Build De Blasio

After a comprehensive climate change study, Manhattan may extend its shoreline

Rendering of East Side Coastal Resiliency project, which will elevate portions of Lower East Side parks. (Courtesy the NYC Mayor's Office)

New York City’s mayor, Bill de Blasio, took to New York Magazine to lay out an ambitious $10 billion plan to protect Lower Manhattan from the worst effects of climate change.

The city will also be advancing $500 million in capital projects right away to beef up the coast with grassy berms, esplanades, sea gates, and by elevating existing infrastructure; but the most surprising measure is an initiative to extend the tip of Manhattan another 500 feet into the East River.

Both initiatives are the result of the Lower Manhattan Climate Resilience Study released today as part of the Lower Manhattan Coastal Resiliency (LMCR) project, which is meant to examine the risks and challenges posed by climate change.

A flood plane diagram of Lower Manhattan

The study area is especially susceptible to flooding in the next 30-to-70 years owing to its proximity to the waterfront and low elevation. (Courtesy the NYC Mayor’s Office)

The study found that by 2050, 37 percent of Lower Manhattan would be susceptible to storm surges, while by 2100 that number would move to 50 percent as sea levels rose six feet. Twenty percent of Lower Manhattan would be vulnerable to daily tidal flooding by that time as well. For an area that holds more than ten percent of New York City’s jobs, and produces ten percent of the city’s gross economic output, flooding on the scale seen during hurricane Sandy would be devastating.

The report also identifies heat waves, extreme precipitation events, and the gradual encroachment of groundwater (which would eat away at the neighborhood’s below-ground electrical and transportation infrastructure) as catastrophic threats.

A sectional diagram of buildings on the coast

A diagram showing the myriad ways in which water could infiltrate Lower Manhattan (Courtesy the NYC Mayor’s Office)

After running through a gamut of different flood mitigation approaches, the report advocates extending the shoreline to prevent flood waters from reaching critical buildings and infrastructure sites as the optimal solution. Requiring buildings to implement individual-level flood mitigation measures would result in a piecemeal, non-standardized application, and building hard storm barriers would impede views and access to the waterfront.

Mayor de Blasio expects that building into the East River could cost up to $10 billion.

“Over the coming years, we will push out the Lower Manhattan coastline as much as 500 feet,” wrote de Blasio in his NY Magazine op-ed, “or up to two city blocks, into the East River, from the Brooklyn Bridge to the Battery. The new land will be higher than the current coast, protecting the neighborhoods from future storms and the higher tides that will threaten its survival in the decades to come.

“When we complete the coastal extension, which could cost $10 billion, Lower Manhattan will be secure from rising seas through 2100.”

A sectional diagram of buildings on an extended coastline

Mayor de Blasio claims that extending the shoreline would provide the most protection from flooding. (Courtesy the NYC Mayor’s Office)

As for funding such an ambitious project, the mayor admitted that the city wouldn’t be able to go it alone, but that President Trump also wouldn’t be willing to contribute. He then called on Democrats to make the project part of their national agenda, to work towards allocating federal funds, and to fast-tracking the extension.

Alongside the resiliency study, the city also released the third iteration of their Climate Resiliency Design Guidelines, which architects and planners can use to future-proof their projects.

Starting in the spring, the city will begin holding public engagement meetings on all of its resiliency capital projects and the in-progress Financial District and Seaport Climate Resilience Master Plan. The input gathered will help guide the city on which district should receive the first phase of the plan.

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