Climate change and cities
Climate change and cities are deeply connected. Cities are one of the greatest contributors and likely best opportunities for addressing climate change. Cities are also one of the most vulnerable parts of the human society to the effects of climate change, and likely one of the most important solutions for reducing the environmental impact of humans. The UN projects that 68% of the world population will live in urban areas by 2050. In the year 2016, 31 mega-cities reported having at least 10 million in their population, 8 of which surpassed 20 million people. However, secondary cities - small to medium size cities are rapidly increasing in number and are some of the fastest growing urbanizing areas in the world further contributing to climate change impacts. Cities have a significant influence on construction and transportation—two of the key contributors to global warming emissions. Moreover, because of processes that create climate conflict and climate refugees, city areas are expected to grow during the next several decades, stressing infrastructure and concentrating more impoverished peoples in cities.File:Kannengießerbrücke Drought 2022.jpg|thumb|upright=1.1|Hamburg, Germany, is a large city that has experienced multiple droughts throughout the years, which has led to decreased economic productivity.High density and urban heat island effect are examples of weather changes that impact cities due to climate change. It also causes exacerbating existing problems such as air pollution, water scarcity, and heat illness in metropolitan areas. Moreover, because most cities have been built on rivers or coastal areas, cities are frequently vulnerable to the subsequent effects of sea level rise, which cause flooding and erosion; these effects are also connected with other urban environmental problems, such as subsidence and aquifer depletion.
A report by the C40 Cities Climate Leadership Group described consumption based emissions as having significantly more impact than production-based emissions within cities. The report estimates that 85% of the emissions associated with goods within a city is generated outside of that city. Climate change adaptation and mitigation investments in cities will be important in reducing the impacts of some of the largest contributors of greenhouse gas emissions: for example, increased density allows for redistribution of land use for agriculture and reforestation, improving transportation efficiencies, and greening construction.
Climate Change and Urbanization
In the most recent past, increasing urbanization has also been proposed as a phenomenon that has a reducing effect on the global rate of carbon emission primarily because with urbanization comes technical prowess which can help drive sustainability. Lists of high impact climate change solutions tend to include city-focused solutions; for example, Project Drawdown recommends several major urban investments, including improved bicycle infrastructure, building retrofitting, district heating, public transit, and walkable cities as important solutions.In order to activate and focus attention on climate change solutions, the international community has formed coalitions of cities such as C40 Cities Climate Leadership Group and ICLEI) as well as policy goals, Sustainable Development Goal 11. Currently, in 2022, there is a deterioration in the progress of the goal. There is limited progress on making cities and human settlements more appropriate to live in Sub-Saharan Africa, Latin America and the Caribbean and the Pacific Island countries. There is fair progress in Central and Southern Asia and Eastern and South-Eastern Asian. However, it has been achieved in Developed countries.
There is an ongoing paradigm shift in urban planning that is focused on development of climate friendly and resilience by using climate urbanism. Climate urbanism aims to protect physical and digital infrastructures of urban economies from the hazards associated with climate change. Being that cities bring in 80% of the world's revenue, it is important for the infrastructure and planning of these urban areas to be planned out using carbon management and climate resilient infrastructure.
