About Socio-Economic Metabolism
Challenge
Materials are at the basis of human society [1]. Urbanization, industrialization, and growing consumption drive the demand for wood, concrete, steel, plastics, chemicals, and various technology materials. Providing adequate access to modern and low-carbon energy services and adapting to climate change further increase resource consumption, as new energy infrastructure and protective measures such as dams and dikes need to be built.
The global use of natural resources has grown at an unprecedented rate, and the number of chemical elements and their combinations used in modern technologies have multiplied. Consequently, the natural resource endowment and the quality of the environment keep declining in most countries, especially in the Global South, which in turn fuels economic, social, and geopolitical conflicts.
Currently, material production accounts for about 23% of global greenhouse gas emissions [2]. This major contribution to global warming, plus the large impacts of mining on land use change [3] and water consumption [4], highlight the need for research on how materials are linked to and can be decoupled from environmental impacts and service provision to people by establishing a circular economy of materials [5]. Resilient and sustained supply of so-called critical materials [6,7,8,9] and the large material requirements of the transition to low-carbon energy [10] are major global concerns involving materials. On the social side, material extraction is often connected to struggles for environmental justice [11].
The SEM approach
Socio-economic metabolism (SEM) is a research paradigm that looks at material and energy turnover and processing at the societal level [12]. SEM researchers study human-controlled stocks and flows of energy and materials and their links to social outcomes and environmental impacts. Under the SEM paradigm, researchers have developed methods and established accounting approaches to measure material use in the economy, model scenarios for transforming material cycles, and provide policy advice regarding resource use constraints of policy interventions [12a]. Material flow analysis (MFA), often combined with energy flow analysis (MEFA), is the basic accounting and modelling method of scientific analysis of socio-economic metabolism [13, 14]. In-use stocks, the material stocks in the built environment, are a key component of society’s metabolism, as they provide services such as shelter and mobility and also provide the resources for future recycling [15].
Applied at the national level, economy-wide MFA [16] gives insights into the material use of national and global economies. In recent years, the research community, together with statistical offices and government departments, has established methodological guidelines for material flow and stock accounts at a national level. Today, this core material use accounting method complements the System of National Accounts by adding the material layer. It is used by Eurostat, or the International Resource Panel, amongst others, to monitor resource use across and within countries.
Economy-wide MFA: Global material flows, waste and emissions, 2019, billion tonnes. Source: Figure 2.8 in United Nations Environment Programme (2024). [17] The first iteration of this figure appeared in Haas et al. (2015), published in the Journal of Industrial Ecology. [5] The accounting scheme used here, Material Flow Accounting, was developed and standardized by members of our community [16].
Socio-economic metabolism is complex and includes many delays, like the lifetime of products in use, and couplings, such as the different materials contained in a single vehicle. For another example, many green technologies that reduce greenhouse gas emissions use critical minerals, making these industries vulnerable to supply disruptions. More detailed accounts of resource use and waste are needed to deepen the understanding of how materials flow through the economy, where losses occur, and where efficiency can be improved. Such detailed material flow accounts form the basis for assessing efficiency and circular economy improvements for businesses and governments at the company, city [18,19,20], regional and national scales [21,22,23], and global scales [24]. The analysis may also focus on certain materials of concern because of their availability or toxic capacity and will identify the impact of regulatory and engineering solutions to metabolic problems. The process flow diagram below is a good example of an explicit system definition and description of material flows of interest.
A typical example of an MFA system diagram, from Han et al. (2014) [25]. Chlorine-containing material flows in 2011. The dashed arrow represents non-chlorine flow; the dashed box represents a plant under construction. The regional and temporal scope of the stocks and flows is also indicated when quantifying the system.
The results of a material flow analysis are commonly visualized in Sankey diagrams like the one below for the cumulative flows in the global steel cycle.
Material flow analysis: the global historical steel cycle in a Sankey diagram, where the numbers represent the accumulated annual flows over the past 115 years. Source: Fig. 3a in Wang et al. (2021) [26]. The flows trace steel from mining through iron making, steel making, fabrication, the different end uses to the end-of-life stage, and recycling. Please check the original publication for an explanation of all technologies and end uses.
