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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.

Global net anthropogenic greenhouse gas (GHG) emissions during the last decade (2010–2019) were higher than at any previous time in human history (high confidence). Since 2010, GHG emissions have continued to grow, reaching 59 ± 6.6 GtCO2-eq in 2019,1 but the average annual growth in the last decade (1.3%, 2010–2019) was lower than in the previous decade (2.1%, 2000–2009) (high confidence). Average annual GHG emissions were 56 ± 6.0 GtCO2-eq yr –1 for the decade 2010–2019 growing by about 9.1 GtCO2-eq yr –1 from the previous decade (2000–2009) – the highest decadal average on record (high confidence).

The sustainable development goals (SDGs) provide a framework of goals, targets, and indicators designed to guide national implementation of sustainable development to 2030. Several aspects of the framework are challenging, including its complex and integrated scope and transformational character. A range of approaches developed in the sustainability sciences can assist countries to address these challenges. In this paper, we evaluate recent scientific literature as well as national practice relating to the use of science-based approaches to support and enable national SDG implementation. The review encompasses >150 articles from the peer-reviewed and grey scientific literature, identifying 22 science-based approaches developed and recommended by experts to support national implementation. We then review and evaluate recent practice and experience of 56 countries in implementing the SDGs and the extent to which these approaches are evident in Voluntary National Reviews (VNRs). Overall, we find some cross-fertilization in the science-policy interface of national SDG implementation, particularly in monitoring and evaluation. While scientific methods for evaluating interlinkages between the SDGs and understanding national transformations have advanced considerably in recent years, they are yet to become a feature of the VNRs reviewed. There is evidence that demand for these approaches is increasing, and it will be critical that researchers understand the needs of policy makers and other stakeholders and design tools that provide practical and actionable evidence that assist countries to understand, quantify, and implement the transformations needed to achieve the SDGs over the coming decade.

This study focused on understanding what sector-region combinations could be targeted to reduce total city water footprints? We used multi-regional input-output analysis of direct and virtual water, across five Australian capital cities and their supporting regions. The key novelty of this study is the high spatial resolution policy-relevant sub-sectoral analysis to identify sector-region combinations to reduce city water footprints. Virtual water footprints were 8-10 times higher than direct water consumption (per capita) in all studied cities. Virtual water from outside the city boundary is almost 20 times higher than the virtual water sourced from within the city boundary in all studied cities. Water-efficiency programs can significantly reduce the virtual water footprints of the studied cities. This includes water-efficiency and recycling on farm, and in food processing (e.g. livestock feed growing, dairy cattle farming, vegetable growing and processing) in rural regions of New South Wales, Queensland, and Victoria. The results are relevant to strategic city water footprints reduction, sustainable sourcing and planning for future disturbance of product supply, and water-sensitive city developments considering both direct and virtual water flows.

Cities are a key target in the global quest for sustainability and are increasingly acting independently to take the lead in sustainability initiatives. To truly achieve sustainability, cities need to ensure that their consumption is compatible with absolute sustainability and validate achievements from a perspective that includes transboundary impacts. The aim of this review is to assess how well these topics are incorporated into commonly used urban sustainability assessment methods, using the safe and just space (SJS) framework definition of a minimum acceptable threshold for both ecological stability and standard of living. The review identified 277 different sustainability indicator frameworks that have been applied to cities and undertook a detailed assessment of the most commonly cited of these. Consumption-based footprint studies were separately assessed to determine the extent to which they measure SJS indicators for cities. Both indicator frameworks and footprint studies had a focus on boundaries of increasing risk, including carbon, water, and land use; however few measured highly exceeded boundaries including nitrogen and phosphorus use, biodiversity, and possibly chemical pollution. Social impacts were well covered in indicator frameworks, except food intake, but largely absent from footprint studies. Cities are largely not measuring their impact on planetary tipping points or transboundary impacts, risking resolving some environmental issues while exacerbating others.

