The Circular Economy and Climate Change: The State of National and Global Evidence on Mitigation Potential

Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 Annual Review of Environment and Resources The Circular Economy and Climate Change: The State of National and Global Evidence on Mitigation Potential Dominik Wiedenhofer,1Hanspeter Wieland,1 Sina Leipold,2,3 Chika Aoki-Suzuki,4Takuma Watari,5 Glenn A. Aguilar-Hernandez,6,7 Simon Graf,1 Oreane Y. Edelenbosch,8Marianne Zanon-Zotin,8 Lisa Kaufmann,1Patricia Fortes,9Willi Haas,1 and Jan Streeck1 1Institute of Social Ecology, BOKU University, Vienna, Austria; email: [email protected] 2Department of Environmental Politics, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany 3Institute for Political Science, Friedrich-Schiller-Universität Jena, Jena, Germany 4Institute for Global Environmental Strategies, Hayama, Kanagawa, Japan 5Material Cycles Division, National Institute for Environmental Studies, Tsukuba, Japan 6Institute of Environmental Sciences (CML), Leiden University, Leiden, The Netherlands 7Academia de Centroamérica, Zapote, San José, Costa Rica 8Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, The Netherlands 9Centre for Environmental and Sustainability Research (CENSE) and Global Change and Sustainability Institute (CHANGE), NOVA School of Science and Technology, NOVA University, Lisbon, Portugal Annu. Rev. Environ. Resour. 2025. 50:563–92 First published as a Review in Advance on August 28, 2025 The Annual Review of Environment and Resources is online at environ.annualreviews.org https://doi.org/10.1146/annurev-environ-111523102441 Copyright © 2025 by the author(s). This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See credit lines of images or other third-party material in this article for license information. 563 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 Keywords circularity, sustainable resource use, ecological economics, integrated assessment model (IAM), computable general equilibrium model Abstract While global resource use and GHG emissions keep increasing, the circular economy (CE) has ascended to the forefront of global policy, business and research agendas. Through narrower, slower,and more closed material cycles,the CE aims to avoid waste and reduce virgin raw material demand, thereby potentially also mitigating energy demand and GHG emissions. We review 75 national to global studies modeling over 500 specific measures.Studies modeling narrower,slower, and more closed material cycles show a combined GHG mitigation potential of on average 17% (0–91%). When CE measures are complemented with energy efficiency and decarbonization of energy supply and industry, an average GHG mitigation potential of 50% (1–100%) is found. This indicates that the CE might have substantial mitigation potentials if combined wisely with other supplyand demand-side measures. Future research should strengthen the links between industrial ecology and economic modeling and fully implement open science principles. These improvements would pave the way toward a more robust, granular, and systemic understanding of the CE’s potential and limits for climate change mitigation and sustainable resource use. Contents 1. INTRODUCTION........................................................... 564 2. CONCEPTUALIZING THE CE AND CLIMATE CHANGEMITIGATION..................................................... 566 2.1. Agreements and Tensions About the CE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567 3. THE CE IN THE GLOBAL POLICY LANDSCAPE . . . . . . . . . . . . . . . . . . . . . . . . . . 571 4. ASSESSING THE EMPIRICAL NATIONAL-TO-GLOBAL LITERATURE................................................................ 572 4.1. Overview of the National to Global Quantitative Evidence Base . . . . . . . . . . . . . 573 4.2. CE Measures Modeled in the National to Global Literature . . . . . . . . . . . . . . . . . 575 4.3. Quantitative Evidence Summary of CE Potentials for Greenhouse GasMitigation............................................................ 576 5. DISCUSSION................................................................. 579 5.1. Greenhouse Gas Mitigation Potentials from Narrow–Slow–Close CEMeasures............................................................. 579 5.2. Future Research Needs to Robustly Quantify Mitigation Potentials of CE . .. 580 5.3. Policy Implications for Realizing the Greenhouse Gas Mitigation Potentials oftheCE................................................................. 582 6. CONCLUSIONS............................................................. 582 1. INTRODUCTION Global raw material extraction, waste, energy use, and greenhouse gas (GHG) emissions are steadily increasing (1–3). Subsequently, the climate crisis is intensifying, and carbon budgets remaining to limit global warming to 1.5–2°C above preindustrial levels are rapidly being used up (4, 5). GHG emissions due to materials production are estimated at 23–35% of global GHG 564 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 emissions, the majority of which are occurring in industry and are driven by investments into material stocks of buildings, infrastructure, and machinery (6, 7). In the high-income countries, material stocks are slowly growing and ageing, increasingly requiring maintenance and replacement. In the middleand lower-income countries, resource-intensive industrialization pathways and widespread underprovision with essential services drive further energy and material demand (8–10). Ongoing global stock expansion therefore results in greater material and energy demand and,subsequently,waste and GHG emissions.Materials-oriented GHG mitigation strategies such as the circular economy (CE) are therefore argued to be necessary to complement established supplyand demand-side measures aiming to improve energy efficiency and decarbonize energy supply,industrial processes, and land uses in the decisive decades for avoiding catastrophic climate change (1, 5, 11). Although the CE concept is sometimes simply interpreted as more recycling, most academic and public interpretations see the CE as addressing the entire life cycle of materials,products, and provisioning systems (12–14). The CE interpreted as systems approach aims to transform how materials are extracted,processed,and used,via measures narrowing,slowing,and closing material cycles (12, 15–17). Such a systems-based interpretation of the CE begins with measures to reduce material demand and improve the resource efficiency of products and service provisioning systems (narrow), extend product and component lifetimes (slow), and increase recycling (close), thereby aiming to avoid raw material extraction and waste, reduce energy use, and help mitigate GHG emissions (18). The CE has ascended to the forefront of global policy, business, and research agendas, with great expectations about its potential to help mitigate climate change and other environmental challenges (12). The prominence of the CE concept stems from its forward-looking focus on solutions to global environmental challenges (19), its reliance on the widely established metaphor of natural cycles (20), and its openness to multiple interpretations—from material cycles to sustainable business profits (21). These qualities attract diverse actors and interests under a broad, inclusive umbrella (17, 22). Depending on the interpretation of the concept (23, 24), some advocate the CE as an obvious win–win situation for sustainable development (15), whereas others call for careful assessments of the CE’s potentials, including possible trade-offs and limitations (24– 