The Louisiana wildfire that upended Katie Henderson’s life was barely a blip on this year’s string of catastrophes. On August 24, just after she’d brought her 7-year-old son home from school, she spotted a red band of flames speeding across the treetops, crackling like static on the world’s largest television. She had time only to hand off her son to a neighbor and herd the family’s four dogs into a horse trailer hooked to their pickup. (Their cat, Windy, she plopped into an unzipped backpack.) As she and her neighbor caravanned out through the backwoods, fire filled her rearview mirror. Her house was so badly damaged that day that her family hasn’t yet been able to move back.
On the scale of disasters, this one was small—Henderson’s house was one of the few affected, and the overall damages will likely be orders of magnitude less than those of the billion-dollar disasters the country racked up this year. Go just a mile down the dirt road to the highway that leads into Evans, a town of a few hundred people, and everything looks fine, Henderson told me. But this localized wildfire is part of a category of catastrophe, sometimes called “low-intensity disasters,” that experts are becoming more concerned about. Although major disasters tend to be the most studied and understood, low-intensity disasters, collectively, may be just as essential to track in the long term.
These events are small enough to escape widespread notice, but they happen frequently, accumulating damages that rival, and in some cases surpass, a major one-off disaster. Periodic flooding on a highway, for instance, might start as a commerce-reducing nuisance, but over time it can shape livelihoods and landscapes. “You’re reducing the foundations of support very gradually, from one event to the next,” Roger Pulwarty, a senior scientist at the National Oceanic and Atmospheric Administration who also conducts research with the United Nations Office for Disaster Risk Reduction (UNDRR), told me. “It’s death by a thousand cuts.”
The way these smaller disasters add together challenges the traditional ways of defining and measuring catastrophes. Insurance companies, for instance, have long divided catastrophes into primary and secondary, or peak and nonpeak perils. Nonpeak perils—events such as floods, thunderstorms, and wildfires—are considered more localized, more frequent, and less costly than peak perils—sudden disasters such as hurricanes and earthquakes. Recently though, even compared with hurricanes, “we’re seeing more flood damage from just extreme-rainfall events that overwhelm local infrastructure,” as well as other localized disasters, Carolyn Kousky, a climate-risk researcher with the Environmental Defense Fund, told me. In fact, globally, nonpeak perils have been the biggest drivers of insured disaster losses every year since 2013 (except 2017—a particularly catastrophic year marked by Hurricanes Harvey, Irma, and Maria), according to a 2021 report from Howden, an international insurance broker that tracks disaster damage. Nonpeak perils are also becoming more frequent and severe, according to Ernst Rauch, the chief climatologist for Munich RE, a reinsurance company that collects data on global disaster damage. As of the first half of this year—marked by about 24 separate billion-dollar disasters in the United States, according to NOAA, and earthquakes in Turkey, Syria, and Morocco—nonpeak perils still formed the bulk of losses worldwide, Rauch told me.
Taken together, frequent, low-intensity disasters can surpass the damage of acute, intense ones. Loretta Hieber Girardet, the chief of risk knowledge, monitoring, and capacity development for UNDRR, thinks of Colombia in 2010 and 2011, when the country experienced a strong La Niña event: The ensuing floods, landslides, mudslides, and torrential rain affected 93 percent of the country’s municipalities and caused more than $6 billion in direct economic losses. “It wasn’t one single disaster but thousands of smaller-scale events” that eroded communities over time, she told me.
At UNDRR, Hieber Girardet’s team has defined a small disaster as one that involves fewer than 30 deaths or fewer than 5,000 houses destroyed, and has found that from 1990 to 2013, 99.7 percent of all global disasters met those criteria. In the U.S., NOAA is responsible for measuring big, billion-dollar disasters; now “we’re starting to consider looking at sub-billion-dollar events, even in the present year,” says Adam Smith, the lead researcher on NOAA’s billion-dollar-disaster reports. Pulwarty, who works for both organizations, said that, in general, looking at the number of people affected and houses damaged, and even traffic wait times and internet-connectivity losses, could better clarify these events and their accumulating damages; tracking them on a national level could illuminate what is an almost “invisible issue.” And giving the damage of low-intensity disasters, a sticker price would help justify the investment in managing and preventing them.
Right now, low-intensity disasters fall into a gray area for assistance: They’re too destructive for a community to handle easily on its own, but not destructive enough to warrant the aid that comes from federal disaster declarations. Because tracking systems are set up to monitor large disasters, national governments might not realize the extent of smaller events’ damage, and even if a community can manage a low-intensity disaster in the near term, it may not have the resources in place to build back more resiliently. “It’s a big gap,” Hieber Girardet said, “and that’s something we’re seeing around the world.”
Falling into that gap can feel like “you’re forgotten about,” Heidi Rochlin, the district superintendent in charge of Antietam Middle Senior High School, told me. In July, heavy rains in Berks County, Pennsylvania, bloated a nearby stream, which ran through the school for days, flooding the basement, knocking out the school’s water and electrical supply, and depositing thick mud and dead fish in the first-floor hallways. The students are spread for the rest of the school year among a local church, a community college, and the district’s two other buildings. Rochlin estimates that the school’s damages total $21.8 million—before adding anything new to guard against future floods—but the Berks County disaster wasn’t large or severe enough for the school to be eligible for federal relief. (The county has applied for and received funds through other means, including low-interest loans made by the U.S. Small Business Administration in coordination with FEMA, but the process can be long and piecemeal.)
Experts are also concerned about damage from changes that happen in slow motion. Ongoing climate stresses—“whether that’s sea-level rise, broad changes in temperature, an extreme rainfall event, or drought—these longer-term things can be equally economically disruptive” as a major climate disaster, Kousky, the EDF researcher, told me. When Grant Ervin, Pittsburgh’s former chief resilience officer, and his team surveyed residents, they found that people’s concerns were about changes gradual enough to have escaped widespread notice: Their basement had started flooding every time it rained; 10 years ago, their backyard was 100 yards long, but storm erosion had shrunk it closer to 50. These problems might not be a huge problem in any immediate time frame, Ervin told me, but over time can have a “catastrophic impact.”
Think about the flooding just from the higher tides that sea-level rise creates. Maybe the floods begin as a minor annoyance for a coastal community; one day a month, you can’t leave your house because the water is too high, Kousky said. But even one day a month of not getting to work or taking a child to school adds up. Bigger disasters can change where people live overnight, but quieter stresses like these, she said, could reshape how and where we reside just as much.
All of this has convinced Hieber Girardet and the other experts I spoke with that these slower-onset events must be tracked and measured. Her UNDRR team will convene scientists this month in Germany to determine how they can actually do so. “Maybe we can start small with a few phenomena, like sea-level rise,” she said, and from there, generate global methods of tracking their effects.
Still, as important as quantifying these events will be, Pulwarty told me, “we don’t have to know these numbers precisely in order to act.” These low-intensity disasters are, in essence, the most manageable, if societies invest in risk reduction. Fine-tuned data will add detail to our picture of the future, but we can already start building for the one that scientists are seeing now.