Global greenhouse gas (GHG) emissions can be traced to five economic sectors: energy, industry, buildings, transport and AFOLU (agriculture, forestry and other land uses). In this topical review, we synthesise the literature to explain recent trends in global and regional emissions in each of these sectors. To contextualise our review, we present estimates of GHG emissions trends by sector from 1990 to 2018, describing the major sources of emissions growth, stability and decline across ten global regions. Overall, the literature and data emphasise that progress towards reducing GHG emissions has been limited. The prominent global pattern is a continuation of underlying drivers with few signs of emerging limits to demand, nor of a deep shift towards the delivery of low and zero carbon services across sectors. We observe a moderate decarbonisation of energy systems in Europe and North America, driven by fuel switching and the increasing penetration of renewables. By contrast, in rapidly industrialising regions, fossil-based energy systems have continuously expanded, only very recently slowing down in their growth. Strong demand for materials, floor area, energy services and travel have driven emissions growth in the industry, buildings and transport sectors, particularly in Eastern Asia, Southern Asia and South-East Asia. An expansion of agriculture into carbon-dense tropical forest areas has driven recent increases in AFOLU emissions in Latin America, South-East Asia and Africa. Identifying, understanding, and tackling the most persistent and climate-damaging trends across sectors is a fundamental concern for research and policy as humanity treads deeper into the Anthropocene.

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.

Non-technical summary The Sustainable Development Goals (SDGs) provide an integrated and ambitious roadmap for sustainable development by 2030. National implementation will be crucial and there is an urgent need to understand the scale and pace of transformations to achieve the goals. There is also concern that achieving socio-economic objectives will undermine longer-term environmental sustainability. This study uses modelling to explore how different policy and investment settings can enable the necessary transformations, adopting Fiji as a use-case. Modest investment over the coming decade can deliver improved performance. However, far more ambitious actions are needed to accelerate progress while managing long-term trade-offs with environmental objectives. Technical summary This paper presents the results from a national scenario modelling study for Fiji with broader relevance for other countries seeking to achieve the SDGs. We develop and simulate a business-as-usual and six alternative future scenarios using the integrated (iSDG-Fiji) system dynamics model and evaluate their performance on the SDGs in 2030 and global planetary boundaries (PBs) and the 'safe and just space' (SJS) framework in 2050. Modest investment over the coming decade through a 'sustainability transition' scenario accelerates SDG progress from 40% to 70% by 2030 but fails to meet all SJS thresholds. Greatly scaling up investment and ambition through an SDG transformation scenario highlights possibilities for Fiji to accelerate progress to 83% by 2030 while improving SJS performance. The scale of investment is highly ambitious and could not be delivered without scaled-up international support, but despite this investment progress still falls short. The analysis highlights where key trade-offs remain as well as options to address these, however closing the gap to 100% achievement will prove very challenging. The approach and findings are relevant to other countries with similar characteristic

The idea of revisiting the biophysical limits of human life on planet Earth has gained renewed momentum in the Anthropocene. The planetary boundaries (PBs) framework has emerged as a strong guardrail concept, even though its capacity to inform the development of absolute sustainability assessments and realistic policies remains unclear. In this paper, we present a current synthesis of the development of absolute environmental sustainability (AES) indicators and assessments informed by PBs. We firstly explore how PBs have been considered in AES research at different scales. We then present a critique of how consensus could be reached in standardising and harmonising the share of globally and locally allocated safe operating spaces. We argue that PBs must be linked to human consumption as the main socio-economic driver and that planetary concerns can only be addressed through a holistic perspective that encompasses global tele-connections. Based on our findings, we provide recommendations for the future design of AES indicators and assessments informed by PBs.

