The role of planetary boundaries in assessing absolute environmental sustainability across scales

Cities, planetary boundaries, and degrowth

Cities are the main hubs of human activity and the engines of economic growth. In pursuit of such growth, cities are transgressing their local environmental boundaries. Ongoing urbanisation increasingly contributes to the human pressure on planetary boundaries and negatively affects planetary health. In a telecoupled world, cities externalise impacts by shifting production and many other functions away from their boundaries. At the same time, urban inhabitants and people who follow urban lifestyles but live outside cities are increasingly disconnected from nature. This Viewpoint highlights the role of degrowth in keeping an urban planet within planetary boundaries and suggests areas for further research and policy. Degrowth calls for meaningfully connecting planetary boundaries with cities and ensuring everyone receives a fair share of their ecological capacity. Degrowth calls for lower use of existing resources, highlights political power asymmetries, and moves beyond pricing interventions. Degrowth addresses three key aspects that connect cities and urban lifestyles to planetary boundaries: reducing production and consumption, connecting people and nature, and including nature (to a more substantial extent) in the design of cities and in what is used and consumed in cities. A radical degrowth transformation of cities is necessary to stay within a safe operating space for humanity.

Revealing Trade Potential for Reversing Regional Freshwater Boundary Exceedance

Applying the planetary boundary for the freshwater framework at the regional level is important in supporting local water management but is subject to substantial uncertainty. Previous estimates have not fully investigated the potential of trade in mitigating regional freshwater boundary (RFB) exceedance. Here, we estimate RFB based on the average results of 15 different hydrological models to reduce uncertainty. We then propose a framework to divide the RFB exceedance/maintenance into contributions from both consumption and trade and further identify trade contribution into six types. We applied the framework to China's provinces, which are characterized by intensive interprovincial trade and a significant mismatch in water resource supply and demand. We found that the current trade pattern limits the role of trade to mitigate RFB exceedance. For the importing provinces exceeding RFBs, 78% of their imported goods and services came from other RFB exceeding provinces. Scenario analysis showed that relying on increased imports alone, even to its greatest extent, will not reverse RFB exceedance in most importing provinces. Increased imports, however, will have an aggregate effect on the trade partners, leading to the exceedance of the national freshwater boundary. We also found that promoting export of goods and services from non-RFB exceeding provinces and reducing their water intensity will help address the imbalance both locally and, in the aggregate, nationally.

Determining sustainability using the Environmental Performance Index and Human Development Index - An alternative approach to the Environmental Human Index through a holistic quantitative dynamic framework

The Environmental Human Index (EHI) was recently proposed and demonstrated as a new sustainability assessment tool which uses data from the Environmental Performance Index (EPI) and the Human Development Index (HDI). However, the EHI has potential conceptual and operational issues in respect to its consistency with established concepts and principles of the coupled environment-human system and sustainability. Specifically, the thresholds of sustainability the EHI uses, the bias towards the anthroposphere, and the absence of unsustainability. These issues raise potential questions concerning the EHI's value and approach adopted to utilise the EPI and HDI data to determine potential or actual sustainability outcomes. Therefore, to demonstrate how the EPI and HDI can be used to determine sustainability outcomes, the Sustainability Dynamics Framework (SDF) is applied in respect to the case study of the United Kingdom 1995-2020. The results indicated strong sustainability occurring throughout the specified period, within a S-value range of [+0.503 ≤ S(t) ≤ +0.682]. The Pearson correlation analysis showed a significant negative relationship between E and HNI-values and between HNI and S-values, and a significant positive relationship between E and S-values. The Fourier analysis indicated a three-phase change in the nature of the environment-human system dynamics over the 1995-2020 period. The SDF application to the EPI and HDI data has shown the importance of using a consistent holistic conceptual and operational framework to determine and evaluate sustainability outcomes.

Knowledge mapping of planetary boundaries based on bibliometrics analysis

The planetary boundaries concept has triggered a vast amount of pure and applied scientific research, as well as policy and governance activities globally. Indeed, it has rapidly become a centerpiece of sustainability study. It is crucial to review the scientific state of the planetary boundaries (PB) concept systematically. However, there is a lack of research on drawing a scientific investigation map of planetary boundaries. Therefore, to clarify the spatial and temporal distribution characteristics, research hotspots, and frontiers of planetary boundaries, a scientometric analysis was performed based on 530 academic publications on planetary boundaries from 2009 to 2021. This paper conducted the analysis by visualizing the social network, dual-map overlay, co-cited references, structure variation article, and co-occurrence keywords with CiteSpace. The results show that as a new achievement and paradigm in sustainable development research, the planetary boundaries framework is gradually getting global attention and promotion, which has increasingly become an interdisciplinary hot research topic. The most productive authors and institutions are concentrated in England, the USA, Germany, and Sweden. Relevant articles were mainly published in journals focusing on ecology, earth, marine, veterinary, animal, economics, and politics. In addition, we summarized four predominant research themes by clustering keywords: the calculation of single boundary threshold and present value, the integration with assessment methods such as life cycle assessment and footprint families, the downscaling of planetary boundaries, and the expansion to economic and social domains. For scholars who are interested in this topic, this paper would be a useful reference and guideline.