26). Practically, CE discussions connect existing concepts into a systems-oriented narrative that bridges policy silos and aims to inspire business and nonprofit activities (17). Meanwhile, the CE seems to be consolidating into its own distinct research field (16) with increasingly shared concepts and overarching research questions (14, 24, 27). This is evidenced by a rapidly growing literature (12, 28)—over 160 reviews (27)—new journals and conferences around the CE, and scientific societies creating new sections, with new associations emerging. The body of CE research focusing on the GHG mitigation potentials due to specific products,technologies, sectors, and business models is also growing rapidly (27, 28). However, previous reviews and most empirical modeling studies suffer from ambiguous CE definitions and varying study scopes across amultitudeofmethodsusingvariablesystemboundaries(29–34).Theseambiguities inhibit cumulative insights into the CE’s contribution to GHG emissions mitigation. Closely relevant reviews addressed CE potentials for GHG mitigation in the European construction sector (35), as well as progress in modeling the CE in macroeconomic optimization models (36,37), or via input–output analysis (38). Subsequently, evidence synthesis as advanced herein will be increasingly relevant to provide robust and context-specific scientific recommendations for policy and business. This review focuses on three aspects of the question of how and to what extent the CE can help mitigate GHG emissions. Section 2 conceptualizes the relation of the CE with climate change mitigation at the global level. Section 3 gives an overview of the global CE policy landscape, drawing on peer-reviewed and gray literature. Section 4 summarizes results from 75 quantitative www.annualreviews.org •The Circular Economy and Climate Change 565 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 prospective studies modeling the CE’s potentials to contribute to climate change mitigation at the national to global level. We include studies addressing CE potentials for metals and ores, nonmetallic minerals, plastics, timber, paper, and natural fibers across multiple sectors and at the economy-wide level. Section 5 discusses main insights and implications for future research. 2. CONCEPTUALIZING THE CE AND CLIMATE CHANGE MITIGATION The CE is usually understood as a systems concept, building on the widely accepted “reduce, reuse, recycle (3R)” waste avoidance hierarchy as well as eco-design principles (39). These 3Rs are nowadays differentiated into 10Rs: refuse, rethink, reduce, reuse, repair, refurbish, remanufacture, repurpose, recycle, and recovery (18, 40). The CE builds on a rich intellectual history (17), from bio-mimicry (18, 39) to extended producer responsibility (41) and resourceand material efficiency (31, 42), as well as sufficiency (43, 44) (see the Supplemental Appendix Section 4 for an overview). The 10R measures address the micro-level of products and the meso-level of business models and specific production–consumption systems (18, 23, 40). Implementing the 10R measures should lead to narrower, slower, and more closed material cycles at the macro-level of the entire economy (18). Narrower cycles are to be achieved via smarter product use and manufacture (refuse, rethink, reduce). Slower material cycles are to be achieved by extending the lifespan of products and their parts (reuse, repair, refurbish, remanufacture, repurpose). More closed material cycles are to be achieved via the useful application of end-of-life and waste materials (recycle, recovery). The CE literature distinguishes sociotechnical and socioecological material cycles, roughly corresponding to nonrenewable (metals, nonmetallic minerals, fossil energy carriers) and renewable resources (biomass) (14,23,45).Nonrenewable materials are to be managed in sociotechnical cycles in which waste is avoided and the value of materials, products, and components is maintained for as long as possible, through slower and more closed material cycles. Renewable biomass materials are also to be kept in use for as long as possible,mainly via cascading uses from high value to lower value applications. For renewable materials and socioecological cycles, the aim of the CE includes the redesign of land systems to restore biosphere integrity and bring biogeochemical flows of phosphor and nitrogen back into the safe operating space of the Earth System (46, 47). Although narrower, slower, and more closed material cycles aim to avoid waste and reduce virgin raw material demand, they can also play an important role in reducing energy use and GHG emissions from energy supply and industrial processes as well as agriculture, forestry, and other land uses (AFOLU) (18). Meanwhile, climate change mitigation measures have mainly focused on supply-side measures, aiming to improve energy efficiency across sectors, decarbonizing the energy system and industry, as well as making land use less GHG intensive (5). Policies usually target energy supply and energy-intensive sectors in industry, housing, and transport, as well as AFOLU (4, 48). Policy goals commonly include expanding renewable energy supply, adopting energy-efficient and carbon-free technologies, increasing public transport, modal shifts and shifting electric vehicles, electrifying energy demand, and increasingly carbon capture and storage (CCS) (4, 5). Uncertain and risky negative emission technologies including CCS have become central in scenarios limiting global warming to 1.5–2°C above preindustrial levels (4, 5). Common policies for AFOLU include improved land management (e.g., reduced methane emissions by improved manure management), carbon sequestration (e.g., reand afforestation), and land conversion (e.g., reduced deforestation and degradation) (5). Recently, demand-side measures aiming to avoid-shift-improve (ASI) upon GHG-intensive activities, products, and services are coming into focus (5, 11). The ASI framework originates in transport studies and is increasingly 566 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 used in demand-side climate change mitigation research, being positioned as a complement to established supply-side approaches helping reduce the reliance on CCS and other negative emissions technologies (11, 49). Clearly there are conceptual overlaps between ASI and the 3Rs and 10Rs in the CE, but these concepts originate from different research communities. For the analytical purpose of this review, we therefore conceptualize ASI as aiming at energy use and GHG emissions, whereas the CE primarily considers materials and products. Here, we provide a first quantitative orientation for how the CE could contribute to climate change mitigation (Figure 1, compiled from References 7 and 8). We locate the CE via the 10Rs and narrow–slow–close outcomes vis-à-vis latest assessments of global material cycles and sectoral global GHG emissions (Figure 1). In the year 2020 (8), 94.7 Gt/year of primary metals and ores, biomass, nonmetallic minerals, and fossil energy carriers were extracted, of which 39.8 Gt/year were used for energy supply, food, and feed, whereas the remaining 64.3 Gt/year were used as technical materials for producing and constructing material stocks of buildings, infrastructure, machinery, and other short-lived goods (Figure 1b). Only 9.5 Gt/year of materials were recycled. The headline indicator circular material use rate (50) quantifies the amount of recycled secondary materials (9.5 Gt/year) in total material inputs into the economy (104 Gt/year),suggesting that the global economy is only 9% circular (8). Similar or even