Modelling frameworks that aim to support policymakers in deriving effective measures to reduce environmental impacts should provide both: quantitative information on locally occurring consumption patterns and production systems as well as assessment of policy scenario outcomes. Regionalised models that can deliver on these aims are emerging, but are currently limited in resolution or have other restrictions. An advanced model can be achieved by exploiting the advantages and overcoming the limitations of top-down and bottom-up approaches. In this article, we describe a highly detailed, spatially-resolved modelling framework that quantifies local activities and simultaneously analyses system-wide environmental and economic effects of planned interventions. We combined an existing, highly detailed bottom-up model for Switzerland (focusing on individual households) with a macro-economic top-down approach by developing a new Swiss sub-national, multi-region input-output model. We conducted two case studies to demonstrate its abilities and to highlight its usefulness. First, production-based greenhouse gas emissions and consumption-based carbon footprints were computed for all Swiss cantons and regional differences, interdependencies as well as embodied carbon flows among regions were investigated. We find that rural cantons have higher production-based emissions per gross domestic product than more urban cantons because of different economic structures. In contrast, certain ‘city-cantons’ entail highest consumption carbon footprints per inhabitant due to high per-capita gross capital formation. Furthermore, this case study discusses the importance of providing regionalised information on effects of measures along the economic value chains. Second, a detailed scenario assuming a realistic lifestyle change for an actual household and a thorough physical retrofit of its home was set up. Regionalised environmental and economic consequences along the supply chains were evalua

A major challenge for cities taking action on climate change is assessing and managing the contribution of urban consumption which triggers greenhouse gas (GHG) emissions outside city boundaries. Using a novel method of creating city-level input–output tables, we present the first consistent, large-scale, and global assessment of three-scope GHG inventories for 79 members of the C40 Cities Climate Leadership Group. These inventories cover the emissions from sources located within city boundaries (Scope 1), emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam, and/or cooling (Scope 2), and all other GHG emissions that occur outside the city boundary as a result of activities taking place within the city (Scope 3). We find that, by only accounting for territorial emissions, without Scope 3, the 79 C40 cities under-report 4% of global annual GHG emissions from six key infrastructure-related transboundary sources (73%) and from service-related sectors (27%). In contrast, when only accounting for consumption-based emissions, the C40 cities would miss the mitigation target on 41% of their territorial emissions. We argue that cities should complement their GHG inventories, adding full Scope 3 to Scopes 1 and 2, and develop low-carbon consumption strategies in addition to current infrastructure-focused action on climate change.

This study reviewed nexus researches, synthesize and discuss insights, methodological practices, and future outlook of water-related energy consumption assessment of the food system. For the first time, the study assessed: (i) the trends and drivers of water-related energy research in different countries, (ii) how water-related energy in the food system is being evaluated (objectives & scale, study dimension & analysis focus, and methods) and (iii) the significance of food-system water-related energy in comparison with other sectors. Of 686 nexus studies undertaken since 1990, 104 studies (15%) quantified water-related energy. Studies have generally broadened in scope through time. The USA, China, and Australia have conducted most studies representing 23%, 17%, 15% of total respectively. A few of the identified major drivers in these countries leading water-related energy assessment are: providing optimal solutions and avoiding problem-shifting, analyzing the challenges and opportunities to reduce water-related energy, and exploring the energy-saving benefits by saving water. Of the 104 water-related energy studies, 65 articles (∼60%) related to the food system, focussed on the agriculture phase for irrigation energy consumption. Existing nexus studies often ignored other phases such as food processing and cooking, which are more energy-intensive. Over 50% of studies used material flow analysis to evaluate water-related energy in the food system. Few of the nexus studies evaluated inter-regional flows or changes through time. Absence of a comprehensive study of the entire food system, and wide variations in study system boundary and definitions, make it difficult to compare sectoral significance. However, the order of sectoral water-related energy consumption (from highest to lowest) identified as industrial, residential, agriculture, and water and wastewater service. Our review demonstrates a tremendous opportunity and need for an overarching framework to enable sy

Slavery is more prevalent today than at any point in human history. Society's heightened scrutiny and new government policy is forcing businesses and nations to act in lieu of reputational, financial, and legal repercussions. However, slavery hides within complex supply chains, making it difficult to identify instances of human exploitation. This study takes a consumption perspective by investigating the potential of footprinting in exposing modern slavery impacts embodied in upstream supply chains. A multi-regional input–output analysis extended with a slavery satellite account enables footprints of direct and indirect incidents of modern slavery to be quantified. The footprints reveal a displacement of slavery from developed to developing nations through the global supply chains of production. Accountability for enslavement significantly increases for countries and regions like North America, Western Europe, Australia, and Japan due to a high dependence on imports with embodied human exploitation. The results expose hotspot sectors, including construction, trade, and agriculture. These footprints go beyond current estimates of slavery in supply chains, revealing hidden impacts and the true risk, which may enable more effective action into improving global social sustainability and support companies to responsibly manage their supply chains.