Safe and sustainable by design: A computer-based approach to redesign chemicals for reduced environmental hazards

Persistency of chemicals in the environment is seen a pressing issue as it results in accumulation of chemicals over time. Persistent chemicals can be an asset in a well-functioning circular economy where products are more durable and can be reused or recycled. This objective can however not always be fulfilled as release of chemicals from products into the environment can be inherently coupled to their use. In these situations, chemicals should be designed for degradation. In this study, a systematic and computer-aided workflow was developed to facilitate the chemical redesign for reduced persistency. The approach includes elements of Essential Use, Alternatives Assessment and Green and Circular Chemistry and ties into goals recently formulated in the context of the EU Green Deal. The organophosphate chemical triisobutylphosphate (TiBP) was used as a case study for exploration of the approach, as its emission to the environment was expected to be inevitable when used as a flame retardant. Over 6.3 million alternative structures were created in silico and filtered based on QSAR outputs to remove potentially non-readily biodegradable structures. With a multi-criteria analysis based on predicted properties and synthesizability a top 500 of most desirable structures was identified. The target structure (di-n-butyl (2-hydroxyethyl) phosphate) was manually selected and synthesized. The approach can be expanded and further verified to reach its full potential in the mitigation of chemical pollution and to help enable a safe circular economy.

National responsibility for ecological breakdown: a fair-shares assessment of resource use, 1970-2017

BACKGROUND

Human impacts on earth-system processes are overshooting several planetary boundaries, driving a crisis of ecological breakdown. This crisis is being caused in large part by global resource extraction, which has increased dramatically over the past half century. We propose a novel method for quantifying national responsibility for ecological breakdown by assessing nations' cumulative material use in excess of equitable and sustainable boundaries.

METHODS

For this analysis, we derived national fair shares of a sustainable resource corridor. These fair shares were then subtracted from countries' actual resource use to determine the extent to which each country has overshot its fair share over the period 1970-2017. Through this approach, each country's share of responsibility for global excess resource use was calculated.

FINDINGS

High-income nations are responsible for 74% of global excess material use, driven primarily by the USA (27%) and the EU-28 high-income countries (25%). China is responsible for 15% of global excess material use, and the rest of the Global South (ie, the low-income and middle-income countries of Latin America and the Caribbean, Africa, the Middle East, and Asia) is responsible for only 8%. Overshoot in higher-income nations is driven disproportionately by the use of abiotic materials, whereas in lower-income nations it is driven disproportionately by the use of biomass.

INTERPRETATION

These results show that high-income nations are the primary drivers of global ecological breakdown and they need to urgently reduce their resource use to fair and sustainable levels. Achieving sufficient reductions will likely require high-income nations to adopt transformative post-growth and degrowth approaches.

FUNDING

None.

Towards Carbon Neutrality in Higher Education Institutions: Case of Two Private Universities in Colombia

This paper addresses the path followed by two private higher education institutions (HEI) in Colombia towards achieving carbon neutrality. The methodology followed by these universities to achieve a carbon-neutral certification, based on the Greenhouse Gas (GHG) Protocol, is first described. The process of developing the GHG inventory, projected towards the carbon neutrality of these organisations while using the standard ISO 14064:2006, involved a series of steps that were consolidated in three phases: (i) definition of the scope, collection of data and emissions quantification; (ii) analysis of results and mitigation actions; and (iii) verification and compensation strategies. Results for the HEIs are shown in terms of the organisational context, carbon footprint measurement, reduction, verification, and compensation. The case is presented for Universidad Pontificia Bolivariana, a multi-campus university that became the first carbon-neutral university in Latin America in 2017, and Universidad Ean, a single-campus university that became the second carbon-neutral university in Colombia in 2021, as verified by the Colombian Institute of Technical Standards and Certification (ICONTEC). This work shows that universities can play a key role in regional and global agendas with their contribution through the incorporation of sustainability strategies, since HEIs can not only achieve carbon neutrality, but they can help other organisations by delivering graduates who are aware of sustainability and provide specific training towards building a sustainability culture, which is needed for regenerative development.

