The new maps also do not adequately highlight the shifting reality wrought by climate change. It’s not just that a warming planet heralds bigger and more frequent storms. According to the National Oceanic and Atmospheric Administration, Louisiana faces the highest rate of sea-level rise of any coastal region on the planet: As seas rise, Louisiana’s land is sinking, part of an ancient geologic process of subsidence accelerated by the levee system itself, which prevents mud from the Mississippi River from replenishing the land. Already, the Corps of Engineers has had to rebuild sections of the new levee system that had sunk six inches below their original height.

According to current projections, roughly 75 percent of New Orleans will be below sea level by 2050, up from 54 percent today. And all the while, canals dug by the oil industry are causing coastal wetlands — the crucial buffer against hurricane storm surges — to fall into the Gulf of Mexico at the rate of a football field every hour. And yet, according to the new map, most of the city is safe.

That is why a likely outcome of this new federal policy is that when — not if — New Orleans floods again, thousands of people will be worse off than they were during Hurricane Katrina: When their homes flood, they will not have flood insurance.

This is not to say that gloomier maps alone would solve the problem. By many measures the National Flood Insurance Program is a failure. The program was supposed to limit federal payouts after flood disasters, while discouraging building in risky areas. But since its inception, development in dangerous places has accelerated, while costs to federal taxpayers for both flood insurance and disaster relief have skyrocketed. As of 2014, after Hurricane Katrina and Superstorm Sandy, the program was $24 billion in debt.

We face a difficult choice. The National Flood Insurance Program can charge an unsubsidized, or “actuarial,” rate for coverage (as Congress decreed in 2012, though it later severely limited how rapidly those rates could rise); doing so would impose crippling costs on homeowners. Or it can continue to subsidize development in dangerous places. But these new maps represent an unwise compromise: blinding residents to their physical vulnerability, while also inviting them to financial ruin.