Globalisation and the outsourcing of industrial manufacturing from developed to less developed countries has an increasing effect on the national energy balances of most developed economies. The current standard metric Total Primary Energy Supply of a country does not take into account the energy embodied in goods and services imported from other countries, leading to the perverse outcome of a country appearing to be more sustainable the more it outsources its energy-intensive industries. Academia has addressed this problem by suggesting the use of the Total Primary Energy Footprint as an additional metric, but there has not been a clear proposal put forward by academia to governments or international institutions about how to officially adopt Consumption-Based Accounting in the field of energy. This article states that acknowledging the existence of embodied energy flows is indispensable when formulating new national and international energy policies for the transition towards energy systems that are socially and environmentally more sustainable. In this study, the Hidden Energy Flow indicator of 44 countries has been quantified using, for the first time, five different Global Multi-Regional Input-Output databases for the latest available year, 2011. The proposed indicator provides a percentage to be added to or subtracted from the Total Primary Energy Used value of a country, provided by the International Energy Agency, to get its real consumption-based energy requirement. This study demonstrates that, from 44 countries analysed, the ten most developed countries demand on average 18.5% more energy than measured by the International Energy Agency; the medium developed 24 countries demand 12.4% more, and the ten least developed countries demand 1.6% less. This means that most developed and medium developed countries displace their indirect energy consumption towards less developed countries in a hidden way. Furthermore, this research supports evidence that direct en

no abstract

Globalisation and the outsourcing of industrial manufacturing from developed to less developed countries has an increasing effect on the national energy balances of most developed economies. The current standard metric Total Primary Energy Supply of a country does not take into account the energy embodied in goods and services imported from other countries, leading to the perverse outcome of a country appearing to be more sustainable the more it outsources its energy-intensive industries. Academia has addressed this problem by suggesting the use of the Total Primary Energy Footprint as an additional metric, but there has not been a clear proposal put forward by academia to governments or international institutions about how to officially adopt Consumption-Based Accounting in the field of energy. This article states that acknowledging the existence of embodied energy flows is indispensable when formulating new national and international energy policies for the transition towards energy systems that are socially and environmentally more sustainable. In this study, the Hidden Energy Flow indicator of 44 countries has been quantified using, for the first time, five different Global Multi-Regional Input-Output databases for the latest available year, 2011. The proposed indicator provides a percentage to be added to or subtracted from the Total Primary Energy Used value of a country, provided by the International Energy Agency, to get its real consumption-based energy requirement. This study demonstrates that, from 44 countries analysed, the ten most developed countries demand on average 18.5% more energy than measured by the International Energy Agency; the medium developed 24 countries demand 12.4% more, and the ten least developed countries demand 1.6% less. This means that most developed and medium developed countries displace their indirect energy consumption towards less developed countries in a hidden way. Furthermore, this research supports evidence that direct en

