In the two years since Hurricane Sandy, New York City has shown the world a natural experiment in how the nation’s largest and wealthiest city rebounds from a historic weather event, and prepares for more extreme events in the future. Rising seas put the city at more risk for flooding from storms, and as an excellent series on WNYC recently showed, heat waves will increase: by 2050, New York City may be as warm as present-day Birmingham, Alabama.

As far as Sandy recovery, some areas have yet to fully come back, and some programs are operating far behind schedule. At the same time, the Rebuild by Design initiative became a fast and pragmatic way to engage top design teams in reconceiving the New York waterfront, with ideas that can improve everyday life as well as bolster the city’s resilience.

It’s no surprise that Manhattan has been the focus of many ambitious plans, including Rebuild’s Big U levee, as the borough remains the core of the city’s economy. An early review of damage from Sandy, at Baruch College in March, 2013, titled Futureproofing Our Cities, showed that the top twelve office towers flooded in downtown Manhattan suffered an average of $100M damage each. Much broader effects included the stranded citizens in high rises and housing projects in Chinatown and on the Lower East Side, and sweeping flood damage in Chelsea and at the South Street Seaport area.

For observers who remember the shock of the terrorist attacks of 9/11/2001, when the viability of this densely-packed borough was in doubt, it helps to realize that the ensuing dark period was immediately followed by a rebound in real estate prices and development – including the opening of the High Line and the invention of an entirely new luxury neighborhood in West Chelsea. Similarly, after Sandy knocked the city out for a week, the city has already started to grow a new skyline of super talls, and is in the process of adding Hudson Yards, practically a city in itself.

But perhaps the boldest response to the storm is Seaport City, a multi-decade development proposal for expanding Manhattan to form a new barrier on the East River, with housing on top. Brandon Kelly updates on the project:

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Hurricane Sandy, which caused billions of dollars in damage and cost thousands of people their homes, was the largest recorded tropical storm in the Atlantic basin. While many parts of the New York metropolitan area have recovered, the devastating effects of Sandy still linger. For city officials, the storm has prompted questions on how to fortify the city for extreme events in the future. Lower Manhattan, which was greatly impacted by Sandy, has become a key area for this discussion.

The June 2013 Special Initiative on Rebuilding and Resiliency (SIRR) report outlines 257 potential initiatives to rebuild Sandy-stricken communities and protect neighborhoods against future risks, including dozens of proposals for Manhattan.

Of these initiatives, one in particular has garnered significant attention: the idea of a multi-purpose levee (MPL) created on the eastern side of Lower Manhattan. The levee, which bears the unofficial moniker “Seaport City,” is the focus of the Southern Manhattan Coastal Protection Study: Evaluatiing the Feasibility of a Multi-Purpose Levee, released in May 2014 by leading design and consultancy firm Arcadis. The study finds the construction of a MPL to be legally and financially feasible.

Seaport City was initially suggested during the Bloomberg administration, and has also been advocated by Mayor Bill de Blasio. When completed, it could include new housing developments for as many as 20,000 people.

The MPL, which would span 1.3 miles from Whitehall Street in the Financial District to the Lower East Side’s Montgomery Street, would extend into the East River; this aspect is not necessarily new, as Manhattan’s shoreline has repeatedly been built outward over the past 250 years to accommodate urban growth. The MPL would be created by adding fill to the existing shoreline, creating new space for both residential and commercial buildings.

The draft from Arcadis describes a newly created neighborhood that would, at its widest, add two city blocks extending into the East River, 500 feet out from the current shoreline. Residents of both market-rate and affordable housing would share the new land with more than seven million square feet of office towers. The ambitious project would be completed over an 80 year time frame.

The 19 foot high levee on which the new community would be built could withstand a 13 foot storm surge like Sandy, even when combined with an additional 6 feet of sea level rise through this century, as climate change impacts take effect. The eastern side of Lower Manhattan is at a low elevation, vulnerable to more floods as sea level rises, and the new levee would shield it in the face of future storm surges.

Of course, Seaport City has some caveats. It would take decades and $20 billion to build, and a substantial commitment on behalf of the city. Secondarily, it would require additional comprehensive studies and approvals before its construction, and there are doubts about the environmental costs of filling in marine habitat in the East River. While the MPL is concentrated on adaptation to rising sea levels in this century, it doesn’t provide a long term solution if levels continue to rise in following decades, as they are expected to – and sea level is not the only challenge facing the future city. New York will have to prepare for a steady stream of heat waves, too.

William Solecki, professor in the Department of Geography at Hunter College, co-chair of the New York City Panel on Climate Change, and advisor to City Atlas, shared his thoughts on the Seaport City proposal during an October 16 interview:

Would the construction of Seaport City be an effective flood protection strategy for Lower Manhattan?

If the design is done well, it can provide protective benefits to the areas that are directly adjacent. Any level of protection is only good as its weakest link. Unprotected areas that are north and south may be more vulnerable to flooding.

Was the concept of Seaport City inspired by Battery Park City?

The reduced level of flooding in Battery Park City during Hurricane Sandy was seen as a testament to its elevated land. Battery Park City was not as adversely affected as the rest of Lower Manhattan because it acted as a barrier. It was presented that the lessons learned from Battery Park City could be translated to the east side.

Does the prospect of new development on Seaport City overshadow its purpose of climate change adaptation?

One of the things we strive for in climate change adaptation is co-benefits. We have to recognize that whatever features are built have to be meaningful the vast majority of the time that there is no extreme event. There is certainly a way to construct new housing that would be socially meaningful.

How would Seaport City affect the real estate market?

It will potentially create thousands of new housing units. It could dampen the overall market in that area because of an increase in housing supply. Or, demand could be high, and Manhattan could become even more desirable – it’s unclear.

Concluding thoughts?

I think it’s audacious. It presents an illustration of how people can meaningfully integrate climate change adaptation into urbanization and city building.

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For more reading about the city and the waterfront:

Andrew Revkin, in his excellent interview with former Mayor Michael Bloomberg (NYT 9/19/14), asked about the wisdom of continuing to develop on the shoreline, when very long term projections suggest the city will need to pull back at some point. The former mayor’s answer perhaps shows the flexibility a very wealthy city can display, as well as the trade-off the present makes against the future. 

Also in the NYT, Alan Feuer takes a look at the rebuilding and resiliency projects around the city, including the Big U: “Building for the Next Big Storm,” (NYT 10/25/14), with video below:

What happens to New York City after 2050 depends on the world’s cumulative carbon emissions. The de Blasio administration unveiled an ambitious plan to cut the city’s emissions 80% by 2050 – the “80 by 50” goal, which connects to the idea of limiting global warming to 2°C. The plan, which builds on the momentum from the Bloomberg administration, is available as a pdf: “One City, Built to Last.”

For the long term viability of the city, 2°C is an important target – but it also represents an enormous change in the way we live and use energy now. The European Union has recently agreed to a 40% cut in emissions by 2030, and yet that is regarded as too little by experts, some of whom call for an 80% cut by 2030, which would be a radical change, performed in order to protect the future of coastal cities among other features of our civilization.

And lastly, from the way-back machine, you can read the document that set the South Street Seaport as a ‘historic district’ in 1977 – the opening statement of which shows how this area connects back to the very earliest days of the city, almost four hundred years ago. For the Dutch, it was the best place to dock.