Hurricane Ida: 4 essential reads about New Orleans’ high hurricane risk and what climate change has to do with the storms

Hurricane Ida: 4 essential reads about New Orleans’ high hurricane risk and what climate change has to do with the storms

Hurricane Ida: 4 essential reads about New Orleans’ high hurricane risk and what climate change has to do with the storms

Hurricane Ida’s winds tore off roofs, including in New Orleans’ French Quarter. AP Photo/Eric Gay
Stacy Morford, The Conversation

Hurricane Ida hit the Louisiana coast with 150 mph winds on Aug. 29, 2021, 16 years to the day after Hurricane Katrina devastated New Orleans on nearly the same path.

Ida was one of the most intense tropical storms on record in the state. Its storm surge was less than Katrina’s, but it quickly flooded streets and homes outside the levee system where many residents were under mandatory evacuation orders. Most of New Orleans’ rebuilt levees appeared to have held, but the powerful winds tore up roofs, knocked down trees and caused “catastrophic damage” to transmission lines, cutting power across the region.

Four articles from our archives, written by meteorologists and atmospheric scientists, offer some insight into why the New Orleans area is at high risk for intense hurricanes and what climate change has to do with these powerful storms.

1. Some areas are more prone to hurricane damage

New Orleans is among the most at-risk places along the U.S. coast for hurricanes. An analysis by the National Oceanic and Atmospheric Administration estimated the area was likely to see a hurricane within 50 nautical miles about once every seven years and a major hurricane about every 20.

A map shows return rate for hurricanes at communities along the coast
The numbers shown here reflect how often a hurricane would be expected within 50 nautical miles. The red dots suggest a hurricane every five to seven years. NOAA

Several characteristics can put a region at higher risk for destructive hurricanes, University of Florida meteorologist Athena Masson explained.

One factor is timing, she wrote. Storms tend to hit Texas and the Atlantic Coast earlier in the season, while the northern Gulf Coast is at higher risk from late August into October. Trade winds tend to push storms away from the western Gulf later in the fall.

Maps showing U.S. areas most at hurricane risk during each month from June to November
The busiest areas during each month of hurricane season. NOAA

Another is the shape of the sea floor. A shallow continental shelf like Louisiana’s can generate a powerful storm surge. Parts of the coast were inundated with more than 9 feet of water as Ida arrived.

Conditions along the storm’s path, particularly the water temperature, largely determine whether a tropical storm becomes a dangerous hurricane, Masson said.

“Three key ingredients are needed for a hurricane to form: warm sea surface water that’s at least about 80 degrees Fahrenheit (26.5 C), a thick layer of moisture extending from the sea surface to roughly 20,000 feet, and minimal vertical wind shear so the thunderstorm can grow vertically without interruption,” Masson wrote.

Hurricane Ida had all three. The Gulf of Mexico’s surface was exceptionally warm as Ida moved through, with temperatures around 85 to 90 F (29.4 to 32.2 C). The storm also had plenty of moisture and very little wind shear to stop it.


Read more: Some coastal areas are more prone to devastating hurricanes – a meteorologist explains why


2. What does climate change have to do with hurricanes?

The 2020 hurricane season broke records with 30 named storms, seven major hurricanes of Category 3 strength or higher, and 10 storms that underwent rapid intensification like Ida did before making landfall.

In analyzing the 2020 season, atmospheric scientists James Ruppert at Penn State and Allison Wing at Florida State University discussed climate change’s role in raising hurricane risks.

A satellite view of the hurricane over the Gulf of Mexico and coast.
Hurricane Ida just before landfall on the Louisiana coast on Aug. 29, 2021. NOAA

On the question of whether climate change affects the number of hurricanes, there is no detectable global trend in hurricane frequency, and studies using computer models have had conflicting results, Ruppert and Wing wrote. But, they said, there is a trend toward more intense storms – those that are Category 3 and higher, like Hurricane Ida.

“Since ocean temperature controls the potential intensity of tropical cyclones, climate change is likely behind this trend, which is expected to continue,” they said. “The U.S. is also seeing more storms with extreme rainfall. With warmer temperatures, more water is able to evaporate into the atmosphere, resulting in greater moisture in the air.”


Read more: The 2020 Atlantic hurricane season was a record-breaker, and it's raising more concerns about climate change


3. Climate change and storm surge

Climate change also affects the level of hurricane damage in another way: It gradually increases the risk from storm surge.

Storm surge – the huge volume of water that the hurricane pushes on shore – is one of the greatest threats to life and property from any hurricane. The height and extent of the storm surge depend on the strength and size of the hurricane, but sea level rise is raising the baseline height of the ocean, Penn State meteorologist Anthony Didlake Jr. explained.

An illustration shows how higher tides raise storm surge levels.
When hurricanes hit at high tide, the tide further raises the water level. Sea level rise also elevates the baseline water level. The COMET Program/UCAR and National Weather Service

“As water warms, it expands, and that has slowly raised sea level over the past century as global temperatures have risen. Freshwater from melting of ice sheets and glaciers also adds to sea level rise. Together, they elevate the background ocean height,” Didlake wrote. “When a hurricane arrives, the higher ocean means storm surge can bring water further inland, to a more dangerous and widespread effect.”


Read more: New Orleans issues evacuation orders ahead of Hurricane Ida as forecasters warn of dangerous storm surge – here's what that means


4. The IPCC on hurricanes

The latest global climate analysis from the United Nations’ Intergovernmental Panel on Climate Change offered similar conclusions.