Global greenhouse gas emissions can be traced to five economic sectors: energy, industry, buildings, transport and AFOLU (agriculture, forestry and other land uses). In this topical review we synthesize the literature to explain recent trends in global and regional emissions in each of these sectors. To contextualise our review, we present estimates of greenhouse gas emissions trends by sector from 1990 to 2018, describing the major sources of emissions growth, stability and decline across ten global regions. Both the literature and data emphasize limited progress towards reducing greenhouse gas emissions. The prominent global pattern is a continuation of underlying drivers with few signs of emerging limits to demand, nor of a deep shift towards the delivery of low and zero carbon services across sectors. We observe a moderate decarbonisation of energy systems in Europe and North America, driven by fuel switching and the increasing penetration of renewables. By contrast, in rapidly industrialising regions, fossil-based energy systems have continuously expanded, only very recently slowing down in their growth. Strong demand for materials, floor area, energy services and travel have driven emissions growth in the industry, buildings and transport sectors, particularly in Eastern Asia, Southern Asia and South-East Asia. An expansion of agriculture into carbon-dense tropical forest areas has driven recent increases in AFOLU emissions in Latin America, South-East Asia and Africa. Identifying, understanding, and tackling the most persistent and climate-damaging trends across sectors is a fundamental concern for research and policy as humanity treads deeper into the Anthropocene.

The former consensus on a link between energy consumption and improved well-being of a country has been scrutinized by scholars for decades and is, succinctly, for the time being a contested thesis. Until the 1970s the relation of energy to well-being was defined as linearly proportional, and in a later period still as an increasing logarithmic function. Recent empirical research falsified the assumption of an overt link between well-being and increased energy consumption in countries with high per-capita energy usage. Going forward, our research shows for the first time a possible proof for a negative correlation between energy consumption and well-being after a Well-being Turning Point (WTP). We used a world data set, not limited to high-income countries but including 176 nations with available data sets. Our findings could support both the logarithmic growth of well-being together with energy, as well as the contradicting saturation theses supporting degrowth, and thus opens the discussion in all directions. In this paper Energy Footprint data within Eora database and Global Multi Regional Input Output methodology have been calculated, which includes also the energy embodied in imported/exported products and services (also known as consumption-based energy accounts). The use of footprint accounts has been demonstrated in our previous research to be necessary when analysing global energy consumption trends; as it records the energy consumption reality better than the usually used Total Primary Energy Supply which is provided by the International Energy Agency. In this paper, we provide in a novel way, some statistical support for an Energy WTP, i.e. a high-energy threshold after which a further consumption increase results in a reduced Human Development Index. We tested our results for possible biases (e.g. excluding outlier countries and including a factor for considering the weight of high population countries) and concluded that a WTP is one possible interpreta

Given the key role of households in driving global emissions and resource use, a change in their consumption behaviours towards more sustainable levels is essential to reduce worldwide adverse environmental impacts. Thereby, focusing on cities is especially important because of today’s large share of the global population living in cities and because local authorities are close to the needs of their residents. However, devising targeted and effective policy measures implies a thorough understanding of prevailing consumption patterns and associated environmental consequences. The goal of this article is to investigate and compare household behaviours and lifestyle-induced carbon footprints in Sydney and Melbourne in order to enhance today’s understanding of household consumption in cities of a high-income, high-emission country. For this purpose, we employed a two-stage clustering approach with a Self-Organising Map and a subsequent Ward-clustering. This allowed for including expenditure data along with socio-economic attributes and thus for recognising lifestyle-archetypes. These emerging archetypes represent households with similar characteristics and comparable consumption patterns. Analysing the archetypes in detail and performing a city-comparison based on multi-dimensional scaling revealed similarities and dissimilarities between the two metropoles. ‘Older’ archetypes seem to behave more alike across cities but show different carbon footprints emphasising the importance of regionalised environmental assessments and of city-specific supply chains. Distinct patterns especially emerged in the high- and low-income segments highlighting the different importance of different lifestyles in each city. Socio-economically similar family-archetypes were found in both cities, but some of them showed diverging consumption behaviours. This article showed that studying household-induced environmental impacts in cities should not rely on macro-trends but should rather be based

