Unnatural but wild: how humans have reshaped fire in the American West

In January, I gave a talk at the Bountiful-Davis Art Council exhibit on wildfire in Utah. After a year that obliterated wildfire records throughout the West, I thought it was important to give some scientific context on this issue that is incredibly important and perhaps not surprisingly politically charged. Whether you live in the western US or not, the future of wildfire is affecting all of us. The recording of the talk and questions is viewable here, and my notes are below.

What science knows about wildfire in the western U.S.

Ben Abbott, January 23^rd

Thank you, Alexandra, and the BDAC for inviting me to speak at this timely and moving exhibit. I am an ecosystem ecologist at Brigham Young University. I study how living and nonliving parts of the Earth system influence one another to sustain life. I want to acknowledge the funding sources that have allowed me to research wildfire over the past 12 years: the Utah Department of Natural Resources, the US National Science Foundation, the Utah Watershed Restoration Initiative, and BYU.

The research that I will talk about today is primarily not my own. It draws from hundreds of studies done by researchers from across the western US and the world. That is how ecological science works—a diverse and vibrant community of collaborators and competitors challenge each other’s evidence and interpretation, building on the findings that prove reliable, rejecting the ones that don’t hold up.

I know that western science is not the only way of understanding what is going on in our world. Indeed, the artwork we are surrounded by demonstrates a different perspective that explores dimensions of reality that science can’t speak to. My talk today draws mainly from western science, but I also hope to integrate knowledge from indigenous peoples. We are gathered on land from the Paiute, Eastern Shoshone, Goshute, and Ute nations. These peoples have lived in this area for centuries and sometimes millennia. We have all-to-often ignored and even denigrated indigenous understanding and management practices, which have a much better and longer track record than the colonial peoples who are now the primary inhabitants of this area [1]. I cannot speak for the indigenous peoples on whose land we live, but I strive to learn from them and work with them to sustain the lifegiving ecosystems on which we all depend. I pray that we can stop fighting across disciplinary or cultural lines and instead acknowledge and act on the wisdom from each way of knowing and living. The environmental challenges that threaten all of us are simply too serious and urgent to waste any more time on pride.

Some dudes we saw on a van watching a wildfire in Greece.

What science knows

The title of my talk is “What science knows about wildfire in the western US.” The title is partially inspired by an extraordinary press conference that former President Trump held with California officials just a few months ago. It was September of 2020 and smoke from wildfires in the western US stretched from New York to Hawaii. My family and I had just returned from a week at the Pitcher family ranch just outside of Rocky Mountain national park. While we there, the Cameron Peak wildfire ignited on the other side of the mountain.

When we saw the pillar of smoke rise over the barn, our host and dear friend Andi tried to convince us to cut our trip short. We were sure she was overreacting and decided to stay. That fire became the largest in Colorado state history at just over 200,000 acres. It is still burning today. On our way home, we counted half a dozen pyrocumulonimbus clouds—giant mushroom clouds that form over megafires because of the water vapor and particulates they release [2]. It looked like we were in the middle of a nuclear attack. A few weeks after our departure, the East Troublesome wildfire, now the second largest in Colorado state history, raced across the mountainside and destroyed Andi’s ranch, killing her neighbors. I no longer think she was overreacting.

Here is a time lapse of the first few hours of the wildfire.

But back to the press conference in California. The firefighters and forest service were asking for more federal support battling the historic wildfires. In California alone, 2020 saw 4.2 million acres burned, more than double the previous record. This record was not a random occurrence. Throughout 2020, hot, dry, and windy conditions baked the western US, including a new world temperature record of 130 degrees Fahrenheit in Death Valley. The officials explained that climate change was supercharging the wildfires, making them too hot, fast, and frequent to manage [3,4]. Trump cut them off by saying, “It’ll start getting cooler, you just watch.” When one of the officials pushed back and said, “I wish that science agreed with you,” the president said, “I don’t think science knows actually.”