lower circular material use rates are found in country-level studies (50–55). Reasons for the low circular material use rate include ongoing stock growth requiring large amounts of primary resources and the large share of fossil fuels in energy supply, as well as relatively low recycling rates for most materials except iron and steel as well as paper. To relate material cycles to GHG emissions,we also show sectoral direct on-site emissions and the GHGs from electricity and heat demand of these sectors, as covered in emissions reporting1 (Figure 1c). Materials-related emissions amount to 25–35% of global GHG emissions in 2019, the majority of which are occurring in industry and are driven by investments into material stocks of buildings, infrastructure, and machinery (6, 7). These emissions occur during the refining of ores into metals (8%), the production of chemicals and plastics (7%), the calcination of cement (3%), and during waste management (4%), as well as along complex global production networks (6, 7). These large materials-related emissions give a first illustration of the potentials of the CE to contribute to climate change mitigation via narrower, slower, and more closed material cycles. 2.1. Agreements and Tensions About the CE Although there is no widely accepted authoritative definition of the CE so far, there are several important points of agreement across most CE definitions (14). These are that the principal aim of the CE is sustainable development, that a fundamental transformation of the economy is required,that the 10R framework is a useful heuristic to conceptualize CE measures,and that policy, business, consumers, and academia are together required as coordinated enablers of a CE transition. Competing definitions and remaining tensions about the CE are because of (16, 57, 58) multiple contributing research fields that so far lack a shared ontological basis, as well as because the CE is a strongly transdisciplinary concept driven by nonscientific stakeholders,from nonprofit organizations such as the Ellen MacArthur Foundation and consulting firms, as well as businesses interests and policy makers. Finally, different paradigmatic worldviews implicitly shape CE discussions, similar to agreements and tensions about the concept of sustainable development (23, 59, 60). 1These allocations of GHG emissions are called scope 1 for direct on-site emissions and scope 2 for the emissions occurring in the supply of electricity and heat. Not shown here is a scope 3 allocation, which would cover all upstream and downstream emissions. www.annualreviews.org •The Circular Economy and Climate Change 567 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 b c a Refuse (R1), Rethink (R2), Reduce (R3): Narrower material cycles, via smarter product use and manufacture 0 10 20 30 40 50 Global scope 1+2 GHG emissions by sector in 2019 (gigatons CO2e/year) Earth system Reuse (R4), Repair (R5), Refurbish (R6), Remanufacture (R7), Repurpose (R8): Slower material cycles, by extending the lifetime of products and components Recycle and downcycle (R9), Recover energy content (R10): Closed material cycles, via useful application of materials World 2020, economy-wide material flows Balancing items (input) 54.3 Gt/year World 2020, economy-wide material flows Balancing items (input) 54.3 Gt/year Balancing items Flows (aggregated) Biomass Buildings Shipping Aviation Land transport Other (industry) Waste Chemicals Metals Cement AFOLU Energy systems Fossil fuels Metals Nonmetallic minerals Dissipative uses of products 0.6 Gt/year Air emissions 45.0 Gt/year Solid and liquid waste 25.4 Gt/year Balancing items (output) 47.0 Gt/year International trade 14.1 Gt/year Material extraction 94.7 Gt/year Material input 104.0 Gt/year Material consumption 104.0 Gt/year Technical use 64.3 Gt/year Domestic processed output 80.3 Gt/year Recycling 9.5 Gt/year Net addition to stocks 31.0 Gt/year Energetic use 94.1 Gt/year AFOLU Industry: metals, chemicals, cement, other industries Energy and food system Industry: waste Industry: waste Use of material stocks Figure 1 Situating the circular economy and its aim to narrow, slow, and close material cycles vis-à-vis global material cycles, energy use, and GHG emissions. (a) Locating the micro-/meso-level 10R measures (40) and their envisioned macro-level outcomes of narrower, slower, and more closed material cycles. (b) Global economy-wide resource use patterns and the resulting waste and emissions, differentiating resources used for energy provision, food, and feed, from the materials processed into long-lived material stocks and short-lived products. Data taken from Reference 8. (c) Global GHG emissions by sector including upstream emissions from electricity and heat provision. Data taken from References 7 and 56. Abbreviations: AFOLU, agriculture, forestry, other land use; GHG, greenhouse gas; Gt, gigatons (109metric tons). 568 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 Optimist Takes CE as a driver of sustainability transition Skeptical Questions CE’s usefulness for sustainability transition Reformist Anticipates CE’s transformative potential, but only if contested conditions are met CE regulations drive progress in resource efficiency policy and business action CE emphasizes technology solutions when barriers to CE are more economic CE raises societal awareness but social objectives need to be included in policies, monitoring, and definitions CE rarely decouples economic growth and environmental impacts CE delivery of environmental and economic benefits is weakly substantiated Focus on managerial-technooptimism hinders transformation Policy needs to address systemic roots of unsustainable resource use (e.g., growth paradigm, capitalism) Policy intervention faces resistance and prioritization for free-market measures hampers progress Industry welcomes growth discourse and CE vagueness to prevent radical change Shifting ownership negatively affects disadvantaged social groups Policies across governance levels need common frameworks for measuring and monitoring Policies should focus on absolute limits and decoupling services from material basis Policy is crucial for CE success Diverse stakeholders and local groups need to be included in CE development CE is a powerful metaphor that breaks silo-thinking, engaging companies and bringing economic benefits Needs closed loops, new business models, data and technology, etc. Needs better conditions for innovation (to ensure value creation aligns with regenerative practices) Needs further research on CE conceptualization, framing, and limitations Needs data on stock growth, quality, and quantity CE is the only form of human development within planetary boundaries as it reduces per-capita environmental pressures A critical eye on rebounds and greenwashing is necessary Economic Social Political Environmental Research Dimensions Figure 2 Three narratives about the circular economy (CE) and the key points of agreements as well as tensions underlying the assessment of academic experts of how and if the CE can contribute to sustainable development and climate change mitigation. Figure adapted from Reference 24. Leipold et al.