Indeed, the urban climate crisis looms large in addressing the myriad concerns that urbanization and climate change engender. Cities are at the hub of climate change impacts, whereas urbanization contributes to extreme weather events, heat waves, and rises in sea level. In the annals of current research, another serious face is given to the matter when cities are projected to face increasingly severe heat waves, which will intensify heat-related health risks for vulnerable populations due to the urban heat island effect.
Table of Contents
What is Climate Change?
Climate change refers to long-term shifts in temperatures and weather patterns, mainly caused by human activities such as burning fossil fuels, deforestation, and industrial processes. These actions increase greenhouse gases like carbon dioxide in the atmosphere, trapping heat and leading to global warming, rising sea levels, extreme weather, and disruptions to ecosystems.
With the concentration of infrastructure and population in urban centers, cities become more vulnerable to climate-related disasters such as flooding and storm surges. Interdisciplinary solutions integrating urban planning, sustainable design, green infrastructure, and community engagement are imperative in overcoming the urban climate crisis. A deeper understanding of the intricacies underlying the urban climate crisis coupled with pre-emptive approaches will better position cities to weather the effects of climate change in a resilient, sustainable, and equitable manner.
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On its own, this is quite the problematic construction, as it brings in other contextual variables, putting the entire frame of sustainability and human well-being globally into a scenario. Urbanization, characterized by rapid city growth, is responsible for energy consumption, waste generation, transportation demand, infrastructure development, which in turn gives rise to greenhouse gas emissions, resource depletion, and environmental degradation.
Climate Change & Urban Heat Increasing Risk for India
According to the Intergovernmental Panel on Climate Change (IPCC), about 70% of the total carbon dioxide emissions are caused by cities, indicating how key urban areas are becoming in enhancing climate change. Moreover, climate change aggravates existing urban challenges, such as heat stress, water scarcity, and extreme weather events, putting already vulnerable urban residents at greater risk.
Failure to reverse the adverse effects of urbanization on climate change would imply terrible consequences, such as grievance social inequality, economic instability, and ecological collapse. Therefore, action in tandem on urbanization and climate change is actually the only way to go for sustainable development, resilience, and a future with some hope for coming generations.
The linkage between urbanization and climate change presents a tangled net of predicaments with profound severities for both the environment and mankind. Urbanization and/or the indefinite growth of cities have figured as a driving force of climate change, land use changes, and urban heat island effect; in turn, climate change aggravates urban vulnerabilities.
Urban Heat Islands – Most Evident Impact of human Intervention on Planet – Earth
Urban areas are warmer than rural areas. This phenomenon is termed as Urban Heat Island.
Urban Heat Island Effect (up to 10°C higher)
Research Shows How Urban Heat Island Effects Are Generating Extreme Weather Conditions
The 2011 Census recorded that nearly 31% of India’s population lives in urban locales contributing to 63% of the country’s gross domestic product. By about 2030, some 40% of India’s population is expected to be living in urban areas, contributing as much as 75% of the GDP of the country. Urbanization and industrial expansion over the past few decades have brought along with them their share of weather extremes that have adversely affected the overall quality of life, especially in urban locations. Scant scientific investigations and studies are available on the changing pattern of UHI and urban growth in major cities of India.
Few observational studies have shown the cause of UHI and its effects on cities. Remote sensing and in-situ measurement studies done over India have proved that UHI intensity is directly impacted by anthropogenic heat sources and specific land-use and land-cover patterns. In most studies, the UHI intensity of different cities was shown to peak at night, with a range of intensities measured between 2.0 and 10.3 °C. A comprehensive documented account of UHI investigation conducted in Indian cities based on observations is compiled.
Research must be prioritized in this direction for the mitigation strategy formulations for the ongoing development of more than a hundred smart cities in India. The future trend and current status of UHI research will inform researchers as to what issues are most pertinent and will help policymakers design effective mitigation and adaptation schemes.
Interconnection of Urbanization and Climate Change
Seven out of ten Earth residents now reside in cities after the 2050 population reached 56 percent (4.4 billion). The financial sector that operates through cities generates 80 percent of the global GDP while proper urban management promotes growth by enhancing innovation and productivity. Urban ecosystem-climate change interactions have emerged as a key point in worldwide environmental discussions since both urban populations are expanding fast and climate effects are rising.