There is plenty that science does not know. That is one of the things that I cherish most in the scientific process—it sheds light on the edges of our knowledge, hopefully rendering us humbler and more open to new information. However, science knows quite a lot about what is going on with wildfire in the western US.

The importance of wildfire to healthy ecosystems

Even before you add humans to the mix, wildfire is a story of paradoxes. Destruction and renewal. Death and rebirth. Disturbance and organization. Accidental and inevitable.

To begin untangling these conundrums, let’s go back to the Silurian period. It was 400 million years ago, and simple plants such as mosses had just begun to colonize the land surface [5,6]. As they spread, these pioneer species were unintentionally setting the stage for the Earth’s first wildfire.

Fire needs three key ingredients:

1. Oxygen
2. Ignition
3. Fuel

The first two ingredients had already been available for millions of years. Oxygen accumulated in the atmosphere from marine cyanobacteria—the first photosynthesizers—and later from marine plant species such as algae. Lightning was even older than that. It had provided ignition since the atmosphere first gathered around our rocky planet. But the mosses were different than their marine ancestors. As they grew and died, they left behind dry organic matter. Their bodies, living and dead, provided the third and final condition enabling wildfire: fuel.

Since that time, the relationship between vegetation and wildfire has only grown stronger [7]. Plants set the stage for wildfire, and wildfire in return sets the stage for plant diversity and growth [8]. This comes to one of the key points I want to get across today. Wildfire is a positive and even necessary part of many ecosystems worldwide [9]. Despite what Smokey the Bear and Bambi tried to teach you, wildfire is crucial to healthy ecosystems. Indigenous people have known this for millennia and have used wildfire to maintain natural patterns of vegetation and also to restructure the landscape to favor plants and animals important to humankind [10].

Here is a very short list of the positive effects of wildfire:

1. Wildfire can increase the diversity of habitat for plants and animals by creating mosaics of different ecological communities
2. By creating openings in the canopy, it increases light penetration, allowing establishment of grasses and other plants on the forest floor
3. It releases nutrients from biomass and soil organic matter, enabling regrowth of fire-adapted species
4. It can cause erosion on hillslopes, providing the sediment that rivers and streams need to rebuild their channels and banks
5. It can awaken the seed bed in the forest floor and in the overstory by opening fire-adapted seeds and cones, allowing regeneration of shrubs and trees
6. It can remove or slow invasive species that have been accidentally or intentionally introduced

 The landscapes and ecosystems that we know and love have been sculpted by wildfire over millions of years. When you look at a mountainside and see different patches of vegetation—meadows and groves—that is often due to wildfire—sometimes decades or centuries in the past [11–13]. Consequently, in ecology, we call wildfire a keystone disturbance. That word usually has a negative connotation, but we ecologists don’t think of disturbance as inherently bad: disturbance is anything that changes an ecosystem.

 On that topic, there used to be a belief, at least in western science, that nature tended towards balance and stasis [14–16]. I think this view largely stemmed from the impatience that is unfortunately typical of our modern way of life. If you only look at sometime for a year, or even ten years, it can seem like it doesn’t change. However, if you could watch an ecosystem for a thousand years, you would see the trees migrating up and down the hillside—occasionally leaping across canyons and lakes. You would see the rivers downcutting and redepositing, jumping their banks. You would not see stasis.

Some charred juniper trunks burned by the Coal Hollow megafire in 2018.

 On the other hand, there are many feedbacks in ecosystems that tend to stabilize and sustain. Otherwise, life would be constantly at risk of going beyond the limits that allow for liquid water and consequently life to flourish. For example, during periods of heat and drought, when wildfire can get out of control, the frequent burning makes the woodiest plants become rare. Other species, less prone to burning or more resistant to it, become dominant [4,17]. Likewise, during periods of global warming, cloud cover becomes more extensive, shading the Earth’s surface and slowing the increase in temperature [18]. Ecosystems are not encyclopedias on a shelf containing a list of species and populations, they are dancers moving across a stage with dynamic tension and direction.

 Too much of a good thing?