The water planetary boundary (PB) has attracted wide academic attention, but empirical water footprint research that accommodates local biophysical boundaries remains scarce. Here we develop two novel quantitative footprint indicators, the water exceedance footprint and the surplus water footprint. The first measures the amount of excessive water withdrawal (exceeded amount of water withdrawn against local water PBs) and the latter evaluates the potential of surplus water that can be sustainably utilised (amount of surplus water available within local water PBs). We quantify the extent to which demand for goods and services in Chinese provinces and cities are driving excessive withdrawal of local and global water resources. We investigate both territorial and consumption-based water withdrawal deficit and surplus against local water withdrawal PBs. We also trace how PB-exceeded water and surplus water are appropriated for producing certain commodities. In 2015, China's domestic water exceedance reaches 101 km3 while the total water exceedance footprint is 92 km3. We find that 47% of domestic excessive water withdrawal is associated with interprovincial trade. Exceeded water transfers were dominated by agricultural trade from the drier North to the wetter South. A revised virtual water trade network informed by exceedance and surplus water footprint metrics could help address sustainability concerns that arise from the trade of water-intensive commodities. Our findings highlight that policy targets need to accommodate PB exceedance of both direct and virtual water use.

For over half a century, worldwide growth in affluence has continuously increased resource use and pollutant emissions far more rapidly than these have been reduced through better technology. The affluent citizens of the world are responsible for most environmental impacts and are central to any future prospect of retreating to safer environmental conditions. We summarise the evidence and present possible solution approaches. Any transition towards sustainability can only be effective if far-reaching lifestyle changes complement technological advancements. However, existing societies, economies and cultures incite consumption expansion and the structural imperative for growth in competitive market economies inhibits necessary societal change.

Recent papers argue that the energy return on energy invested (EROI) for renewable electricity technologies and systems may be so low that the transition from fossil fuelled to renewable electricity may displace investment in other important economic sectors. For the case of large-scale electricity supply, we draw upon insights from Net Energy Analysis and renewable energy engineering to examine critically some assumptions, data and arguments in these papers, focussing on regions in which wind and solar can provide the majority of electricity. We show that the above claim is based on outdated data on EROIs, on failing to consider the energy efficiency advantages of transitioning away from fuel combustion and on overestimates of storage requirements. EROIs of wind and solar photovoltaics, which can provide the vast majority of electricity and indeed of all energy in the future, are generally high (≥ 10) and increasing. The impact of storage on EROI depends on the quantities and types of storage adopted and their operational strategies. In the regions considered in this paper, the quantity of storage required to maintain generation reliability is relatively small.

Despite calls for large-scale reductions in material use and efforts to initiate a “circular economy” that promotes recycling and reuse, a limited decoupling between overall resource extraction and economic growth has been historically found. This is particularly true if resource use is measured with the life-cycle or consumption-based material footprint (MF) indicator that allocates material extraction to final goods and services. However, this indicator treats capital goods as final products rather than part of the production process. In this paper, we introduce the capital-augmented material footprint (CAMF), a new indicator of material use that includes all the materials embedded in capital goods. Results for 49 countries and regions over the period 1995–2015 show that for mineral use, about 50–60% of the total footprint of final consumption is embodied in capital goods, whereas for biomass, the figure is around 10%. The largest increase in material requirements was observed in non-OECD countries and in service sectors in general. More countries achieve relative and absolute decoupling when using the CAMF as indicator of material use. Our results underpin the need for comprehensive indicators when assessing options to decrease the impacts of consumption.

© 2020 Elsevier Ltd Consumption-based carbon footprint (CBCF) assessments have become increasingly important in studying the drivers of climate change from a consumer perspective. A wide range of studies and approaches for CBCF have been presented, yet a systematic and interpretative synopsis of the literature is missing. We present a comprehensive review of more than 100 CBCF studies published in Scopus-indexed journals until 2019. We analyze the methodological and conceptual development of spatially related CBCFs and provide guidance for future research. While the recent emergence of several global multi-region input-output (MRIO) models has meant remarkable development in assessment accuracy, there is space for improvement in hybrid-modeling and increasing sectoral detail. Furthermore, it was recognized that studies published under the same CBCF label actually fall into two categories with different definitions and potentially significantly different outcomes. We suggest labeling these as Areal CF (ACF) and Personal CF (PCF) in the future. ACF encompasses the CBCF of economic activities within selected geographic boundaries, and the global production and delivery chain emissions of the goods and services consumed therein, including those consumed by visitors. PCF covers the consumption of the residents of the area regardless of where the consumption takes place but excludes the consumption of visitors within the area in question. ACF analyses typically include government consumption and investments, whereas PCF analyses normally exclude these. This scope issue is seldom brought up in individual studies, and it currently takes a lot of effort and expertise to classify existing studies, which hinders their usability for policy-making. In addition, we suggest that future studies position themselves among previous studies on the same location, discuss potential reasons for differences in the results, and consider these when drawing policy conclusions.

