New research article I co-authored, just published online by Elsevier’s Sustainable Cities and Society.
Vigier, M., Ouellet-Plamondon, C. M., Spiliotopoulou, M., Moore, J., & Rees, W. E. (2023). To what extent is sustainability addressed at urban scale and how aligned is it with Earth’s productive capacity?. Sustainable Cities and Society, 96, 104655.
Abstract
Humanity’s demand for resources exceeds annually the Earth’s productive capacity (EPC), defined as the total regenerative and assimilative capacities of our planet. This article asks what role is given to living within EPC by cities in the quest for urban sustainability and how comprehensively are high-income cities assessing and reducing their impact. Our methodology comprises three steps: 1. urban sustainability literature review, 2. verification of sustainability frameworks and indicators aligned with the goal of living within earth’s productive capacity, 3. study of high-income cities that have intentionally reduced their carbon footprint over the 1990-2020 period. Eleven sustainability frameworks were identified as fully aligned with the goal of living within EPC. Most cities work with indicators related to climate change; however, a singular focus risks underestimating cities’ total global ecological impacts. A shortlist of 24 cities who achieved at least a 15% reduction in their carbon footprint between 1990 and 2020 was developed. These reductions were insufficient in magnitude to meet climate stability goals. To achieve a just transition towards living within EPC, cities must confront their overconsumption by using EPC compliant tools and frameworks, and develop specific reduction targets considering global limits, local responsibilities, and capacities to mitigate.
Introduction
Humanity is in a state of global ecological overshoot, which means that annual demand for bioresources to support human societies exceeds what Earth can produce on a yearly basis (Rees, 2020; Global Footprint Network, n.d.). For several decades, the global scientific community has been calling for an absolute reduction of material throughput, energy use and environmental degradation in the global economy by 80 % or 90 % compared to 1990 levels (Ripple et al., 2017; von Weizsäcker et al., 2009; Millennium Ecosystem Assessment, 2005; Byrne et al., 2001; Meadows et al., 1972).
In 2022, cities hosted almost 60 % of the human population, which accounted for 80 % of global greenhouse gas (GHG) emissions and 75 % of the planet’s material resource consumption, making them crucial actors for global environmental degradation and mitigation (Ghaemi & Smith, 2020; Ortega-Montoya & Johari, 2020; Swilling et al., 2018). Rising pressure from urban regions derives from both per capita consumption growth (rising income) and increasing populations. High-income cities are mainly responsible, although some lower-income cities’ environmental impacts have attained the scale of their wealthy counterparts through a combination of rapidly increasing population and growing affluence (Moran et al., 2018).
This article discusses the role of the “One Planet” paradigm, addressing learning to live within Earth’s productive capacity (EPC), in urban planning strategies. First, we examine the state of the literature. We define what sustainability entails, discuss how cities can be catalysts for change and, through this lens, we review the methods currently applied in sustainability-oriented planning and assessments at the city scale. We then explain the methods we used to research relevant tools and frameworks that might empower cities to achieve living within EPC. We identify cities that are actually reducing their impact on Earth and those that are leading in this reduction. Finally, we discuss the findings and explore the implications for urban futures.
The popular meaning of “sustainable development” was set out in the 1987 Brundtland Report, as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (WCED, 1987). The subsequent literature on “sustainability” reveals several meanings which often conflict with each other and with actual practice – for example the concept of “green growth” which does not account for laws of physics that impose natural resource limits and is considered an oxymoron to sustainability by many researchers (Calisto Friant et al., 2020; Hassan & Lee, 2015; Moore, 2013; Eyong & Foy, 2006; Rees, 1989). This discrepancy between terms employed and practical realities highlights the need to use agreed-upon, comprehensive and accurate definitions to avoid incoherent action on urgent environmental matters. This could be achieved by specifying goals for “strong sustainability,” an approach that acknowledges that ecosystem services are crucial for human survival and cannot generally be substituted by human-made capital (Mirabella & Allacker, 2021; Hassan & Lee, 2015; Pelenc et al., 2015; Neumayer, 2003).
Achieving sustainability is not easy. Global biocapacity is decreasing in step with economic and population growth and associated increases in energy/material demand and rampant pollution. Demand for food is driving land-use change as industrialized agriculture—the most damaging of human technologies—causes deforestation that directly reduces global carbon sinks and biodiversity, amplifying global warming and imposing additional stress on land (IPCC, 2019; Moore et al., 2012).