But what about 2020? Clearly wildfire isn’t always constructive, right? Indeed, when a severe wildfire occurs, the destruction can be breathtaking. 

Video of a severe burn scar from the 2020 Range Fire in the foothills of Mount Timpanogos.

It’s clear that the question isn’t as simple as: is wildfire good or bad? The question is: how is the role of wildfire in ecosystems changing through time? Is this more of the same, or is it something new? To answer those questions, we need to think about how to quantitatively describe a wildfire. Here are five dimensions that are often measured to characterize a wildfire:

1. Extent
2. Severity
3. Frequency
4. Patchiness
5. Speed

Together, these create the wildfire regime of an ecosystem. The wildfire regime directly changes the consequences of wildfire for an ecosystem and the people who live in it. Frequent but low severity fires can have completely different consequences than rare and high severity burns. So, is wildfire regime changing in the West and specifically in Utah? The answer is a resounding yes [19–21]. For context, let’s take another journey into the past—this time just a few tens of thousands of years.

We live in the Great Basin, a province of 200,000 square miles in the western US—an area larger than California. During the last glacial period, about 20,000 years ago, things looked very different in the Great Basin. Giant pluvial lakes—vast inland seas—filled many of the valleys with hundreds of feet of freshwater. We know the largest of these inland seas as Lake Bonneville, which covered much of Utah, including the Wasatch Front and the building where we are meeting today. About 15,000 years ago, lava flows near current day Pocatello diverted the Bear River into Lake Bonneville’s watershed and the sudden influx of water increased the lake level. As it reached 5,000 feet above sea level, it finally overtopped its basin—like a vast overfilled bathtub. The low point was at the Utah-Idaho boarder—Red Rock Pass. The enormous lake began to overflow into the Snake River Basin. What was initially a small trickle began cutting through the soft sediment, growing until it was a flood of biblical proportions. It dug a canyon 300 feet deep in a matter of weeks, swelling into a torrent with 3-times the flow of the largest river on Earth, the Amazon, at flood stage.

The rapid draining of the lake was only the beginning of the changes for this region. Changes in the Earth’s orbit and ocean circulation in the Pacific resulted in a gradual but substantial decrease in precipitation [22,23]. The climate became warmer and drier, and the vegetation and peoples in this area changed where and how they lived to suit [24].

As the climate changed, so did the wildfire regime. There were cycles of more and less wildfire throughout this period of drying, including after the arrival of humans about 12,000 years ago [12,25]. There were several megadroughts (dry periods of more than 10 years) that occurred naturally before the arrival of Europeans, including a nearly 20-year drought in the 1500s [26]. During those periods, the wildfire regime temporarily intensified, typically followed by a recovery period of less intense fire when vegetation shifted or regrew.

A half-burned national forest sign near Nebo Creek burned during the 2018 Pole Creek megafire that made my dad evacuate.

After the settling of the West by European-Americans, our relationship with wildfire fundamentally changed in two ways. First, incorrect understanding of ecosystem ecology and dismissal of indigenous ecological knowledge led to a destructive policy of fire suppression. In the first half of the 20^th century, wildfire was viewed as a wholly negative phenomenon. Local, territorial, and federal agencies set out to rid the West of this destructive force. This resulted in a major “wildfire deficit,” where less area burned per year than needed to, resulting in massive fuel accumulation [27,28]. There is a good Wikipedia article on this subject, but basically, we tried to armwrestle wildfire into submission until the 1960s, when we grudgingly wizened up and started to allow a more natural wildfire regime. Second, a new kind of climate change started in the mid-20^th century [29]. Cycles of wet and dry, cold and hot, stopped going up and down. Year after year, they started to all go up [29]. This climate change was much more rapid and consistent than the orbital-driven creep out of the last glacial period. We now know that this ongoing climate change is more abrupt than at any time in the Earth’s history [30]. While the slow melt of the interglacial took millennia [31], this new fossil-fuel-powered climate change increased temperature by a full degree Celsius in a matter of decades. This disrupted air flow from the Pacific Ocean, triggering the most severe megadrought in thousands of years [26].

