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New York Mayor Bill de Blasio proposed a $10 billion plan to push out the lower Manhattan coastline as much as 500 feet, or two city blocks, to protect from flooding that’s expected to become more frequent as global temperatures rise.

The project would protect the South Street Seaport and the Financial District, along the eastern edge of lower Manhattan, an area just 8 feet (2.4 meters) above the water line, de Blasio said. Portions of the extended land would be at 20 feet above sea level. The city can’t build flood protection on the existing land because it’s too crowded with utilities, sewers and subway lines, he said.

“The new land will be higher than the current coast, protecting the neighborhoods from future storms,” according to the plan de Blasio announced Thursday. “Extending the shoreline into the East River is the only feasible way to protect these vulnerable and vital parts of the city.”

Sandy Aftermath

The neighborhood was flooded in 2012 by a storm surge brought by Hurricane Sandy, which caused $19 billion in damage to real estate and infrastructure. The area includes Wall Street, center of one of the world’s financial capitals, $60 billion of property, 75 percent of the city’s subway lines, 90,000 residents and 500,000 jobs. The extension will secure lower Manhattan from rising seas through 2100, de Blasio said.

“It’s one of the core centers of the American economy, the financial capital of the world, and it should be a national priority. But the fact is, it is not,” said de Blasio, who has said he’s considering a 2020 run for president. “This should be a case where the federal government is asking us how it can help. That’s just not happening.”

President Donald Trump’s skepticism that climate change is the result of carbon-dioxide emissions from the use of fossil fuels means that the city can’t rely on federal funds unless someone else occupies the White House, de Blasio said. Climate scientists overwhelmingly consider such emissions as the driver of rising global temperatures.

The extension would jut out into the East River north of the Brooklyn Bridge, up the east side to the Bowery. It would be part of an overall resiliency plan for Lower Manhattan that includes a $500 million project to fortify the area with a U-shaped expanse of grassy berms and removable storm-barriers that can be anchored in place as storms approach, de Blasio said.

On Staten Island, which also experienced devastation from the storm, the city has received $615 million in federal funding to create a protective seawall on its eastern shore. Other fortifications have been installed along the southern Queens shoreline in the Rockaways, including a boardwalk that will also act as a barrier to tidal surges.

Marine Life

Tim Dillingham, executive director of the New Jersey-based American Littoral Society, which advocates for protecting coastal environments, said he worries about the effect of the proposal on marine habitat.

“We very rarely accept the rationale that you can sacrifice the environment for economic development,” Dillingham said by phone on Thursday. “We would want to see alternative ways to do that.”

Ideas to build some sort of seawall around lower Manhattan have circulated for years, including one proposed in 2013 by then Mayor Michael Bloomberg. The former mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.

That plan, dubbed “Seaport City,” included major private sector development, which would take more time to implement, de Blasio said. This project is focused on resiliency, de Blasio said.

While de Blasio should be commended for “thinking big,” his proposal doesn’t contain a rigorous cost-benefit analysis comparing it to other proposed mega-engineering resilience projects, said Roland Lewis, president of the Waterfront Alliance, a New York-based advocacy group. It also doesn’t have enough regional sweep to take into account other equally vulnerable areas, he said.

“All options should be on the table, but we need to have a full understanding of the trade-offs,” Lewis said. “Most important, there is no time. Solutions based on the best analysis with robust and real public input are needed to address the urgency of now.”

Jesse Keenan, a faculty member and researcher at the Harvard Graduate School of Design who advises governments on climate resilience and adaptation, said the instinct to hold back climate change with walls and other infrastructure projects can sometimes create a false sense of security at great cost and for a limited amount of time. But New York City is an exception.

“I can’t think of anywhere else in America where there would be a stronger impetus to make this kind of investment,” said Keenan, who co-authored a 2014 study on protecting Southern Manhattan’s coast that grew out of the Seaport City idea. “Given the elevation and total amount of economic output and productivity from this part of the country, we really have no other alternative.”

That doesn’t mean de Blasio’s proposal will be easy. The main drawback, Keenan said, is the amount of red tape the city must clear.

“Once you talk about moving into the water, you’re talking about a level of coordination with the U.S. Army Corps of Engineers, and likely Congress and other environmental stakeholders, that could significantly lengthen and complicate it,” Keenan said. “But maybe that’s inevitable. Maybe we shouldn’t run away from that.”

The process would also include years of local land-use hearings and environmental impact studies that could delay construction until 2025 or later, de Blasio said. The mayor said residents that experienced Sandy’s devastation may want changes while supporting the concept.

“After Sandy you don’t find many climate-change deniers in New York City,” de Blasio said. “This is the existential threat, the core issue that we all must face as soon as possible.”

–With assistance from Stacie Sherman.

Related:

• Lloyd’s Index Shows $92B at Risk in North American Cities Each Year
• U.S. Cities Ranked Most Vulnerable to Coastal Floods Due to Climate Change
• What If an Irma-Like Hurricane Hit the New York City Metro Area?

Topics New York Flood Climate Change