Another research stream is the compilation of in-use stock accounts at high spatial resolution, which enables the estimate of the exact location of future waste flows. More importantly, the high-resolution maps can be compared against other high-resolution maps of population density, socio-demographic factors, and travel behavior to deepen our understanding of how material stocks are linked to service provision and well-being outcomes.
Country-wide spatial distribution of the material stocked in buildings for Japan, 2009. Cell size is 1 km² using the geographical information systems data set. Source: Japan map of material stocks, Tanikawa et al. (2015) [27].
Dynamic MFA studies show how in-use stocks and material cycles [28, 29, 29a] evolve over time. They quantify the accumulation of stocks in our economy [30], such as the material demand for the energy transition [31, 32]. A focus of dynamic MFA is on industrial countries, such as Japan [21] and China [22, 23], which often depend on imports and have large production industries and consumption levels. Dynamic MFA helps identify future ‘urban mines’ (recycling potential) and allows us to estimate the decline of ore grades as a response to growing demand [33]. Thus, such studies provide necessary information for assessing the potential of circular economy strategies, e.g., in the global building sector [24] (see figure below) or for cement [34].
Circular Economy Potentials: Life-cycle emissions from homes with and without Material Efficiency strategies in 2050 in G7 countries, China and India. Source: UNEP International Resource Panel (IRP) (2020) [24].
Practical applications, current trends, and new research avenues in SEM research
Numerous industry and policy implementations of MFA exist, see the examples on the industry and policy applications side: https://is4ie.org/sections/metabolism/pages/41
On the research side, the high-resolution mapping of in-use stocks continues as new data sources become accessible to the research community (see the figure below for an example).
Global maps of mobility infrastructure stocks for the year 2021 at 5 arcmin resolution, showing total materials in mobility infrastructure networks per square kilometer. Source: World map of infrastructure stocks, Wiedenhofer et al. (2024) [35].
MFA studies are now linked to supply chain assessment, e.g., via MFA-LCA combinations [36, 36a], and to assessments of the economic implications of changed consumption and circular economy measures, e.g., to estimate rebound effects [37]. Increasingly, MFA studies are linked to social and environmental impacts [38]. To study the social and environmental aspects of material use more systematically, the energy and material service cascade [39] (figure below) offers a framework that combines the key elements of socio-economic metabolism (material services, stocks, and flows) to human well-being on the one hand and materials and to environmental impacts on the other hand. Different social and environmental links of material can be studied, as well as different decoupling options along the cascade. The framework allows for coupling MFA studies to the assessment of legal instruments and economic incentives at the different stages of the cascade, as well as to explore the link between material stocks, product stocks, product functioning, service provision, and well-being.
The energy and material service cascade involves different stages of coupling between human well-being and climate impacts. Each stage of the cascade offers possibilities for reduced environmental impacts through more efficient technologies, alternative energy sources (e.g., sunlight), or reduction in energy demand. The cascade shown here is based on the energy service cascade proposed by Kalt et al. [39]. Image source: [40]
The multi-stage cascade and its link to culture, lifestyle, regulations, and economics enable us to systematically expand the traditional set of economic indicators to include well-being indicators beyond GDP that measure how effectively basic human needs are being met, alongside high-level information on material use, waste, energy use, emissions, and water use. This refined understanding of human material use in the energy and material service cascade leads to an expanded set of indicators that is critical to redesigning our provisioning systems to achieve a good life for all within planetary limits.
References
The references below show the spectrum of SEM research. Many more colleagues have contributed to an enormous body of research on understanding the links between society, materials, and the environment.
