Tropical Storm Barry Could Hit the Gulf Coast With ‘Unprecedented’ Flooding. Climate Change Is Likely to Blame

The Mississippi River is already bursting as a result of months of flooding in the midwest and south — and Tropical Storm Barry is about to make the situation more dire.

Although the storm is not expected to directly make landfall in New Orleans, and is instead projected to hit at least 85 miles to the city’s west, its impact could still be devastating to a city where memories of Hurricane Katrina in 2005 still loom large. When Barry hits, officials say that the storm is likely to be “unprecedented” because it will cause three kinds of flooding all at once: a storm surge from the Gulf of Mexico, heavy rainfall and flooding in the swollen Mississippi and its western distributary, the Atchafalaya River.

Experts warn that the storm system and the midwestern flooding are ominous signs of things to come. As climate change warms the atmosphere, particularly extreme weather events are likely to become more common. Some scientists also say that the warming climate is making the hurricane season longer.

Bren Haase, the executive director of the Coastal Protection and Restoration Authority, tells TIME that the situation is “unprecedented,” noting that the Mississippi River is rarely this high during the hurricane season. In New Orleans, the Mississippi River is expected to reach its highest levels since 1950; the Atchafalaya is expected to reach the third-highest crest on record.

“I would remind everyone this is the 258th consecutive day of the flood fight on the Mississippi River. That is the longest in history,” Louisiana Gov. John Bel Edwards said at a press conference Thursday. “And if Tropical Storm Barry becomes a hurricane as we fully expect it will, this will be the first time that we’ve had a hurricane make landfall in Louisiana while the Mississippi River was at flood stage. And it isn’t just the Mississippi. We have elevated river levels across Louisiana.”

Haase says that state officials are mobilizing to ensure that the system of locks, levees and floodgates are ready to go ahead of the storm. To prepare for additional flooding, some areas have actually opened up their floodgates to let the wind blow out some of the water to make room for more, and communities are using pumping systems to clear out existing floodwater. This year, heavy rain and extreme weather in the region has already led to significant flooding.

In the years since Hurricane Katrina, Haase argues that the state has been making extensive improvements to its systems to protect the region from flooding and to prepare for weather exacerbated by climate change. Since the Coastal Protection and Restoration Authority was founded in 2005, it has built or improved hundreds of miles of levees and constructed 60 miles of barrier islands and berms.

“There’s an extensive network of both levees, floodgates, flood walls and things of that nature in the greater New Orleans area. That area has the best flood risk reduction system that it’s ever had,” Haase says.

Alex Kolker, an associate professor at Louisiana Universities Marine Consortium, a marine science research institution, tells TIME that if the storm moves west, its greatest impact is likely to be near the Atchafalaya River, in areas such as Terrebonne Parish, home to the city of Houma.

“Those have levee systems to protect them, but I think you’re probably coming close to the threshold of safety,” Kolker says.

Climate change likely helped to create the conditions that are making this storm worse. For instance, a warmer atmosphere can hold more water, which makes storms dump more rain; abnormally warm water in the Gulf of Mexico can strengthen storms; and rising sea levels can make floods bigger.

Peter Gleick, a Pacific Institute climate scientist, warns that Tropical Storm Barry is “exactly a climate change story.”

“No climate scientist is saying these storms are caused by climate change. That’s a difficult thing to show,” Gleick says. “What we’re saying is that climate change is increasingly influencing these very damaging events. And it’s that influence that’s going to grow over time as we continue to fail to get climate change under control.”

Although extreme weather is likely to impact communities around the world, Gleick argues that New Orleans is particularly vulnerable. Not only is the city low-lying, but it is located between a powerful river –– the Mississippi –– and the Gulf of Mexico.

“New Orleans is not a place you want to be when these kinds of disasters strike,” Gleick says. “Eventually, these kinds of preparations aren’t going to be enough. You can’t build levees everywhere high enough to protect against uncontrolled sea level rise. You can’t defend every coastal city from worsening typhoons and hurricanes. We’re going to inevitably see more and more climate disasters, and we can do things to lessen the impact, but we’re not going to be able to avoid all disasters.”