(24) empirically synthesized prevalent agreements and tensions about the CE into three diverging narratives reflecting different paradigmatic worldviews about the CE, extended upon early conceptual considerations (23) (Figure 2). They (24) distinguish a techno-optimist narrative that treats the CE as synonymous with innovation, entrepreneurship, and sustainability, as well as a reformist transformative narrative accepting the CE’s potentials while highlighting potential limits and trade-offs with other socioeconomic goals as well as emphasizing the need for strong policy guardrails. The third worldview identified by Leipold et al. (24) is a skeptical narrativethatemphasizes how the CE distractsfromthecontradiction of endless economic growth on a finite planet, how it can easily be misused for greenwashing, and that it might reinforce structural inequalities and exploitative relationships. All narratives do agree that strong policy and www.annualreviews.org •The Circular Economy and Climate Change 569 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 governance and a diversity of stakeholder voices are crucial for the success of a CE, as well as that biophysical monitoring and assessment methods need to be advanced (24). From Leipold et al.’s study on worldviews and narratives about the CE (24) and the wider literature, we also summarize seven key tensions about the CE’s potential below (Sections 2.1.1–2.1.7). 2.1.1. Decoupling economic growth from resource use and greenhouse gas emissions is/is not possible with regulatory reforms. Whether economic growth can coexist with ecological limits is a key tension in the CE discourse. While optimist CE narratives promote efficiency and technological solutions to do more with less, especially skeptical positions argue that the CE sustains business-as-usual (BAU) growth models without structurally challenging them (20, 26, 61). 2.1.2. Encouraging entrepreneurship and innovation will/will not benefit the environment. Optimists claim that CE entrepreneurship and innovation will benefit the environment while skeptics and reformists argue that so far innovation has accelerated economic growth, usually resulting in rebound effects that ultimately increase resource use (62,63).All narratives do agree that regulation and strong governance are necessary to ensure that the CE is aligned with sustainable development and to prevent misleading claims. 2.1.3. The environmental benefits of CE implementation strategies are/are not proven. Optimists argue that CE measures are a win–win situation for environmental and economic goals while skeptics and reformists point out that problem-shifts and rebound effects are widespread. The environmental and GHG mitigation benefits of specific CE measures are tricky to assess, with conflicting evidence (29). This is partly because of different research assumptions and data sources, and partly because measures often focus on optimizing specific aspects of production– consumption systems,without addressing the entire business model and life cycle of products.For example, increasing paper recycling without ensuring a carbon-free energy supply might increase overall GHG emissions along the entire paper life cycle (64). 2.1.4. Efficiency, not sufficiency, will primarily create a sustainable CE. CE optimists promote efficiency and technical solutions, focusing on supply-side measures such as optimizing resource use and improving recycling processes. In contrast, reformists and skeptics argue that such technology-focused solutions alone are not enough and that complementary demand-side measures are necessary to reduce consumption and shift production patterns (61, 65). 2.1.5. Justice and equity are/are not a prerequisite for an environmentally sustainable CE. Although much of the current CE debate has ignored issues of justice and equity (27), skeptics argue especially that production and consumption drive historical and current inequalities, so addressing these concerns through resource redistribution is essential for a CE to contribute to sustainable development. Justice is crucial to ensure that all stakeholders are included, resources are distributed fairly, and those harmed by CE strategies are compensated (66, 67). This is particularly important in today’s globalized supply chains, where any ambitious CE measure will likely have repercussions globally (68, 69). 2.1.6. An environmentally sustainable CE should be achieved locally, not globally. Especially skeptics and some reformists argue that the CE needs to be localized with shorter supply chains and regional production as well as reuse and recycling to minimize environmental impacts and strengthen local communities.Optimists tend to argue that the CE needs to focus on globalized supply chains, as those are seen as beneficial for the common good and achieving economic efficiency. This tension is especially relevant in the Global South, which often supplies raw materials to the Global North (8, 52), raising questions about fair CE implementation worldwide. 570 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 2.1.7. An environmentally sustainable CE should focus on the common good, not on profitability. Optimists tend to see profitability and market growth as primary drivers for CE implementation, together with policy and governance. Reformists tend to argue that CE measures and circular business models can be less profitable economically while yielding larger social and environmental benefits. Skeptics emphasize that CE should help promote social and environmental justice (67), even if this comes at the expense of short-term profits. In summary, though a consensus definition would be important for policymaking and businesses to orientate and evaluate their efforts, a truly final definition might be elusive, owing to the transdisciplinary nature of the CE as a concept and its implications for specific sectors and sociocultural contexts (14, 24). We do note that the CE discussion is increasingly moving beyond a product-centric resource efficiency perspective toward embracing the complexity involved in implementing the CE for sustainable development and considering potential trade-offs among social, ecological, and economic goals. 3. THE CE IN THE GLOBAL POLICY LANDSCAPE CE policies originate in wasteand materials-oriented thinking, with climate change mitigation only recently becoming a major new emphasis. The first explicit CE policies originated in Japan in the 1990s, operationalizing the 3Rs heuristic into the sound material-cycle society concept (70). Shortly after, the CE was taken up in Chinese policy, focusing on industrial symbiosis and waste management (71). In 2015 and 2018, the European Union (EU), enacting their first CE policies (72),mainly aimed at improving resource efficiency,avoiding waste,improving end-of-life waste management, and increasing recycling; there was little direct reference to GHG mitigation. Recently, countries in North America (73), Latin America and the Caribbean (74), and several Asian countries (75) have also started developing CE policies. At least 75 national calls to action, roadmaps, and operational strategies were identified as of 2024, and at least 10 more are being developed (76, 77). As of 2024, the CE has come center stage in the global policy discussion, for example, in the United Nations Environment Assembly (UNEA) 5.2 resolution on the CE (78), the G20 Resource Efficiency Dialogue (https://g20re.org/), and the G7 Alliance on Resource Efficiency (https://www.g7are.com/). There, the CE is interpreted as a tool for addressing the triple planetary crisis of pollution, climate change, and biodiversity loss at the global level, potentially also alleviating materials criticality and supply security. In 2024, the UNEA-6 Ministerial Declaration called on Member States and United Nations observer states to develop resource efficiency and CE strategies (79).Multiple regional roadmaps and coordination efforts are being established,e.g., in the EU,Africa and the Association of Southeast Asian Nations (ASEAN) countries (76). Meanwhile, the