[1] On the materials basis of modern society. T. E. Graedel, E. M. Harper, N. T. Nassar, and Barbara K. Reck. PNAS 112 (20) 6295-6300, 2013. https://doi.org/10.1073/pnas.1312752110
[2] Increased carbon footprint of materials production driven by rise in investments. By Edgar G Hertwich. Nat. Geosci. 14, 151–155 (2021). https://doi.org/10.1038/s41561-021-00690-8
[3] A pantropical assessment of deforestation caused by industrial mining, by Stefan Giljum, Victor Maus, Nikolas Kuschnig, and Anthony J. Bebbington. PNAS 119 (38), 2022. https://doi.org/10.1073/pnas.2118273119
[4] Water footprinting and mining: Where are the limitations and opportunities? By Stephen A. Northey, Gavin M. Mudd, Elina Saarivuori, Helena Wessman-Jääskeläinen, and Nawshad Haque. Journal of Cleaner Production Volume 135, 1 November 2016, Pages 1098-1116. https://doi.org/10.1016/j.jclepro.2016.07.024
[5] How Circular is the Global Economy?: An Assessment of Material Flows, Waste Production, and Recycling in the European Union and the World in 2005. By Willi Haas, Fridolin Krausmann, Dominik Wiedenhofer, and Markus Heinz. Journal of Industrial Ecology, 2015. https://doi.org/10.1111/jiec.12244.
[6] Six Years of Criticality Assessments: What Have We Learned So Far? T. E. Graedel, Barbara K. Reck. Journal of Industrial Ecology, Volume 20, Issue 4, Pages 692-699, 2016. https://doi.org/10.1111/jiec.12305
[7] Incorporating critical material cycles into metal-energy nexus of China’s 2050 renewable transition. Peng Wang, Li-Yang Chen, Jian-Ping Ge, Wenjia Cai, and Wei-Qiang Chen. Applied Energy, Volume 253, 1 November 2019, 113612. https://doi.org/10.1016/j.apenergy.2019.113612
[8] Assessing the supply risks of critical metals in China's low-carbon energy transition. Pengfei Yuan, Dan Li, Kuishuang Feng, Heming Wang, Peng Wang, Jiashuo Li. Global Environmental Change, Volume 86, May 2024, 102825. https://doi.org/10.1016/j.gloenvcha.2024.102825
[9] Supply risks associated with lithium-ion battery materials. Christoph Helbig, Alex M. Bradshaw, Lars Wietschel, Andrea Thorenz, Axel Tuma. Journal of Cleaner Production, Volume 172, 20 January 2018, Pages 274-286. https://doi.org/10.1016/j.jclepro.2017.10.122
[10] Future demand for electricity generation materials under different climate mitigation scenarios. Seaver Wang, Zeke Hausfather, Steven Davis, Juzel Lloyd, Erik B. Olson, Lauren Liebermann, Guido D. Núñez-Mujica, and Jameson McBride. Joule, Volume 7, Issue 2, 15 February 2023, Pages 309-332. https://doi.org/10.1016/j.joule.2023.01.001
[11] Environmental justice and natural resource extraction: intersections of power, equity and access. Stephanie A. Malin, Stacia Ryder & Mariana Galvão Lyra. Environmental Sociology Volume 5, 2019 - Issue 2, Pages 109-116. https://doi.org/10.1080/23251042.2019.1608420
[12] https://en.wikipedia.org/wiki/Social_metabolism
[12a] Contributions of sociometabolic research to sustainability science, by Helmut Haberl, Dominik Wiedenhofer, Stefan Pauliuk, Fridolin Krausmann, Daniel B. Müller & Marina Fischer-Kowalski. Nature Sustainability volume 2, pages 173–184 (2019). https://doi.org/10.1038/s41893-019-0225-2
[13] Society’s Metabolism. The Intellectual History of Materials Flow Analysis, Part I, 1860– 1970. Marina Fischer-Kowalski. Journal of Industrial Ecology, Volume 2, Issue 1, Pages 61-78. 1998. https://doi.org/10.1162/jiec.1998.2.1.61
[14] Material Flow Analysis from Origin to Evolution. Thomas E. Graedel. Environ. Sci. Technol. 2019, 53, 21, 12188–12196. https://doi.org/10.1021/acs.est.9b03413
