Prioritizing Nature-Based Solutions and Technological Innovations to Accelerate Urban Heat Mitigation Pathways

Canada is warming at double the rate of the global average caused in part to a fast-growing population and large land transformations, where urban surfaces contribute significantly to the urban heat island (UHI) phenomenon. The federal government released the strengthened climate plan in 2020, which emphasizes using nature-based solutions (NBSs) to combat the effects of UHI phenomenon. Here, the effects of two NBSs techniques are reviewed and analysed: increasing surface greenery/vegetation (ISG) and increasing surface reflectivity (ISR). Policymakers have the challenge of selecting appropriate NBSs to meet a wide range of objectives within the urban environment and Canadian-specific knowledge of how NBSs can perform at various scales is lacking. As such, this state-of-the-art review intends to provide a snapshot of the current understanding of the benefits and risks associated with the implantation of NBSs in urban spaces as well as a review of the current techniques used to model, and evaluate the potential effectiveness of UHI under evolving climate conditions. Thus, if NBSs are to be adopted to mitigate UHI effects and extreme summertime temperatures in Canadian municipalities, an integrated, comprehensive analysis of their contributions is needed. As such, developing methods to quantify and evaluate NBSs’ performance and tools for the effective implementation of NBSs are required.

Nature-based solutions (NbS) have emerged as a key strategy for sustainably addressing multiple urban challenges, with rapidly increasing knowledge production requiring synthesis to better understand whether and how NbS work in different social, ecological, economic, or governance contexts. Insights in this Perspective are drawn from a thematic review of 61 NbS review articles supported by an expert assessment of NbS knowledge in seven global regions to examine key challenges, fill gaps in Global South assessment, and provide insights for scaling up NbS for impact in cities. Eight NbS challenges emerged from our review of NbS reviews including conceptual, thematic, geographic, ecological, inclusivity, health, governance, and systems challenges. An additional expert assessment reviewing literature and cases in seven global regions further revealed the following: 1) Local context-based ecological knowledge is essential for NbS success; 2) Improved technical knowledge is required for planning and designing NbS; 3) NbS need to be included in all levels of planning and governance; 4) Putting justice and equity at the center of urban NbS approaches is critical, and 5) Inclusive and participatory governance processes will be key to long-term success of NbS. We synthesized findings from the NbS review results and regional expert assessments to offer four critical pathways for scaling up NbS: 1) foster new NbS research, technological innovation, and learning, 2) build a global NbS alliance for sharing knowledge, 3) ensure a systems approach to NbS planning and implementation, and 4) increase financing and political will for diverse NbS implementation.

The increase in the resolution of atmospheric models for numerical weather prediction and climate simulations allows for a more accurate description of the physical processes at urban scale. Furthermore, a common trend is occurring in most countries: the number of people living in towns keeps on growing remarkably, therefore it becomes increasingly important to study the living conditions in urban or metropolitan areas under demographic and climate change. In these scenarios, the interest in properly modelling the physical processes in urban areas has gained wide attention in the research community. In particular, the convection-permitting atmospheric models, associated with urban parameterizations, are able to resolve the heterogeneity of cities with applications to heat stress assessment and the development of urban climate adaptation and mitigation strategies. In this perspective, a bulk urban canopy parameterization, TERRA_URB, has been developed for the multi-layer land surface scheme of the COSMO regional atmospheric model. This parameterization has already demonstrated to be able to accurately describe the overall properties of urban areas and to correctly reproduce the prominent urban meteorological characteristics for different European cities. Thus, in the framework of the transition from the COSMO model to the new Icosahedral Nonhydrostatic (ICON) Weather and Climate regional model, TERRA_URB needs to be implemented in ICON. In this work, we present the results for TERRA_URB in ICON-LAM (the limited area model version), for some cities of the Italian peninsula at a mesh size of 2 km. At this stage of the implementation, although further investigations in calibration and in the use of more realistic urban canopy parameters are needed, the preliminary results are really encouraging, since some urban key features are already properly represented, such as urban heat island and urban dry island phenomena. The comparison of these results with available observations is promising. Therefore, this work provides strong evidences regarding the added value of TERRA_URB to ICON in modelling the complex urban canopy interaction processes with the atmosphere.