Global Environment Facility and the Multilateral Development Banks have initiated various CE financing initiatives (80). CE policies so far mainly target brokering, fiscal instruments, research, as well as producer and product requirements, and business support, as well as circular resource and waste management (76). Examples are the 2nd European Union Circular Economy Action plan (81) and the US REMADE Institute,2as well as multiple efforts in China and other Asian countries (82–85). Specific measures range from shifting taxation, digital product passports, requirements for 2The REMADE Institute was founded in 2017 and is the only national institute and a public-private partnership established and funded in part by the US Department of Energy’s Office of Advanced Materials and Manufacturing Technologies with an initial investment of $140 million (https://remadeinstitute.org/ about/). www.annualreviews.org •The Circular Economy and Climate Change 571 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 energy-intensive reprocessing. These authors (108) also show that wealthier Chinese provinces could close material cycles decades earlier than less-developed ones, due to higher end-of-life material availability, suggesting that context-specific CE strategies are necessary. Berrill et al. (109) show that for buildings in the USA, renovation and electrification reduce emissions more than rebuilding, as new homes generate higher embodied emissions and tend to be larger, offsetting efficiency gains. As operational emissions decline, embodied emissions dominate, highlighting the need for smaller homes and low-carbon materials. Mastrucci & Rao (110) demonstrate that the substitution of GHG-intensive materials can help attain decent living standards in India with substantially reduced emissions and energy consumption while also lowering construction costs. Examples for trade-offs between more closed cycles via increased recycling and decarbonizing energy supply are found for plastics (99, 111) and shifting chemical feedstocks (112) from fossil fuels to carbon capture and utilization (CCU). For example, replacing all chemical feedstock by CCU would require low-carbon electricity amounting to up to 55% of the globally projected electricity generation in 2030. Although CCU could reduce annual GHG emissions by up to 3.5 Gt CO2e in 2030, it would also compete for low-carbon electricity that could be used for impactful GHG mitigation measures, such as heat pumps and electric vehicles; similar issues are found for very high plastics recycling rates (99, 111). For energy use, we find an average mitigation potential of 14% (0–48%, 13 data points) from the combined modeling of CE measures (Figure 5). When modeling CE measures together with energy efficiency and decarbonization, we find energy use mitigation potentials of 22% (+22– 92%, 23 data points). Importantly, some studies suggest that energy use for concrete and steel production, as well as buildings and infrastructure, might increase in absolute terms even with CE measures, energy efficiency, and decarbonization. For example, Gaspard et al. (102) find an increase of 6% for French buildings, de Souza & Pacca (113) find an increase of 11–22% for steel and cement industries in Brazil, and Haas et al. (124) find an increase of 14–22% for buildings, transport, and electricity sectors in Austria. These findings reflect that energy use is a prerequisite for production and consumption and that many CE measures might require similar energy use compared to primary materials production. Metals and especially iron and steel cycles are of significant interest in the CE literature, because the steel industry is responsible for approximately 7% of global GHG emissions and is considered a challenging sector to decarbonize (114). Although the industry has well-established recycling routes via electric arc furnaces, future demand for steel is projected to more than double in the coming decades (3). Global progress in decarbonizing the steel sector has largely stagnated since 1995 (115). Technological efficiency improvements have been offset by the growth of carbon-intensive steel production, particularly in China. Some potentials for narrower steel cycles through avoiding waste are still available, for example, avoiding the 26% of liquid steel that is currently lost as process scrap and never reaches final products (116). The literature therefore suggests that it is essential to narrow metal cycles by rapidly stabilizing per capita metal stock levels (1, 117), as well as reducing the GHG emission intensity of production, particularly within fast-growing middle-income countries (118, 119). Enhanced recycling becomes the major strategy once sufficient material stocks are accumulated and coming to their end of life to supply recycling. However, achieving a CE at the regional or national level is challenging, because no single country possesses the complete set of technologies as well as fully decarbonized energy systems for high recycling without GHG emissions (69, 120). Advanced recycling technologies that can efficiently process scrap metal may be unavailable or unaffordable in regions with underdeveloped infrastructure,leading to lower recovery rates and poorer quality of recycled metals. The metal cycle extends beyond national borders and operates 578 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 on a global scale; approximately two-thirds of global metal ore extraction are destined for international trade (8). In addition, manufactured products and scrap often cross borders multiple times. For example, Serrenho et al. (121) find that regardless of changes in the United Kingdom’s iron and steel industry, GHG mitigation requires addressing the United Kingdom’s reliance on net steel imports from other carbon-intensive producers. Therefore, a net-zero GHG CE for metals seems more sensible on a global scale (120, 122). Nonmetallic construction minerals are quite different in this regard, as large volumes and high weight are prohibitive for large-scale long-distance transport, making regionalized recycling networks a much more useful strategy (123). The feasibility of reusing or recycling demolition waste largely depends on the distance between supply sources and end-use sites because of the high (environmental) cost of transportation. Despite limitations in the evidence base, we conclude that CE measures alone can have substantial GHG mitigation potentials, which more than double on average when modeled in combination with energy efficiency and the decarbonization of energy supply and industrial processes (Figure 5).The large ranges of mitigation potentials found across the 75 studies (Figure 5) indicate three important challenges: First,because some studies provide more detailed results than others, the ranges of mitigation potentials shown suffer from reporting bias, as some individual measures might have small mitigation potentials, whereas combined CE scenarios have in total higher potentials. Second, the much smaller potentials of slowing material cycles via lifetime extensions might also be biased because of the limited evidence about individual measures across all studies; this is a challenge in clearly attributing mitigation potentials across multiple measures and crucially so because most scenarios run until the year 2050. Third, a substantial portion of GHG mitigation benefits may occur later, especially for already long-lived stocks like buildings and infrastructure (105, 124). Although energy efficiency and decarbonization are crucial complementary strategies (Figure 5), the lack of detailed scenario results from the reviewed literature inhibits fully disentangling the contributions of each materials-oriented circularity measure, vis-à-vis other supplyand demand-side measures for climate change mitigation. Therefore, implementing FAIR data standards is crucial for facilitating robust and granular evidence synthesis in the future. 