[15] The role of in-use stocks in the social metabolism and in climate change mitigation. Stefan Pauliuk and Daniel B. Müller. Global Environmental Change, Volume 24, January 2014, Pages 132-142 https://doi.org/10.1016/j.gloenvcha.2013.11.006
[16] Methodology and Indicators of Economy-wide Material Flow Accounting. M. Fischer-Kowalski, F. Krausmann, S. Giljum, S. Lutter, A. Mayer, S. Bringezu, Y. Moriguchi, H. Schütz, H. Schandl, H. Weisz. Journal of Industrial Ecology, Volume 15, Issue 6, 2011, Pages 855-876. https://doi.org/10.1111/j.1530-9290.2011.00366.x
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[18] Understanding the evolution of cities through urban stocks: A comparative analysis of Andean and coastal urban areas in Peru. Claudia Cucchi, Ramzy Kahhat, Matías Gutiérrez, Alexis Dueñas, Carlos Mesta, Samy García, Johann Fellner. Journal of Industrial Ecology, 2024, Volume 28, Issue 4, Pages 813-827. https://doi.org/10.1111/jiec.13501
[19] Cities as organisms: Urban metabolism of the four main Danish cities. Maud Lanau, Ruichang Mao, Gang Liu. Cities, Volume 118, November 2021, 103336. https://doi.org/10.1016/j.cities.2021.103336
[20] The landscape of city-level GHG emission accounts in Africa. Binyuan Liu, Yuli Shan, Riemer Kuik, Xiande Ji, Lazarus Chapungu, Xiaofan Yang, Klaus Hubacek. Journal of Industrial Ecology, 2025, available online. https://doi.org/10.1111/jiec.13562
[21] Material stocks and flows accounting for copper and copper-based alloys in Japan. Ichiro Daigo, Susumu Hashimoto, Yasunari Matsuno, Yoshihiro Adachia. Resources, Conservation and Recycling 53 (2009) 208–217. https://doi.org/10.1016/j.resconrec.2008.11.010
[22] Anthropogenic Cycles of Arsenic in Mainland China: 1990–2010. Ya-Lan Shi, Wei-Qiang Chen, Shi-Liang Wu, Yong-Guan Zhu. Environ. Sci. Technol. 2017, 51, 3, 1670–1678. https://doi.org/10.1021/acs.est.6b01669
[23] Uncovering the evolution of substance flow analysis of nickel in China. Xianyang Zeng, Hongxia Zheng, Ruying Gong, Disna Eheliyagoda, Xianlai Zeng. Resources, Conservation and Recycling, Volume 135, August 2018, Pages 210-215. https://doi.org/10.1016/j.resconrec.2017.10.014
[24] IRP (2020). Resource Efficiency and Climate Change: Material Efficiency Strategies for a Low-Carbon Future. Hertwich, E., Lifset, R., Pauliuk, S., Heeren, N. A report of the International Resource Panel. United Nations Environment Programme, Nairobi, Kenya. https://www.resourcepanel.org/reports/resource-efficiency-and-climate-change
[25] Industrial metabolism of chlorine: a case study of a chlor-alkali industrial chain. Han, F., Li, W., Yu, F. et al. Environ Sci Pollut Res 21, 5810–5817 (2014). https://doi.org/10.1007/s11356-014-2518-3
[26] Efficiency stagnation in global steel production urges joint supply- and demand-side mitigation efforts. Peng Wang, Morten Ryberg, Yi Yang, Kuishuang Feng, Sami Kara, Michael Hauschild & Wei-Qiang Chen. Nature Communications volume 12, Article number: 2066 (2021) https://doi.org/10.1038/s41467-021-22245-6
[27] The Weight of Society Over Time and Space: A Comprehensive Account of the Construction Material Stock of Japan, 1945–2010. Hiroki Tanikawa, Tomer Fishman, Keijiro Okuoka, Kenji Sugimoto. Journal of Industrial Ecology, Volume 19, Issue 5, Pages 778-791. Special Issue on Frontiers in Socioeconomic Metabolism Research, 2015. https://onlinelibrary.wiley.com/doi/full/10.1111/jiec.12284
[28] Outlook of the World Steel Cycle Based on the Stock and Flow Dynamics. Hiroki Hatayama, Ichiro Daigo, Yasunari Matsuno, Yoshihiro Adachi. Environ. Sci. Technol. 2010, 44, 16, 6457–6463. https://doi.org/10.1021/es100044n
