Big, destructive wildfires used to be rare enough events to be remembered for decades. But over the past several years, apocalyptic images from wildfires have become a mainstay on the news in the late summer and fall: “firenados” of 100- mph-plus wind and flame, neighborhoods leveled in minutes, eerie orange skies and moonscapes of scorched earth.

California, the hardest hit state, has repeatedly broken its own wildfire records. The Thomas Fire in Ventura and Santa Barbara Counties that consumed some 280,000 acres in 2017 was at the time the largest in state history. It has been topped six times since then.

But the explosion of wildfire activity has not been confined to the Golden State. The three largest fires in Colorado history occurred in 2020. Similarly, western Oregon experienced a rash of wildfires without precedent in size and ferocity; 600,000 acres burned west of the Cascade crest — approximately 10 times as many acres as typically burned annually in that region from 1984 to 2018.

Fires that decimated huge swaths of property were unusual until quite recently. While the occasional wildfire burning under hot and dry conditions might do considerable damage, insurance companies considered fires to be small potatoes compared with storms and floods. The Tunnel Fire, which destroyed nearly 3,000 homes in Oakland in 1991, stood as the most destructive fire in California history until 2017.

In 2018, though, the Camp Fire in Northern California, which leveled the town of Paradise, became the year’s most destructive natural disaster of any kind. It destroyed more than 18,000 structures and killed 85 people. Wildfires that mow down thousands of homes are now a regular occurrence: in 2020, California had four such fires.

As heavy as property losses have been, damage to structures may not even be the most significant impact associated with wildfires. For several weeks last fall, as wildfires raged from Los Angeles to Washington state, smoke blanketed cities across wide swaths of the West Coast. Air quality ranked as the worst in the world (temporarily displacing a dozen Asian cities), with the Air Quality Index numbers in Portland topping 500. For reference, numbers above 150 are considered unhealthy, even for healthy people. The smoke was also not isolated along the West Coast; it spread east, with haze visible in New York.

Wildfire smoke is made up of gases and fine particulate matter (aka soot), which can be very hazardous to health, especially for older people and children. Exposure to fine particulate matter — known as PM2.5, because the particulates are smaller than 2.5 micrometers in diameter — is linked to a variety of lung and heart pathologies, and even short-term exposure to dense PM2.5 pollution has been shown to lead to increased risk of serious illness. One academic paper estimates that wildfire smoke results in some 500 additional deaths each year in the United States. Severe smoke can also disrupt businesses, as people seek shelter from its harmful impacts. While PM2.5 pollution has declined nationally in recent decades, the Western U.S. has experienced an increase, with as much as half of the region’s PM2.5 pollution now coming from wildfires.

Wildfires are also disrupting energy systems in the Western United States. Several of California’s most destructive fires, including the Camp Fire, were ignited by power lines owned by Pacific Gas & Electric, the utility that serves much of the northern portion of the state. Since the Camp Fire, PG&E has on several occasions responded to hot dry wind conditions by shutting off power to hundreds of thousands of households and businesses rather than risk a repeat. Southern California Edison, which distributes electricity to much of the southern part of the state, is also taking no chances — shutting down portions of its system in expectation of high winds.

Given the scale of damages in an incident like the Camp Fire, these power shutdowns — known as public safety power shutoffs — are arguably prudent when fire danger is very high. Nonetheless, they are extremely costly.

When power is shut off, businesses and schools are forced to close, households and grocery stores can lose perishable frozen foods and vulnerable people may lose power needed to run medical devices. Michael Wara of the Stanford Woods Institute for the Environment estimated that a shutoff event in October 2019 cost California’s economy up to $2.5 billion. While, so far, power supply shutoffs have primarily been a California phenomenon, Portland General Electric cut power to more than 5,000 Oregonians last September due to wildfire weather conditions.

Why More Fire?

The rash of western wildfires is hardly just bad luck. It is a result of our decreasing ability to prevent or control fire in Western environments as several trends conspire to worsen fire conditions.

Wildfire is a natural part of many Western ecosystems, which count on burns to renew the land and maintain diversity. Historically, large amounts of land were burned every year, in part because native peoples used fire to maintain the landscape for productive uses.

While fire activity in the Western U.S. has varied over time, during the 20th century it was at the lowest levels that can be estimated from the past 1,500 years. In part, the 20th century’s historically low level was due to the fact that native people were no longer using fire to manage their environment. In part, it was because throughout much of the century, federal and state land management agencies viewed wildfire as an adversary and sought to suppress it entirely. The U.S. Forest Service in particular regarded wildfire as a threat to timber harvested from its domain. In 1935, it established the “10 AM” policy, which set a goal of extinguishing all fires by 10 the morning after they were discovered.

As the 20th century progressed, ecologists learned more about the role fire plays in healthy Western ecosystems, leading to changes in attitude — and policy — toward fire within the management agencies. However, ending the “war on fire” was not as easy as flipping a switch.

