Editorials

The idea that ‘context matters’ has become a cliché in many scenarios, but it doesn’t make it less true in urban settings: the neighborhood you live in, the way you move through the city, the places you visit, all of these change the way we experience urban life. But context is not only about spaces; it also means people and how we interact with each other. A long commute could be just as lonely whether you are in an empty bus or surrounded by others in rush hour with everyone wearing earphones. This month’s issue puts the spotlight on both parts of the urban experience to paint a more complex picture.

Over millennia, cities have evolved into new versions of themselves. This issue of Nature Cities explores pressing urban alterations in this moment of history, including conflicts wrought by gentrification and the unfolding iterations of climate change.

Urban areas concentrate people from many different backgrounds, but these people are not distributed uniformly or randomly in space. This is the key issue that segregation studies want to raise, and it is one that has long had social and policy implications. In many cities, similar groups of people live close to each other, with few opportunities to share residential, work or leisure spaces with other groups — this in turn results in fragmentation and isolation. These unequal distributions are often a consequence of historically constructed social hierarchies, such as race and class systems, that allow certain groups to enjoy urban goods while others suffer the consequences of urban ills.

There are many definitions of what a city is, but most seem to stress the importance of density. However, whether it be the density of people, buildings, goods, services or species, the interactions among these factors are also key in determining this definition. Cities consist of more than cement and humans; they contain complex inter-relationships among different species living in close proximity, the proximity of which intensifies their interactions. How does nature influence cities and vice versa? And how do these influences inform our understanding of the nature of cities? The content in this issue illustrates these ideas with examples from around the world.

We are urbanizing Earth, drawing ever more people and supporting resources into cities. As we grapple with the varied but related implications, the time is ripe for an outlet focused integratively on this broad horizon.