When Hurricane Sandy rampaged through the Caribbean and up the East Coast to New Jersey in the fall of 2012, it killed more than 200 people, destroyed homes and crops and even entire towns, knocked out power, flooded streets, halted public transportation and other vital businesses… the list of deadly devastation from this extreme event goes on and on. The economic impact alone has been estimated at more than $62 billion.
For the first time, experts – including Philip Orton, research associate professor of ocean engineering at Stevens Institute of Technology – have put a dollar value on how much of that price tag is linked to human-caused climate change-related sea level rise during the storm.
Specifically, in the paper “Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change,” published in May 2021 in the journal Nature Communications, researchers from Stevens, Climate Central, Rutgers University and other institutions suggest that human-caused climate change cost $8.1 billion in repair, response and recovery from Hurricane Sandy, and exposed an additional 71,000 people and 36,000 homes to the hurricane’s flooding.
“The paper starts with hydrodynamic modeling to simulate the flooding from Hurricane Sandy as it occurred, and compare it to all the plentiful data on high water marks and measurements in the waterways as to where and how deep the water actually was during Sandy,” Orton explained. “The next step is simulating it with different sea levels to represent possible scenarios covering a range of uncertainty in how much human-caused sea level rise there has been since 1900. We chose that date because it’s when we start to have a good understanding of how much climate change is human-caused versus natural. My contribution was in helping plan the study and perform the flood modeling. The damage modeler then used the resulting water depths over ground across the whole region to compute the monetary damages, which comprised about 13 percent of the total financial cost of the storm.”
According to the team’s findings, from 1900 to 2012, the total sea level rise in the New York area was roughly 34 centimeters. Of that, about 15 to 20 centimeters is natural sinking of the land, and another 10 centimeters is due to human activity. Those higher levels allowed the flooding to run deeper and further inland, where it ravaged even more lives and property.
“That 10 centimeters, or roughly a third of a foot, is a conservative estimate, and though it might not seem like much, it makes a big difference when your home is being flooded,” Orton said. “Once flood waters overtopped seawalls, every additional half-foot was another 25 percent padded on to the financial impact, so you can see why it could be such a significant portion of the billions of dollars in costs from this historic storm.”
Beyond the direct understanding this report offers into the impact of human-caused climate change effects during Hurricane Sandy, Orton noted that the paper has much larger and even more meaningful implications.
“What's important is that we’ve demonstrated a method of computing a key part of the monetary impact of anthropogenic climate change,” he said. “That’s important to quantify, because faced with reducing our impact on climate, we see that it can be very expensive – involving everything from changing our energy systems, to changing agricultural systems, and even building with concrete.
Quantifying the damages from climate change, right now as well as in the future, becomes very important to helping motivate people to invest in those changes.”
This methodology for estimating human-caused climate change-related damages from coastal flooding events can be replicated for any storm, to further quantify the costs.
“We now have detailed sea level rise information localized to any part of the coast, around the country and around the world, and that’s an advancement,” Orton said. “Whether it’s a storm surge event or sunny-day nuisance flooding, we can now estimate how much of that flooding occurred due to anthropogenic sea level rise, as well as how much additional damage. Aggregated across all the floods that are happening around the nation, the price tag is large. Without that sea level rise, many people would have not had the terrible experience of recovery after Hurricane Sandy. If our study can help people understand that destructive impact, perhaps they’ll be more willing to take steps to prevent such devastation in the future.”