Bridging planetary boundaries and spatial heterogeneity in a hybrid approach: A focus on Chinese provinces and industries

Communicating the finiteness of the Earth system at sub-global scales is necessary to guide human activities within a safe operating space. Despite the numerous efforts committed to downscaling planetary boundaries (PBs) at multiple scales, neither top-down nor bottom-up approaches adequately account for the spatial heterogeneity and integrity of local and global natural systems. To overcome these shortcomings, we developed a hybrid approach that combines bottom-up aggregation and top-down adjustment for downscaling five crucial PBs (i.e., climate change, nitrogen and phosphorus cycles, freshwater use, and land use change) to Chinese provinces and industries. In addition to the widely applied equity principle, we further incorporated the eco-efficiency principle into the downscaling of PBs under the proposition that safeguarding finite PBs should be reconciled with the pursuit of maximizing human welfare. Environmental sustainability at multiple scales was subsequently assessed with the complementary use of environmental footprints and downscaled PBs. The results demonstrate that 1) China suffers from severe unsustainability because of the transgression of PBs for phosphorus and nitrogen cycles, carbon emissions, and cropland use; 2) provinces in West and North China perform worse than other provinces in terms of the eco-efficiency in manufacturing industries, including Electronic equipment, Textiles, and Wood processing and furnishing, rendering these industries that are more unsustainable; and 3) industries with varying eco-efficiencies account differently for the provincial PBs. Construction dominates the provincial shares of carbon PBs, whereas Agriculture and Food processing and tobacco contribute most to the other four PBs. Our findings suggest that improving eco-efficiency in most manufacturing industries is the key to saving resources, reducing emissions, and safeguarding local boundaries.

Development and application of an in-house library and workflow for gas chromatography-electron ionization-accurate-mass/high-resolution mass spectrometry screening of environmental samples

This work presents an optimized gas chromatography–electron ionization–high-resolution mass spectrometry (GC-EI-HRMS) screening method. Different method parameters affecting data processing with the Agilent Unknowns Analysis SureMass deconvolution software were optimized in order to achieve the best compromise between false positives and false negatives. To this end, an accurate-mass library of 26 model compounds was created. Then, five replicates of mussel extracts were spiked with a mixture of these 26 compounds at two concentration levels (10 and 100 ng/g dry weight in mussel, 50 and 500 ng/mL in extract) and injected in the GC-EI-HRMS system. The results of these experiments showed that accurate mass tolerance and pure weight factor (combination of reverse-forward library search) are the most critical factors. The validation of the developed method afforded screening detection limits in the 2.5–5 ng range for passive sampler extracts and 1–2 ng/g for mussel sample extracts, and limits of quantification in the 0.6–3.2 ng and 0.1–1.8 ng/g range, for the same type of samples, respectively, for 17 model analytes. Once the method was optimized, an accurate-mass HRMS library, containing retention indexes, with ca. 355 spectra of derivatized and non-derivatized compounds was generated. This library (freely available at https://doi.org/10.5281/zenodo.5647960), together with a modified Agilent Pesticides Library of over 800 compounds, was applied to the screening of passive samplers, both of polydimethylsiloxane and polar chemical integrative samplers (POCIS), and mussel samples collected in Galicia (NW Spain), where a total of 75 chemicals could be identified.

Revisiting the application and methodological extensions of the planetary boundaries for sustainability assessment

The planetary boundaries (PBs) delineating the safe operating space for human activities have been broadly recognized as a well-grounded framework for global sustainability assessment. This paper provides a comprehensive review of the application and methodological extensions of the PBs by linking with multiscale environmental sustainability assessments. We find that the targeted scales, sharing principles and sustainability perspectives jointly determine the downscaling of the PBs-a complex process that needs to take into account the biophysical, socioeconomic, ethical and cultural dimensions. Despite the varying sharing principles, in general both top-down and bottom-up approaches have been employed to define the environmental boundaries at sub-global scales on which the various PBs highly differ in their threshold behaviors. To clarify the responsibility of different stakeholders for sustainable development, the PB-informed sustainability assessment should refer to a specific perspective (i.e., production-, consumption-, or life cycle-based). Furthermore, the methodological extensions of PBs have the potential to monitor the progress and gaps of the globally consensus-based Sustainable Development Goals (SDGs). To achieve the SDGs within the PBs, there is a great need for a thorough transition of socioeconomic systems towards a prosperous, just and sustainable future.

City footprints and SDGs provide untapped potential for assessing city sustainability

Cities are recognised as central to determining the sustainability of human development. However, assessment concepts that are able to ascertain whether or not a city is sustainable are only just emerging. Here we review literature since the Sustainable Development Goals (SDGs) were agreed in 2015 and identify three strands of scientific inquiry and practice in assessing city sustainability. We find that further integration is needed. SDG monitoring and assessment of cities should take advantage of both consumption-based (footprint) accounting and benchmarking against planetary boundaries and social thresholds in order to achieve greater relevance for designing sustainable cities and urban lifestyles.