Tag: climate

The impacts of climate change and urbanization necessitate innovative urban climate adaptation strategies. Scenario approaches, particularly backcasting, are valuable tools for developing such actions. This perspective paper conceptually, topically, and methodologically discusses backcasting, advocating for its application in urban climate adaptation planning, especially concerning green infrastructure, and highlighting the utility of GIS-based modeling. Cities are significant contributors to climate change and are increasingly vulnerable to extreme weather events like heatwaves, droughts, and floods, exacerbated by ongoing urbanization. Urban climate adaptation measures, such as green infrastructure (e.g., parks, green roofs, bioswales), are vital to mitigating these vulnerabilities. Green infrastructure reduces heat stress through cooling and evaporation, manages flood risks by enhancing water infiltration and retention, and offers recreational benefits. Scenario approaches help estimate the current and future impacts of these measures by modeling interactions between climate, biodiversity, and human systems, and evaluating uncertainties of potential adaptation actions. Scenarios can be categorized into predictive (extrapolating current trends), explorative (anticipating possible changes), and normative (focusing on desired futures, such as backcasting). Backcasting begins with a desirable future state and works backward to identify the strategies, targets, pathways, and actions required to achieve that future. Unlike predictive or explorative scenarios that often rely on historical data and existing trends, backcasting emphasizes what *should* happen, potentially necessitating transformative changes to socio-ecological systems. While traditionally focused on future aspirations, backcasting has sometimes been conflated with "pastcasting," which analyzes past changes to the present. This paper proposes a combined approach where backcasting integrates elements of pastcasting, recognizing that future developments cannot be entirely divorced from past actions and existing urban planning frameworks. The proposed integrated backcasting approach involves three main steps. First, define the boundaries of the current state by identifying urban challenges, existing planning strategies, and targets, incorporating pastcasting to assess what goals have been set and achieved historically. Second, develop a desirable yet plausible future scenario based on these identified strategies, targets, and past actions, utilizing spatial data and engaging experts and stakeholders in co-creative, participatory processes. Third, develop pathways by formulating new urban planning strategies, policy measures, and specific development milestones. This step works backward from the future scenario to the present, outlining the intermediate actions needed to reach long-term goals. An illustrative example transforms a densely built-up street into a greener environment with green roofs and walls, and walking/cycling paths, demonstrating how existing policies and past developments inform future visioning. Applying backcasting to urban climate adaptation planning, particularly through green infrastructure, is beneficial due to its long-term, goal-oriented focus, holistic systems approach, and potential for extensive stakeholder involvement. By prioritizing a desirable future, backcasting encourages ambitious and transformative adaptation actions, crucial for addressing long-term climate change impacts. The division into pathways and milestones allows for continuous monitoring and quantification of adaptation efforts. Furthermore, backcasting’s holistic perspective acknowledges cities as complex socio-ecological-technical systems, promoting multi-functional green infrastructure that offers co-benefits like biodiversity enhancement and improved health outcomes. Stakeholder engagement, encompassing diverse expertise from practitioners, planners, citizens, and scientists across various city departments, fosters comprehensive, collaborative scenarios and enhances the acceptance and implementation of proposed adaptation actions. Geographic Information Systems (GIS) are recommended as a methodological tool to support this integrated backcasting approach. Although GIS has been underutilized in backcasting, its capabilities for visualizing desired future scenarios, performing spatial statistics (e.g., quantifying land cover changes, accessibility, network analyses), and accommodating the heterogeneity and systemic interactions of urban areas make it ideal. GIS-based modeling can identify vulnerable hotspots and illustrate existing conditions, urban planning strategies, and desired future states. It enables the quantification of potential impacts of green infrastructure implementations and helps evaluate the sufficiency and plausibility of designed scenarios against urban and national targets. Ultimately, GIS serves as a valuable communication tool, making complex scenarios more tangible and promoting acceptance of urban climate adaptation plans among stakeholders. Challenges include managing diverse spatial data resolutions, overcoming institutional resistance, and resource intensity, especially in cities with informal developments or those in the Global South, where data availability can be limited. However, the potential for innovative and transformative urban development outweighs these limitations. #ClimateChangeAdaptation #UrbanPlanning #Backcasting #GreenInfrastructure #GISModeling #Sustainability #SocioEcologicalSystems #StakeholderEngagement