While traditional value engineering (VE) is primarily driven by cost saving, this study aims to comprehensively and reliably investigating the impact of traditional VE on the embodied greenhouse gas (GHG) emissions in the Australian built environment. An Australian-specific hybrid life cycle assessment (LCA) is developed and applied to a mixed-use building complex located in central Sydney, Australia. A list of GHG emissions intensities (GEIs) for 118 construction products is derived from hybrid LCA, demonstrating an average increase of 20% than the corresponding process-based GEIs. By applying the hybrid GEIs, the assessment of the case study building proves that traditional VE can potentially provide environmental benefits through the dematerialisation of the building. These benefits are small in this instance, with a capital cost reduction of 0.72% equating to an embodied GHG reduction of 0.32%, or a total of −267 t CO2e (i.e. -3 kg CO2e/m2 gross floor area), but if such savings were rolled out across the entirety of new building stock in Australia, the accumulated GHG emissions reduction would be significant. Concrete, reinforcing steel and timber formwork are the hotspots for cost and embodied GHG emissions reduction. Manufacturing and electricity are the originating industries that jointly contribute to more than 80% of the embodied GHG emissions.

A peer-to-peer sharing approach for the accommodation sector such as Airbnb has been suggested as a more environmentally sustainable alternative to conventional forms of accommodation services. This study evaluates the carbon footprint of Airbnb hosts in Sydney. The Airbnb platform and its hosts together generate direct and indirect carbon footprints in the range of 7.27 to 9.39 kg CO2e per room and night. The extra income of Airbnb hosts leads to additional, induced carbon footprints. By modelling four different scenarios, the induced carbon footprint of Airbnb hosts range from 3.84 to 602 kg CO2e/room-night. Findings challenge the prevalent notion provided by many previous studies that the sharing economy helps to use under-utilized resources, thus decreasing environmental impacts. This study contributes to peer-to-peer accommodation literature and to the widening public debate on the environmental sustainability of the sharing economy.

Understanding carbon emissions embodied in trade is an important prerequisite for the effective formulation of climate mitigation policies. Based on input–output analysis and panel regression models, this study proposes a multi-step forecasting procedure to simulate carbon emissions embodied in bilateral trade. We calculate carbon emissions embodied in the trade between China and Australia during 2000–2014 and forecast the same for the period 2015–2022 under four different development scenarios. The results show that, during 2000–2014, net carbon outflow from China to Australia increased from 2.2 to 15.5 Mt CO 2 , concentrated in textile and heavy manufacturing sectors. The simulation results show that, the forecasts of “R&D focus” and “GDP focus” scenarios constitute the lower and upper bounds of embodied emissions, and the latter is more than two times of the former in 2022 both for embodied emissions in Australia's exports and China's exports. Finally, conclusions are drawn and policy implications are discussed.

Background: Current climate change mitigation policies, including the Paris Agreement, are based on territorial greenhouse gas (GHG) accounting. This neglects the understanding of GHG emissions embodied in trade. As a solution, consumption-based accounting (CBA) that reveals the lifecycle emissions, including transboundary flows, is gaining support as a complementary information tool. CBA is particularly relevant in cities that tend to outsource a large part of their production-based emissions to their hinterlands. While CBA has so far been used relatively little in practical policymaking, it has been used widely by scientists. Methods and design: The purpose of this systematic review, which covers more than 100 studies, is to reflect the policy implications of consumption-based carbon footprint (CBCF) studies at different spatial scales. The review was conducted by reading through the discussion sections of the reviewed studies and systematically collecting the given policy suggestions for different spatial scales. We used both numerical and qualitative methods to organize and interpret the findings of the review. Review results and discussion: The motivation for the review was to investigate whether the unique consumption perspective of CBA leads to similarly unique policy features. We found that various carbon pricing policies are the most widely supported policy instrument in the relevant literature. However, overall, there is a shortage of discussion on policy instruments, since the policy discussions focus on policy outcomes, such as behavioral change or technological solutions. In addition, some policy recommendations are conflicting. Particularly, urban density and compact city policies are supported by some studies and questioned by others. To clarify the issue, we examined how the results regarding the relationship between urban development and the CBCF vary. The review provides a concise starting point for policymakers and future research by summarizing t

