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Cities are a major source of greenhouse gas emissions (GHGs), but they can play a significant role in climate change mitigation by adopting and implementing GHG emission reduction plans, policies and measures. Circular economy measures are recognized to contribute significantly to decarbonization. However, in the literature there is a lack of quantitative analyses on circular measures in cities and their impact on urban GHG emissions. The paper aims to contribute to the literature on the relation between circular cities and climate change mitigation by focusing on circular interventions applicable in three high-impact sectors in cities: energy systems, mobility and built environment, in order to investigate their impacts in terms of emission reductions and contribution to decarbonization. The study covers four cities around the world accounting for more than 10 million of inhabitants and 2,000 km2 of metropolitan area: Bogotá, Colombia; Genoa and Milan, Italy; Glasgow, UK. The methodology uses a Global Trade Analysis Project (GTAP) modelling approach to develop production and consumption-based emission baselines for the four cities and to assess impacts of selected circular measures in the three sectors on the baselines. According to the in-depth analysis of the four considered urban contexts, the majority of the emissions generated by activities carried out within the urban borders are emitted outside the borders in the form of emissions scope 3, thus demonstrating how today's cities are large consumers of goods produced outside their borders, requiring the use of a consumption-based approach for emissions inventory. The results on the modelling of the GHG reduction impact of circular measures show that there is a relevant emission reduction potential in Scope 1 and 2 emissions in cities and highlight the need to prioritize decarbonization of electricity supply in order to ensure relevant emission reductions across the three sectors. The results also demonstrate the potential to reduce supply-chain Scope 3 emissions through urban measures. [Display omitted] • Four different urban contexts around the world are taken in account. • Three sectors are investigated: energy, mobility and built environment. • A consumption-based emission accounting method is used to assess the effective impact of cities. • Impacts of different GHG emission reduction interventions are evaluated for each city. [ABSTRACT FROM AUTHOR]

Cities are a major source of greenhouse gas emissions (GHGs), but they can play a significant role in climate change mitigation by adopting and implementing GHG emission reduction plans, policies and measures. Circular economy measures are recognized to contribute significantly to decarbonization. However, in the literature there is a lack of quantitative analyses on circular measures in cities and their impact on urban GHG emissions. The paper aims to contribute to the literature on the relation between circular cities and climate change mitigation by focusing on circular interventions applicable in three high-impact sectors in cities: energy systems, mobility and built environment, in order to investigate their impacts in terms of emission reductions and contribution to decarbonization. The study covers four cities around the world accounting for more than 10 million of inhabitants and 2,000 km2 of metropolitan area: Bogotá, Colombia; Genoa and Milan, Italy; Glasgow, UK. The methodology uses a Global Trade Analysis Project (GTAP) modelling approach to develop production and consumption-based emission baselines for the four cities and to assess impacts of selected circular measures in the three sectors on the baselines. According to the in-depth analysis of the four considered urban contexts, the majority of the emissions generated by activities carried out within the urban borders are emitted outside the borders in the form of emissions scope 3, thus demonstrating how today's cities are large consumers of goods produced outside their borders, requiring the use of a consumption-based approach for emissions inventory. The results on the modelling of the GHG reduction impact of circular measures show that there is a relevant emission reduction potential in Scope 1 and 2 emissions in cities and highlight the need to prioritize decarbonization of electricity supply in order to ensure relevant emission reductions across the three sectors. The results also demonstrate the potential to reduce supply-chain Scope 3 emissions through urban measures. [Display omitted] • Four different urban contexts around the world are taken in account. • Three sectors are investigated: energy, mobility and built environment. • A consumption-based emission accounting method is used to assess the effective impact of cities. • Impacts of different GHG emission reduction interventions are evaluated for each city. [ABSTRACT FROM AUTHOR]

The International Maritime Organisation has set a goal to achieve a 50% reduction of the total annual greenhouse gas emissions related to the international shipping by 2050 compared to the 2008 baseline emissions. Thus, companies are looking for solutions and measures to align with the Organisation's goal. Marginal Abatement Cost Curves have been extensively used in the literature to rank several Greenhouse Gas mitigation measures based on their costs of reducing an additional unit of pollution. In this paper an expert-based, bottom-up approach was employed to construct Marginal Abatement Cost Curves for a globally operating ship-management company. Several mitigation measures were examined for the following vessel categories (a) Containerships 8000+ TEU, (b) Containerships 2000–2999 TEU, (c) Bulkers 35000–59999 DWT, and (d) Gas Tankers <49999 CBM. Furthermore, the fuel price fluctuation and carbon taxation were used to investigate the sensitivity of baseline Marginal Abatement Cost Curves. The measures, which remain cost-effective under all sensitivity analyses, undergo a Pareto Analysis and a Marginal Cost-Effectiveness Analysis. The results suggest that most of the recommended mitigation measures are of an operational and technical nature, with exception the burning of Liquified Natural Gas and the installation of Flettner Rotors for the Gas Tankers. The company could save up to 17% CO 2 emissions and approximately 2 million dollars per year compared to the 2019 baseline by employing all recommended mitigation measures to all vessel categories. In addition, Carbon Storage and Capture could become a cost-effective solution with appropriate carbon taxation, but it is not the ultimate solution since it does not lead to independence from fossil fuels. The study also reveals that depending on the operating condition, even within the same vessel category, different mitigation measures should be employed. • Expert-based, bottom-up and company-specific MACCs for the shipping sector. • GHG mitigation measures' cost-effectiveness for Containerships, Bulkers and Tankers. • Comprehensive way of ranking measures with negative marginal abatement costs. [ABSTRACT FROM AUTHOR]