When fires threatened homes, they needed to be fought just as aggressively as ever. And more and more of the Western landscape in once-uninhabited places was becoming dotted with homes. With this population growth came expanded residential development into places known to geographers as “wildlandurban interface” areas, or WUI (pronounced “wooey”) areas for short. Here, residential areas abut wild lands, making it more difficult to use controlled burns as a prophylactic protecting against uncontrollable wildfire.

In certain forest types — especially forests like the ponderosa pine forests found in the Sierra and northern California, on the east side of the Cascades, and in the northern Rockies — fire had historically maintained ecological diversity across the landscape. Park-like forests of tall old pines were spontaneously sustained by low-intensity fires that kept the undergrowth relatively open. Occasional more intense fires would create patches where new forest could compete with older trees for sunlight. The diverse landscape, itself a product of fires, also served to regulate fire, providing natural breaks in vegetation to halt fire spread and preventing large highintensity fires from becoming the norm.

But lacking periodic fire, the landscape became more homogenous. Park-like forests gave way to understories of dense vegetation, which, given the chance, carried fire high up into the forest canopy, turning low-intensity ground fires into much more dangerous crown fires.

As the climate warmed, opportunities for this kind of dangerous fire became more frequent. Climate change has meant that dry vegetation predominates for larger portions of the year — in part because snow melt occurs earlier — creating a greater opening for fires.

While the suppression of fire exacerbated wildfire risk in dry Western forests like those dominated by ponderosa pine, climate change independently increased wildfire risk throughout the West. In the chaparral shrub lands of southern California, fire season is stretching into the fall when warm “Santa Ana and Diablo winds” blew from the desert, during which any ignition could potentially turn into a fast-spreading conflagration. This, coupled with an increase in sources of ignition due to population growth and residential incursion, meant that even though California’s chaparral was no denser than it had been historically, the shrub lands began to suffer more frequent fires.

Likewise, fire exclusion cannot be blamed for increasing fire activity in wet parts of the Pacific Northwest. The western slope of the Cascade Range in Oregon and Washington was historically too humid to sustain much wildfire. There, forests dense with fuel are not a legacy of fire exclusion, just the norm. But though these fuel-laden forests were once nonthreatening because they were damp, the events of last September showed that they are now potentially dangerous vectors of fire.

Thanks to the combined result of fire suppression, climate change and increased sources of ignition, wildfire activity throughout the Western U.S. has climbed steadily over the past several decades, outpacing our ability to contain it. From the 1970s to the past decade, areas burned in large forest fires increased by more than 1,200 percent. The giant, ferocious fires of the past several years are just a shocking continuation of the trend.

Understanding the underlying causes of increases in wildfire activity is a start to creating strategies for containing the damage. The devastating consequences in recent years are, of course, one more reason (among a long list) to address climate change aggressively. However, climate change requires globalscale solutions, and even in an ideal world the climate would be too big a boat to turn around quickly. Moreover, the history of wildfire in the Western U.S. makes it clear that burning is intrinsic to the ecology of the region, and we were mistaken to aim to suppress it entirely. Therefore, we need strategies to help us live with it better.

Forest and Land Management

Forest management came to the public’s attention as a possible solution for wildfire risk when, after the 2018 Camp Fire, President Trump asserted that “raking” the forest floor would mitigate wildfire risk. While his comment was rightly mocked, it did allude to a real problem of excessive vegetation in many Western forests, and the potential role for management to mitigate fire hazard.

In Western forests where suppression of wildfire has led to an accumulation of brush and young trees in forest understories that were historically more open, forest managers can reduce fire risk by thinning these fuels. This is frequently done through mechanical thinning projects in which small trees or other fuels are physically removed from the forest, or through controlled burns in which fires are intentionally set during favorable conditions to remove fine fuels on the forest floor. Removing understory vegetation in these forests reduces opportunities for lowintensity ground fires to become high-intensity crown fires, which are significantly more destructive and difficult to contain.

These “fuel treatments” (as mechanical thinning and prescribed fire projects are collectively known) can be implemented near communities to make controlling wildfires easier when they do (almost inevitably) occur. They can also have ecological benefits, reducing the crowding that can make forests prone to pests and disease.

Fuel treatments may also reduce potential health impacts from smoke. While prescribed fires themselves emit smoke, their use can be limited to times when their emissions will not push pollution to dangerous levels and when wind is unlikely to blow smoke toward population centers. As the history of wildfire management in the Western U.S. makes clear, fire and therefore smoke are an intrinsic and inescapable component of the ecology of the region. By tolerating low levels of smoke from prescribed burns, though, we may be able to avoid the severe events that seriously damage health.

So why haven’t fuel treatments already solved the fire risk problem? A major reason is funding. Fuel treatments can be expensive, especially because pricier mechanical thinning is often needed to reduce excessive fuels before cheaper prescribed burns can be safely used. And then there is the backlog: a huge amount of land is in need of fuel treatments. According to the U.S. Forest Service, up to 80 million of the agency’s nearly 200 million acres of land need forest restoration treatments (among which fuel treatments are a primary example). While the Forest Service spends approximately $350 million per year on fuel treatments, it can treat only a measly 1.4 million acres per year.