5. DISCUSSION 5.1. Greenhouse Gas Mitigation Potentials from Narrow–Slow–Close CE Measures This quantitative review of 75 national to global level modeling studies exploring over 500 individual measures shows large GHG mitigation potentials of narrow–slow–close CE scenarios across a large spectrum of sectors, product groups, and materials (Figures 4 and 5). Energy efficiency and decarbonization of energy supply and industry emerge as clearly complementary strategies,which help bring sectors closer to net-zero GHG emissions. Net-zero GHG energy supply is repeatedly identified as a condition of the possibility for a net-zero CE in the future. For example, increased paper (64) and plastics (99, 111) recycling, as well as replacing chemical feedstocks from fossil fuels with carbon captured and utilized (112), might not mitigate GHG emissions as long as the industry’s energy supply is not decarbonized. Importantly, trade-offs can occur when the GHG mitigation potentials of high recycling rates require substantial amounts of low-GHG electricity supply, which might also be used to decarbonize other sectors more effectively (111, 112). Most materials cannot be recycled without material and quality losses (26, 61). Plastics and paper degrade with each reprocessing,and recycling of metals involves losses and requires substantial energy, which still comes largely from nonrenewable sources. Hence, closed material cycles www.annualreviews.org •The Circular Economy and Climate Change 579 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 are most usefully understood as an aspirational theoretical benchmark (125). Clearly, there are large untapped potentials due to low recycling rates for many materials and countries. Many of the reviewed studies emphasize that beyond closing loops, narrowing via demand reduction and resource-efficient product design and provisioning are crucial for a CE to reduce GHG emissions. 5.2. Future Research Needs to Robustly Quantify Mitigation Potentials of CE We identify three future research needs emerging from the following limitations. First, more robust and granular modeling of the CE’s potentials for GHG mitigation requires addressing the dynamic interconnections of materials cycles, waste, energy, and material stocks and linking them to models depicting socioeconomic dynamics (32, 95, 96, 126). Single modeling approaches do not provide a sufficiently comprehensive and robust multidimensional assessment of the CE for climate mitigation (95, 96, 126). IOA and LCA do not reflect the dynamics of energy transitions and CE measures, including the deployment of new technologies and improved processes over time. MEFA models do not endogenously capture the trade-offs between material flows and the necessary adjustments in energy systems. IAMs and CGE models—extensively used to support macro-level mitigation decisions and policies—frequently lack biophysical consistency and usually do not present the necessary value-chain granularity. Second, data limitations regarding economy-wide material cycles (127, 128) and the absence of harmonized classification systems for materials,as already available for energy,hamper current CE assessments.Information on material and energy trade-offs, product maintenance costs, recycling limits based on regional or national scrap quality and quantity, and consumer behavior—including willingness to change habits and the magnitude of rebound effects—often are scattered across detailed studies with variable system boundaries or are completely unavailable. Third, an often overlooked issue is transport and trade. Circular supply chains frequently involve fragmented shipments, multiple handling points, and possible additional transport steps (e.g., from consumers to collection, sorting, and recycling units), the impacts of which on GHG emissions are yet unclear. Similarly, the implications of CE measures in certain world regions on key trading partners and across global supply chains are not properly addressed in the reviewed literature. Five research efforts therefore seem essential, which are being addressed in ongoing projects around the world, including Horizon Europe–funded work.3First, ongoing efforts aim to integrate industrial ecology with a variety of economicand processed-based IAMs, aiming to capture the complexities associated with material cycles and stocks,as well as rebound effects and other socioeconomic implications, and the technology shifts needed for climate mitigation (32, 129–131). Based on aligned system boundaries, industrial ecology and economic approaches could then providemultidimensional assessments ofbiophysicaland socioeconomic costs,benefits,andtrade-offs of different CE transformation pathways (49, 95). Second, expanding biomass use to substitute GHG-intensive materials such as concrete and steel is widely discussed and modeled, however, often with overly simple assumptions. Currently, material uses of biomass for construction and various products (timber, paper, fibers) play a minor role compared to biomass use as energy carrier and for food and feed (8, 132). Biomass does have the potential to be biodegradable and carbon neutral within limits, although intensifying land use and growing biomass demand are already creating a critical land squeeze (133, 134). Further work is necessary to understand an environmentally sustainable level of biomass extraction and 3For example, see https://circomod.eu,https://circeular.org,https://co2nstruct.dtu.dk,https:// mapsresearch.eu/, and https://www.realpostgrowth.eu/. 580 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 land use (47, 133, 134). This includes the carbon opportunity costs of harvesting timber for the construction of buildings versus the growth of natural carbon stocks in forests (104, 135–137). It also pertains to the carbon opportunity costs and net GHG benefits of more circular/cascading biomass use, e.g., prioritizing reuse of timber over burning for energy, or leaving forests to grow (35, 138–140). Third, common conceptual frameworks as proposed herein are required to facilitate the synthesis of study results into overarching insights. This starts with establishing standardized data exchange protocols and a data ontology (30, 141), as well as creating comprehensive, robust and open databases on historical material flows and stocks across various products and sectors (142– 145). Necessary data to represent higher-tier R-measures aiming to narrow and slow are often insufficient, requiring work-intensive surveys and field work. Integrating empirically driven and context-specific microand meso-level research into macro-level modeling is a key task here. Ongoing efforts by the industrial ecology community (145, 146), the Integrated Assessment Modeling Consortium (IAMC; https://www.iamconsortium.org), the International Transport Energy Modeling (iTEM) network (https://transportenergy.org/), and the Energy Demand changes Induced by Technological and Social innovations (EDITS) network (https://iiasa.ac. at/projects/edits) are working on such ontologies and templates, aiming to facilitate contributions to the 7th Intergovernmental Panel on Climate Change (IPCC) assessment and beyond. Herein, we advanced the narrow–slow–close grouping of the many possible specific CE measures and the clear delineation