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Cities face substantial risks of economic and physical losses from repeated exposure to climate hazards exacerbated by climate change. Drawing from the climate action and policy mix literatures, this study conceptualizes "climate action mix" defined as the diverse policy actions adopted by city governments to adapt to and mitigate the effects of climate hazards. This study makes a key contribution by analyzing the relation between the variety of hazards and the diversity of cities' climate action mixes. Deploying a modified Shannon diversity index, we develop a new measure of climate action mix by considering the breadth across different actions, and the depth of these efforts as measured by the progress along the policy cycle. We study an expansive range of mitigation and adaptation actions without imposing any domain or jurisdictional limitations in 162 cities across the United States. The analysis reveals a bifurcation in approaches where some cities have not adopted any policies, while others have a diverse mix of adaptation and mitigation actions in various stages of policy progression. We find that climate hazards drive local action—cities that experience multiple threats react by taking a diverse mix of climate actions. Cities broadly utilize global climate networks that offer policy learning opportunities and local networks that might promote a shared understanding of environmental threats leading to diverse climate action mixes. Finally, a city's capacity to develop climate adaptation and mitigation plans is positively related to a diverse portfolio of climate actions. [ABSTRACT FROM AUTHOR]

Research on nature-based solutions, green infrastructure, and ecosystem services to support climate action in cities has proliferated over the past decade. However, relatively little attention has been paid to the unique features of urban forests under climate change. This paper addresses this gap by providing an integrative critical review of 44 articles published during the 2000-2020 period. The review allowed to identify three key themes that require further research: (1) the need to strengthen the framing of urban forests under climate change in the light of other discourses; (2) the need to better understand the complexity of urban forest benefits and exposures, and (3) the need to facilitate further knowledge integration to support more informed and inclusive decision making. The paper concludes by highlighting prospects for collaboration across science, policy and practice contexts. [ABSTRACT FROM AUTHOR]

The Paris Agreement aims to limit global mean temperature rise this century to well below 2 °C above pre-industrial levels. This target has wide-ranging implications for Europe and its cities, which are the source of substantial greenhouse gas emissions. This paper reports the state of local planning for climate change by collecting and analysing information about local climate mitigation and adaptation plans across 885 urban areas of the EU-28. A typology and framework for analysis was developed that classifies local climate plans in terms of their alignment with spatial (local, national and international) and other climate related policies. Out of eight types of local climate plans identified in total we document three types of stand-alone local climate plans classified as type A1 (autonomously produced plans), A2 (plans produced to comply with national regulations) or A3 (plans developed for international climate networks). There is wide variation among countries in the prevalence of local climate plans, with generally more plans developed by central and northern European cities. Approximately 66% of EU cities have a type A1, A2, or A3 mitigation plan, 26% an adaptation plan, and 17% a joint adaptation and mitigation plan, while about 33% lack any form of stand-alone local climate plan (i.e. what we classify as A1, A2, A3 plans). Mitigation plans are more numerous than adaptation plans, but planning for mitigation does not always precede planning for adaptation. Our analysis reveals that city size, national legislation, and international networks can influence the development of local climate plans. We found that size does matter as about 80% of the cities with above 500,000 inhabitants have a comprehensive and stand-alone mitigation and/or an adaptation plan (A1). Cities in four countries with national climate legislation (A2), i.e. Denmark, France, Slovakia and the United Kingdom, are nearly twice as likely to produce local mitigation plans, and five times more likely to produce local adaptation plans, compared to cities in countries without such legislation. A1 and A2 mitigation plans are particularly numerous in Denmark, Poland, Germany, and Finland; while A1 and A2 adaptation plans are prevalent in Denmark, Finland, UK and France. The integration of adaptation and mitigation is country-specific and can mainly be observed in two countries where local climate plans are compulsory, i.e. France and the UK. Finally, local climate plans produced for international climate networks (A3) are mostly found in the many countries where autonomous (type A1) plans are less common. This is the most comprehensive analysis of local climate planning to date. The findings are of international importance as they will inform and support decision-making towards climate planning and policy development at national, EU and global level being based on the most comprehensive and up-to-date knowledge of local climate planning available to date. [ABSTRACT FROM AUTHOR]