Background
More than half of the world's population is in cities, consuming a large portion of food and goods produced outside of cities. The UN projects that 68% of the world population will live in urban areas by 2050. In the year 2016, 31 mega-cities reported having at least 10 million in their population, 8 of which surpassed 20 million people. However, secondary cities - small to medium size cities are rapidly increasing in number and are some of the fastest growing urbanizing areas in the world further contributing to climate change impacts.Emissions
Cities globally house half of the world's people, consume 80% of the world's energy and 70% of its natural resources, and contribute more than 70% of global emissions. Cities and regions are also particularly vulnerable to climate-related hazards and pollution. Climate danger and pollution also disproportionately affect the poor, increasing inequality. With half of the world population residing in urban areas, there will be an increase in energy usage that comes with Climate Change. One of these will be AC, since climate change comes with higher temperatures many people will start needed more cooling systems, so this results in more air conditioning and newer models of cooling systems. Although more people are living in cities which can result in shortages, cities actually emit less carbon than rural areas since house sizes are smaller, more gas heat over propane is used, less carbon fueled transportation is used, and more people share communal spaces such as laundry rooms and kitchens. While cities create some problems, it is important to realize that the denser population creates less carbon emissions which benefits climate change. New policies now focus on the reduction of emissions from coal-fired power plants as well as increasing motor vehicle efficiency.With regard to methods of emissions counting cities can be challenging as production of goods and services within their territory can be related either to domestic consumption or exports. Conversely the citizens also consume imported goods and services. A recent study discovered that 40% of strategies focus on reducing emissions from municipal operations that account for 1–5% of total urban emissions, while neglecting imported goods and industrial activities. To avoid double counting in any emissions calculation it should be made clear where the emissions are to be counted: at the site of production or consumption. This may be complicated given long production chains in a globalized economy. Moreover, the embodied energy and consequences of large-scale raw material extraction required for renewable energy systems and electric vehicle batteries is likely to represent its own complications – local emissions at the site of utilization are likely to be very small but life-cycle emissions can still be significant.
Field of study
The research perspective of cities and climate change, started in the 1990s as the international community became increasingly aware of the potential impacts of climate change. Urban studies scholars Michael Hebbert and Vladmir Jankovic argue that this field of research grew out of a larger body of research on the effects of urban development and living on the environment starting as early as the 1950s. Since then, research has indicated relationships between climate change and sustainable urbanization: increase employment cities reduces poverty and increases efficiencies.Two international assessments have been published by the Urban Climate Change Research Network at The Earth Institute at Columbia University. The first of which was published in, the first of which was published in 2011, and the second of which was published in 2018. These papers act as summaries of the scholarship for the field similar to the Intergovernmental Panel on Climate Change reports. A third report is to be published between 2023 and 2025.
Cities as laboratories
Cities are good subjects for study because they can invest heavily in large-scale experimental policies that could be scaled elsewhere. Multiple scholars approach this in different ways, but describe this "urban laboratory" environment good for testing a wide variety of practices. For example, the book Life After Carbon documents a number of cities which act as "urban climate innovation laboratories". These cities as laboratories offer an efficient way to detect climate change by looking at the effects of the greenhouse effect on rooftops, street trees, and other environmental variables within a city setting. Though this method of looking at the heat waves effects in cities, it will offer a way of seeing the problem of the effect of heat that will be solved by cities within the future.Health impacts
Climate change has been observed to have caused impact on human health and livelihoods in urban settings. Urbanization commonly occurs in cities with low and middle income communities that have high population density and a lack of understanding of how climate change, which degrades their environment, is affecting their health. Within urban settings, multiple climate and non-climate hazards impact cities which magnify the damages done to human health. For example, heatwaves have intensified in cities due to the combination of multiple factors adding to climate change. With heatwaves constantly increasing temperatures in cities, it has caused many heat-related illnesses such as heat stroke or heat cramps. The rise of temperatures due to climate change have also changed the distribution of diseases from mosquitoes, causing a rising rate of infectious diseases.Alongside infectious diseases and heatwaves, climate change can create natural hazards such as floods, droughts, and storms due to rising sea levels. It also harms those even more who have COVID-19, asthma, illnesses, etc.
Hospitals and other healthcare places are also a big contributor to climate change with them being responsible for 4-5% global carbon dioxide emissions. They are due to medications, such as asthma inhalers, anesthetic gasses, patient and staff transportation, electricity, HVAC, and waste management.
The impacts on human health in urban settings is more profound in economically and socially marginalized urban residents. Low-income and remote populations are more vulnerable to physical hazards, undernutrition, diarrheal and other infectious diseases, and the health consequences of displacement. Urban neighborhoods burdened by heat islands and other climate change problems can also experience clusters of violence, amplifying intersecting vulnerabilities in these communities.