New York City mayor Bill de Blasio announced a huge climate-focused infrastructure effort on Thursday, calling for a project that could, among other things, extend lower Manhattan two blocks into the East River and cost as much as $10 billion.

Sea level rise due to climate change has long been a cause of concern for New York City. According to the Lower Manhattan Coastal Resilience survey, released today, 37 percent of lower Manhattan will be at risk for storm surges by 2050. By 2100, sea levels could rise by as much as six feet, scientists say. “We don’t debate global warming in New York City. Not anymore,” wrote de Blasio in a post in New York Magazine. “The only question is where to build the barriers to protect us from rising seas and the inevitable next storm, and how fast we can build them.”

The plan also includes more projects costing around $500 million, which would include resiliency measures like elevating parks and building removable flood barriers in lower Manhattan that can be used when a storm approaches. However, this strategy won’t work for the Financial District and South Street Seaport. These neighborhoods are on the very tip of the island and, according to de Blasio, are so crowded that it’s not feasible to build flood protection on the existing land. Instead, the city would like to develop approximately two more blocks of land (or about 500 feet) into the East River. “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,” de Blasio wrote.

The new development will be the latest of the city’s efforts to protect itself from climate change. Other initiatives include a five-mile seawall around Staten Island and sand dunes around the Rockaways. And this isn’t the first time Manhattan has built land out into the waters that surround it (or proposed adding more). Over the past few centuries, the city has built itself out and up by dumping heaps of earth into the river and harbor.

It is still unclear where all the funds for this latest land-building initiative will come from, and planning for the “The Financial District and Seaport Climate Resilience Master Plan” will take about two years. But in his New York Magazine op-ed, de Blasio wrote that some of the funding should come from “big federal dollars.”

“This is infrastructure, just as vital as roads, rails, and bridges. It’s national security, just as critical to keeping people safe as any military hardware. Preparing for climate change has to be a national priority, backed by tens of billions in federal investment. Lives are on the line.” de Blasio wrote.