This study investigates the climate emergency declaration (CED) movement in cities and its effects and synergies with local climate planning. Urban areas are experiencing a wide range of climate-induced extreme events, particularly those located in the Mediterranean hotspot. The focus is on Italian cities, which have only recently become key players in climate planning. The method is based on the collection, analysis, and comparison of data on CEDs and local climate plans (LCPs), integrated with information on city membership in climate networks, to extrapolate key performance indicators of the CED movement. The results show that the CED movement can motivate municipalities to become more ambitious in climate action. As of February 2021, the "climate emergency" movement was supported by 105 Italian cities geographically concentrated in the northern regions (66.7%). The motivation behind a CED is often attributable to local populations calling for concrete climate action (91.1% referred to the Fridays for Future movement) but also to a greater perception of the impacts of climate change (85.6% referred to the Special Report on Global Warming of 1.5 °C). Networking plays an important role (85 cities in the Covenant of Mayors). Interestingly, 36 cities (34.3%) were not engaged in local climate planning previously, but the CED shows now they see the urgency to act. 24.4% cities aim at carbon neutrality in their CEDs (most with local adaptation aspirations), with a much smaller fraction of cities doing so in LCPs and generally lower ambition in terms of greenhouse gas emission reduction targets. [Display omitted] • Case study: 105 IT cities that have declared climate emergency (66.7% in the north). • Motivation: 91.1% refer to the FFF movement, 85.6% to the 2018 IPCC Special Report. • Networking: 85 cities are members of CoM and 33 of the Italian Green City Network. • 34.3% of the CED cities had not previously a mitigation or adaptation plan. • 24.4% of CEDs aim at carbon neutrality, while LCPs have less ambitious GHG targets. [ABSTRACT FROM AUTHOR]

A growing body of literature suggests that an economic case may exist for investment in large-scale climate change mitigation. At the same time, however, investment is persistently falling well short of the levels required to prevent dangerous climate change, suggesting that economically attractive mitigation opportunities are being missed. To understand whether and where these opportunities exist, this article contrasts macro-level analyses of climate finance with micro-level bottom-up analyses of the scale and composition of low-carbon investment opportunities in four case study developing world cities. This analysis finds that there are significant opportunities to redirect existing finance streams towards more cost-effective, lower-carbon options. This would mobilize substantial new investment in climate mitigation. Two key explanations are proposed for the failure to exploit these opportunities. First, the composition of cost-effective measures is highly context-specific, varying from place to place and sector to sector. Macro-level analyses of climate finance flows are therefore poor indicators of the micro-level landscape for low-carbon investment. Specific local research is therefore needed to understand the opportunities for cost-effective mitigation at that level. Second, many opportunities require enabling governance arrangements that are not currently in place. Mobilizing new low-carbon investment and closing the ‘climate finance gap' therefore requires attention to policy frameworks and financing mechanisms that can facilitate the exploitation of cost-effective low-carbon options. Policy relevance The importance of increasing investment in climate mitigation, especially in developing nations, is well established. This article scrutinizes four city-level studies of the scope for cost-effective low-carbon investment, and finds that significant opportunities are not being exploited in developing world cities. Enabling governance structures may help to mainstream climate considerations into investments by local actors (households, businesses and government agencies). While climate finance distributed through international bodies such as the Green Climate Fund may not always be a suitable vehicle to invest directly in disaggregated, local-level measures, it can provide the incentives to develop these governance arrangements. [ABSTRACT FROM PUBLISHER]

A number of cities in the United States have devised climate action plans (CAPs) to mitigate the effects of climate change. However, few of these plans address strategies to adapt to the long term effects of climate change that will occur in the near and distant future. The research presented in this article examines why cities choose to embed adaptation provisions in their CAPs. Our study codes the content of CAPs for all cities ( N = 98) in the United States with populations greater than 50,000. We find cities that frame problems associated with climate change in the language of hazards are more likely to include adaptation strategies in their CAPs than cities that focus on other types of environmental harm. Our findings suggest that more robust efforts to plan for climate change will require the activation of communities of interest beyond those that have been instrumental in setting the current climate agenda. [ABSTRACT FROM AUTHOR]

Cities are central to the fight against climate change, but the IPCC recently noted that many cities — and particularly those in the developing world — lack the institutional, financial and technical capacities needed to switch to low emission development paths. Based on detailed case studies of three Asian cities, this paper finds that the adoption of low emission development strategies (LEDS) at the urban level could be economically attractive. However, it also argues that without a coordinated multi-level, cross-sectoral governance framework these opportunities for low carbon urban development are likely to be left unexploited. As these governance conditions are frequently not in place, we argue that these case study cities, and cities in similar contexts, are likely to miss even the economically attractive low carbon development opportunities and become increasingly locked in to higher cost, higher carbon development paths. Due to their growing size and importance, we conclude that the presence or absence of governance arrangements that enable the adoption of low carbon development strategies in Asian cities will have global implications for climate change. [ABSTRACT FROM AUTHOR]

