New York City is a megalopolis surrounded by water. An increasing threat with global warming. Seven years ago, the "Big Apple" was hit by Hurricane Sandy, ravaging entire neighborhoods and killing 48 people.

In these social housing units in the south of Manhattan, a wave of 4 meters swept over and trapped the inhabitants. "People did not expect something similar to happen," says Aixa Torres, president of the local residents' association. "We see it on TV, it happens in the Pacific, it does not happen in Manhattan ... Well if, it happened here."

After Sandy, New York City launched a $ 20 billion action plan, the "Big U" project, on which architect Simon David worked. In the absence of consensus, work will only begin in the spring of 2020. "We need to create a barrier (to stop the waves, Ed.) Sometimes it has to be a slope, sometimes a wall or a door that can go up and down depending on the In fact, all of this must be a barrier to the ocean. "

According to the latest projections, the water level in New York is expected to rise by nearly two meters by the end of the century, not counting Sandy-type hurricanes, which would be more frequent and more violent. For climatologist Klaus Jacob, a radical solution is needed. "Ultimately, we will have to leave these shores at sea level. We have no choice and today we close our eyes on it," he says.

New York has a short-term plan, but the United Nations says it again: you have to think even further. UN Secretary-General António Guterres hopes to convince heads of state and government at the climate summit to be held in New York on Monday.