[29] Stock dynamics and emission pathways of the global aluminium cycle. Gang Liu, Colton E. Bangs & Daniel B. Müller. Nature Climate Change volume 3, pages 338–342 (2013). https://doi.org/10.1038/nclimate1698
[29a] Modeling metal stocks and flows: a review of dynamic material flow analysis methods. Esther Müller, Hilty LM, Widmer R, Schluep M, Martin Faulstich. Environmental Science & Technology, 04 Feb 2014, 48(4):2102-2113. https://doi.org/10.1021/es403506a
[30] Anthropogenic cycles of the elements: A critical review. Chen, W.-Q., and T.E. Graedel, Environmental Science & Technology, 46, 8574-8586, 2012. https://doi.org/10.1021/es3010333
[31] Total material requirement for the global energy transition to 2050: A focus on transport and electricity. Takuma Watari, Benjamin C. McLellan, Damien Giurco, Elsa Dominish, Eiji Yamasue, Keisuke Nansai. Resources, Conservation and Recycling, Volume 148, September 2019, Pages 91-103. https://doi.org/10.1016/j.resconrec.2019.05.015
[32] Energy–materials nexus of electrified vehicle penetration in Japan: A study on energy transition and cobalt flow. Akito Ozawa, Shinichirou Morimoto, Hiroki Hatayama, Yurie Anzai. Energy, Volume 277, 15 August 2023, 127698. https://doi.org/10.1016/j.energy.2023.127698
[33] Modelling future copper ore grade decline based on a detailed assessment of copper resources and mining. S. Northey, S. Mohr, G.M. Mudd, Z. Weng, D. Giurco. Resources, Conservation and Recycling, Volume 83, February 2014, Pages 190-201. https://doi.org/10.1016/j.resconrec.2013.10.005
[34] Efficient use of cement and concrete to reduce reliance on supply-side technologies for net-zero emissions. Takuma Watari, Zhi Cao, Sho Hata & Keisuke Nansai. Nature Communications volume 13, Article number: 4158 (2022). https://doi.org/10.1038/s41467-022-31806-2
[35] Mapping and modelling global mobility infrastructure stocks, material flows and their embodied greenhouse gas emissions. Dominik Wiedenhofer, André Baumgart, Sarah Matej, Doris Virág, Gerald Kalt, Maud Lanau, Danielle Densley Tingley, Zhiwei Liu, Jing Guo, Hiroki Tanikaw, and Helmut Haberl. Journal of Cleaner Production, Volume 434, 139742, 2024. https://doi.org/10.1016/j.jclepro.2023.139742
[36] Quo vadis MFA? Integrated material flow analysis to support material efficiency. Joris Baars, Mohammad Ali Rajaeifar, Oliver Heidrich. Journal of Industrial Ecology, Volume 26, Issue 4, Pages 1487-1503. https://doi.org/10.1111/jiec.13288
[36a] Combinations of material flow analysis and life cycle assessment and their applicability to assess circular economy requirements in EU product regulations. A systematic literature review. Robin Barkhausen, Leon Rostek, Zoe Chunyu Miao, Vanessa Zeller. Journal of Cleaner Production, Volume 407, 25 June 2023, 137017. https://doi.org/10.1016/j.jclepro.2023.137017
[37] Integrating Dynamic Material Flow Analysis and Computable General Equilibrium Models for Both Mass and Monetary Balances in Prospective Modeling: A Case for the Chinese Building Sector. Zhi Cao, Gang Liu, Shuai Zhong, Hancheng Dai, and Stefan Pauliuk. Environ. Sci. Technol. 2019, 53, 1, 224–233. https://doi.org/10.1021/acs.est.8b03633
[38] Environmental, Social, and Economic Implications of Global Reuse and Recycling of Personal Computers. Eric Williams, Ramzy Kahhat, Braden Allenby, Edward Kavazanjian, Junbeum Kim, Ming Xu. Environ. Sci. Technol. 2008, 42, 6446–6454. https://doi.org/10.1021/es702255z
[39] Conceptualizing energy services : A review of energy and well-being along the Energy Service Cascade. Kalt, G., Wiedenhofer, D., Görg, C. & Haberl, H. Energy Research & Social Science 53, 47–58 (2019). https://doi.org/10.1016/j.erss.2019.02.026
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