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“The problem is that we are seeing these impacts and these changing storms faster, and adaptation is simply not keeping up with them,” says Lauren McPhillips, a hydrologist at Pennsylvania State University who studies urban flooding.

New York is relatively forward-thinking when it comes to flood preparation, McPhillips said. Over the years, the city has created more permeable architecture such as green roofs and rain gardens, as well as upgraded pumps and drainage pipes. These improvements have intensified since Sandy.

“We’ve learned a lot from Sandy’s experience,” New York Governor Katie Hochul said at a press conference the morning after the hurricane. “We have restored fault tolerance; our coastal coastlines are in much better condition than they were before. But where we have vulnerability is on our streets. “

Sandy plays an important role in any flood discussion in New York. But the difference between Hurricane 2012 and Ida illustrates the complex flood threat facing the city as a result of climate change. Sandy caused a violent storm surge as the ocean rushed into the city. Ida poured several inches of water across the city in a short time, a problem that sea barriers and other coastal defenses cannot solve.

While New York and other coastal areas are more vulnerable to rising sea levels, any urban area can experience so-called pluvial flooding caused by rainfall. “The way we built New York City caused a flood problem,” says Timon McFirson, urban climate resilience researcher at New School and a member of the New York City Climate Change Commission.

Impenetrable surfaces such as concrete cause water to rush down instead of sinking into the ground as it might in meadows or forests. And if enough water is drained, the consequences can be fatal.

With contributions from researchers such as McFirson, New York has developed plans to improve its protection against storm-triggered flooding. The Stormwater Resilience Perspective Plan, released in May 2021, included a city-wide flood risk assessment and proposed solutions, ranging from social strategies such as educating local city councils about flood risks to engineering practices such as increasing green roofs. and rain gardens.

The city’s environmental department is reviewing plans for areas hit particularly hard during the worst storms. A cloud tolerance study completed in 2018 examined strategies for dealing with extreme rainfall. Pilot plans for an often flooded area in Queens included green infrastructure such as flooded walkways in the park, as well as a basketball court designed to retain water during major floods.

But implementing these or any other stormwater management solutions will require significant funding, and some will take a decade to develop. “To solve this problem, we need to literally rebuild the city,” McPheerson says. And he expects the price to be hefty – probably hundreds of billions of dollars. In some cases, he said, the study already suggests ways to protect the city from flooding, but pulling together the money and political will to act is still difficult.