The combination of built infrastructure with vegetation and multiple human city events produces a collection of ecosystem services that build both city toughness and resident quality of life. Urban ecosystems function as dual systems to supply provisioning services of water and food while performing regulatory duties which include thermal regulation and air quality maintenance as well as stormwater management.
A sophisticated network exists between climate change and urban ecosystem services which changes dynamically (Figure below).
Factors Affecting Urbanization and Climate Change
Multiple elements combine to drive urbanization and climate change including demographic trends and economic growth as well as energy usage and modifications to land uses such as Population growth, Industrialisation and economic development, Energy consumption and fossil fuel use, Land use changes and deforestation, Urban planning and infrastructure, etc.
The growth of human population creates substantial influence on these phenomena. Urban centers expand because people need more resources together with better infrastructure and housing while worldwide population numbers continue to grow. The expansion creates more greenhouse gas emission outputs.
Experts estimate that by 2050 the world population will rise to 9.7 billion while most people will reside in urban areas. Industrial processes and economic advancement provide people with employment options that pull them towards urban centers for residence. Industries generate high levels of greenhouse gas emissions through their consumption of fossil fuels together with their industrial operation processes.
Global Warming Rate is Increasing in India
Indian manufacturing plants together with construction sites present major release points for greenhouse gases across the country. The expansion of industries leads to growth in carbon emissions that creates environmental effects of global warming. Utilizing only fossil fuels to create power while relying on transportation alone functions as one of the biggest causes of global warming. Manmade energy requirements from urban development trigger greater greenhouse gases unless people focus on renewable energy alternatives.
United States remains a substantial contributor to worldwide carbon emissions because its citizens use an excessive amount of energy as the nation depends on fossil fuels to create electricity and operate transportation systems. India ranks as a top coal-consuming nation because of its extensive electricity production using coal and oil and natural gas which creates high global warming emissions. Built environment development in urbanization processes causes the destruction of natural land and destroys habitats in these areas.
Deforestation Impacts on Climate Change
The process of deforestation generates climate change because it diminishes carbon storage areas which allows trapped carbon to escape into the atmosphere. The Amazon rainforest serves as a major carbon-sink since its rapid clearing through agricultural activities and urban progress and large-scale development projects results in greater emissions of carbon into the atmosphere.
The three areas of agricultural expansion together with infrastructure and urban development resulting from population growth cause extensive deforestation throughout Indian territories. Urban areas created from destroyed forests become sources of carbon emissions while causing devastating effects on biodiversity.
City development plans along with infrastructure projects both affect how much heat cities produce and the way cities resist climate change effects. Environmental hazards become increased and buildings require more energy while transportation systems operate inefficiently if urban development lacks proper planning.
Copenhagen Denmark illustrates sustainable urban planning success by establishing extensive public transport systems and bicycle-friendly infrastructure and ecological green areas that result in reduced emissions and strong climate resilience. India alongside other developing nations experiences urbanization primarily because of infrastructure development which includes transportation networks housing and utilities.
Alternatively, infrastructure development, including transportation networks, housing, and utilities, influences urbanization in developing nations such as India. Improved infrastructure attracts people to urban areas and facilitates economic growth. The development of metro rail systems in cities like Delhi and Kolkata has improved connectivity and accessibility, further fueling urbanization.
Impacts of urbanization on climate
Natural transformations speed up within urban centers while the consumption of substantial energy and GHG emissions from these areas leads to global warming. The effects that cities produce on the environment depend on multiple elements which consist of city planning alongside urban layout and economic activities as well as population growth and cultural practices and weather variability among other concerns.
The essential regulating services for urban resilience consist of vital invisible operations that protect plant pollination and control floodwaters along with diseases and manage air and soil quality. Urban vegetation including trees operates as an effective greenhouse gas reducing system since they use carbon dioxide through biomass storage and photosynthesis.
How Evolving Climate Change is Affecting Earth
Plants alongside trees face challenges to their development and survival because of evolving climatic conditions. Higher temperatures produce root injuries which reduce moisture absorption capabilities and modify soil microorganisms while affecting the way plants acquire nutrients. Trees in urban settings which receive inadequate nutrition rates show slower growth but remain unstable and receive higher vulnerability to external factors.
