Mayor Bill de Blasio yesterday announced a $10 billion plan to protect lower portion of Manhattan, home of Wall Street, from sea level rise and the next major storm by expanding the island’s coastline by two city blocks into the East River.

The plan would create new land between piers from the Brooklyn Bridge to the Battery, and would install “grassy berms in parks and removable barriers that can be anchored in place as storms approach,” the mayor said.

“It will be one of the most complex environmental and engineering challenges our city has ever undertaken and it will, literally, alter the shape of the island of Manhattan,” de Blasio wrote in the New York Magazine.

“The new land will be higher than the current coast, protecting the neighbourhoods from future storms and the higher tides that will threaten its survival in the decades to come.”

Compared to other parts of the island, Lower Manhattan is especially close to sea level, with some parts rising just five feet above it, and scientists estimate that sea levels could rise 18 to 50 inches across New York State by 2100.

Six years ago, Hurricane Sandy slammed into New York City. The storm put 51 square miles of it under water. Seventeen thousand homes were damaged or destroyed, and forty-four New Yorkers lost their lives.

Although its primary purpose seems to be a buffer against storm surges, Mayor de Blasio said that by raising the land, people and property could also be protected against sea level rise.

Mr de Blasio said: “We’re going to build it, because we have no choice.”

“This should be as much a national priority as a local one — protecting the global centre of commerce, the Federal Reserve, the home to a sector of our economy that touches every town and region in America.”

“It should be backed by big federal dollars.”

De Blasio said the question of what might be built on the new land remains an open one, but suggested parks or schools could be possibilities.