In densely populated cities surrounded on all sides by water—the borough of Manhattan in New York City as a prime example—the risks from sea level rise and climate change are not just hypotheticals; they are existential threats.

Superstorm Sandy in October 2012 was a wakeup call, causing 44 deaths and more than $19 billion in damage in the city alone. But it was not an anomaly—extreme weather events and flash floods have only intensified since then there, and across the globe.