The urban heat island (UHI) phenomenon has differential impacts on energy use and carbon emissions in buildings depending on the climate of the region and the urban planning strategies in place. This study explores the differential effects of UHI on energy use and carbon emissions in warm and cold climates, using North Africa and North Europe as case studies. We address the following research questions: 1) How does the UHI phenomenon impact energy use and carbon emissions in buildings in these regions? 2) What urban planning strategies are currently in place to mitigate the negative impacts of UHI on energy demand and emissions in these regions? 3) How effective are these strategies in mitigating the negative impacts of UHI on energy demand and emissions in both warm and cold climates? 4) What additional urban planning strategies could be implemented to reduce further the negative impacts of UHI on energy demand and emissions in both warm and cold climates? The UHI increases energy bills and emissions due to the higher demand for cooling energy in warm climates, while in cold climates, UHI reduces energy demand and emissions by decreasing the need for heating energy. Urban planning strategies, such as incorporating green space, using reflective materials, choice of colors, and designing for natural ventilation, can effectively mitigate the negative impacts of UHI on energy demand and emissions in both warm and cold climates. However, the effectiveness of these strategies varies depending on the climate of the region and the specific urban context. In this study, we will provide a recommendation for urban planning strategies that can be implemented to further reduce the negative impacts of UHI on energy demand and emissions in both warm and cold climates. Our study contributes to the understanding of the UHI phenomenon. It provides insights for urban planners and policymakers in developing effective strategies to reduce energy use and carbon emissions in buildings and cities.

Nature-based solutions (NBS) is a collective term for solutions that are based on natural processes, in healthy or restored ecosystems, and their services to address the three pillars of sustainability, including climate-related challenges. Soil and Water Bioengineering (SWB or SWBE) is a hazard mitigation and restoration discipline formally established and structured since the aftermath of World War II, but finding its roots in age old applications, which have many objectives in common with NBS. However, a structured comparison of SWB and NBS terminologies and objectives is lacking, and this is much needed to highlight that SWB are amenable to the concept of NBS in the context of climate change adaptation and disaster risk reduction (DRR). This work presents a comparison between the definition of SWB, NBS, and other terminologies that fall under the NBS concept. A matrix was created to compare NBS and NBS-related terminologies with the three main aspects of the SWB practice: “main aims”, “fields of application” and “other objectives”. Results from the comparison confirm that NBS is a unifying concept to prioritise nature to integrate climate change adaptation, mitigation, and disaster reduction efforts, embracing also many aspects of SWB criteria and applications. Thus, SWB can and should be recognized as having always been an NBS.

