Twice now, the United States has withdrawn from the world’s most important international treaty on climate change, the Paris Agreement, and mayors weren’t having it. While national governments stall, cities are passing ambitious climate plans, nonprofits are piloting solutions, and firms are investing in green practices on their own initiative. These efforts are connected in ways that neither urban sociology nor organization studies has fully grasped on its own. Nicole Marwell and Michael McQuarrie once diagnosed a “missing organizational dimension” in urban sociology. My book Cities in Action: Organizations, Institutions, and Urban Climate Strategies takes that diagnosis seriously and follows it to the terrain of climate change. Here are five reasons why these fields belong together.

1. Civic capacity predicts climate action better than corporate presence does

Urban scholars have long studied what makes cities tick—with shifting demography, greedy growth coalitions, and tense political contestation among the top analytical contenders. But cities are also composed of organizations, and their mix matters. Across more than 1,500 American cities, I found that the density of nonprofit organizations predicts sustainability action more reliably than the presence of corporations—and not just the polluting ones but even those with strong records of social responsibility. The effect holds for all nonprofits, not just environmental ones. This finding resonates with Robert Sampson’s insight about a neighborhood’s capacity for collective action. Organizations shape civic capacity at the scale of the city—and organization scholars can explain why.

2. Cities learn from one another through networks that look a lot like organizational fields

The former city manager of Palo Alto told me that before raising a problem with anyone in the US government, he’d rather pick up the phone and call the mayor of Barcelona. These intercity connections are not incidental. In my data, I identified distinct network clusters in the global network of intercity associations, each serving different types of cities with different agendas, like C40 for leading cities, Southeast Sustainability Directors Network for cities in the US South, or UN-Habitat for cities around the developing world. Practices spread through these networks via the same mechanisms of imitation, competition, and professional socialization that organization scholars know well but are organized by geography rather than by industry.

3. The protagonists of urban climate action are professionals

Benjamin Barber’s If Mayors Ruled the World cast heroic mayors as the key actors in urban climate governance, inspiring scholarship and leadership at places like the Bloomberg Center for Cities at Harvard. My evidence complicates that picture: Cities led by appointed professional managers turn out to be more proactive on sustainability than those led by elected mayors. The backbone of this work comes from the hard work of chief sustainability officers, resilience officers, and city managers whose professional networks span states and countries. One described her role as the city’s “foreign minister.” Another set her alarm for five in the morning after the Paris withdrawal, determined to beat East Coast rivals to the press release. These professionals operate in an institutional field, and their influence far exceeds their visibility.

4. Green innovation grows from the bottom up

A common assumption is that sustainability scales through public policy: Government passes a rule, organizations comply. My research on green buildings across more than five thousand American communities found the opposite. In city after city, nonprofits and universities built the first certified green buildings before any policy required them to. In my book, I discuss an instance at the San Mateo Public Library, where a rolling blackout during a community meeting in a stuffy room inspired the library to take action that, in turn, changed a city’s trajectory. I also consider the green construction of the University of Cincinnati and the Cincinnati Zoo, both of which went green before any municipal incentive existed. I call this process “distributed adoption,” and the sequence it follows (catalysis, legitimation, scaling) describes a general pattern of urban innovation that becomes visible only at the intersection of these two fields.

5. The widening gap between cities is an organizational problem

Inequality within cities—gentrification, segregation, unequal exposure to pollution and heat—receives considerable scholarly attention. My research uncovered a dimension that has drawn far less, with the exception of pioneering work in economic geography: the gap between cities. About a hundred of the world’s 360 largest cities are completely disconnected from the networks that distribute knowledge, funding, and professional support to their better-connected peers. The same institutional infrastructure that empowers leading cities simultaneously leaves others behind. Low-income residents of organizationally isolated cities will bear the costs of climate change because of structures their cities lack. Understanding why requires the tools of both fields at once.