has been the world’s most dynamic emerging area of economic development and trade in recent decades. Here, we reveal the significant and imbalanced environmental and socio-economic effects of the region’s growths during 1995–2015. Owing to the intra-regional trade of goods and services, APAC economies grew increasingly interdependent in each other’s water and energy use, greenhouse gas (GHG) and PM_2.5 emissions, and labor and economic productivity, while the environmental and economic disparity widened within the region. Furthermore, our results highlight APAC’s significant role in globalization. By 2015, APAC was engaged in 50–71% of the virtual flows of water, energy, GHG, PM_2.5, labor, and value added embodied in international trade. While the region’s final demand and trade grew less resource- and emissions-intensive, predominantly led by China’s transformations, APAC still lags behind global averages after two decades. More joint efforts of APAC economies and attention to sustainable transformation are needed.

The environmental and socio-economic implications of the growth in welfare and trade in Asia-Pacific (APAC) remain unclear. Here the authors show that over the past two decades (1995–2015), owing to intraregional trade, the APAC economies have grown increasingly interdependent in natural resource use, air emissions, and labor and economic productivity.

Imbalance of carbon embodied in South-South trade: Evidence from China-India trade

China and India are the countries with the largest increase in carbon emissions and one of the fastest growing economies in the world. A better understanding of the carbon emissions embodied in China-India trade can service to curb carbon emission in both countries. In this work, we investigated temporal change and driving forces of the carbon emissions embodied in China-India trade from 2000 to 2015 using the Multi-Regional Input-Output model and Structural Decomposition Analysis. The results showed China was a net exporter of embodied carbon and a net exporter of trade in China-India trade, which indicated that China increased its environmental costs while gaining economic benefits. And the imbalance in China's embodied carbon trade was far greater than the trade imbalance. The industrial structure of China's export of embodied carbon and India's export of embodied carbon were difference, although electricity and heavy manufacturing industries dominated the embodied carbon exports of China and India. The decomposition results showed the leading contributor to increase in the embodied carbon emissions of China and India was the increase in final demand, in which the effect of per capita demand was the main driving factor affecting the change of embodied carbon emissions. The carbon intensity coefficient effect was the driving factor in suppressing the increase in embodied carbon emissions in China and India. This research could enrich the study of carbon emission embodied in South-South trade.

Driving forces of nitrogen flows and nitrogen use efficiency of food systems in seven Chinese cities, 1990 to 2015

The effects of population growth (PG), dietary changes (DC), native rural-to-urban migration (NM), migration from regions distant from the cities (M), and agricultural patterns and practices (AP) on N use in food systems and the food trade, and on apparent and virtual nitrogen (N) and N use efficiencies (NUE), at the city scale, are not well understood. Here we selected seven Chinese cities as the study subjects, analyzed the food trade effects on apparent and virtual N inputs and NUE, and quantified the relative magnitudes of these factors on N inputs to cities' food systems during 1990-2015, by designing several scenarios. Our results show that food-sink cities are relying more and more on external food and feed, but in 2015 they transferred 33.8-74.9% of their N input for food or feed productions to areas outside their boundaries, and the food trade showed different effects on the virtual N cost of food N consumption. Apparent NUEs of food systems were 33.1-74.9% higher than those calculated from virtual N costs in Beijing, Tianjin, Shanghai, Lanzhou and Xiamen in 2015. But in cities that export large amounts of food and feed-for example, Chongqing and Changchun-apparent NUE was underestimated by 4.0-46.4% relative to virtual NUE. Native PG, DC, NM, M, and AP accounted for 1.2-14.1%, -6.6-30.0%, 0.6-8.2%, -7.7-131.0%, and -43.8-12.8%, respectively, of the increase in virtual N inputs associated with cities' food systems in 2015, compared to 1990. Our study concludes that M, DC, and AP changes should be considered for mitigating N input in these Chinese cities, and virtual N exports induced by the food trade should also be included if the city is a net food exporter. Selective food trade could help improve the NUE of cities' food systems, and virtual NUE should be used as an indicator, rather than apparent NUE.

The impacts of data deviations between MRIO models on material footprints: A comparison of EXIOBASE, Eora, and ICIO

In various international policy processes such as the UN Sustainable Development Goals, an urgent demand for robust consumption-based indicators of material flows, or material footprints (MFs), has emerged over the past years. Yet, MFs for national economies diverge when calculated with different Global Multiregional Input-Output (GMRIO) databases, constituting a significant barrier to a broad policy uptake of these indicators. The objective of this paper is to quantify the impact of data deviations between GMRIO databases on the resulting MF. We use two methods, structural decomposition analysis and structural production layer decomposition, and apply them for a pairwise assessment of three GMRIO databases, EXIOBASE, Eora, and the OECD Inter-Country Input-Output (ICIO) database, using an identical set of material extensions. Although all three GMRIO databases accord for the directionality of footprint results, that is, whether a countries' final demand depends on net imports of raw materials from abroad or is a net exporter, they sometimes show significant differences in level and composition of material flows. Decomposing the effects from the Leontief matrices (economic structures), we observe that a few sectors at the very first stages of the supply chain, that is, raw material extraction and basic processing, explain 60% of the total deviations stemming from the technology matrices. We conclude that further development of methods to align results from GMRIOs, in particular for material-intensive sectors and supply chains, should be an important research priority. This will be vital to strengthen the uptake of demand-based material flow indicators in the resource policy context.