Climate change poses a significant threat to urban environments, leading to rising temperatures due to the urban heat island effect, where urban infrastructure absorbs and re-emits solar radiation. This phenomenon increases the risk of heat-related illnesses and is exacerbated by poorly planned city development. Given that only 40 percent of the urban areas projected for 2030 currently exist, substantial urban growth is anticipated, making sustainable city planning crucial. Nature-based solutions, such as incorporating vegetation into urban design, offer effective strategies to mitigate these issues by absorbing carbon dioxide and reversing ecosystem degradation. Among various methods to combat the urban heat island effect, plant-based solutions have proven most successful. Urban green spaces are vital for modern dense cities, yet there is ongoing debate regarding the optimal amount of green space needed and the adequacy of current provisions. The World Health Organization recommends easy access to green areas, suggesting that residents should live no more than 300 meters from a green space of at least half a hectare. Vegetation in urban settings can significantly reduce the effects of extreme climate, decrease energy consumption, and enhance physical and psychological well-being, thereby improving the quality of urban life. In tropical regions, where buildings are exposed to intense sunlight, incorporating plants for shade can substantially reduce solar radiation, cool structures, and improve energy efficiency. While traditional tree planting for shade has been practiced for generations, innovative application strategies have emerged. Tree canopies effectively cool the ground by blocking sunlight and regulating heat radiation from buildings. For tropical cities, species like Ceylon Ironwood, known for their dense branching and high leaf coverage, provide excellent shading. This shading reduces absorbed heat radiated into the air, promotes evapotranspiration, lowers ambient temperatures, and enhances thermal comfort. The use of plants to modify microclimates can lower indoor and outdoor temperatures by more than 3 degrees Celsius. The effectiveness of shading varies among plant species. In situations where space for large trees is limited, living walls, which are vertical garden systems that irrigate and sustain plants, offer a viable alternative. These living walls can influence microclimates by reducing surrounding temperatures and may also contribute to water treatment. Vegetation integrated into building exteriors serves dual purposes: it reduces heat transfer into buildings and enhances their aesthetic appeal. Green facades, where plants like vines and creepers grow directly on the building surface or on light frameworks, and green walls, which involve systems for cultivating various plant species on wall surfaces, are common living wall systems that boost a building's energy efficiency. Continuous green walls, or vertical gardens, typically use lightweight, permeable frames for individual plant placement. Selecting appropriate climbing plants, such as Double Rangoon for green facades and Yellow Trumpet vines or Curtain Creepers, is essential for optimal performance and a sustainable living environment. These plants not only create more pleasant microclimates but also contribute to air purification. Urban farming, a practice with historical roots evident in places like Machu Picchu and the Hanging Gardens of Babylon, is experiencing a modern resurgence. People have historically cultivated gardens to improve their quality of life, and today, urban garden integration emphasizes reducing greenhouse emissions and greening cities. Green infrastructure can facilitate the revitalization of underutilized urban spaces, offering opportunities for small-scale farming that can provide food to city residents and further reduce carbon emissions. Rooftops, balconies, and vacant lots are ideal locations for urban farms. The presence of vegetation demonstrably influences a building's microclimate, with plants capable of reducing temperatures by 1.32 to 5 degrees Celsius compared to hard surfaces due to evapotranspiration. Urban greening plays a critical role in mitigating the urban heat island effect, particularly in spaces between buildings. Utilizing plants to moderate heat and lessen reliance on artificial cooling is a foundational step toward addressing the challenges posed by rapidly warming cities. #ClimateChange #UrbanPlanning #GreenInfrastructure #UrbanHeatIsland #NatureBasedSolutions #GreenBuilding #SustainableCities #VerticalGardens #ThermalComfort