Fuel treatments are also subject to significant political pushback. Prescribed fires do produce smoke and are sometimes viewed as risky due to their potential for escaping the planned boundaries. Mechanical thinning projects are seen by some as logging under a different name, in part because projects targeted more toward generating profits than toward reducing fire risk have sometimes been sold as fuel treatment in efforts to win political approval.

Last, the potential role for fuel treatments to reduce fire risk differs from place to place. In the chaparral of southern California, fires actually recur more often today than they did before the 20th century. In chaparral country, recent increases in fire activity are being driven by climate change and increases in ignition sources (camping, power lines) and not by increases in fuels. Broadscale reintroduction of managed fire is not needed. What are needed in these areas — and throughout the Western U.S. — are strategies for living with the increased threat of wildfire under climate change.

Coexisting with Fire

Even in places where fuel treatments can help to restore forests and reduce fire risk, the ecological history of fire coupled with the reality of climate change suggest it is unlikely that any part of the Western U.S. could be brought back to the low wildfire environment of the mid-20th century. While forest and land management can make a difference, communities in high-risk areas also need to prioritize strategies for adapting to new realities.

Gilbert White, a 20th-century American geographer who provided early research on management of risk in flood plains, wrote that “floods are acts of God, but flood losses are largely acts of man.” Similarly, the risk that wildfire poses to private property depends in large part on where and how homes are built.

Between 1990 and 2010, the number of homes in WUI areas across the U.S. grew by 40 percent. By 2050, California is expected to add approximately 600,000 homes in high hazard areas. As more homes are built in high wildfire hazard areas, more homes are at risk of loss. Note, too, that the demands on fire management grow disproportionately as a consequence, since the firefighters must work harder to defend homes (and lives) than to contain incidents in the wilderness.

The most obvious fix is for communities to limit exposure by discouraging development in high-risk areas — and by encouraging development in lower risk areas. This is more easily said than done. Many — no, most — West Coast cities have faced affordable housing shortages in recent years, as jobs and amenities pulling new residents to these cities have not been matched by increased construction of housing. As a result, development has often been pushed to outlying areas where land is cheaper, but where fire hazards are greater. By allowing or encouraging increased density in lower hazard areas, we might see a decrease in the rate of construction in high fire hazard areas. Higher density housing out of harm’s way that displaces high-risk development is a gift that keeps on giving: new homes in a high fire hazard area create risk we will be living with indefinitely.

Location isn’t everything, though. Communities can limit exposure to risk by requiring buildings to be hardened against fire, and by making sure owners maintain their properties to minimize fire risk. A large body of research indicates that how homes are built and maintained can drastically influence the likelihood they are damaged in a fire. Building materials, such as fire-safe shingles and tiles and fire-resistant siding, can reduce risk of loss. Moreover, most structure losses in fires are due to embers that ignite a home or nearby vegetation. Homeowners can reduce risk of damage by keeping roofs and gutters clean and by maintaining areas free of vegetation surrounding their home.

One way communities can ensure homes are built in fire-safe ways is through building codes; California is a leader in this regard. In 2008, the state required new homes built in high fire hazard areas to meet stringent firesafe specifications. And, no surprise, it has made a difference. Data collected by Cal Fire (the state’s battle-weary fire management agency) indicate that, within the area burned by the 2018 Camp Fire, 52 percent of homes built in high fire hazard areas after 2008 were damaged or destroyed, compared with almost 80 percent of homes built before 2008.

Adapting to wildfire will take more than just reducing risk to homes, though; the past several years have demonstrated that fire presents a variety of risks. As wildfire activity continues to rise across the Western U.S., smoke will become an increasing health threat. Accelerating work to restore and reduce fuels in Western forests could make a difference here. However, smoke is likely to remain a serious concern in the near term. Communities can prepare by investing in air filtration systems in public buildings and schools. State and federal governments could assist families in heavily affected areas in buying household air filtration systems.

There is also significant work to be done to adapt to the threat of wildfires within the electricity sector. Utilities, which (the courts say) may be held liable when their equipment is found to have ignited a fire, will need to invest significantly in equipment and vegetation maintenance to reduce the potential for dangerous ignitions. Meanwhile, to reduce the need to shut off power to thousands of customers at the first hint of risk to power lines many miles away, they could also help to create largely self-sufficient “microgrids” that would allow more targeted power shutoffs in the highest risk locations.

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Given the realities of climate change and the sprawl of housing in dangerous areas, the risk of dangerous fires isn’t going to recede. One way or another, we’re going to have to adapt.

No single strategy will accomplish this. And virtually none of the needed changes will be costless or sold easily to communities and developers. But the alternative to decisive action is easily predictable: more fire, more property destruction and damage to health both direct and indirect. A rational fire management policy may be expensive — but not as expensive as business as usual.