Fleeing Disaster Is Hard. Climate Change Is Making It Harder

Hurricane Ida and California wildfires are two sides of the same coin: On a warmer planet, it’s getting harder to evacuate from extreme events.
truck in the road
Motorists flee South Lake Tahoe on Monday as the Caldor Fire approaches. Climate change is making already-complicated evacuations even more complex.Photograph: David Odisho/Bloomberg/Getty Images

In Louisiana, Hurricane Ida made landfall on Sunday, devastating communities with 150-mile-per-hour winds and towering storm surges. And in California, the Caldor Fire, which has burned 320 square miles and destroyed over 700 structures, rapidly advanced toward South Lake Tahoe on Monday. In a scene eerily reminiscent of the chaotic 2018 evacuation of Paradise during the Camp Fire—when 86 people died, many in their cars on the road out of town—evacuees sat in gridlock, desperate to flee the approaching flames. The blaze now threatens to destroy more than 34,000 structures.

Hurricanes and wildfires are two very different disasters supercharged by a common force: climate change. A warming climate doesn't cause such events, to be sure, but scientists have shown time and time again that it does intensify them. “Both are the opposite sides of the coin of a future warming climate,” says atmospheric and climate scientist Vasu Misra of Florida State University. “You have extremes on both sides—extremely dry weather and extremely wet events occurring simultaneously on the same continent.” And the two have something else in common: When they strike, it’s getting harder for people to get away from them.

“More frequent, severe, and faster-growing wildfires and hurricanes increase the size and frequency of disasters and evacuations, and decrease the warning time,” says Keith Porter, a researcher at the University of Colorado Boulder’s Natural Hazards Center. That’s partly because it’s getting harder to predict their behavior. Warming ocean temperatures accelerate the intensification of hurricanes, and a drier, hotter climate makes for wildfires that grow with unprecedented speed and ferocity. “In a rapidly changing climate, it gets harder to do accurate risk assessment, because the analyst can't rely as heavily on nature's past behavior,” Porter adds. “We have less historical guidance and proof for costly evacuation decisions.”

Climate change is adding yet more complexity to an already complex situation. “With rapidly changing hazards such as wildfires, we definitely see that people have to make a lot of quick decisions in conditions of uncertainty,” says Nnenia Campbell, a sociologist at the Natural Hazards Center. “And it’s further complicated by things like the Covid-19 pandemic, where sometimes that means that people have an additional layer of decisionmaking that needs to happen.”

Heat and lack of rain are the main culprits making wildfires worse. Climate change has helped sap the West of moisture, producing mountains of ultra-dry tinder. Historically, smaller fires would periodically clear out brush, but today a history of fire suppression means that fuel keeps building up. “What we are seeing more consistently and more regularly is the fact that these fires are growing larger and larger, sooner than they typically would have in the past,” says Issac Sanchez, battalion chief of communications for the California Department of Forestry and Fire Protection, also known as Calfire. “So when August rolls around, late July rolls around, we're seeing these dry conditions that are absolutely a result of climate change.” 

California used to suffer its most catastrophic wildfires in the autumn, when seasonal winds could push huge blazes like the Camp Fire, and before winter rains arrived to wet the landscape. But the state’s second-largest wildfire ever, the Dixie Fire, started this year in mid-July and has burned nearly 1,300 square miles. It remains only 50 percent contained.

These supercharged wildfires have grown so big and intense that they’re behaving in ways that are confounding even seasoned firefighters. In fact, some fires are now burning so hot that they’re actually creating thunderclouds, which roll across the landscape sparking new fires. Plus, now fires are scorching over the landscape more rapidly. All of this is making it that much more complicated for agencies like Calfire to make evacuation plans. Typically, they estimate a fire’s potential route and arrival time using information about temperature, humidity, and prevailing winds. But, says Thomas Cova, who studies wildfire evacuations at the University of Utah, “it's very hard to predict what's going to happen in an era that's unprecedented. The time available is what's changing. That's what I think, is that the fires are moving quicker. It's easy to find firefighters who say that we've never seen fire move at that rate.” 

(This is not to say that fire agencies like Calfire aren’t supremely good at what they do. The successful evacuation of South Lake Tahoe is a testament to that: Over 20,000 people made it out, long before the fire reached the edge of town.)

