Climate change-fueled flooding could hit Louisiana the hardest. Can it be stopped?
The water came swiftly, blocking roadways, seeping into homes and forcing some to leave their cars on highways to flee for safety.
June 1 marks the official start of hurricane season. But two weeks before what’s projected to be another highly active season, south Louisiana parishes were pummeled by the kind of sinister spring storm that’s become all too common in recent years.
Lake Charles, still recovering from last year’s hurricanes Laura and Delta, saw hundreds of homes flooded and more than 12 inches of rain, the third heaviest rain event in the city’s history, Lake Charles Mayor Nic Hunter said at a televised media briefing May 18.
“It will eclipse what we consider a 100-year event,” Hunter said. “And it’s becoming a misnomer because we are experiencing these 100-year events much more often than every 100 years.”
For state climatologist Barry Keim, who has studied the recent trend of intense spring showers, the floods could be a sign of how climate change will impact Louisiana in the coming decades as temperatures rise.
While annual rainfall has remained fairly steady in Louisiana, storms in recent years have been dropping more water in shorter amounts of time, Keim said.
“When you put 10 inches of rain on the ground in three hours, which has happened in New Orleans a few times in the last couple years, it completely overwhelms the drainage capacity,” Keim said. “All of that is more or less consistent with what we’d expect in climate change.”
More intense rainstorms are only one facet of the threat Louisiana faces.
Climate models show that fluctuating sea levels and temperatures could create more powerful, slower moving hurricanes and higher storms surges, Keim said. Compounding the issue is aging infrastructure, low land elevation and vastly diminished barrier marshland, which Keim said can reduce storm surge by 1 foot for every 3 miles of marshland.
“So if you have 30 miles of wetlands, the storm surge is knocked down by 10 feet. That’s a big deal. And we used to have 90 miles of wetlands,” Keim said. “Louisiana is probably the most vulnerable state in the U.S. to climate change.”
Now, a 2021 report by First Street Foundation, a New York-based non-profit flood policy research group, shows how much that vulnerability could cost Louisiana homeowners.
First Street found that Louisiana has 241,000 residential properties at risk of significant flooding. Most are in the southern parishes, said Jeremy Porter, head of research and development at First Street. Currently, flooding can be expected to cause $745 million in annual economic damages to those properties. By 2051, the report found that annual economic loss estimates would skyrocket to $2.5 billion, an increase of 245%.
Among counties where residential properties are projected to see the nation’s largest increases in economic damage, five of the top six are south Louisiana parishes. Leading the state is Assumption Parish (expected cost increase of 1,478%), followed by St. Martin Parish (1,397%), Terrebonne Parish (664%), Lafourche Parish (549%), and Lake Charles' Calcasieu Parish (497%).
Porter said Louisiana is built to absorb current risk. But when current flood protections were modeled against future climate predictions, it became clear that much more work is needed to avert future catastrophe.
"When we did that, we saw that almost nowhere is there as big of an impact," Porter said of Louisiana.
A fix for the floods?
The report's findings are supported by Louisiana's Coastal Master Plan, a planned 50-year, $50 billion effort to study the threats of climate change, land loss and implement countermeasures in coastal parishes.
While First Street’s analysis focused solely on residential property damage, the Coastal Master Plan projects that Louisiana's total annual flood damage will increase from $2.7 billion to $12.1 billion over the next half century.
Protecting Louisiana's dissolving coastline is paramount to mitigating the risk, said Jordan Fischbach, director of planning and policy research at The Water Institute of the Gulf, who has assisted with the Master Plan for the past decade.
The state lost 1,900 sq. mi. of marshland between 1932 and 2010, according to the U.S. Geological Survey. Over the next 50 years, the Master Plan predicts the state could lose another 2,250 sq. mi. as sea levels rise between 1-3 feet and stronger hurricanes inundate the coast.
"The coast as we as we knew it decades ago is no longer there. The coast that we know today is not going to be the Louisiana coast that we have in the future," Fischbach said. "So the Master Plan tries to build toward a sustainable coast, while acknowledging that not all areas can be saved."
While the entirety of the needed $50 billion has not been procured yet, the plan's 124 projects ranging from levees to marsh creation could save or create 800 sq. mi. of coastland. Fischbach said that could reduce the annual flood risk from $12 billion to $3.8 billion by year 50 of the plan.
Further inland, a separate state-led endeavor called the Louisiana Watershed Initiative has allocated $163 million to improve drainage infrastructure and floodplain management north of the coast.
"The question is, do you invest before disasters to make communities more resilient, and reduce these impacts, or do you spend the money post-disaster trying to clean up and rebuild again?" Fischbach said. "Research shows that investments pre-disaster are much more cost effective."
'There's definitely something different'
Surveys show that the majority of Louisianians support climate change mitigation efforts. One 2019 poll of 1,000 voters conducted for Restore the Mississippi River Delta found that 71% believed in climate change and 96% said elected officials should prioritize coastal land loss.
Still, experts are concerned that many homeowners are unaware of future risk.
FEMA flood maps are often outdated, Porter and Fischbach said. And unlike the First Street analysis, FEMA flood maps do not account for flooding from heavy rainfall or small waterways, Porter said.
That's something Dick Gremillion found out first-hand when his Lake Charles home received 2-3 inches of water in the May flood despite being outside FEMA's special flood hazard areas.
Gremillion is the Calcasieu Parish Director of Homeland Security and Emergency Preparedness. It was the first time his house had flooded since he moved in 32 years earlier.
"There's definitely something different. We're getting a lot more concentrated rainfall in different areas," Gremillion said. "Part of the answer is preventing dwellings from being in a floodway. But my house wasn't expected to flood."
Parishes such as Calcasieu have taken a proactive approach by requiring new construction to be freeboarded — elevated 1 ft. higher than FEMA's base elevation standard. The Coastal Master Plan also accounts for "non-structural risk reduction" and recommended elevating more than 22,000 structures.
Alberto Galan is the assistant to the administrator of the Calcasieu Parish Police Jury, which passed the freeboarding requirement in 2017.
Galan said he wishes it had been passed sooner.
"If we would have had those 10 years ago, we probably wouldn't have nearly as many structures damaged over the past several storms," Galan said.
More drastically, the Master Plan recommended buying out 2,400 structures in places where the risks are too high for residents to remain.
Louisiana has been one of the nation's pioneers in climate change-fueled relocations of communities. The state has begun the relocation of three communities, including Isle de Jean Charles, where the indigenous Biloxi-Chitimacha-Choctaw Tribe has seen their southeast Louisiana island shrink from 22,000 acres to 320 since 1955.
On May 21, days after the flood, Gov. John Bel Edwards announced the latest relocation effort, a $30 million voluntary buyout for residents of the Greinwich Terrace neighborhood in Lake Charles.
"You need to think big in terms of the kinds of solutions that are needed," Fischbach said. "This flood risk is an existential crisis for Louisiana's communities."