The local heat mitigation capacity of urban green areas decreased because of the elevated temperature associated with climate change. Heat stress rises as a significant climate change effect compared to other variables.
Stress produces detectable modifications in these areas as it disrupts foraging behaviors and affects the complete growth of pollinators and their pollination functions. Climate change will progress to worsen its detrimental effects which scientists project will significantly impact tropical and temperate regions. Heat waves extend in duration and appear more often due to climate change effects to become the key reason behind these impacts.
Tropical regions that currently exist in warm climates face the most serious threats from these events. Climate change will affect tropical areas to a higher magnitude than temperate areas because temperature increases are expected to occur.
Health Impacts Due to Climate Change & Urban Heats
The UHI effect could contribute to more occurrences of dehydration and heat exhaustion and heatstroke cases. Extreme heat events create additional risk for elderly citizens and children together with individuals with health issues. The tropical climes of Kolkata and Chennai in India generate severe summer heat waves that produce high rates of heat-induced medical problems and death among defenseless demographic groups.
Environmental degradation
The process of developing ground-level ozone and other pollutants becomes more likely because urban temperature increases damage air quality. Urban heat increases the occurrence of rainfall events which results in both quicker flood surges and excessive stormwater drainage throughout urban areas. Open city surfaces obstruct groundwater absorption so urban regions experience flooding along with contaminated water runoff.
Water stress
Urban growth creates water resource pressure from three main factors: excessive drinking water needs and increasing wastewater production and water that runs off during storms. marines with considerable heat islands consume more water for irrigation activities and landscape maintenance together with residential drinking purposes which results in greater water scarcity across existing water-shortage zones. Indian cities Jaipur and Ahmedabad experience worsening water scarcity because the urban heat island effect creates higher cooling needs that put strain on their limited water supply.
Social inequities and economic cost
External climate risks affect different areas of urban populations inequitably because of existing socio-economic divisions that make conditions worse. People who lack financial stability and belong to excluded groups commonly reside in climate hazard zones where they experience unequal exposure to heat waves and flooding risks. Moreover, their increased vulnerability stems from limited heat relief options and inadequate green area access as well as elevated risks to their health. Social differences become worse because urban heat exposure varies unevenly between population groups.
Cities face economic hardships as a result of urban heat islands because they lead to elevated healthcare expenses and productivity declines and damage infrastructure. Research demonstrates that heat-related illnesses together with productivity losses in city areas will increase dramatically during the following decades in developing world countries. The economic consequences of urban heat island effect in Indian cities result in rising healthcare budgets together with diminished agricultural output and broken down infrastructure due to excessive heat events.
Climate change produces direct impacts on urban territories
The urban space experiences multiple severe consequences because of climate change which creates complex problems that surpass basic environmental issues. Climate change has led to rising occurrences and intensified intensity of extreme weather phenomena which affect poor nations along with coastal regions worldwide. A summary of literature examining climate change effects on urban areas from various nations appears in Table 1.
Table 1. Climate change impacts on urban environments.
| S.N. | Climatic variable | City/Area | Effect on the urban environment | References |
| 1. | Rise in Temperature | Africa and Asia continent | Change in precipitation pattern | Anand & Seetharam |
| 2. | Variations in rainfall patterns | USA | Flooding | Weiskopf et al. |
| 3. | Increasing sea levels | Coastal towns of San Francisco | Threats to wetland ecosystems; carbon sequestration | Plane et al.; Speak et al. |
| 4. | Rise in temperature, Heat waves | Bucharest, Romania, and Leipzig, Germany | Heat stress; Urban heat island formation | Carlan et al. |
| 5. | Changes in precipitation patterns | Leipzig, Germany | Decreased urban productivity | Kabisch et al. |
| 6. | Changes in precipitation | Leipzig, Germany | Droughts, floods in urban areas | Haase & Hellwig |
| 7. | Changes in precipitation patterns | East Africa | Effect on sanitation, hydration, and the spread of water-borne illnesses | Bett et al. |
| 8. | Elevated temperatures and extended heat waves | Mississippi | Stress on urban tree foliages | Ayanleye et al. |
| 9. | Variations in precipitation patterns | Florida | Hurricanes and storms; | Landry et al. |
| 10. | Changes in precipitation pattern | Kampala, Uganda | Droughts, floods | Sabiiti et al. |
Climate-induced changes in precipitation levels endanger both human wellness and electricity requirements and create stress on stormwater management through heatwave heat islands that produce flooding events. The sustainability along with resiliency of urban ecosystems faces negative consequences from climate change which then modifies ecological functions and biodiversity distribution.