We define Earth’s Productive Capacity as the regenerative and assimilative capacities of the ecosphere. Related concepts include ‘global biocapacity’ and ‘net primary production.’ These terms all refer to crucial life-support functions of the ecosphere: i.e., the photosynthetic production of biomass (food and fiber) and/or the assimilation of biodegradable wastes. Carrying capacity is defined as the average maximum number of people that Earth could support indefinitely, at a specified material standard, without impairment of the regenerative and assimilative capacities of supportive ecosystems. Hence for global sustainability, Earth’s maximum human population at average living standards (Earth’s carrying capacity) must remain within global ecological limits which are ultimately defined by Earth’s productive capacity (EPC). One Planet Living implies living at or below Earth’s ecological carrying capacity (CC). At present average material standards, humanity is in deep ecological overshoot, consuming bioresources faster than ecosystems can produce them and dumping wastes in excess of ecosystems assimilative capacity.
The concept of carrying capacity can also be applied to the maximum population of a given species that a particular habitat can host, i.e., the natural services it can provide to accommodate the needs of the species for water, food, and shelter (Hui, 2006). Overshoot occurs when humans (or any species population) consume more annually than its supportive ecosystems (available biocapacity) can generate. When in overshoot, the population is using more than net primary production (harvestable surplus) and is thus depleting its productive capital (fish stocks, old-growth forest, soils, etc.) The global human enterprise is in overshoot.
Regenerative systems are essentially self-producing systems such as ecosystems (a macro-level form of so-called ‘natural capital’) and human societies. The latter generate so-called ‘social capital’ including the values, cultural norms, skills and institutions needed to support the continued production of the human enterprise. The transition to sustainability requires the human enterprise to transition from overshoot to regenerative development, capable of meeting aspirations for human wellbeing and flourishing within global ecological limits.
Thus, the concept of Earth’s productive capacity (EPC) encompasses the finite character of our planet’s resources through recognition of quantitative environmental limits or planetary boundaries (PBs). It sets the maximum anthropogenic pressure (consumption of resources and assimilation of wastes) that our planet can sustain without triggering irreversible degradation (Świąder, 2018; Steffen et al., 2015). The goal of living within EPC (i.e., One Planet Living) is salient for decision makers because it sets quantitative targets for global environmental protection and holds the promise of establishing specific thresholds for various material sectors under municipal authority, such as water and materials stocks and flows associated with construction and operation of city buildings, infrastructure maintenance and even waste management (Galli et al., 2020; Hachaichi & Baouni, 2020; Li et al., 2020; Świąder et al., 2018; Swilling et al., 2018, Rees, 2012).
From a thermodynamic perspective, cities are complex open systems whose residents and economies are dissipative structures (Tan et al., 2019; Rees, 2012). Cities are heavily dependent on flows of energy and material resources imported from their hinterlands to sustain their structural evolution and operations (Moore, 2013; Rees, 2012). With globalization, those interdependencies have increased and high-consuming cities have been able to impose substantial material burdens on distant ecosystems, burdens that remain invisible to conventional analysis (Kissinger & Rees, 2010). This increased reliance on other regions for food and natural resources highlights the pressure that cities generate on natural capital outside their political boundaries (Galli et al., 2020; Ortega-Montoya & Johari, 2020; Kissinger & Rees, 2010). Historically, urban development and associated socio-economic benefits such as job opportunities, technology, innovation, and knowledge transfer have been viewed favourably while their ecological costs have been largely ignored, thereby underappreciating cities’ biophysical connectivity and dependence on rural ecosystems (Rees & Roseland, 1992).
Despite driving most environmental degradation, urban regions are simultaneously the loci for solutions to mitigate it. Because they concentrate important monetary, material, and energy flows, cities are strategically positioned to advance resource conservation and circular urban economies; they could thus help catalyze a global sustainability transition (Hachaichi & Baouni, 2020; UNEP, 2017; Moore et al., 2013; Rees & Roseland, 1992). Several transnational groups have emerged—such as ICLEI – Local Government for Sustainability, the C40 Cities, and the Carbon Neutral Cities Alliance (CNCA)—to boost capacity-building and guide cities to monitor and reduce their environmental impacts through tested frameworks, methodologies, and accounting standards (Frantzeskaki et al., 2019; Fuhr et al., 2018; C40 Cities & ARUP, 2016). Their member cities represent a significant share of environmental degradation and their actions and leadership towards impact reduction make them an important hope for mitigation (CNCA, 2018; C40 Cities & ARUP, 2016).
No single indicator can evaluate urban environmental impacts in their entirety; instead several proxies can be used (Baabou et al., 2017; Galli et al., 2012). Some cities monitor their energy and material flows, others monitor their impact on the environment through ecological footprint analysis, but most concentrate their efforts on GHG emissions and climate mitigation (Mirabella & Allacker, 2021; Sanches & Bento, 2020; Baabou et al., 2017; Musango et al., 2017). GHG emissions are generally categorized in terms of their physical sources. Scope 1 and Scope 2 categories describe the emissions occurring within a city’s boundaries (direct emissions) and encompasses the different emissions considered in a production-based approach, whereas the Scope 3 category encompasses emissions occurring in distant ‘elsewhere’ and along external supply chains serving production and consumption within the city (indirect emissions) (Wiedmann et al., 2020).