<p>Soil and Water Bioengineering (SWB) is a discipline established in the second half of XX century, finding its roots in ancient practices, which implies the use of vegetation and natural materials for natural hazards mitigation and ecosystem restoration. Nature-based solutions (NBS) is a recent collective term for solutions supported and/or inspired by nature to address climate-related challenges.</p><p>Although NBS cover a wide range of approaches based or inspired by natural processes and have many objectives in common with SWB, almost no attempts have been done so far to find overlaps and differences, which is needed especially when definitions are linked to legislations and funding mechanisms.</p><p>We present the results of a systematic comparison of NBS definitions, and other terminologies that fall under the NBS concept, with the definition of SWB. First, we identified applications that are related to the NBS umbrella concept, with their relative definitions, with a special focus on flood risk mitigation, ecosystem restoration, landslide and erosion mitigation. The applications analysed include: Watershed Management or hydraulic-forestry arrangements (WM), Nature-based Solutions (NBS), Green/blue Infrastructure (GI), Urban Forestry (UF), Ecological Engineering (EE), as well as Ecosystem-based Disaster Risk Reduction (Eco-DRR).</p><p>Secondly, a comparison matrix was proposed and developed. The matrix was developed by comparing the main aspects of SWB practice with the aims of the other NBS-related applications.</p><p>The structure of the matrix was the following:</p><ul><li>each row represents each of the 3 main aspects of SWB practices: namely "main aims", "fields of application" and "other objectives";</li> <li>the matrix columns designate all the other NBS-related terminologies, named above.</li> </ul><p>The three main aspects of the SWB discipline cover the following:</p><ul><li><em>main aims</em>: the four main objectives of SWB; namely: technical, ecological, landscape and socio-economic objectives.</li> <li><em>fields of application</em>: main domains of applications and fields of interventions;</li> <li><em>other objectives</em>: the multi-purpose functions exerted by SWB.</li> </ul><p>Excerpts from relevant peer-review and grey literature on NBS were included in the matrix to cross-check the 3 main aspects of the SWB practice. We observed that SWB approaches have at least 2 "aims" in common with all the terms, particularly that all 3 main aspects are covered by the NBS definitions. In terms of "fields of application", the highest number of similarities are found between SWB and EE, and, to a smaller extent, WM, GBI and Eco-DRR.</p><p>In this work we conclude that SWB discipline can be recognized as a concept falling under the NBS unifying concept to prioritise nature to integrate climate change adaptation, mitigation and disaster reduction efforts. SWB overlaps and, in some cases, compliments many NBS-related terminologies. Thus, SWB can and should be recognized as having always been an NBS.</p>

Valuation of urban nature-based solutions in Latin American and European cities

China increasingly engages in environmental diplomacy through South-South cooperation across the developing world. Since 2019, the rise of the discourse of Nature-based Solutions (NbS) within this cooperation has been exponential. Coined just over ten years ago, NbS refers to the underexplored potential of leveraging the natural world to address socio-environmental challenges. The concept finds particular resonance in China, where it demonstrates strong parallels with the domestically-pioneered concept of Ecological Civilization – the ruling paradigm when it comes to all realms of Chinese environmental governance. Building on the global discourse, NbS has been adapted to the Chinese context, creating what some call “Chinese-style” NbS that prioritizes large-scale interventions and ecological engineering over grassroots preservation. China’s NbS are not only being pursued domestically, but also increasingly abroad through the country’s Belt and Road Initiative. From Southeast and Central Asia to Africa and Latin America, this article surveys Chinese-led or financed projects that fall under the broad umbrella of NbS. We provide a comparative analysis of these interventions – or the conspicuous lack of such interventions – to show the current status and future prospects for China’s growing sphere of influence when it comes to advancing NbS in the Global South. We find that China’s embrace of this concept in environmental diplomacy is directly related to the potential for NbS to serve as a tool for helping the country’s vision of an Ecological Civilization “go global.” The consonance between the rhetoric of NbS and Ecological Civilization, combined with the global reach of NbS, provides a powerful platform for taking Chinese environmental discourse to the global level.