from energy efficiency and decarbonization as a first step toward such a framework. Fourth, linking CE scenarios to the latest shared socioeconomic pathways (SSPs), as for example in Reference 147, as well as ongoing efforts toward developing a new postgrowth SSP (148), would help to show the wider relevance of CE measures in the context of various other supplyand demand-side measures being explored. The SSPs are a common framework connecting research on mitigation,adaptation,and impacts,and since their inception in 2014 they have been developed further (149, 150), with substantial quantitative updates4released in 2024. Developing additional, regionally specific CE pathways, grounded in empirical evidence, could improve transparency and integrate microand meso-level empirical research into macro-level models. This would facilitate future evidence synthesis for policy, as well as for assessment reports conducted by the IPCC or the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Finally, another important avenue for macro-level CE research is to deepen the engagement with environmental-economic monitoring and reporting frameworks. Statistical agencies are increasingly compiling CE-relevant information to provide progress toward policy targets. These efforts build on economy-wide material flow accounting as part of the System of EnvironmentalEconomicAccounts,which arealreadyused to monitor thecircularmaterial use rate ofnationsand the global economy (50, 52–54, 132). Here, it is important to see that energy and emissions monitoring have a relatively long history and by now provide relatively granular and consistent data, as the accounting is hosted by international bodies such as the International Energy Agency, the International Renewable Energy Agency, the Food and Agriculture Organization, and the United Nations Framework Convention on Climate Change. In comparison, economy-wide monitoring of material cycles, stocks, and circularity is relatively young (127, 128). Therefore, the biophysically consistent integration of materials–energy–GHG monitoring is therefore another important research frontier. 4Refer to https://depts.washington.edu/iconics/ and https://www.iamconsortium.org/event/iconicsand-iamc-joint-webinar-shared-socioeconomic-pathways-ssps-update/. www.annualreviews.org •The Circular Economy and Climate Change 581 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 5.3. Policy Implications for Realizing the Greenhouse Gas Mitigation Potentials of the CE Despite the promising GHG mitigation potential found (Section 4), the CE risks fragmentation and misuse without clear boundaries and careful assessment of trade-offs. Although the CE concept bridges academia, business, and policy like few other sustainability concepts (16), its broad appeal is both a strength and a challenge. The CE draws in diverse interests and perspectives, which can lead to fragmented implementation or even co-optation by powerful actors. The disagreements outlined in Section 2.1 and the research gaps in Section 5.2 reveal key compromises and risks in CE strategies.Beyond thermodynamic and biophysical limits, meaningful assessments must also account for critical societal and (geo)political trade-offs. A fundamental societal risk is increasing global consumption and rebounds undermining the promise of absolute and deep decoupling of resource use from economic growth (13, 151, 152). Although some CE strategies can extend product lifetimes or improve materials efficiency, these gains are often outweighed by increasing global consumption. For instance, technological efficiency improvements in the steel sector have been offset by the growth of high-carbon intensity steel production, particularly in China. Researchers therefore warn of rebound effects: Efficiency gains that lead to price reductions can lead to higher consumption and negate the climate benefits (62, 108). Geopolitical tensions and trade-offs across spatiotemporal scales further constrain a CE global vision. As more countries implement circular strategies, global demand for secondary materials and recyclable inputs could intensify. This risks stripping local communities—especially in resource-rich but economically disadvantaged regions—of the materials they need to build up their own economic systems (52). Conversely, efforts to achieve local self-sufficiency could challenge global supply chain dependencies. To add to the complexity, current patterns of resource flows between the Global North and South perpetuate colonial extractivist dynamics. Access to CE technologies is not evenly distributed. Wealthier countries and groups often have better infrastructure for repair, recycling, or reuse while others become hotspots for dumping waste or extracting raw materials (52, 153–155). How can scientific evidence help to design policies that avoid these societal and political trade-offs and risks? Our analysis suggests some immediate policy implications. Binding resource reduction targets, for instance, should complement existing recycling and reuse goals to avoid rebound effects.Furthermore, divestment from linear production and consumption systems and investments in new infrastructures and technologies—in the Global North and South— are needed. Any public funding for CE initiatives should be tied to social co-benefits, such as improved labor conditions or reduced extraction from the Global South. CE regionalization strategies could support repair centers, regional recycling infrastructure, or bio-based loops that strengthen local economies and communities while reducing environmental pressures. Finally, establishing a common vocabulary and data infrastructure is essential. One way forward could be the creation of an independent CE accountability body—one that sets standards to develop evaluation frameworks and monitors net sustainability gains across environmental, social, and economic dimensions. This body could be supported by systemic, transdisciplinary CE research, embedding questions of power, equity, and cultural practice into how we design and evaluate CE policies. 6. CONCLUSIONS The 75 reviewed modeling studies exploring the CE at national to global levels show great climate change mitigation potentials, especially if CE measures are complemented with energy efficiency 582 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 and decarbonization. We find that the CE can potentially reduce material use and GHG emissions more than energy use, whereas mitigation potentials are less clear. At the same time, we summarized a set of biophysical, social, and (geo)political trade-offs and risks inherent in many CE strategies. These trade-offs and risks inform a set of interconnected future research needs, which are being addressed in multiple large-scale research projects around the world. Currently, the lack of consistent baseline information and scenario data poses challenges for granular evidence synthesis and specific science-based policy recommendations. We therefore highlight the need for more open science, FAIR data, and interdisciplinary collaborations linking industrial ecology with traditional and heterodox economic approaches to facilitate more policy-relevant evidence synthesis in the future. Finally, we emphasize that evidence synthesis needs to go hand in hand with adequate policy processes, embedding questions of power,equity, and cultural practice into the design and evaluation of CE policies.A politically transparent and coordinated approach to these trade-offs and risks is not something that is just nice to have; it is a prerequisite for an environmentally and socially sustainable