by David Dixon, principal-in-charge of planning and urban design, and Steve Wolf, senior designer
Hurricane Sandy’s banal name belied its dramatic impacts. The morning after the storm’s passage we learned just how vulnerable large American cities have become to the impacts of climate change—and New York found itself, as usual, at the center of the action, with seven East River tunnels filled with water, Manhattan below 34th Street without electricity, and flooding in every borough.
“New weather patterns…and old infrastructure,” said New York Governor Andrew Cuomo, with uncharacteristic understatement, “are not a good combination.” He asserted, however, that a new generation of resilient infrastructure designed with rising seas and fiercer storms in mind offered New Yorkers a singular opportunity to “build this city back stronger and better.” His words should resonate around the globe; the assets at risk from coastal flooding in the ten most vulnerable cities worldwide equaled 5% of global GDP in 2005, according to the OECD. That proportion will nearly double over the next 60 years as cities grow and sea levels rise.
Although no scientist argued that climate change directly caused Sandy, climatologists almost universally agree that it amplified the storm and its impact (for instance here and in an excellent and accessible discussion here). Record-breaking water terperatures fed energy into the system, extra water in the atmosphere boosted rainfall, and above Greenland a “blocking front” linked to polar-ice loss forced the storm inland rather than allowing it to take a typical offshore course toward the North Atlantic. Crucially for New York, rising sea levels exacerbated storm damage. In the 20th century, New York harbor has risen nearly a foot, creeping gradually up the seawall built around lower Manhattan at the start of the 20th century. The outlook for the 21st century makes that increase look like chump change: By 2100, melting polar ice and thermal expansion will push the world’s oceans to a much higher new normal. The IPCC (Intergovernmental Panel on Climate Change) projects that sea levels will rise between 7 inches and 2.5 feet, but other models that factor in more significant melting of polar ice project rises of up to 6 feet. Additionally, New York sits in a sea-level “hot spot” running from North Carolina to Massachusetts where currents, water temperatures and other conditions could add as much as another foot to that total.
After Hurricane Katrina (our previous “once-in-a-lifetime” storm), New Orleans taught us that America lacks the financial resources and the political tools to relocate entire communities threatened by rising seas to safer ground. The reality of more and increasingly destructive storms like Sandy means that coastal communities will need to focus on rising seas. Governor Cuomo’s call for “stronger and better” suggests that the billions of dollars communities will spend to protect themselves can, with smart planning, also enhance those communities. Protection from rising seas does not have to mean a design driven by engineering. Urban design that assures walkability, sense of place, human scale and delight will need to play a starring role in building resilience.
New York has already studied raised ventilation grates to block subway flooding, in the process reconceiving them as voluptuous street furniture. Solutions like this suggest how urban design can guide climate-change response, here delivering subway protection below ground and a more walkable environment above. In fact, a 2010 show at the Museum of Modern Art suggested a suite of imaginative (and more sweeping) physical interventions in the harbor that would both build the city physically and dampen the destructive power of storm-driven waves. (Also here.)
As noted, New York hardly stands alone. The OECD projects that by 2070, 150 million people in coastal cities—primarily Asian capitals like Calcutta, Shanghai, and Singapore—will regularly encounter what we now call 1-in-100-year flooding. (Several US cities besides New York show up on this list of global misfortune, including Miami, Virginia Beach, and New Orleans). Outside the US, cities have already begun to respond to climate change, building seawalls that become waterfront parks, the foundations for expanded financial districts, or found land for performing arts centers. The Netherlands has for decades pioneered ways of transforming water-control measures from potential infrastructure nightmare into valued community-building assets—creating barrier islands as beach resorts, inventing new ways to use water as an urban amenity, and looking to rising seas as a new source of energy.
As Americans and their elected officials reframe the discussion about resilience in the wake of Sandy, we will need to look at best practices around the globe for models. And the best ones have almost uniformly turned to good design and urban planning to turn their response to climate change into the building blocks of stronger, healthier, more appealing cities.