Worldwide, increasing urbanization and anthropic activities are causing environmental degradation, resulting in biodiversity loss, lack in ecosystem services provision vital for humans and other living organisms, and climate change. Heatwaves, exacerbated by the urban heat island phenomena (UHI), which consists in the flux of higher temperatures in urban areas compared to surrounding natural areas due to the high concentration of artificial materials with low level of albedo, are among the most critical climate change effects. In addition to the environmental risks associated with heatwaves, these extreme events can also have a strong impact on human health, especially for some social categories such as children or the elderly, as well as fragile subjects. Nature-based Solutions (NbS), defined as solutions inspired by nature or which consist in the integration of natural elements in the urban environment, can reduce the impact of heatwaves, improving local environmental quality. In particular, the positive contribution of NbS in improving outdoor thermal comfort is mainly related to the capacity of shading provided by vegetated elements, as well as the evapotranspiration capacity and the high levels of albedo of leaves. Although the introduction of NbS proved to be a promising strategy to reduce climate change-related risks, one of the most critical aspects is related to the design, planning, and prevision of their performances. Regarding this last aspect, computational modelling constitutes a promising approach due to its pre-design application and their cost-effectiveness. Several computational approaches have been developed during the last years to quantify the potential of group of trees and other NbS to locally reduce the effects of heatwaves and improve outdoor thermal comfort. While most of the models consider mainly urban morphology and solar radiation as meaningful parameters to run real time analysis, other more accurate approaches have been developed. Envi-met is among the computational-fluid dynamics software which allow designers to run accurate microclimate simulations also considering plants contribution. However, this approach presents some critical issues, related to its graphical interface for 3d modeling and the limited amount of information on plant performance. This paper proposes a methodological approach to improve the effectiveness of the simulations to quantify NBS performance in relation to outdoor thermal conditions, by working on the plant modelling. In particular, the parameters considered are: foliage albedo, transmittance, emissivity of leaves, leaf weight and the height and the width of plants.  In this research we model for one urban case study selected plant species, considering the parameters listed above, and to compare the results of three simulation approaches for the analysis on outdoor comfort: 1) a simplified model in stationary conditions which considers geometric parameters, 2) a CFD model to consider thermodynamic parameters with default values from the ENVI-met database, 3) a CFD model which consider more accurate thermodynamic parameters coming from literature and other existing databases. The analysis and comparison of the results will allow understanding how the thermodynamic parameters of plants affect their performances and if the consideration of geometries only allows obtaining significant results (i.e., comparing thermodynamic and stationary conditions modeling).

Cities encounter today systemic societal challenges.Therefore, a comprehensive and holistic approach to overcome them is needed, instead of dealing with them individually.The New Urban Agenda proposed a new paradigm shift in sustainable development, calling for a global action on well-management and well-planning of urban spaces in cities in a sustainable and equitable approach, in order to boost health, well-being and quality of life.The NBS Cluster GoGreen Routes project aims to help solve urban and territorial challenges towards an inclusive, resilient, healthier and sustainable future ahead with naturebased solutions (NBS), in order to provide environmental, social and economic benefits through systemic adaptation interventions.In this paper we described the framework to the exploratory analysis on the NBS Cluster Go Green Routes , conducted under the EU-funded H2020 project GO GREEN ROUTES.The exploratory analyses on the NBS Cluster Go Green Routes project was intended to bring new insights in the debate about NBS.Specifically related to the integration of humanecological well-being and health in cities.This paper reflects on four domains, challenges, impact, and definitions of wellbeing and health in general, coupled with the key enablers and barriers identified by stakeholders in the 4 workshops held during 2021.This paper contributes to filling knowledge and evidence gaps.With the aim to broaden the discussion and advance the understanding of environmental and ecological, political socio-economic perspectives related to NBS interventions in public spaces as a drive for human and ecological well-being and health in cities and enhance NBS mainstreaming.

The concept and application of nature-based solutions (NBS) have been rapidly progressing in Europe and Latin America, reflecting a transition in the way that urban governance is perceived. There is a large call for the collaborative, polycentric, and interdisciplinary governance of NBS. However, research on options for operationalising these governance processes in different contexts is still insufficient. This study explores and analyses the operationalisation of NBS adaptive governance in Europe and Latin America. Seven cities that are part of the project EU-H2020 CONEXUS have been selected as case studies: Barcelona, Bogotá, Buenos Aires, Lisbon, Santiago de Chile, São Paulo, and Turin. This contribution aims to (i) understand how NBS governance processes are managed; (ii) identify the main positive and negative factors that influence NBS adaptive governance; and (iii) understand common factors and relationships that can hinder or drive forward adaptive governance for NBS in the investigated contexts. The results revealed common priorities indicating a shared pathway for Europe and Latin America; however, context-dependent specificities were also observed. These findings can be used to support cities in both European and American contexts in developing plans and actions for the more efficient enabling of NBS implementation and governance through adaptive governance.