CE. Ultimately, the macro-level climate benefits of a CE depend on who controls the loops, who benefits, and who pays the price. SUMMARY POINTS ■The circular economy (CE) is a materials-oriented strategy that aims to narrow, slow, and close economy-wide material cycles, avoiding waste and reducing primary material demand, and thereby mitigate energy demand and GHG emissions. ■The CE is complementary to and partially integrates other materials-, energyand GHG-oriented supplyand demand-side mitigation strategies, such as material efficiency, avoid–shift–improve, energy efficiency, and material substitution, as well as dietary change, sustainable land use, degrowth, and postgrowth. ■Although CE policy originates from a few pioneering countries originally focusing on resource efficiency and avoiding waste, in 2024 more than 79 countries reference the CE within their Paris Agreement Nationally Determined Contributions (NDCs) to climate change mitigation. ■Competing interpretations of the CE’s potentials and limits, combined with the lack of a generally accepted definition, result in tensions about how to operationalize, analyze, and implement the CE in a systems-oriented manner. ■Neither concrete measures nor monitoring systems to ensure climate change mitigation through circularity at the national level have been developed yet. ■Studies modeling national to global material cycles find substantial GHG mitigation potentials of on average 17% (0–91%) from measures solely narrowing,slowing,and closing material cycles. ■When CE measures are modeled in combination with energy efficiency and decarbonization of energy supply and industry, GHG mitigation potentials reach on average 50% (1–100%). ■There are significant variations in the materials, energy and GHG mitigation potentials reported across national-to-global-level studies due to ambiguous system definitions arising from diverse disciplinary backgrounds and the inherent complexities involved in www.annualreviews.org •The Circular Economy and Climate Change 583 Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 modeling the numerous interdependencies among material cycles, energy systems, and GHG emissions across sectors and supply chains. FUTURE ISSUES ■Agreed upon CE frameworks and indicators are required to show CE potentials, tradeoffs,and synergies for climate change mitigation at national levels,ideally extending upon established economy-wide CE monitoring frameworks in the European Union, China, and Japan. ■The unintended consequences of national CE policies on key trading partners, particularly those in the Global South, as well as the dependence on global coordination and collaboration to achieve domestic CE goals should be addressed more explicitly in future work. ■Ensuring biophysical consistency in the analysis of economy-wide material cycles,energy use, material stocks, and GHG emissions is crucial for understanding how CE measures interact with socioeconomic dynamics as well as other supplyand demand-side GHG mitigation measures. ■It is crucial to clearly define and report the specific modeled measures and their respective materials, energy, and GHG mitigation potentials ideally in a standardized format to facilitate disentangling the respective contributions and trade-offs among CE measures as well as energy efficiency and decarbonization efforts. ■Understanding GHG mitigation potentials from socioecological biomass cycles requires systematically assessing trade-offs between ecosystems and socioeconomic systems over time, which substantially increases modeling complexity and is currently oversimplified in most life cycle assessment studies. ■Shared concepts and scenario narratives, as well as open science principles and findable, accessible, interoperable, and reusable research data (FAIR), ideally in widely used data exchange formats, are needed to facilitate the combination of models, the comparison of results, and the synthesis of evidence. ■Connecting CE scenarios with the shared socioeconomic pathway framework is importantsothatthe Intergovernmental Panel on ClimateChange andother assessmentefforts can integrate the potentials of the CE into evidence synthesis. DISCLOSURE STATEMENT The authors are not aware of any affiliations, memberships, funding, or financial holdings that might be perceived as affecting the objectivity of this review. AUTHOR CONTRIBUTIONS D.W.contributed to the article’s conceptualization,methodology,investigation,resources,writing of the original draft, review and editing, visualization, supervision, project administration, and funding acquisition. H.W. contributed to the article’s investigation, methodology, formal analysis, 584 Wiedenhofer et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 141.244.126.58 On: Wed, 08 Oct 2025 08:18:55 EG50_Art22_Wiedenhofer ARjats.cls September 26, 2025 16:39 data curation, visualization, and writing of the original draft. S.L. and C.A.-S. contributed to the article’s investigation and writing of the original draft. T.W. and G.A.A.-H. contributed to the article’s investigation, data curation, and review and editing. S.G. contributed to the article’s investigation,formal analysis, data curation, visualization,and writing of the original draft.O.Y.E., M.Z.-Z., and P.F. contributed to the article’s investigation, data curation, and writing of the original draft. L.K. contributed to the article’s investigation, data curation, and review and editing. W.H.contributed to the article’s conceptualization,investigation,and writing of the original draft. J.S. contributed to the article’s conceptualization, methodology, formal analysis, investigation, data curation, visualization, supervision, writing of the original draft, and review and editing. ACKNOWLEDGMENTS The authors received funding from The European Union’s Horizon Europe program (CircEUlar, grant agreement number 101056810 and CircoMod, grant agreement number 101056868), the Energy Demand changes Induced by Technological and Social innovations (EDITS) project, coordinated by the Research Institute of Innovative Technology for the Earth (RITE) and International Institute for Applied Systems Analysis (IIASA), funded by the Ministry of Economy, Trade, and Industry (METI), Japan, and the Austrian Science Fund project REMASS (project number 10.55776/EFP5). T.W. received funding from the Environment Research and Technology Development Fund (JPMEERF20241002) provided by the Ministry of the Environment of Japan. G.A.A.-H. is a Marie Curie Research Fellow funded by the European Commission under Marie Skłodowska-Curie Actions (grant agreement number 101103532). P.F. is supported by the Portuguese Foundation for Science and Technology (DOI 10.54499/UIDB/04085/2020, DOI 10.54499/UIDP/04085/2020, and 2020.00038.CEECIND). T.W. received funding from JSPS (Japan Society for the Promotion of Science) KAKENHI (24K03142). We thank our student research assistant Emily Rischer for help with referencing, as well as academic.ai, a university-run implementation of ChatGTP 4.0, for help with English language editing. LITERATURE CITED 1. Creutzig F, Simoes SG, Leipold S, Berrill P, Azevedo I, et al. 2024. Demand-side strategies key for mitigating material impacts of energy transitions. Nat. Clim. Change 14:561–72 2. United Nations Environment Programme, International Resource Panel (UNEP-IRP). 2024. Global Resources Outlook 2024 - Bend the Trend. UNEP-IRP. http://wedocs.unep.org/handle/20.500.11822/ 44901 3. Watari T, Nansai K, Nakajima K. 2020. Review of critical metal dynamics to 2050 for 48 elements. Resour. Conserv. Recycl. 155:104669 4. 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