Cities worldwide are grappling with the escalating issue of urban heat, a direct consequence of climate change and the urban heat island (UHI) effect. The UHI effect, where urban areas experience significantly higher temperatures than surrounding rural areas due to heat absorption by dark surfaces and infrastructure, poses substantial health risks, contributes to premature deaths, and damages urban infrastructure. With average city temperatures 1-7°F warmer during the day and up to 5°F warmer at night compared to rural counterparts, there's an urgent need for effective cooling solutions to mitigate these impacts. While air conditioning offers a seemingly straightforward solution, its widespread use exacerbates the problem by expelling hot air into streets, creating a detrimental feedback loop. In cities like Tokyo, over-reliance on air conditioning has contributed to a 3°C rise in average temperatures over the past century. This necessitates the exploration of more sustainable and integrated cooling strategies. One primary approach involves increasing urban green infrastructure. Planting more trees creates crucial shade, naturally regulating temperatures. A study published in The Lancet demonstrated that increasing tree cover to 30% in 93 European cities could prevent over 2,600 premature deaths linked to excessive urban heat. For residential buildings, retrofitting with green roofs and walls is effective in reducing the UHI effect. Research is underway to test the thermal performance of materials like hempcrete combined with green wall constructions. The need for greenery is particularly acute in lower-income communities, which often have fewer trees and parks, leading to higher heat exposure. For instance, neighborhoods with a majority of people in poverty in the US have 25% less tree canopy. Penrith City, Australia, exemplifies extreme urban heat challenges. As one of the hottest living environments globally, with temperatures reaching 48.9°C, residents in poorly constructed social housing often resort to makeshift cooling methods. Experts advocate for less conservative planning and building design, drawing lessons from traditionally hot cities that incorporate architectural features like fast-growing vines, breezeways, and courtyards, or interior stacks in high-rise buildings designed to summon breezes. Beyond vegetation, altering urban surfaces is another key strategy. Campaign groups like the Smart Surfaces Coalition (SSC) advocate for a combination of reflective, porous, and green surfaces, alongside increased tree and solar PV coverage. This integrated approach can achieve significant cooling. For example, while trees can cool a city by 1-2 degrees, combining them with reflective roofs, roads, and parking lots can lead to a 5-7 degree reduction. US cities like Los Angeles and Phoenix are applying reflective coatings to roads, while New York City’s program to resurface dark roofs has led to up to a 30% reduction in air conditioning demand on treated buildings. Baltimore's city-wide smart surface strategy aims to reduce temperatures by 1.7°C across the city and 2.4°C in downtown by 2050. However, the implementation of such projects often faces challenges, including a lack of comprehensive policy support and a focus on lowest-cost surface designs rather than considering climate and health benefits. Even historically cooler regions are now experiencing extreme heat. In 2003, England recorded 2,193 heat-related deaths in just 10 days due to temperatures reaching 38.5°C, with such heatwaves projected to occur every other year by the 2040s. To address this, building design strategies include considering orientation to reduce solar gain, maximizing daylight, and utilizing manual or automated exterior shading devices. Green façades can reduce cooling loads and local temperatures by up to 10°C, also reducing particulate matter. Improved insulation and adherence to standards like Passivhaus, which limits internal temperatures to 25°C for no more than 10% of the year, are crucial. Projects like EU-funded Ignition in Manchester demonstrate the value of collaborative, nature-based solutions to mitigate UHIs. There is a pressing need for municipalities to recognize urban heat as an immediate problem and implement comprehensive strategies for long-term resilience. #UrbanHeatIsland #ClimateChange #GreenInfrastructure #SustainableDesign #CoolingSolutions #UrbanPlanning #Retrofit #ResilientCities #SmartSurfaces