Research articles

Meehan and colleagues study access to running water in large US cities since 1970, finding that the 2008 financial crisis worsened household ‘plumbing poverty’ in many cities. This disproportionately impacted households of color and generally squeezed lower-income households into more precarious living situations.

Plants are vital to healthy cities, yet urban environments filter the plant traits we find. This study assesses the relative dominance of different seed dispersal modes among plants that establish in cities without human intent, finding that many disperse their own seeds and that seed dispersal by water is less common.

This study characterized the intercity domestic migration flows in four countries, and found that in the USA, the UK and Canada, flows from big cities serve as shocks in smaller nearby cities, but not in France.

Yazar and coauthors investigate the incorporation of procedural justice—fair and inclusive decision-making processes—among the climate-ambitious cities in the C40 network. They find that less than half of C40 cities emphasize procedural justice in climate planning, thereby limiting their ability to meaningfully address systemic inequality.

Using two socioeconomically different neighborhoods in Seattle, this study shows that place-based peer-to-peer resource sharing can substantially improve community resilience in both types of neighborhoods. Strong ties were about 1.5–3 times as effective as weak ties, and the neighborhood with lower socioeconomic status (SES) required more ties to achieve an optimal sharing rate than the neighborhood with higher SES.

This study analyzes the impact of 1,436 air-quality-monitoring stations in Chinese cities. It found that these stations led to an 8.03% reduction in PM_2.5 concentrations in urban areas. Within these areas, they resulted in 0.57% more reduction in PM_2.5 concentrations in technically accessible areas compared to non-accessible areas, which also experienced an increase in housing prices and a decrease in air-quality-induced mortality.

Cities and urbanization concentrate benzene, a carcinogen and brain toxin found in petroleum. This study estimated associations between benzene exposure and brain disorders in urban adults in the UK, finding elevated risks of dementia, major depression and anxiety disorder even at low benzene levels.

Green spaces are known to help cool cities, but they contribute humidity while reducing heat—and both matter. Using smart sensors mounted on bicycles, this study finds that daytime temperature reductions in urban green spaces are largely offset by humidity increases but that urban vegetation causes a net reduction in humid heat at night.

Parks provide deep value to urban residents, but the distribution of those services is unclear. This study finds that US urban residents have unequal access to the crucial environmental, social and health amenities of urban parks.

This study compiles detailed data on urban green spaces and analyzes the quantity and spatial configuration of green spaces in 371 cities in 11 countries in Latin America. Although there is high heterogeneity, climate seems to be the main determinant of differences in green space amount among cities compared with socioeconomic conditions and the built environment.

This study used a mixed-methods approach to map out crime patterns over time in Nottingham. It found that the district of Bestwood, the site of a large governance-type organized crime group, has lower crime rates in certain categories than comparable districts with no such group.

As the world urbanizes, we need better understanding of how urbanization and urban environments affect people cognitively. This study uses human brain activity, assessed using functional magnetic resonance imaging, to predict the number of visits to various locations within Lisbon, Portugal, when exposed to geotagged images from Flickr.

To understand how organizations produce urban integration, that is, connections across lines of difference, Brandtner et al. conducted a survey of 863 civil society organizations in five global cities: San Francisco, Seattle, Shenzhen, Sydney and Vienna. They find that neighborhood income and the share of migrant populations are associated with whether organizational practices aim at connecting people or institutions.

This study looks at policies and programs chronologically in Mexico City in response to COVID-19 at different governance levels. It found that the crisis management programs did not succeed in establishing a multiscalar decision-making process, and proximate scales such as the domestic space or the neighborhood were ignored.

Vast volumes of textile waste are generated by consumers in wealthy cities. Without the knowledge, infrastructure or resources to manage the intensifying material flows of post-consumer textiles locally, textile waste is overwhelmingly exported to the Global South. Vladimirova et al. analyze local ecosystems of actors managing post-consumer textiles in nine Organisation for Economic Co-operation and Development cities to understand the power dynamics and systemic lock-ins that are hindering more circular and sufficient use of textile resources and propose policies for municipalities to address this problem.

This study uses a qualitative mixed-methods approach to study how delivery cyclists navigate Sydney and Melbourne, Australia. It identified positive experiences and that these riders face the same concerns as all cyclists with the added challenges of weather and consumer demand.

This study looks at the diurnal temperature fluctuations in Kolkata through a model that tests the influence of rooftop photovoltaic solar panels on urban surface energy budgets, near-surface meteorological fields, urban boundary layer dynamics and sea breeze circulations. It found that panels heat cities during the day (up to 1.5 °C) but cool them at night (up to 0.6 °C).

This study used the case of summer 2018 in London to show that rooftop photovoltaics could have reduced heat-related mortality by 12% while cool roofs could have reduced it by 32%. In addition, rooftop photovoltaics generate up to 20 TWh of electricity.

How widespread is the possibility of creating ‘15-minute cities’? Using openly available data, the authors measure access to essential services and what points of interest would have to be relocated to create 15-minute cities. With novel quantification, they demonstrate remarkable differences among cities across different regions of the globe.

This study proposes that the optimal allocation of roof area for rooftop agriculture and photovoltaics is 61% of the flat rooftop area to the former and the rest for the latter. However, maintaining this productivity requires considerable water use and materials.