There is increasing interest in the potential of cities to contribute to climate mitigation. Multiple assessments have evaluated the scale and composition of urban GHG emissions, while others have evaluated some aspects of urban mitigation potential. However, assessments of mitigation potential tend to be broadly focused, few if any have evaluated urban mitigation potential on a measure-by-measure basis, and fewer still have considered the economic case for investing in these measures. This is a significant knowledge gap as an economic case for action could be critical in building political commitment, strengthening institutional capacities, securing large-scale finance and targeting investment and implementation in cities. In this paper, we conduct a comparative analysis of the results of five recently completed studies that examined the economic case for investing in low-carbon measures in five cities: Leeds in the UK, Kolkata in India, Lima in Peru, Johor Bahru in Malaysia and Palembang in Indonesia. The results demonstrate that there is a compelling economic case for cities in both developed and developing country contexts to invest, at scale, in cost-effective low-carbon measures. The results suggest that these investments could generate significant reductions (in the range of 15–24% relative to business-as-usual trends) in urban carbon emissions over the next 10 years. Securing these savings would require an average investment of $3.2 billion per city, which if spread over 10 years equates to 0.4–0.9% of city GDP per year. However, the savings generated in the form of reduced energy bills would be equivalent to between 1.7% and 9.5% of annual city-scale GDP, and the average payback period of investments would be approximately 2 years at commercial interest rates. We provisionally estimate that if these findings were replicated and similar investments were made in cities globally, then they could generate reductions equivalent to 10–18% of global energy-related GHG emissions in 2025. While the studies offer some grounds for optimism, they also raise important questions about the barriers to change that prevent these economically attractive options from being exploited and about the scope for mitigation based on the exploitation of only the economically attractive options. We therefore discuss the institutional capacities, policy environments and financing arrangements that need to be developed before even these economically attractive opportunities can be exploited. We also demonstrate that, in rapidly growing cities, the carbon savings from such investments could be quickly overwhelmed – in as little as 7 years – by the impacts of sustained population and economic growth. We conclude by highlighting the need to build capacities that enable the exploitation not only of the economically attractive options in the short term but also of those deeper and more structural changes that are likely to be needed in the longer term. [ABSTRACT FROM AUTHOR]

The frequency and severity of many types of extreme weather events may be changing because of climate change. To date, most vulnerability studies and resulting toolkits for decision makers, while state of the art, only address a specific subset of possible extreme weather events and mitigation and adaptation efforts. This paper extends Haddon's strategies to facilitate a holistic, systematic analysis of the options that communities have to cope with uncertain impacts from multiple hazards in multiple sector of society. This framework distinguishes between efforts to reduce the hazard, the exposure, and the vulnerability, thus helping end the semantic confusion of the meaning of adaptation and mitigation. Two case studies demonstrate the merits of the proposed framework. First, we show how the framework can facilitate the systematic identification of mitigation and adaptation strategies for a sector such as human health. Second, we apply the framework to a particular hazard, anthropogenic climate change, in three cities in US Northeast. We find that the three cities pursue a range of strategies, with varying degrees of effort. Comparing cities reveals that some still have unused capacities, especially in terms of reducing the exposure and vulnerability to climate-enhanced hazards. Spreading efforts across multiple feasible strategies increases the robustness of the cities' policy approach and diversifies the cities' investment in the face of an uncertain future. Subsequent work, such as a cost-benefit analysis, would help a decision maker to evaluate policy options and steer research efforts appropriately. [ABSTRACT FROM AUTHOR]

This paper considers the very large differences in adaptive capacity among the world’s urban centres. It then discusses how risk levels may change for a range of climatic drivers of impacts in the near term (2030–2040) and the long term (2080–2100) with a 2°C and a 4°C warming for Dar es Salaam, Durban, London and New York City. The paper is drawn directly from Chapter 8 of Climate Change 2014: Impacts, Adaptation and Vulnerability, the IPCC Working Group II contribution to the Fifth Assessment Report. It includes the complete text of this chapter’s Executive Summary. The paper highlights the limits to what adaptation can do to protect urban areas and their economies and populations without the needed global agreement and action on mitigation; this is the case even for cities with high adaptive capacities. It ends with a discussion of transformative adaptation and where learning on how to achieve this needs to come from. [ABSTRACT FROM PUBLISHER]

