New Orleans celebrated its 300th anniversary this year, and there is a palpable sense of pride and creative energy here. Air travel in and out of Louis Armstrong International Airport (MSY) is on the rise, up 20 percent from 2015 to 2017. The new airport gleams across the runway, promising to welcome this burgeoning population of jet travelers in the Gulf South. The future looks bright, from the air.

Less so from the ground. At an average of four and a half feet above sea level, MSY is the second-lowest elevation of any airport in the world, just above Amsterdam’s Schiphol. The low elevation of New Orleans, combined with easily overwhelmed pump systems and an elaborate system of levees, makes the area especially vulnerable to flooding. Meanwhile, the nearby coast is eroding at a staggering rate—roughly a football field’s worth every 100 minutes. Earlier this year, The New York Times reported that the federal government was retiring place names by the dozens for islands and bays that have “simply ceased to exist.”

Almost an island, New Orleans is particularly susceptible to coastal erosion. The grand opening of the new terminal was pushed from February 2019 to May after its gravity-based main sewer line was found to be sagging, requiring a pressurized system with lift stations to be constructed. It’s hard to depend on gravity when construction is already taking place at such a low elevation. What “ground” rests beneath is hardly firm, and it will continue to shift around and change consistency each year. Local developers even refer to the soil here as “gumbo.”

Read: How humans sank New Orleans

With tropical storms and hurricanes intensifying each year, a tone of bitter resignation sets in here during late summer, mixed with some gallows humor. A colleague at Tulane told me that the university had already acquired land on the north shore of Lake Pontchartrain, for rebuilding its campus when—not if—the city is finally submerged and rendered unlivable from a big storm. A Tulane official confirmed that this was pure myth, but assured me that the organization does have a robust disaster-recovery plan in place. The short distance from wild rumor to deliberate preparedness reflects a common (if often repressed) attitude here: New Orleans’s days may be numbered.

So why build a new, billion-dollar airport here? From an ecological perspective, the site is already doomed.

MSY is hardly the only American airport undergoing significant renovations right now. In Los Angeles, LAX is in the midst of a $14 billion renovation. In New York, La Guardia is getting an $8 billion upgrade, and JFK a $13 billion overhaul. Kansas City (MCI) has a new, $1.4 billion terminal in the works.

MCI’s investment might be more secure than the others; it is far away from any coast and thus not threatened by rising sea levels. But anyone who has seen a perfectly smooth travel day snarled by a storm across the country knows that when a single airport is taken out of commission, the ripple effects can be staggering. Airlines scramble to accommodate rerouted passengers, and flights get delayed when planes are grounded 3,000 miles away. Extrapolate this to entire airports suddenly rendered useless because of the unstoppable flows of a rising ocean. While it is mostly airports in coastal cities that will be affected directly by climate change in the coming decades, other sites will also be affected.