It discussed evidence that hurricanes are now more intense than they were 40 years ago, are intensifying more rapidly and are slowing in their forward movement, leading to more rainfall. The influence of greenhouse gas emissions in these changes is still being determined; reductions in particulate pollution have also had important effects, said Robert Kopp, an author of the report’s chapter on oceans and sea level rise.

“The clearest effect of global warming is that a warmer atmosphere holds more water, leading to more extreme rainfall, like that seen during Hurricane Harvey in 2017,” Kopp explained. “Looking forward, we expect to see hurricane winds and hurricane rains continue to increase.”


Read more: IPCC climate report: Profound changes are underway in Earth's oceans and ice – a lead author explains what the warnings mean


Editor’s note: This story is a roundup of articles from The Conversation’s archives.The Conversation

Stacy Morford, Environment + Climate Editor, The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The GOP’s ‘Black’ Problem

WELCOME TO TAMPA: Some 200 protesters braved inclement weather from Tropical Storm Isaac today to rally against the presence of the GOP convention in Tampa, Florida. Protesters cried out against Republican policies on immigration, health care, and the economy. (Photo: Mladen Antonov/Newscom)

News that a Republican candidate is getting a low percentage of the black vote typically draws a yawn.

But prominent black Republicans, such as Romney-Ryan adviser Tara Wall, likely gasped at the new NBC-Wall Street Journal poll that suggests the ticket is currently getting zero percent of the black vote. How do you get zero percent with all those #BlackConservativeForMittRomney tags on Twitter?

Truthfully, the poll’s results aren’t literal, being within the 3.1 percent margin of error. But there’s a link between the poll and Romney’s actions that should cause black Republicans like Wall to do some soul-searching.

Since May, Wall has been Romney’s senior communications adviser emphasizing African American outreach (UrbanFaith news editor Christine Scheller spoke to her back in June). Wall held a similar role with President George W. Bush’s 2004 reelection campaign where he gained 11 percent of the black vote. She’s among a group of black advisers who have been schooling (apparently not well) Romney on what black voters need to hear from him. They don’t expect to outpoint the nation’s first African American president, but want Romney to at least hold on to the 4 percent of the black vote that McCain received in his 2008 loss to Obama.

I interviewed Wall last week on my radio show and her comments about the poll were predictable: You can make numbers say anything you want. Obviously, black Republicans weren’t among those polled. Excitement for President Obama has dipped as people continue to struggle economically. Efforts to appeal to black voters are gearing up (at this writing there was no section on Romney’s website under the “communities” geared specifically towards black or Hispanic voters).

However, I was struck by Wall’s response concerning the GOP’s elephant in the room — its race-baiting tactics.

It’s often said that blacks, particularly black Christians, are as socially conservative (pro-life, pro traditional marriage) as the Republican platform claims to be.  So why aren’t black voters aligned with Republicans over Democrats? The GOP’s racist bent is what keeps black voters at bay. Wall objected passionately.

“That’s false. I reject that notion,” she said. “… Racism comes in many forms. I think that is a discussion in a broader context that we as a community have to have on an ongoing basis. But to simply blanketly [sic] say that Republicans don’t speak out and are racist, I think that’s patently false. There are racist elements in society everywhere and in every party and in every place.”

TOUGH TASK AHEAD: Tara Wall is charged with shaping the Romney campaign’s communication strategy — including its message to the black community, which is presently showing no love for Mitt.

That last sentence is certainly true. Democrats play race games as well and President Obama has been tepid on addressing racism. However, it’s well documented that much of today’s Republican base is of the Dixiecrat tradition — anti-big government, pro-state’s rights, segregationists. In response to Democrat President Lyndon B. Johnson signing civil rights legislation in the 1960s (Northern moderate Republicans urged him to), Southern conservative democrats began fleeing to the GOP. They were lured by the GOP’s “Southern strategy” during the Goldwater and Nixon years. To compete with Democratic gains, the GOP saw white southerners as fertile ground for new voters. Understanding the buttons to push, they stirred fears of big government and black people to win them over. No deep ideological motive, just money + votes = power.

Blue states turned red. The party of Abraham Lincoln took on the spirit of Andrew Johnson. Blacks fled the GOP. The legacy continues today.

Wall and other black Republicans know this history well. She has been among those critical of the GOP’s alienating minorities, especially in light of America’s “browning” as Hispanic populations grow. She has even produced a documentary about this titled, Souled Out that has apparently been tucked away for the moment.

As an independent who votes his interests, I admire black conservatives who are truly sincere in their beliefs to diversify the GOP. Think about it. If Romney beats Obama, who would be at the table of influence in the West Wing fighting for black issues? We need advocates in both political parties. Besides, there are sellouts on both sides who dine and grow fat as the masses of black people suffer from high unemployment, health disparities, incarceration rates, and wealth gaps.

The gentleman in me held my tongue from lashing out at Wall about the race baiting. I didn’t have to. The following day her boss, during a campaign stump in Michigan where he and his wife, Ann, were born, pulled a line from the Southern strategy playbook. Before an overwhelmingly white audience, Romney quipped: “No one’s ever asked to see my birth certificate; they know that this is the place that we were born and raised.”

It was an obvious wink to the birthers who believe Obama is un-American, unqualified, and should go back to Africa.

Sound familiar?

Yawn.