Like the people that said for a decade saying N.O. hadn't been hit in 40 years, was overdue, and was not prepared? It was even in a documentary.
Katrina wasn't a one off, very far from it. N.O. has been inundated with flood many times over many years. What happened in N.O. was what you call "inevitable".
The old original part of town didn't even flood in Katrina. Only what has been expanded and made habitable by levees.
A little history from
http://frenchquarter.com/history/KatrinaHistory.php which gives a brief history of N.O. disasters.
"Those who count the Katrina aftermath as our darkest hour might consider 1794, when a hurricane struck on August 10, another brought rain and flood on the 21st, and the city (then just the French Quarter) burned a second time on December 8, followed by looting. Governor Carondelet faced the desolation without FEMA to blame or complain about and without America coming to the rescue with troops and billions of dollars. But the city rose again."
Same for earlier hurricane related disasters, like the 47" of rain in 36 hours in Houston in 1979 the NA rainfall record, Alicia that caused billions in damage in Houston in the 80's, back to storms like Carla, a cat 5, all the way back to the 1928 Okeechobee hurricane killing 2500 and the 1900 storm in Galveston, the largest loss of life in any U.S. natural disaster with 6000 to 8000 dead.
The spanish flu was also pretty much buried in history. Simply not talked about, and not taught in history books until recent years. Pandemics such as typhoid, yellow fever, diphtheria, and cholera were common in the day, and WWI was killing scads of people at the time as well.
In warming if there is a "big one" it would be something that took years to happen, like ocean current changing followed by years of cooling or warming at a few tenths up to a degree a year for a wide 5+ degree change. Not a hurricane.
Overpopulation and viral pandemics have truly catastrophic potential for humanity. AGW not so much, and not so fast IMO.