The Science Behind Hurricane Ida’s Strength

Hurricane Ida finally dissipated Sept. 4, but the damage she left remains to be dealt with.

     The hurricane, currently classified a Category 4 hurricane by the National Weather Service, touched down Aug. 5 on the coast of Louisiana.

     It became a tropical depression Aug. 30, then a tropical cyclone, absorbing into another developing low as it reached the Northeast.

     Second only to Hurricane Katrina, which cost $125 billion, Ida is the second-most damaging hurricane to hit Louisiana. She left 109 citizens dead and thousands injured, with over $50 billion in damages.

     Normally, hurricanes move at an average speed of 20 miles per hour, on ocean or on land, and slow down as they lose power. Ida, however, stalled to about 10 miles per hour over Louisiana, increasing damage in a more concentrated space.

     This is uncommon for hurricanes, but with the rise of global warming, warmer air and ocean temperatures are slowing down tropical storms to a concerning degree.

     The University of Wisconsin-Madison reported in 2020 that according to their data, hurricane severity is increasing as temperatures on Earth climb.

     Collaborating researcher James Kossin noted in his report that “just a 10 percent slowdown in hurricane translational speed can more than double rainfall totals caused by a one-degree Celsius increase of global warming.”

     Kossin, a researcher with the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information, published a paper in 2018 comparing 68 years of forward translation speeds, or the speed at which a hurricane moves.

     According to Kossin’s works, warmer temperatures smooth out differences between two important air pressure systems, resulting in less forceful movements needed to push hurricanes along.

     A warmer atmosphere holds more moisture, allowing for an already saturated storm like a hurricane to carry more water and drop it over land.

     An example of this is Hurricane Harvey in 2017: after stalling over Houston for days, it poured over 50 inches of rain onto the city and surrounding areas.

     Although Harvey’s behavior is not directly due to climate change, Kossin says storms like these are examples of the increased risks cities face when storms slow down.

     “It’s becoming increasingly clear that tropical cyclone behavior is changing in very dangerous ways all across the globe as the planet warms,” he told reporter Eric Verbeten in January. “This can have huge impacts to cities that are not used to seeing these types of storms hit their shores.”

     Officials and citizens also question their cities’ readiness for more serious storms.

     Louisiana governor John Bel Edwards recently completed a $14 billion plan to upgrade New Orleans’s water levees, which catastrophically failed in 2005 during Hurricane Katrina.

     They held up against Hurricane Ida, passing their toughest test since they were built.

     But experts worry even the levees aren’t enough for future storms.

     Bea Link, a senior research engineer at the University of Maryland, notes that the government used a “benefit-cost” analysis to build the levees, meaning the levees will need to be reinforced sooner, was a mistake.

     Link served as director of the Interagency Performance Evaluation Task Force, which conducted the forensic assessment of levee failures for the Defense Department after Katrina.

     The problem with a benefit cost analysis, according to Link, is that the government is basing their levee designs on a standard that is nor based on how much risk a community can live with—instead, they’re based on past storm losses or expected insurance costs.

     She worries that with global warming, the levees and the more powerful storms could be a recipe for disaster.

     “In an era where global warming is causing more intense storms, higher storm surges, and more rainfall, using such outdated factors is inadequate,” she said.

     Hurricane Ida is one of many severe hurricanes to come, and Link stresses the importance of correct protection, especially for cities below sea level such as New Orleans.

     “We’re stuck on a record with a glitch in it,” she said. “We’re stuck in this one place in the soundtrack, and we can’t get by it.”

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