Cities across the globe recognise their role in climate mitigation and are acting to reduce carbon emissions. Knowing whether cities set ambitious climate and energy targets is critical for determining their contribution towards the global 1.5 °C target, partly because it helps to identify areas where further action is necessary. This paper presents a comparative analysis of the mitigation targets of 327 European cities, as declared in their local climate plans. The sample encompasses over 25% of the EU population and includes cities of all sizes across all Member States, plus the UK. The study analyses whether the type of plan, city size, membership of climate networks, and its regional location are associated with different levels of mitigation ambition. Results reveal that 78% of the cities have a GHG emissions reduction target. However, with an average target of 47%, European cities are not on track to reach the Paris Agreement: they need to roughly double their ambitions and efforts. Some cities are ambitious, e.g. 25% of our sample (81) aim to reach carbon neutrality, with the earliest target date being 2020.90% of these cities are members of the Climate Alliance and 75% of the Covenant of Mayors. City size is the strongest predictor for carbon neutrality, whilst climate network(s) membership, combining adaptation and mitigation into a single strategy, and local motivation also play a role. The methods, data, results and analysis of this study can serve as a reference and baseline for tracking climate mitigation ambitions across European and global cities. • 78% of cities have a mitigation plan with targets (avg. 47% GHG reduction). • Only 25% of cities strive for carbon neutrality, most by 2050, avg. By 2045. • 90% of cities striving for carbon neutrality are members of a climate network. • Ambition is driven by city size, climate networks, M-A combination, local motivation. • European cities must double their ambitions to meet the aims set by the Paris Agreement. [ABSTRACT FROM AUTHOR]

• More than 12 000 policies reported in 315 MEIs of signatories to the CoM have been assessed. • An aggregation process for harmonizing the policies submitted in the MEIs has been conducted. • Policies have been classified according to two policy criteria and correlated with the grouping of signatories according to contextual drivers. • The methodology provided in the study can be further used to assess potential differences with submitted SEAPs. The Paris agreement recognises the key role of local authorities in reaching the 1,5 °C target. The Covenant of Mayors (CoM) has been an unprecedented phenomenon in the arena of transnational initiatives in climate action at local level. The initiative has expanded tremendously over the past 10 years, covering more than 9 600 local authorities and 327 million inhabitants as of June 2019. This study analyses policies and measures adopted and implemented by local authorities, signatories to the CoM, as reported in their Monitoring Emission Inventories (MEI). More than 12 000 policies reported in 315 MEIs have been assessed. The policies adopted in municipalities across Europe have been classified according to two criteria: (1) the type of policy tool and (2) the field of action. The aggregated policies have then be correlated with the grouping of signatories according to three "contextual" drivers. The contextual drivers allow identifying the factors that may influence the distribution of climate and energy policies and successful examples and methodologies that may be replicated in other cities with comparable characteristics and similar contexts. Overall, results show that the most common policies cover municipal assets and structures. The policies adopted by local governments do change with the population and, therefore, the focus on municipal assets changes with the increase of population, while local authorities' Gross Domestic Products and climatic conditions have limited influence on the selection and distribution of policies in the framework of this study. [ABSTRACT FROM AUTHOR]

With nearly 70% of the world population expected to live in cities by 2050, assessing the sustainability of urban systems, both existing and future ones, is becoming increasingly relevant. Making cities more sustainable is a global priority, which is highlighted by 'Sustainable Cities and Communities' being listed as one of the Sustainable Development Goals (SDG) adopted by United Nations Member States in 2015. This Virtual Special Issue (VSI) explores the implementation and assessment of policies and technologies that contribute to the transition to a sustainable, energy efficient and regenerative society. We organized the issue according to four main research themes: 1) Renewable Energy Systems (i.e., different types of systems, qualitative assessments and public acceptance); 2) Sustainable Built Environment (which includes construction, operation and refurbishment); 3) Multi-Scale Models (considering urban sustainability transition from building to districts, or cities and regions to multi-country comparisons and their scaling across different countries); and 4) Governance and Policy (climate change mitigation and adaptation plans/policies that are reported across countries, urban services and infrastructures). This paper serves two purposes. The first is to provide an analysis about patterns, correlations and synergies found across the different topics that have been addressed over the last 20 years in the literature about cities' sustainability paths. A bibliometric analysis and a contingency matrix show the degree of correlation between scientific journals and main topics addressed by published articles. Secondly, the paper acts as an Editorial to the VSI, introducing the wealth of research articles and topics included in it. Both the bibliometric analysis and the papers published in this VSI demonstrate the interconnectedness of energy consumption, pollutant emissions and the competition for finite resources. The aim is to present advances and challenges of this exciting and ever-evolving research field to inform and guide future studies of urban sustainability. • We carried out a bibliometric analysis of the literature using the Cortext Manager platform· Using network analysis of a corpus of paper spanning 20 years we identified 8 major clusters. • The paper serves also as editorial for a virtual special issue dealing with urban sustainability pathways. • The virtual special issue is organised in four main themes, which touch upon different Sustainable Development Goals. [ABSTRACT FROM AUTHOR]