The Heat Is On

Illustration: Boo Paterson

Two weeks after Avery Hill began his doctoral program in biology at Stanford in the fall of 2017, he got a call from his mother: Wildfire was approaching the dried-out forests near the family’s property on the outskirts of Napa. Thousands of their neighbors had already fled.

Hill put down his research—on the impact of climate change on forests—and drove home. He spent three weeks helping his parents and grandparents evacuate and then return, hauling boxes and replacing burned water lines as the forest still smoked from the Nuns Fire. They were lucky. “The only reason the houses were standing is because firefighters were there,” he said. In total, a complex of fires, including the Nuns Fire, burned more than 56,000 acres and destroyed 1,355 structures in Sonoma and Napa counties. 

From 2017 to 2020, wildfire in California destroyed more than 45,000 structures and resulted in the deaths of 183 people. In 2020, the California Department of Forestry and Fire Protection (Cal Fire) reported more than 4.2 million acres burned—the largest wildfire season ever recorded. And the damage from wildfire reaches beyond the charred West. In July, smoke from California drifted to New York, making air across the continent unhealthy to breathe. 

‘Sometimes the most obvious approach from one perspective is not the most obvious from another.’

We need to approach the risks and consequences of wildfire more holistically, says Chris Field, professor of earth system science and of biology, director of the Woods Institute for the Environment and Hill’s adviser. “It’s gotten to the point where everyone understands we have a big problem and we’re not doing enough.” He says that business as usual—literally turning a hose on each blaze—is untenable in our increasingly complicated climate. And besides, new technologies are poised to help us reduce fire risk before so much as a spark is seen.

Thinking more broadly about fire suppression and fuel reduction means exploring ideas from unlikely places. “Sometimes the most obvious approach from one perspective is not the most obvious from another,” Field says. To that end, he and more than a dozen other Stanford faculty, postdoctoral scholars and graduate students from such diverse fields as law, economics, psychology and medicine have formed an interdisciplinary initiative to consider our wildfire problem from new angles. They hope to help governing bodies deploy their limited funds in ways that effectively address fire management and human health in a changed climate. Members of the group are working to understand how wildfire is changing, predict serious future threats, and create new approaches to stop fires before they start via practical systems focused on fuels, ignitions, relocation, and extensive and intensive health impacts. They call themselves FIRE. 

Just Downwind

Professor of earth system science Noah Diffenbaugh, ’97, MS ’97, who studies the impacts of climate change on environmental and human health, says that in addition to fires in the state becoming more frequent, more destructive and more dangerous, California’s fire season has gotten longer. “It’s unambiguous that wildfire risk is increasing.” A 2020 study led by Diffenbaugh showed that since the 1980s, California’s rising temperatures and 30 percent decrease in autumn rains have more than doubled the frequency of fall days with extreme wildfire weather. More fires over an extended season make it difficult to share our primary defenses—firefighters and firefighting equipment—among communities and countries. California’s fire season, for example, now overlaps with Australia’s. Diffenbaugh reported that there are many ways to improve our wildfire defense, including upgrading emergency communication systems, promoting fire resilient construction, and reducing fuel loads (combustible materials) in fire-prone areas. 

But flames aren’t the only issue. “The smoke is impacting millions more people than the fires themselves,” Diffenbaugh says. Wildfires result in higher particle pollution in the air—smoke, dust and tiny bits of metal that aggravate respiratory and heart problems, even for people who live far from an active inferno. According to a study by associate professor of earth system science Marshall Burke, ’02, wildfires now account for up to half of all air pollution in the American West.

Thumbs up with factoid from Gabrielle Wong-Parodi, an assistant professor of earth system science, who analyzed national surveys and found that people who have experienced wildfire smoke pollution are more supportive of climate change action.

Prescribed burns—fires set intentionally for land management—could reduce the number and severity of wildfires. But until recently, public health departments discouraged them, partly because of an assumption that the smoke they created was as bad as that from wildfires. “This didn’t make sense,” says Kari Nadeau, professor of medicine and of pediatrics. Her team compared blood samples from children exposed to each type of smoke and found that those exposed to wildfire smoke had more compromised immune systems than those exposed to smoke from prescribed burns. What’s more, kids with asthma had more attacks during wildfire smoke exposure than during prescribed burns.

Prescribed burns are safer in large part because people can plan for them. “[They can get] out of town, or stay indoors with an air filter or air-conditioning,” Nadeau says. But even if they can’t avoid outdoor air, smoke from prescribed burns poses lesser health risks because of the composition of modern wildfire smoke. “So many ‘wild’ fires now involve residences and commercial buildings,” Nadeau says. “People could have Drano and Liquid-Plumr and all sorts of plastic in their homes, and when that catches fire, the pollutants can go into the air.” They don’t come down, she adds, until there’s rain—and then they enter the water supply.

Hot Tech

Accurate data about where fire is likely to occur could help to prioritize fire control measures, including prescribed burns. But traditional means of judging dryness (gathering branches for analysis, for example) are difficult to scale. So ecohydrologist and assistant professor of earth system science Alexandra Konings uses remote sensing to assess likely points of ignition via satellite. Microwave radar signals reach through foliage and down to the ground. From the returned signals, her team can spot moisture deep in a forest’s canopy, and artificial intelligence can identify patterns in dryness, pinpointing the likeliest locations of future fires.

Michael Wara, director of the Climate and Energy Policy Program at the Woods Institute, recommends steps to protect Californians from wildfire. They would cost approximately $3 billion.

Like Konings, assistant professor of materials science and endocrinology Eric Appel hopes to change the default mode of putting out fires. “We’re trying a more proactive approach,” he says. While working on a way to use hydrogels as a delivery mechanism for drugs, Appel realized the same principle could be applied to wildfire prevention. He wondered if retardant—commonly dropped to squelch active flames—could be sprayed in ignition-prone areas before a fire starts. More than 80 percent of fires today ignite near roadsides or utilities infrastructure, so he knew where the spray should go. The challenge was in making it stick—not to mention endure months of sun and wind. So Appel invented a nontoxic, biodegradable goo that serves as a carrier fluid for fire retardant. The viscoelastic fluid (it has liquid and solid properties, and resembles skim milk) sticks to the surfaces of plants. “You could spray it on in summer and it wouldn’t wash off until the rainy season,” Appel says. Dubbed Fortify, the goo is commercially available and expected to earn approval for use on federal lands this fall.

Meanwhile, California sizzles on. In 2020, Avery Hill, the doctoral student, helped his family evacuate twice. “This has crystallized my resolve to focus on the risks from fire,” he says. He’s studying “zombie forests”—places where the climate has changed but the flora hasn’t. And he’s sleeping lightly, waiting for the next call from home.


Katherine Ellison, ’79, is a Pulitzer Prize–winning former correspondent for Knight Ridder Newspapers and the author of 10 nonfiction books. Email her at stanford.magazine@stanford.edu.