Clouds associated with a tropical disturbance bubbled up over the Gulf Coast on Wednesday, July 10, 2019. Credit: NOAA

How Climate Risks Get Compounded: Louisiana Grapples With Heavy Rain, Tropical Storm Barry, and Swollen Mississippi

, Policy Director and Lead Economist, Climate & Energy | July 12, 2019, 1:03 pm EDT
Bookmark and Share

Heavy recent rains, along with the looming threats from tropical storm Barry, are putting New Orleans and other Louisiana communities at risk of major, life-threatening flooding.

Images from earlier this week show city streets turned into rivers as close to 9 inches of rain fell in three hours. The National Hurricane Center (NHC) is predicting that tropical storm Barry could come ashore on Saturday as a Category 1 hurricane. Meanwhile, the Mississippi is flowing very high due to heavy rains in the Midwest and South Central US earlier this year. Additional rain and storm surge from Barry mean that flooding is forecast to be extensive, and warnings have been raised that some levees in Louisiana could be overtopped or come close to that.

This chain of compound climate-related risks highlights the kinds of unprecedented threats climate change is forcing on people.

Tropical storm Barry threatens to worsen flood risks

The National Hurricane Center, local national weather offices of the National Oceanic and Atmospheric Administration (NOAA), and local officials are providing regularly updated information about the risks from Tropical Storm Barry, which has the potential to become a hurricane. Flash flooding and extended flood conditions are the greatest risks, especially given already high waters.

This morning, the NHC advisory highlighted three main dangers, which as of this writing are:

  • Storm surge, which can cause significant, and potentially life-threatening, coastal flooding. Depending on when the storm hits relative to the high tide, predictions for storm surge are:

Mouth of the Atchafalaya River to Shell Beach: 3 to 6 feet

Shell Beach to Biloxi, Mississippi: 3 to 5 feet

Intracoastal City to the Mouth of the Atchafalaya River: 3 to 5 feet

Lake Pontchartrain: 3 to 5 feet

Biloxi, Mississippi to the Mississippi/Alabama border: 2 to 4 feet

Lake Maurepas: 1 to 3 feet

  • Heavy rainfall. Total rain accumulations from Barry alone are expected to be 10 to 20 inches over south-central and southeast Louisiana and southwest Mississippi, with isolated maximum amounts of 25 inches. The slow-moving storm will produce extensive flooding over the weekend and into next week.
  • Hurricane or tropical-force winds. A hurricane warning is in effect from Intracoastal City, Louisiana to Grand Isle, Louisiana. A tropical storm watch is in effect from the east of the mouth of the Pearl River to the Mississippi/Alabama border. Tropical force wind squalls could extend as far as portions of the Alabama coast and the western Florida panhandle.

Credit: NOAA

And these risks come on top of the existing high river levels of the Mississippi. That’s why dangerous, life-threatening flooding is the number one danger from these compounding climate-related extreme events. 

As NOAA just noted, the US has just experienced its wettest 12 months on record–again. Along the Mississippi, that has contributed to record flooding and high water levels.

Keeping safe

Governor Edwards has declared a state of emergency and mandatory evacuations are underway in Plaquemines Parish and Jefferson Parish. President Trump has also declared a federal emergency in Louisiana, allowing for federal resources to be deployed to help the state prepare. The areas between Intracoastal City, Louisiana and Shell Beach, Louisiana are particularly at risk.

New Orleans Mayor Cantrell has also declared an emergency for the city and intense preparations are underway to get ready for the storm.

Residents in the path of the storm should pay careful attention to warnings from authorities, especially as flash flood conditions can change quickly and catastrophically. Flood waters often carry toxic substances, including sewage, chemicals and animal wastes, so people should be careful about being exposed to floodwaters.

Residents of New Orleans can track street closures due to flooding. Entergy is predicting widespread power outages in Louisiana. Oil and gas rigs in the Gulf of Mexico are also being evacuated, and the interruption of operations is contributing to a spike in oil prices.

No longer an isolated risk

Unfortunately, catastrophic flooding associated with extreme precipitation events is no longer an isolated risk for Louisiana. In recent years, the state has experienced multiple flood-related disasters.

In 2016, for example, the state suffered devastating floods when 20 to 30 inches of rain fell in parts of southeast Louisiana and southwest Mississippi over a period of three days. Scientists from NOAA and other colleagues showed this event was made at least 40 percent more likely and 10 percent more intense due to climate change.

This weekend the area will experience a major confluence of flood risks—high water levels on the Mississippi due to earlier rainfall, exacerbated by heavy rainfall earlier this week and now the looming threat of storm surge and extremely heavy extended rainfall associated with hurricane Barry—each of which bears the fingerprints of climate change in some way. The combined effect of these risk factors should not be underestimated and is likely to cause significant harm to existing infrastructure in the region designed to protect life and property.

Quoted in a recent news article, John Barry, a historian and former member of the Southeast Louisiana Flood Protection Authority, called current conditions “unprecedented in recorded history.” He went on to say, “I can say that when I was on the board, we were always concerned about a surge coming up the river and overtopping the levees, and we did have conversations with the corps about it. But what we expected was a surge of 15 feet on a river running at 3 to 4 feet. That’s not what we’re going to see this time.”

St. Bernard Parish President Guy McInnis similarly said: “There is no protocol for this unprecedented event. We’re asking our families in St. Bernard Parish to be prepared and have a plan for your families’ safety.”

Storm Surge Warning for central Louisiana coast east through Biloxi, MS, including portions of Lake Pontchartrain where there is the danger of storm surge inundation of 3 feet or more above ground. Credit: NOAA

Repeated trauma to communities

Each of these extreme events falls as a fresh blow to communities, and their cumulative effect is devastating. Right now, it is important to focus on making sure those in the path of the storm have all the resources they need to keep safe, and for residents to heed all warnings from officials.

In the weeks and months to come, communities will need help getting back on their feet. Experience shows that communities of color and low-income communities often bear a disproportionate brunt of disasters and struggle the most to recover. It will be critical to target recovery efforts to meet the needs of these communities, including ensuring access to affordable housing, health services, childcare and jobs.

Action needed to address climate change

Let’s also keep the big picture in mind: climate change is increasing the risks of these types of extreme events, oftentimes compounding those risks. To truly protect communities, we cannot just react to these events as one-off disasters; we must reckon with these emerging, complex and interrelated challenges, and we must address the root cause, climate change.

We urgently need federal action to help build climate resilience and put the country on a path steep cuts in heat-trapping emissions.

If you are able and would like to support a community-based and community-led effort for equitable climate disaster recovery, please consider donating here.

(This fundraiser is administratively managed by the Gulf Coast Center for Law & Policy. 100% of proceeds will go directly to the United Houma Nation  and Zion Traveler’s Cooperative Center  — where local Black & Native people will use a collective process to determine how to use the funds.) 

 

NOAA
NOAA

Posted in: Global Warming Tags: , , , ,

Support from UCS members make work like this possible. Will you join us? Help UCS advance independent science for a healthy environment and a safer world.

Show Comments


Comment Policy

UCS welcomes comments that foster civil conversation and debate. To help maintain a healthy, respectful discussion, please focus comments on the issues, topics, and facts at hand, and refrain from personal attacks. Posts that are commercial, self-promotional, obscene, rude, or disruptive will be removed.

Please note that comments are open for two weeks following each blog post. UCS respects your privacy and will not display, lend, or sell your email address for any reason.