NO.storm prep_29.JPG (copy)

New Orleans streets flooded from a rainstorm July 10.

Hurricane preparation in New Orleans used to be a lot more straightforward. Unless a storm was Category 3 or higher, most people hunkered down with the recommended supplies (and some liquid refreshment) and waited it out — unless city officials or the much-trusted Nash Roberts, WWL-TV’s late meteorologist and hurricane expert, told us to evacuate.

No more. Things natural and man-made have combined against us, most notably climate change, which both supercharges hurricanes and brings Midwest floodwaters that sluice down the swollen Mississippi River, pressing against levees built nearly a century ago to protect New Orleans from the mighty river’s annual floods.

This is the first hurricane season since the U.S. Army Corps of Engineers told Congress that the levees it designed and built after Hurricane Katrina — to protect us from storm surges — are sinking faster than anticipated. Meanwhile, the New Orleans Sewerage & Water Board continues to grapple with century-old, crumbling infrastructure as well as decades of mismanagement and neglect.

Twenty-four years ago, what was known then as the “May 8 flood” astounded southeast Louisiana, causing $3.1 billion in damages and killing seven people. It was labeled a freak occurrence; then-Mayor Marc Morial speculated that it might be a “500-year flood.”

That was barely a generation ago. Since then we’ve seen rainstorms that produced what could be considered “100-year floods.” One of those struck in the early morning hours of July 10. Every flood seems to bring a new nasty surprise; this one sent torrents of water into neighborhoods that don’t traditionally flood, including Uptown, the Irish Channel and the French Quarter.

Planning for hurricanes or tropical storms reflects not only what officials say, but also a new algebra of risk assessment. We’ll all evacuate in the face of a major hurricane, but what about a Category 1 or “mere” tropical storm? Is it moving quickly or slowly? Does it have a broad rain field? Is the ground already saturated? Is my neighborhood prone to flooding? Are we on the storm’s “wet” or “dry” side? Is it expected to strike near the mouth of the Mississippi River and possibly move upriver? What is the river’s height? Do we trust what the Corps of Engineers is saying? The Sewerage & Water Board? Entergy? It’s a complex equation to be sure.

Here’s another factor: What if a Gulf storm suddenly becomes a major hurricane and then strengthens to Category 5 just before landfall? That’s what happened last year when Hurricane Michael slammed the Florida Panhandle and wrought destruction for hundreds of miles inland.

This new storm-born algebra is only going to get more complicated in coming years as climate change continues. This year has seen record-breaking temperatures in Europe and an actual heat wave in Alaska that sent residents scurrying for air conditioners. While this past winter brought calmer weather to much of North America, Australia saw wildfires and deadly heat waves.

The world is changing, and we must adapt to those changes. The new calculation of risk assessment is a start, but it’s purely reactive. Our nation and the world must become more proactive — because we can only adapt so much before the changes overwhelm us.

This is a commentary from Gambit, produced independently from reporters at the paper.