The rising sea levels directly endanger wetland ecosystems found in coastal towns. Urban vegetation yield decreases because of temperature fluctuations as well as changes in precipitation which often leads to thermal stress and reduced primary productivity. Changes in the wood chemical composition due to heat affect its ability to resist rot damage alongside vermin attack and mold growth.
Rising Sea Levels Threaten Coastal Cities
The increasing sea levels produced by climate change create major risks that force coastal cities to face adaptation issues. The rising temperature in the planet triggers icecaps and glaciers melting while prompting ocean expansion leading to increasing water levels in the sea. Densely populated coastal cities face high dangers from sea level rise because their critical infrastructure exists in immediate proximity to the shorelines.
Risk in Coastal Ecosystems
The increased risks to coastal ecosystems together with elevated storm flood hazards and contamination of freshwater supply from saltwater represent the main outcomes of sea level rise. Coastal erosion serves as a significant effect among others. Between 1993 and the present the global average sea level rose by 100 mm while the annual rate of increase measured as +2.6 mm to +2.9 mm shows a margin of error at ±0.4 mm.
A spatio-temporal map showing global sea-level trends at mm/yr exists in Figure below over the period 1993 to 2020. The predictions indicate average sea levels will elevate by approximately 6 feet across the world during the course of the 21st century.
Expansion of global average sea levels by 1.6 feet during 2070 could endanger 150 million global residents and damage assets worth $35 trillion. Twentieth most susceptible yet fast-growing port cities of the world face the most severe risks. Nicholls demonstrated that growing populations and rising economic importance of coastal cities both take part in increasing coastal flooding risk especially among developing nations.
Human well-being in urban climates
Urban climate conditions impact human beings through multiple difficult and intricate factors which consist of heat fluctuations and high humidity and degrading air quality and structural elements and socioeconomic gaps. Inadequate living conditions raise the risk of heat-related stress for local inhabitants most especially the most vulnerable groups in society. The key human health dangers resulting from climate change and urbanization appear in the following figure.
The poor conditions within homes that lead to overcrowding and inadequate ventilation will intensify health problems during extreme weather incidents such as floods and heat waves. The air in urban environments suffers degradation because vehicles and industrial facilities along with different pollution sources release damaging substances.
Respiratory illnesses and cardiovascular diseases together with premature death appear as direct health consequences of excessive air pollution levels. Petroleum and pollutants from urban sources encounter high temperatures to produce enhanced health hazards for city residents especially during heat waves which produce peak pollution conditions. The 2015 heatwave in India produced a thousand deaths among outdoor working individuals and elderly citizens.
The hospitalization rate and mortality numbers increase dramatically when heatwaves strike Chicago along with Paris as well as other locations. Summer heatwaves in Indian megacities reach temperatures above 45°C which causes many heat-related fatalities and hospitalizations in both Ahmedabad and Delhi. The excessive population density in India along with China results in massive air pollution in their urban zones largely caused by industrial operations and construction dust and vehicle exhaust emissions.
Prolonged exposure to dirty air causes lung cancer in addition to asthma and chronic obstructive pulmonary disease (COPD). During times with bad air quality cities which have high pollution rates experience elevated numbers of patients admitted to hospitals with respiratory issues as documented in Beijing China and Delhi India.
Delhi’s Air Quality Level Exceed Safe Limits
Particulate matter levels in Delhi exceed safe limits on frequent occasions during severe air quality crises which create major public health problems. Green spaces together with adequate housing have a direct effect on the total health of people living in urban areas.
People cannot engage in outdoor activities when green spaces are scarce because this situation worsens urban heat islands while raising stress levels and creating anxiety. Urban residents face a higher incidence of mental health issues than rural people based on documented research thus necessitating extensive mental health programs for cities.