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As with fires, one of the factors driving hurricanes is heat. “Coastal waters are warming up significantly,” says Misra, of Florida State University. When Hurricane Ida moved over the Gulf of Mexico, it fed on abnormally warm water, which resulted in ferocious winds just as the storm was making landfall. 

Hurricanes are complex phenomena, of course, so there are other factors at play, like the state of the atmosphere at a given time. Scientists need more data to fully understand the trend towards the rapid intensification. Warmer water, says Misra, “does not necessarily mean that all storms that make landfall will eventually end up being stronger than the current storms. But that should certainly ring an alarm bell.”

So, too, should the fact that a warmer atmosphere holds more moisture. “Under the right conditions, when convection occurs, then it is going to squeeze more moisture out from the same volume of air in a future warm climate than the current climate,” says Misra. “So the threat of the tropical cyclone—whether it rapidly intensifies or not more frequently in the future—is going to be far more, with more rain coming out.” A hurricane’s winds weaken once it makes landfall, since it’s no longer feeding on warm gulf waters. But it still continues to dump rain as it moves inland, which could lead to devastating flooding throughout the southern and eastern states.

Hurricane forecasters can accurately predict the path of a storm days ahead of time, providing state and local governments with invaluable data to inform evacuations; these models work, and they save countless lives. But climate change is going to create new challenges for modeling, as it changes how hurricanes behave. “Most of our weather prediction models don't do a great job of forecasting rapid intensification,” says Misra. “So that in itself is a huge problem for preparing to mitigate the impact of the hurricane.” 

The extreme ferocity of today’s natural disasters is also making it harder for citizens to parse their own risk. “People set expectations based on their prior experiences, and this stuff is outside of people's experiences,” says Ann Bostrom, a risk communication researcher at the University of Washington. “A hurricane or wildfire ramping up to greater intensity is faster than people have experienced.” Someone who might have safely stayed home during one of these disasters 20 years ago—either because they refused to leave or didn’t have the means to—may well find themself in extreme peril today.

While rapid hurricane intensification is a danger for everyone, it's the worst for people who don't have the resources to get out quickly. “A lot of the people who are living right along the coast are either extremely wealthy or extremely poor,” says Kyle Burke Pfeiffer, director of the National Preparedness Analytics Center at the Argonne National Laboratory. And for the poor, he continues, “maybe they don't have access to a vehicle, or maybe don't have the funds or the ability to leave their job or their home. And, many times, they're living in structures that are not engineered to sustain the external loads placed upon them by various hazards, such as hurricanes.”

California has a similar problem: Astronomical housing prices along the coast have pushed more people east into the state’s wildland urban interface, where cities meet the forest. Paradise is one such town, as is South Lake Tahoe. “With more people out in these areas—and the fact that [the areas are] drier—leads to more ignitions near communities,” says Cova, of the University of Utah. So fires tend to start closer to town and move faster. “That affects the evacuations, because the time available can be below what you need, like it was in Paradise.” Retirees, in particular, are flocking to these places, but any older residents who have mobility problems will find it more difficult to evacuate as a fire approaches. 

In the face of such enormous threats, is there anything we can do to make sure people can evacuate safely? Certainly, scientists will improve their forecasting models, which will help sharpen the accuracy of alerts. Controlled burns, especially around mountain towns, might limit the number of fires that rapidly get out of hand. And gulf states can provide people with transportation and lodging to ensure that everyone can evacuate, not just the well-to-do. 

“One of the things that I think is not often discussed enough is the need for emergency planning at the community level,” says Campbell of the Natural Hazards Center. “It's easy to pass these decisions along and talk about individual choice, rather than the constraints that communities and groups face. And that's something that I'm particularly concerned about.” To be clear, there’s no one-size-fits-all solution here, as each community has its own constraints—lack of transportation, for instance—so each one needs a custom plan.

The higher-level conundrum has more to do with where we decide it’s safe to even build communities. Right now, Americans aren’t just living in the danger zones of ever-more-powerful wildfires and hurricanes—they’re flocking there. “I think we need to have some national conversations about just how we design our lives in the 21st century,” says Pfeiffer. “Climate risks are going to be increasingly something we grapple with.”


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