Urbanization processes reshape space — and the human and non-human relationships that play out in and through space — over time. The intensification of urbanization poses a range of threats to the natural environment and correspondingly to the socioeconomic welfare of urban residents. The articles in this issue highlight how, from the soil upon which cities are built to the trees, water and air that give life to urban spaces, inequality has become embedded as a structuring feature of urban natural environments.
Too often, inequality results in violence. In her World View, Sweet argues that considering violence against women (VAW) is essential to contend with urban inequality, and to do so, urban planning must learn new ways to incorporate time, space, and relationships into analysis. Planning tends to be concerned with urban space and relationships in the form of buildings, streets and transportation, and how these relate to each other in plans for the future; but this approach has limitations that prevent a fuller engagement with common urban problems like VAW. In systematic and personal ways, VAW is enacted by bodies upon other bodies, which are all spaces of their own. Through nonlinear processes, connections and timeframes, VAW ingrains gender-based inequality into city life in ways that require further study to understand and address.
Dynamics of inequality layer into cities from the ground up. The Article by Luo et al. studies pathogens in urban soils. They combine a global field survey from 17 countries with a high-resolution local soil survey around Shanghai to analyse the diversity of pathogenic fungi. They found that Trichosporon is a dominant pathogen prevalent at global and local scales, and socioeconomic factors explained variation in Trichosporon levels that could not be accounted for by other factors. Lower-income cities and urban areas are thus more subject to exposure and illness. This study demonstrates that social inequality plays an important role in shaping the natural environment of cities at a range of scales, and specifically cities’ pathogenic microbiomes.
On the surface of cities too, in the trees and water, inequality layers over time. This issue’s Article by Salazar-Miranda et al. shows how redlining, a set of policies and practices dating from the 1930s that assigned lower property values in US cities based on race and class ingrained inequality into the urban natural landscape such that it persists still today. Using a newly available dataset of digitized Home Owners’ Loan Corporation (HOLC) maps, from the Richmond Digital Scholarship Lab’s Mapping Inequality database, Conzelmann et al. conduct the most comprehensive study of US cities’ tree canopy coverage to date, reinforcing earlier work that demonstrated there is currently less tree canopy coverage, and thus more risk of extreme heat, in formerly redlined neighbourhoods. They also show that flood risk is higher in redlined areas, indicating that along multiple vectors, lower income people and people of colour suffer persistent legacies of inequality in US cities, including vulnerability to climate change impacts.
Across continents, similar patterns repeat. In 14 European cities, Rocha et al.’s Article explains, heat exposure is higher for underprivileged populations, in part because there is less green infrastructure to mitigate the heat for them. Lower-income residents, tenants, immigrants and unemployed citizens do not have equivalent access to the cooling benefits in cities that upper-income residents, nationals and homeowners do.
In the Global South, the unequal impacts are extreme. Sethi & Vinoj’s Brief Communication reports that urbanization of Indian cities has led to a 60% increase in their warming. By separating the effects of urbanization from other regional heat sources, the authors demonstrate that the process of urbanization itself is a critical factor warming the atmosphere in city after city, especially in developing cities that are expanding road networks. In the current context of accelerating urbanization in India, it is especially important in cities that are developing now to change the direction of urbanization to a more sustainable path.
Across the Global South and Global North, carbon reduction efforts are essential to deal with climate burdens. Even so, there will still be gaps in reaching carbon neutrality. In their Article, Rodriguez Mendez et al. argue that these gaps can be filled with carbon dioxide removal (CDR) at the urban scale, which involves transferring carbon dioxide from the atmosphere to durably store it. They estimate that storage potentials from vegetation, from soils and the built environment, and from direct air capture in indoor ventilation systems have a global carbon-storage potential of up to 1 gigatonnes of CO2 per year. Given the layered effects of urban inequality, the promises of CDR will heavily depend on sustainable and just governance and policy implementation within and across cities.
For the articles in this issue, time, space and relationships reflect deeply layered urban dynamics of inequality and violence. At the same time, these elements also characterize cities’ cherished diversity and difference. According to Burns in her I and the City, Lisbon is a place where time moves slower, in part because of how the space and relationships of the Portuguese city are shaped, through hills, cobblestones, pedestrian traffic and the breeze carrying a neighbour’s music. This pace heightens “senses more acute”, as appreciation for life comes more readily without the rush, marrying past and future in the present.
Urbanization changes relationships with time and space, which in turn reshape the contexts in which relationships emerge. These processes layer into the natural world over time, making human inequalities a structuring feature of natural urban space.