For any urban sustainability assessment, a first step consists in clearly delineating the spatial area to be considered. There is a lack of consensus regarding what constitutes a ‘city’; several perspectives exist and choosing one over the others depends on the goals and objectives of the particular environmental assessment (Balouktsi, 2020; Albertí et al., 2017). For urban decision makers, choosing administrative boundaries, the area over which the city administration has jurisdictional authority would be the most relevant choice. These boundaries delimit the system to be studied, and the accounting approach defines how the responsibility of the environmental impacts will be assigned to consumers, producers, or according to their geographical location, as shown in Fig. 1.
A consumption-based approach estimates emissions attributable to consumption by the inhabitants of the city being studied, no matter where in the world those emissions occur. The production-based approach estimates emissions occurring in the city from manufacturing, including emissions attributable to locally produced goods exported for consumption by people somewhere else (Ghaemi & Smith, 2020; Wiedmann et al., 2020; Moran et al., 2018; C40 Cities, 2017). The choice of approach depends on the purpose of the analysis. Either approach can be used for high-income or low-income cities (Wiedmann et al., 2020). For high-income cities, the former offers a potentially more comprehensive assessment of a city’s global impacts because it includes the embodied emissions associated with imported goods and services. Furthermore, it should be noted that these approaches measure quite different things; they are not alternatives.
Taken together, these differing approaches help develop a more robust and representative image of cities’ contribution to overall environmental pressure through consumption and production activities. This allows for a fairer attribution of the impacts by preventing any burden shifting (Mirabella & Allacker, 2021; Balouktsi, 2020; Swilling et al., 2018; Kissinger & Rees, 2010). Keep in mind that because of globalization and trades, (over)consumption in wealthier countries and cities translates directly into pollution, land degradation and resource depletion in less wealthy, developing parts of the world from where manufactured goods and agricultural products are imported (Khalil & Al‐Ahwal, 2020; Ortega-Montoya & Johari, 2020).
Section snippets
Research methods
The overall purpose of this paper is to determine the extent to which sustainability, and how Earth’s productive capacity (EPC) in particular, is addressed worldwide by cities wanting to reduce their impacts. This analysis was conducted following a funnel research method, presented in Fig. 2. The first step was to verify the existence of sustainability frameworks and indicators that were both adapted to represent urban realities while being compliant with the objective of living within EPC. The
Frameworks for achieving urban sustainability
Our literature review identified 33 urban sustainability frameworks used by single cities or by clusters of cities (e.g., the Global Footprint Network and the Resilient Cities Network). Twenty-one provided full coverage of the five main domains of consumption but only 11 were fully EPC-aligned (i.e., living within the regenerative and assimilative capacities of Earth was an explicit target – Fig. 4). Nineteen additional frameworks were partially aligned with EPC meaning that the goal of One
Discussion and implications
EPC constitutes the context in which we all live and must respect for future generations to get an equitable chance to live and thrive (Galli et al., 2020). However, the high-income, leading cities identified in this research with CF reductions of only 21 % – 49 % since 1990 are far from the 80 % – 90 % reduction called for by the scientific community (Rees, 2020; Ripple et al., 2017; von Weizsäcker et al., 2009; Millennium Ecosystem Assessment, 2005; Byrne et al., 2001; Meadows et al., 1972).
Conclusion
The mounting urgency of humanity’s environmental predicament calls for a bold, holistic, and systemic response (IPCC, 2021; Spratt et al., 2020). Unprecedented policy action during the COVID-19 pandemic has shown that urgent and effective action is possible if governments make it a top priority. We posit that the One Planet living goal—living within our planet’s regenerative and assimilative capacities (EPC) — should receive the same treatment. Global CF and EF with consistent methods are
CRediT authorship contribution statement
Marie Vigier: Methodology, Validation, Writing – original draft, Visualization, Writing – review & editing. Claudiane M. Ouellet-Plamondon: Conceptualization, Methodology, Project administration, Funding acquisition, Supervision, Writing – original draft, Writing – review & editing. Maria Spiliotopoulou: Methodology, Validation, Writing – review & editing. Jennie Moore: Conceptualization, Methodology, Funding acquisition, Supervision, Writing – review & editing. William E. Rees: Writing –
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was supported by the Canadian Social Sciences and Humanities Research Council (SSHRC), the Canadian Institutes of Health Research (CIRH) and the Natural Sciences and Engineering Research Council (NSERC) with their Knowledge Synthesis Grant for research in the theme Living Within the Earth’s Carrying Capacity.
