Urban ecology and human health: implications of urban heat island, air pollution and climate change nexus

Urban Ecology ◽  
2020 ◽  
pp. 317-334
Author(s):  
Nidhi Singh ◽  
Saumya Singh ◽  
R.K. Mall
Author(s):  
Sajjad Hussain SAJJAD ◽  
Nadège Blond

Global trends show that the world's population is growing with 250,000 new human beings per day, or 100 million a year. This significant growth of the population, coupled with a phenomenon of globalization and an increase in the average standard of living of individuals, first of all poses the problem of energy resources. In fact, major part of this energy, almost 96%, is produced from fossil fuels (petrol, natural gas, coal). The use of fossil fuels also poses environmental problems (pollution of water, soil, air, and all that results from it - loss of biodiversity, reduction of vital resources, etc.). Its combustion notably releases gaseous and particulate species into the atmosphere that are highly harmful to human health and ecosystems, and greenhouse gases (GHGs) that warm the climate on a global scale. The consequences of air pollution on health and associated costs are well identified. The possible consequences of climate change on our societies living in urban areas in form of development of urban heat island (UHIs) which make the cities warmer than its surrounding non-urban areas are also clearly identified. Without adaptive measures or enhancing the resilience capabilities, it further pushes us towards a very uncertain future. Other observations made on different areas across the world already show very significant impacts on the water resources (strong droughts), on the crops (lower yields) and thus on the basic food of our food chain. Another observation is that the population is concentrating more and more in the cities. Since 2007, the population of cities represents more than 50% of the world population. By 2030, this percentage is expected to exceed to 60%. Today almost 75% of total global energy is consumed in urban areas today. Favored by the dense presence of polluting activities and urban objects, very localized peaks of concentrations of a large number of harmful pollutants such as particles, nitrogen oxides and certain hydrocarbons are observed in urban atmosphere. If the reduction strategies of air pollution are not associated with significant growing urban population, it will pose even more health problems. Urbanization, through the alteration of natural land into artificial surfaces, the horizontal and vertical extension of buildings, the activities they generate, and the amount and type of energy they consume, also raises the problem of local warming of cities, the urban heat island, which tends to make cities populations even more vulnerable to climate change and air pollution. Some advantages of these urbanized spaces are to exploit: they concentrate the activities, well developed thus they can limit the needs of energy and resources through sharing; urban heat island reduces winter energy needs in the coldest countries, and increases the atmospheric mix of air pollution. Awareness of the environmental problems created by our lifestyles associated with their direct and indirect costs (present and future) is progressively increasing and regularly drives the policies to take measures to reduce the impacts of human activities and ensure the durable development of our societies. But what is a sustainable or durable future? How to qualify sustainability? Which indicators can be used? All of these questions need to be addressed quickly in order to evaluate the actions that will be taken. In transforming phase of the cities with use of modified form of buildings’ materials, space management, modes of eco mobility, alternative uses of energy etc., the research (public and private) is currently strongly mobilized to ensure technological innovation in all sectors (building, materials, mobility, informatics, etc.), which will enable us to reduce our impacts. The actors involved in spatial planning must also accelerate the integration of energy and atmospheric issues in their development projects and in particular those affecting the cities (production and distribution of energy, mobility, buildings, agriculture, waste, tourism, economic development, etc.). They must ensure that all projects lead to a drastic reduction in our energy consumption, to a better air quality that respects the health of ecosystems, to a climate protection and its effects, short and long term. Thus, the problems of the city become more and more multidisciplinary. Today the cities are a place of all issues since they welcome, and will continue to host most of the population for a long time. However, tools and knowledge in urban areas have yet to be developed, as the urban environment is complex because of its heterogeneity, and its dynamics of evolution are strongly influenced by localized sectoral policies that are not always consistent. To discuss the major issues of urban areas, an interdisciplinary conference titled “European International Conference on Transforming Urban Systems (EICTUS-2019)” was organized by Zone Atelier Environnementale Urbaine (ZAEU) from 26 – 28 June 2019 at Université de Strasbourg. The major themes of this conference were air, climate (risks, resilience, vulnerability, adaptation), energy; mobility; adaptation to climate change; urban governance, economy; public initiatives, planning, society and environment and associated risks; health and social inequalities; land cover landuse change, urban sprawl, urban forms; urban agriculture, nature in cities; sustainable urbanism and architecture; urban water and sustainability; and Smart, sustainable buildings and housing. Almost 160 abstracts were received and 108 people from 28 countries presented their work on 20 different topics as mentioned below.


Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 546
Author(s):  
Andreas Matzarakis

In the era of climate change, before developing and establishing mitigation and adaptation measures that counteract urban heat island (UHI) effects [...]


Urban Science ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 19
Author(s):  
Robert Dare

This article presents a customized system dynamics model to facilitate the informed development of policy for urban heat island mitigation within the context of future climate change, and with special emphasis on the reduction of heat-related mortality. The model incorporates a variety of components (incl.: the urban heat island effect; population dynamics; climate change impacts on temperature; and heat-related mortality) and is intended to provide urban planning and related professionals with: a facilitated means of understanding the risk of heat-related mortality within the urban heat island; and location-specific information to support the development of reasoned and targeted urban heat island mitigation policy.