The analysis of mental health patterns in New York and London along with other cities proves that urban residents face more mental health challenges than rural residents. Rapid development of Indian cities including Bangalore and Kolkata generates elevated mental stress and health disorders that primarily affect impoverished community members.
Urban Development without Any Proper Steps
Urban development establishes ideal mosquito habitats that boost the transmission of dengue fever and leads to increased risks of disease spread through chikungunya and malaria transmission. The rapid expansion of Indian urban districts has produced numerous unsanitary and improperly drained remote settlements where mosquitoes can multiply efficiently.
Dengue fever outbreaks affect tropical cities specifically during their monsoon seasons where urban density elevates the risk for residents especially in Rio de Janeiro Brazil along with other such cities.
Waterborne diseases including cholera and typhoid as well as gastroenteritis spread through insufficient water and sanitation infrastructure in urban areas. The water quality management issues in Dhaka Bangladesh and Chennai India lead to outbreaks of waterborne diseases that occur during monsoon floods and after flood events. A review of research findings through Table indicates how urbanization affects human health alongside climate change in different countries.
Effect of climate change on human health.
| Location | Responsible key Climatic variable | Impact on human health (Disease/Illness/ fatalities caused) | References |
| USA, Canada, China, and Egypt | Global warming and Heat waves | Vector-borne diseases- onchocerciasis, and malaria resulted in several fatalities | Kalkstein & Smoyer; Kolstad & Johansson |
| Doha (Qatar) | Flood/ Storms | Waterborne diseases resulted in fatalities, several injuries, and property loss | Ajjur & Al-Ghamdi |
| Fiji and Peru | Global Warming | Diarrhea | Kolstad & Johansson |
| European & Australian cities | Temperature Rise | Salmonella | D’Souza et al. |
| Massachusetts & Canada | Temperature Rise | Salmonella, Campylobacter & Escherichia coli | Naumova et al. |
| Japan | Temperature Rise | Gastroenteritis | Onozuka et al. |
| Dhaka (Bangladesh) | Temperature Rise | Noncholera Diarrhea | Hashizume et al. |
| United States | Increased temperatures and extreme weather events | Higher rates of stress, anxiety, depression, and post-traumatic stress disorder (PTSD) among affected populations | Clayton et al. |
| Australia | Climate change, heat stress | Rural communities are particularly vulnerable to climate change, experiencing increased heat-related illnesses, respiratory issues from bushfire smoke, and mental health impacts due to drought and resource scarcity. | Hanna & McIver |
| India | Increased temperature and heat stress | significant increase in heat-related mortality, particularly among vulnerable populations such as the elderly and those with pre-existing health conditions. The frequency and intensity of heatwaves have been rising due to climate change. | Murari et al. |
| Europian cities | Extreme weather events, heatwaves | Increased mortality and morbidity from heatwaves, changes in the distribution of infectious diseases, and health impacts from extreme weather events like floods | Kovats & Hajat |
| Sub-Saharan Africa | Temperature rise, variability in precipitation | Climate change is expanding the range and seasonality of vector-borne diseases such as malaria and dengue fever, thereby increasing the disease burden | Caminade et al. |
| Brazil | Heat stress, floods | Climate change exacerbates health risks in the Amazon basin through increased incidence of infectious diseases, malnutrition due to impacts on agriculture, and heat stress. | Confalonieri et al. |
Thus, socio-economic inequalities largely contribute to the vulnerability of urban populations to climate-related threats. They are mostly imposed on the marginalized. For instance, low-income groups and ethnic minorities are most likely affected by various environmental hazards due to limited access to health services, housing activities, and job security.
For example, in cities like Sao Paulo, Brazil, informal settlements lack access to basic services like clean water and sanitation, so the residents face negative health impacts during extreme weather and hindered adaptation.
Likewise, in Delhi, India, the urban poor in informal settlements like slums face more susceptibility to respiratory ailments and heat-related illnesses during heatwaves and air pollution episodes aggravated by overcrowded and poorly ventilated houses.
Moreover, climate-induced disasters and environmental degradation may lead to displacements and forced migrations, particularly with the marginal communities found hazard-prone in floodplains or coastal zones. Often these social inequities further enhance vulnerability to the displaced populations, which confront barriers in accessing housing, livelihood opportunities, and social support networks within host communities.
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