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September 13, 2021

Hurricane Ida: Worse Than "Worst‑Case"


Its devastating physical and social impacts can teach us new lessons about resiliency planning and emergency management. Unless we take heed—and action—the climate risk hellscape is upon us.

Rich Sorkin, Alan Blumberg, & Pat Harr
Jupiter Intelligence

Hurricane Ida’s brutality was visited over a broad geographical area within the continental United States.

Scores of lives were lost from the Gulf Coast to the Northeast Corridor, 1,400 miles (2,250 km) away. Louisiana’s power grid suffered widespread damage, New Orleans and its nearby parishes were devastated by flood and wind, tornadoes ripped through New Jersey, and catastrophic flooding from intense precipitation inundated that state, metro New York, and western Connecticut. Economic losses may approach $100 billion.

Ida’s impacts were driven by a series of worst-case scenarios, both physical and social in nature, that in combination led to a toll worse than previously imagined. Most troubling: as the oceans and the overall climate warms, the conflation of physical and social worst-case events is likely to become routine for future storms. As climate change worsens, so does our ability to define worst-case outcomes.

Unless society takes action on a broad front—from slashing emissions to funding resiliency initiatives and hardening infrastructure to challenging and revamping emergency management strategies—a series of worse worst cases will dwarf the tragedies that Ida inflicted on an often unsuspecting and underserved population. We indeed will live in a climate-change-caused hellscape.

What were some of the factors that contributed to Ida’s devastation?

In Louisiana

The Physical Worst Case

Hurricanes are fueled by passing over warm water at the ocean’s surface and below: the warmer the water, the more intense the hurricane. Ida passed over an area of extreme ocean heat content that provided the fuel for its rapid intensification from a tropical depression to CAT 4 hurricane status in less than 72 hours, and in immediate proximity to landfall. In a disturbing pattern, Ida was the fourth Gulf Coast hurricane in the past five years to undergo rapid intensification to CAT 3-5 intensities at landfall; the others were Harvey (2017), Michael (2018), and Laura (2020).

The Social Worst Case

Flood defenses, upgraded via a massive, $14.5 billion infrastructure project following Hurricane Katrina in 2005, did not fail and they kept high-population-density areas from flooding. However, less densely populated areas—outside the Katrina control system, and in parishes that are often underserved—suffered severe flooding and infrastructure damage.

The flood-defense story remains concerning, however. Because Ida grew from tropical depression to CAT 4 hurricane in less than 72 hours, the full evacuation of a major population center such as New Orleans would have been impossible, nor could shelter-in-place precautions be fully implemented. Many people remained at risk, but the resilience engineering measures of the past 16 years may have been crucial to saving a significant number of lives.

Moreover, the damage to power generation and supply facilities impacted the entire region, regardless of population density or flood-related damage. Ida’s CAT 4 winds knocked down over 30,000 utility poles, more than hurricanes Katrina, Ike, Delta, and Zeta combined.

Over 1,000 people perished from Katrina. Ida took a dramatically smaller toll in Louisiana: ten direct (and over 20 indirect) fatalities. Most flood control facilities and warning systems were effective, and, despite Ida’s swift intensification prior to landfall, many residents seemed to heed warnings and take precautions as best they could.

In the Northeast Corridor

The Physical Worst Case

Nearly half of Atlantic hurricanes that “re-curve” (travel northward and then northeastward) undergo a process by which they transition from a tropical to a midlatitude cyclone, the types of storms that normally impact the Northeast. This transition occurs when the tropical cyclone encounters a pre-existing and developing midlatitude cyclone—leading to extreme rainfall as the combination of tropical and midlatitude energy sources act to “wring out” the atmosphere. However, these events usually occur over the North Atlantic, as the system turns to the northeast and moves out to sea.

During Ida, this process began in earnest when the storm was still over the land, not the ocean. As Ida, now a post-tropical cyclone, encountered the developing midlatitude cyclone and jet stream, the atmosphere became highly efficient in generating extremely intense and spatially concentrated periods of rain.

In addition, Ida’s extreme precipitation fell over many locations which only eight days earlier had been waterlogged by Hurricane Henri; rivers and streams had also been swollen by an unusually rainy summer.

Finally, while precipitation amounts were high, the most damaging and extreme conditions were driven by extraordinary rainfall rates that dumped massive amounts of precipitation over extremely short periods of time.

The Social Worst Case

Advance warnings about Ida from the National Weather Service were abundant, accurate, and contained language intended to convey the potential severity of possible events. Yet for reasons ranging from a lack of experience with such events to an inability for processes and infrastructure to react to warnings and events (perhaps from “alarm fatigue”), the region suffered catastrophic loss of life and property. Public officials have acknowledged that inadequate awareness, planning, and action led to this disaster.

While the memory of Sandy is less than nine years old, Ida’s flood devastation happened over areas less damaged by the 2012 hurricane. Whereas resilience engineering was proven to be effective in New Orleans, similar efforts are sorely needed to account for extreme or prolonged precipitation over the northeast. Flood mitigation measures for major infrastructure such as road, rail, and subway networks must be improved.

Flooded basement apartment units were a major cause of death: 11 people perished in New York City alone. This tragedy has led to renewed calls to regulate, or curb the proliferation of, basement apartments in urban areas that are often used by elderly and the poor. This raises deep-seated social equity issues that probably will take long consensus-building processes to resolve.

In addition, citing the problem of “alarm fatigue” from constant, county-wide severe weather watches and warnings, some observers are urging that the National Weather Service and emergency planners initiate ways to reach and motivate a more precisely targeted audience of people at risk: those who are in the path of a stream at flood stage or an oncoming tornado or hurricane. The unsuspecting may be cut off from information sources without access to a smartphone or cellular service. Some of the forewarned may choose to “ride out” the event, but lives may be saved among those who simply haven’t heard the warning clearly or understood its gravity.

“New Normal” Means New Worst Cases

Climate change is raising the bar by which worst case scenarios will be measured and defined. It is demonstrably increasing the frequency and severity of tropical cyclones, and their impacts will be felt in geographies where hurricanes and tropical storms were rarely felt before: no place is safe from this threat.

The worst outcomes from Ida were caused by different “failures” to prepare. Citizenry, policy-makers, public officials, planners, and emergency management experts must devote greater energy, resources, and commitment to resiliency engineering projects and revamped emergency and city planning strategies, to prevent needless—and frequent—loss of life and destruction.

Rich Sorkin is Jupiter CEO and Co-founder.

Dr. Alan Blumberg is a Jupiter Co-founder and Advisor.

Dr. Pat Harr is a Jupiter Science Fellow.

Jupiter Intelligence is the global leader in climate analytics for resilience and risk management. For further information, please contact us at

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