Nature-based solutions (NbS) emerge with the aim of facing the several different challenges imposed by climate change and the extreme conditions that humanity is facing. The main purpose of this study is to evaluate NbS related research and teaching in order to prompt environmental education in Latin America. As a means to obtain information about the types of courses and undergraduate research and/or postgraduate training that has being done, investigation groups from Argentina, Brazil, Chile, Mexico and Peru were reached with the help of the Pan-American Constructed Wetlands Network (HUPANAM). This information was complemented with a Web of Science (WoS) review of Nbs publications in Latin America in 2010–2020. Within the study period 2010–2020, a total of 706 studies related to NbS were found in Latin America, being the groups in Brazil (319), Mexico (151), and Chile (83) the ones that led in the number of published research. Additionally, during the study period, an increase of 65% from 2010 to 2020 of publications in WoS could be observed due to the studies conducted by different researchers from Latin America. The most studied topics regarding NbS are constructed wetlands (CW) (38%), biofilters (23%), and stabilization ponds (16%). In terms of the promotion of environmental education related to NbS, a series of books, book chapters and courses can be found. For instance, the book “Constructed Wetlands: Design and Operation”, the book chapter “Strategies of the constructed wetlands operation under the perspective of the global change scenario” and undergraduate courses and summer schools related to CW can be highlighted.KeywordsNature-based solutionsEnvironmental educationLatin AmericaSustainable development goalsBibliographic reviewConstructed wetlands

Quantifying the influence of nature-based solutions on building cooling and heating energy demand: A climate specific review

to estimate the improvement of thermal comfort at a microclimatic level after using Nature-based Solutions (NBS) and albedo mitigation strategies in a square located in a densely built-up district of the city of Rome and subject to the phenomenon of Urban Heat Island. on the basis of the microclimatic simulation results of the current conditions of the area, obtained using the ENVI-met software, several microclimate cooling scenarios were developed and simulated; these scenarios included the integration of different layers of vegetation (herbaceous, shrubby, and arboreal) with different configurations and in different quantities and of different surfaces with high albedo index. the studio area is Piazza Mancini, located in the Flaminio district of Rome. the main outcome measures calculated from the simulations were the intensity of the Urban Heat Island (UHI) and the Universal Thermal Climate Index (UTCI) to estimate the perceived discomfort associated with heat and the potential improvement of such perceptions through the scenarios considered. the simulations based on data from 22.07.2021 showed a progressive reduction of UTCI and of the UHI in the three considered scenarios. From the first scenario, which provides for greening and replacement of the asphalt with a higher albedo, it goes to the second and third scenario, which included also changes in the structure of the square (scenario 2) and functional optimization by inserting a shading structure (scenario 3). Scenarios 2 and 3 show a decrease in UTCI of almost 7ºC and UHI of about 2ºC compared to the actual state. the three presented scenarios show how it is possible to improve the conditions of the healthiness of space (reducing the UHI by about 1.5°C) and that it is possible to transform mitigation actions into opportunities for the regeneration and enhancement of urban public spaces.

Governments across Latin America and the Caribbean (LAC) face challenges in extending and maintaining infrastructure to serve their populations, especially as climate change and ecosystem degradation endanger communities and infrastructure assets across the region. To help address these challenges, the Inter-American Development Bank (IDB) aims to increase its support of Nature-based Solutions (NBS) in accordance with the banks 2020 Environmental and Social Sustainability Mainstreaming Action Plan. This Issue Brief serves two main functions. First, it describes IDB's growing focus on NBS and provides a tour of IDBs main offerings regarding NBS project support and investment. Second, it serves as a baseline of IDBs activities related to NBS from which the bank and partners can build upon moving forward. Going forward, IDB will ramp up support for clients to incorporate NBS considerations and opportunity analysis in country agreements and throughout all stages of project preparation, from investment identification to execution.