William Solecki is a professor of geography at Hunter College, director of the CUNY Institute for Sustainable Cities and co-chair of the NYC Panel on Climate Change. Clarion spoke with him during CUNY’s first week of classes after Superstorm Sandy.
Q: In a 2010 report, “Climate Change Adaptation in New York City,” the NYC Panel on Climate Change said bluntly that “climate change is now under way.” Cutting New York’s production of greenhouse gases is essential, the report says, but “some impacts from climate change are inevitable due to greenhouse gas effects already in the pipeline.” With sea levels projected to rise two to five feet by the 2080s, the report says that New York must prepare for “more intense and frequent extreme events” such as severe coastal flooding, even while we strive to keep the water’s rise on the low-end of projections. In the wake of Sandy, what kind of adaptation measures do you think New York should adopt?
A: I think we’re going to need both “hard” engineering interventions, like innovative ways to protect subway tunnels, and “soft” approaches, such as reconstructed wetlands. There are a range of options, and, at this point, I don’t think any one option can be excluded.
Often a mixture of various approaches is most beneficial. Putting all your eggs in one basket can lead to unintended consequences.
Q: What kinds of engineering measures should be considered?
A: Certainly sea walls are getting a lot more attention after Sandy. They’re sort of the charismatic megafauna of these approaches – the way polar bears get so much attention on global warming. Sea walls are big, they’re dramatic. They’re expensive and take a long time to build, and they’re something we need to consider.
One potential design would involve building some kind of structure at the Verrazano Narrows and places like Perth Amboy and the Upper East River. Other people have talked about something that would run all the way from Sandy Hook to Breezy Point – obviously an even bigger undertaking.
Classically, what such barriers have done is created a sense of security for those inside, potentially displacing added risk to those outside. Sometimes those kinds of technological investments have failed, and they’ve encouraged development in areas that turned out to be vulnerable.
There are issues of cost: when I first heard this discussed for New York City, it was estimated at $2 billion, now it’s more like $10 billion. On the other hand, the direct and indirect costs from Sandy may be around $100 billion for the main US-continental impact, so you could argue it’s wasteful not to build this.
Q: What are some other engineering options to consider?
A: Engineering can come on many scales. Besides big regional projects, you can target specific things – bulkheading specific buildings or infrastructure like subway tunnels – to prevent flooding. In some areas in Lower Manhattan, subway grates have been elevated to protect against water 6 to 12 inches above sidewalk level. These are designed against rain inundation, which is often the bigger problem. But the same idea could, in principle, be used against storm surges.
Building design is something that starts to get into “softer” responses. If you’re going to be rebuilding in the coastal zone – and that’s a question that some areas have debated – reconstruction can be required to be elevated. That’s the case in much of Florida today. In New York, people are now asking whether basements are the best place for a building’s furnace.
Q: What are some other ideas that don’t rely on keeping water out?
A: There are many ways to use ecosystem services to promote absorption of water. Promoting increased porosity of urban surfaces, like new paving materials for streets and parking lots, can promote increased infiltration of water to the earth below.
There are also “blue roof” water retention facilities, or proposals for temporary water storage areas along highway medians. The idea is, if you have water coming into a system, maybe you can channel it into a holding area.
Wetlands, of course, can play a very large role. Besides avoiding their destruction, we need to think about ways to regenerate some of what we have lost.