Why is Circular economy important for Climate change mitigation?
From concrete for shelter to metals for appliances, material consumption forms the foundation of human development and flourishing. With increasing populations and expanding wealth, global material consumption has seen a precipitous increase (e.g. from 27 to 90 billion tonnes per year in the 1970-2018 period alone [1]).
This flow of materials includes chemicals, food, fuel, and so-called structural materials used in products (such as buildings, infrastructure, and appliances). These materials are often discarded after use [1, 2].
The so-called ‘linear model’ from extraction via manufacturing and use to disposal has led to resource depletion and waste generation [1].
Moreover, the massive use and production of materials are also associated with the extensive use of energy [3].
As a result, the related greenhouse gas (GHG) emissions associated with the production of structural materials have also grown rapidly, from 5 to 11.5 GCO2eq in the 1990-2015 period (from 15% to 23% of total global GHG emissions [4]). The emissions from structural materials are often ‘difficult-to-decarbonise’. As such, high levels of material consumption pose a major challenge for meeting climate targets [5-7].
Emissions caused by material production as a share of total global emissions 1995 vs. 2015
source: Hertwich 2021
In this context, the ‘circular economy’ (CE) has been presented as an alternative to the current linear model [8].
It aims to reduce primary material consumption by
1) reducing the amount of material input (“narrowing loops”),
2) keeping products and material longer in use (“slowing loops”), and
3) recovering or recycling materials and reducing losses (“closing loops”) [9].
By reducing primary material consumption, the circular economy directly reduces resource depletion and environmental degradation risks. Similarly, it also reduces the energy use and GHG emissions associated with the production of the materials.
The potential for GHG emission reductions via CE and material efficiency strategies has been highlighted in several recent scientific publications, including those of the International Resource Panel (UNEP IRP) [1, 10].
The potential is also increasingly appreciated by policymakers. For example, the European Commission targets CE strategies in three legislative proposals – the Circular Economy Action Plan, the Green Deal, and the Renovation Wave – while the Chinese government discusses the circular economy in its 14th 5-year plan and the Circular Economy Plan.
A critical reason for this interest is that current climate policy worldwide still fails to reach the rapid decarbonisation rates required to implement the goals of the Paris Climate Agreement by a wide margin [11].
The CE could address the primary production of several materials associated with high emission footprints, which are relatively hard-to-abate. Reducing material consumption via CE strategies can effectively complement other climate policies related to energy efficiency and decarbonisation [12]. Due to the required speed of emission reductions and challenges in difficult-to-decarbonise sectors, CE strategies might play an essential role in meeting climate targets.[1, 6, 13].
Global carbon footprint of materials in 2015:
(A) by emitting process,
(B) by material produced,
(C) by first use of materials by downstream production processes
Source: Hertwich et al., 2020
References:
1. IRP, Global Resources Outlook 2019: Natural Resources for the Future We Want. A Report of the International Resource Panel. . 2019, United Nations Environment Programme. : Nairobi, Kenya.
2. Graedel, T.E., et al., What Do We Know About Metal Recycling Rates? Journal of Industrial Ecology, 2011. 15 (3): p. 355-366.
3. Van der Voet, E., et al., Environmental Implications of Future Demand Scenarios for Metals: Methodology and Application to the Case of Seven Major Metals. Journal of Industrial Ecology, 2018. 23(1): p. 141-155.
4. Hertwich, E.G., Increased carbon footprint of materials production driven by rise in investments. Nature Geoscience, 2021. 14(3): p. 151-155.
5. Davis, S., et al., Net-zero emissions energy systems. Science, 2018. 360: p. eaas9793.
6. Luderer, G., et al., Residual fossil CO2emissions in 1.5-2 °c pathways. Nature Climate Change, 2018. 8(7): p. 626-633.
7. Sharmina, M., et al., Decarbonising the critical sectors of aviation, shipping, road freight and industry to limit warming to 1.5–2°C. Climate Policy, 2021. 21(4): p. 455-474.
8. Kirchherr, J., D. Reike, and M. Hekkert, Conceptualizing the circular economy: An analysis of 114 definitions. Resources, Conservation and Recycling, 2017. 127: p. 221-232.
9. Bocken, N., K. Miller, and S. Evans, Assessing the environmental impact of new Circular business models. 2016.
10. Hertwich, E., et al., Resource Efficiency and Climate Change: Material Efficiency Strategies for a Low-Carbon Future. . 2020, International Resource Panel. United Nations Environment Programme: Nairobi, Kenya.
11. Roelfsema, M., et al., Taking stock of national climate policies to evaluate implementation of the Paris Agreement. Nature Communications, 2020. 11(1).
12. Pauliuk, S., et al., Global scenarios of resource and emission savings from material efficiency in residential buildings and cars. Nature Communications, 2021. 12(1): p. 5097.
13. Edelenbosch, O.Y., et al., Comparing projections of industrial energy demand and greenhouse gas emissions in long-term energy models. Energy, 2017. 122: p. 701-710.