The study of urban ecology has grown rapidly over the past couple of decades as the planet becomes increasingly more urbanized. The field started as the study of ecology within the green spaces of cities, and has since evolved into a multidisciplinary approach to understanding the city itself as an ecosystem with interacting social, ecological and technical components.
A variety of social processes contribute to vulnerability to heat, including variation in social capital and legacies of disinvestment, which can affect vulnerability to heat waves. Furthermore, differences in intra-urban surface temperature can be as large or larger than urban-rural temperature differences, and a number of social-ecological-technical infrastructure interactions have been found to determine climate outcomes in cities. For instance, the dense distribution of tall buildings influences the spatial pattern of solar radiation intensity and duration and so influences air temperatures. The highly heterogeneous distribution of vegetation in cities is a primary determinant of heat exposure, which is often greater for poor, elderly, and minority segments of the population, who are often less able to cope [McPhearson 2016: 9].
With an ultimate aim of fostering resilience among the world’s ever-growing cities, urban ecologists envision a transdisciplinary, participatory “ecology for cities” approach that integrates research and practice. Such collaboration could result in the beneficial integration of gray and green urban infrastructure.
Traditional risk-avoiding engineering designs for infrastructure design focus on hard, resistant elements such as increased-diameter sewage pipes for stormwater management or tanks to store sewage. In contrast, more flexible, diverse, and ecologically based elements include green infrastructure such as parks, permeable pavement, swales or retention basins, or agricultural and vacant land sites in urban areas. Urban infrastructure therefore mediates the relationships between human activities and ecosystem processes and may exacerbate or mitigate human impact depending on how it is developed [McPhearson 2016: 11].
McPhearson, Timon, et al., 2016, Advancing Urban Ecology toward a Science of Cities, BioScience, https://academic.oup.com/bioscience/article/66/3/198/2470145.
 See “Heat Planet,” for further explanation of heat dynamics of cities.