2021 ◽  
Author(s):  
Tim van der Schriek ◽  
Konstantinos V. Varotsos ◽  
Dimitra Founda ◽  
Christos Giannakopoulos

<p>Historical changes, spanning 1971–2016, in the Athens Urban Heat Island (UHI) over summer were assessed by contrasting two air temperature records from established meteorological stations in urban and rural settings. When contrasting two 20-year historical periods (1976–1995 and 1996–2015), there is a significant difference in summer UHI regimes. The stronger UHI-intensity of the second period (1996–2015) is likely linked to increased pollution and heat input. Observations suggest that the Athens summer UHI characteristics even fluctuate on multi-annual basis. Specifically, the reduction in air pollution during the Greek Economic Recession (2008-2016) probable subtly changed the UHI regime, through lowering the frequencies of extremely hot days (T<sub>max</sub> > 37 °C) and nights (T<sub>min</sub> > 26 °C).</p><p>Subsequently, we examined the future temporal trends of two different UHIs in Athens (Greece) under three climate change scenarios. A five-member regional climate model (RCM) sub-ensemble from EURO-CORDEX with a horizontal resolution of 0.11° (~12 × 12 km) simulated air temperature data, spanning the period 1976–2100, for the two station sites. Three future emissions scenarios (RCP2.6, RCP4.5 and RCP8.5) were implanted in the simulations after 2005. The observed daily maximum and minimum air temperature data (T<sub>max</sub> and T<sub>min</sub>) from two historical UHI regimes (1976–1995 and 1996–2015, respectively) were used, separately, to bias-adjust the model simulations thus creating two sets of results.</p><p>This novel approach allowed us to assess future temperature developments in Athens under two different UHI intensity regimes. We found that the future frequency of days with T<sub>max</sub> > 37 °C in Athens was only different from rural background values under the intense UHI regime. There is a large increase in the future frequency of nights with T<sub>min</sub> > 26 °C in Athens under all UHI regimes and climate scenarios; these events remain comparatively rare at the rural site.</p><p>This study shows a large urban amplification of the frequency of extremely hot days and nights which is likely forced by increasing air pollution and heat input. Consequently, local mitigation policies aimed at decreasing urban atmospheric pollution are expected to be also effective in reducing urban temperatures during extreme heat events in Athens under all future climate change scenarios. Such policies therefore have multiple benefits, including: reducing electricity (energy) needs, improving living quality and decreasing heat- and pollution related illnesses/deaths.</p><p> </p>


2021 ◽  
Vol 13 (17) ◽  
pp. 9617 ◽  
Author(s):  
Wesam M. Elbardisy ◽  
Mohamed A. Salheen ◽  
Mohammed Fahmy

In the Middle East and North Africa (MENA) region, studies focused on the relationship between urban planning practice and climatology are still lacking, despite the fact that the latter has nearly three decades of literature in the region and the former has much more. However, such an unfounded relationship that would consider urban sustainability measures is a serious challenge, especially considering the effects of climate change. The Greater Cairo Region (GCR) has recently witnessed numerous serious urban vehicular network re-development, leaving the city less green and in need of strategically re-thinking the plan regarding, and the role of, green infrastructure. Therefore, this study focuses on approaches to the optimization of the urban green infrastructure, in order to reduce solar irradiance in the city and, thus, its effects on the urban climatology. This is carried out by studying one of the East Cairo neighborhoods, named El-Nozha district, as a representative case of the most impacted neighborhoods. In an attempt to quantify these effects, using parametric simulation, the Air Temperature (Ta), Mean Radiant Temperature (Tmrt), Relative Humidity (RH), and Physiological Equivalent Temperature (PET) parameters were calculated before and after introducing urban trees, acting as green infrastructure types that mitigate climate change and the Urban Heat Island (UHI) effect. Our results indicate that an optimized percentage, spacing, location, and arrangement of urban tree canopies can reduce the irradiance flux at the ground surface, having positive implications in terms of mitigating the urban heat island effect.


2020 ◽  
Vol 12 (21) ◽  
pp. 3491 ◽  
Author(s):  
Mingxing Chen ◽  
Yuan Zhou ◽  
Maogui Hu ◽  
Yaliu Zhou

Global large-scale urbanization has a deep impact on climate change and has brought great challenges to sustainable development, especially in urban agglomerations. At present, there is still a lack of research on the quantitative assessment of the relationship between urban scale and urban expansion and the degree of the urban heat island (UHI) effect, as well as a discussion on mitigation and adaptation of the UHI effect from the perspective of planning. This paper analyzes the regional urbanization process, average surface temperature variation characteristics, surface urban heat island (SUHI), which reflects the intensity of UHI, and the relationship between urban expansion, urban scale, and the UHI in the Beijing–Tianjin–Hebei (BTH) urban agglomeration using multi-source analysis of data from 2000, 2005, 2010, and 2015. The results show that the UHI effect in the study area was significant. The average surface temperature of central areas was the highest, and decreased from central areas to suburbs in the order of central areas > expanding areas > rural residential areas. From the perspective of spatial distribution, in Beijing, the southern part of the study area, the junction of Tianjin, Langfang, and Cangzhou are areas with intense SUHI. The scale and pace of expansion of urban land in Beijing were more than in other cities, the influencing range of SUHI in Beijing increased obviously, and the SUHI of central areas was most intense. The results indicate that due to the larger urban scale of the BTH urban agglomeration, it will face a greater UHI effect. The UHI effect was also more significant in areas of dense distribution in cities within the urban agglomeration. Based on results and existing research, planning suggestions are proposed for central areas with regard to expanding urban areas and suburbs to alleviate the urban heat island effect and improve the resilience of cities to climate change.


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