Carbon accounting results for the same city can differ due to differences in protocols, methods, and data sources. A critical review of these differences and the connection among them can help to bridge our knowledge between university-based researchers and protocol practitioners in accounting and taking further mitigation actions. The purpose of this study is to provide a review of published research and protocols related to city carbon accounting, paying attention to both their science and practical actions. To begin with, the most cited articles in this field are identified and analyzed by employing a citation network analysis to illustrate the development of city-level carbon accounting from three perspectives. We also reveal the relationship between research methods and accounting protocols. Furthermore, a timeline of relevant organizations, protocols, and projects is provided to demonstrate the applications of city carbon accounting in practice. The citation networks indicate that the field is dominated by pure-geographic production-based and community infrastructure-based accounting; however, emerging models that combine economic system analysis from a consumption-based perspective are leading to new trends in the field. The emissions accounted for by various research methods consist essentially of the scope 1-3, as defined in accounting protocols. The latest accounting protocols include consumption-based accounting, but most cities still limit their accounting and reporting from pure-geographic production-based and community infrastructure-based perspectives. In conclusion, we argue that protocol practitioners require support in conducting carbon accounting, so as to explore the potential in mitigation and adaptation from a number of perspectives. This should also be a priority for future studies.

The sustainable development goals (SDGs) provide an integrated, evidence-based framework of targets and indicators to support national planning and reporting. For countries to begin implementation of the SDGs, it is critical to build the evidence base for action. The integrated nature of the SDG targets mean that progress towards one target is also linked through complex feedbacks to other targets, placing demands on science and research to support national implementation. A range of different tools and approaches are recommended by experts, and an emerging challenge is to coherently apply and combine these different approaches to support decision-making. This study makes a significant contribution to filling this knowledge gap, adopting a novel integrated assessment approach to support the prioritisation of SDG targets through a case study for 22 countries in the Arab region. The research adopts a multi-criteria analysis decision framework which assesses and prioritises SDG targets based upon their ‘level of urgency’, ‘systemic impact’, and ‘policy gap’. A range of complementary evidence- and science-based approaches are applied within the assessment framework, including baseline assessment and benchmarking of indicators, systems and network analysis of target interlinkages, and mapping of policy alignment and gaps. The study highlights the strengths and weaknesses of each of these analytical approaches, and demonstrates how they can be rapidly combined and applied.

Companies increasingly need detailed information on global impacts related to their products and services. This article describes a quantitative analytical approach that supports a better understanding of value-chain wide corporate sustainability performance. We use an extended multi-regional input-output model to analyse the global supply chains of products and projects for selected impact indicators (energy, greenhouse gases and water) by supply chain tier, industry sector and country. As a case study, we conduct a hotspot analysis of four sample projects from a single company in the wind energy sector. Calculated energy payback times vary between 8.1 and 12.5 months, and greenhouse gas intensities vary between 11.7 and 18.3 g CO2-e/kWh across the four projects. Impacts in the country of installation and production are mainly caused by the electricity, metal and concrete sectors. The supply chain dominates the overall impacts, with supplier tiers 2 to 4 causing the largest share of greenhouse gas emissions. The results allow management to better prioritize actions to manage and alleviate global impacts more effectively. In the future, the company that participated as our case study will base its carbon reduction strategy on the applied approach described in this paper.