How Density Makes Us Safer During Natural Disasters

In the face of threats natural or man-made, history has shown that our first impulse is often to diffuse the population. The 1956 Highway Defense Act, for instance, was enacted to achieve two goals: first, to spread Americans out from concentrated inner cities in the event of a Soviet nuclear attack; and second, to create a network of highways with bridges elevated enough to transport American intercontinental ballistic missiles. Today, as we confront climate-related risk, population diffusion may be a knee-jerk response, but it is important to remember that this sprawl only exacerbates the problem. Policies that support the development of dense urban areas are critical tools in mitigating climate-related risks.

In the long run, we already know that urban dwellers consume less energy per capita than their suburban and exurban counterparts, which makes the case for the importance of density in tackling climate-related risks. But even in the shorter term, cities allow us to be more resilient. In the aftermath of Sandy, higher-density neighborhoods with centralized infrastructure such as underground power and mass transit generally fared better and recovered more quickly than lower-density areas. It is particularly telling that in the aftermath of Sandy, higher-density neighborhoods—from downtown Brooklyn and Battery Park City up to Harlem—were up and running within a week. By contrast, lower density areas like Staten Island and Breezy Point—with their single-family homes, elevated power lines, timber construction, and auto-dependency—took longer to recover. Dense conditions come with a greater number of redundancies, a fundamental characteristic of resiliency. Most residents of high-density areas don’t rely on a single hospital or one grocery store. Instead, they have a network of them, allowing one or a few to malfunction without creating a system failure.