Observed area burned in the Western US attributed to natural causes and anthropogenic climate change. Currently, half of the area burned each year is attributable to climate. Adapted from [20]

What is changing in Western Wildfire?

The combination of our management-driven wildfire deficit and the unprecedented human-caused climate change of the last 50 years has completely reshaped the wildfire regime in the West. There has been a doubling in the annual area burned in the western US since I was born in 1984 [20,32]. The area of severe wildfire has increased 8-fold in some areas [19]. The fire season is extending in both directions, with wildfires starting earlier in the spring and burning later into the fall. Blistering vapor pressure deficit—the inverse of humidity—is dessicating fuels, creating miles upon miles of stacked stove wood [33]. The sinuosity of the jet stream is increasing, creating a standing wave that deflects moisture from the Pacific Ocean to the north, reducing the frequency but increasing the severity of rain events [26]. Fire-adapted invasive species such as cheatgrass are carrying wildfire into ecosystems where it was only an infrequent visitor, such as sagebrush steppe and juniper forests [34,35].

Relationship between fuel aridity (largely a function of vapor pressure deficit) and annual wildfire area in thousands of hectares. Were poor forest management the primary cause of the increase in wildfire, there would be a much weaker relationship. Adapted from [20].

It is hard to overstate the societal consequences of these changes. 21^st century wildfires are causing infrastructure damage, ecological harm, air pollution, polluted water supplies, and most importantly loss of human life [4,36,37].

Where do we go from here?

When we face an environmental crisis, we have three general options: Avoid, Adapt, or Suffer. Avoiding or preventing the problem is clearly the best option. When that doesn’t happen, we can adapt to the new conditions with technological or cultural tools. If we refuse to recognize the problem at all, we suffer its full consequences.

 Honestly, we need hearty and speedy helpings of both avoidance and adaptation. Here are a few recommendations about what to do next:

1. Be clear about the causes of our current crises. It’s not just former president Trump who thinks we can rake our way out of this problem. I speak with lawmakers and citizens every month who blame the Forest Service for poor “fuel management.” The truth is, there are limits to fuel management, and when things get as dry as they did last year, all the logging in the world won’t solve what is ultimately a climatic problem. If we want our forest and shrub ecosystems to persist, we have to get the climate back to the range where these ecosystems evolved and flourished.
2. Reduce exposure of human lives and infrastructure. The fact that the “wildland urban interface” is even a thing is a failure in planning. Most of the human casualties occur on the front lines. We simply need to stop building on the edge (or middle) of the forest. If people have private property in wildfire prone areas that they want to develop, it should be done on their bill—not the public trust. If they want insurance, it should not be underwritten by the government. We are currently encouraging risky development in ecologically sensitive and societally dangerous areas.
3. We need more pro-active wildfire management. While logging, raking (whatever that means), and snipping with puller bunchers have not proven reliable for reducing high intensity wildfire, the indigenous wildfire management practices of controlled burns do. We need more small and frequent wildfire than we have had in many years. Implementing traditional wildfire management practices is the only way to get out of the huge wildfire deficit hanging over our heads. 
4. Conserve contiguous areas and reduce pressure from grazing. Large and contiguous ecosystems are much more resilient to disturbance. If you only have tiny fragments of habitat, than any fire is a tragedy. When you have interconnected networks of forest, shrub, river, and lake, wildfire is a habitat creator. Encroachment into fire-prone habitat contributes to this problem, but the biggest culprit is livestock. Subsidized grazing on public lands is degrading habitat at continental scales. The fences, roads, and cabins that follow fragment habitat and spread invasive species, increasing vulnerability to natural and artificial wildfires. Given the many other ecological and health costs of meat, we would be living in a much more dynamic and healthy world if we stopped subsidizing the destructive practices of raising and eating animals [38–40].
5. Finally, the only long-term solution is to reduce fossil fuel emissions to stop climate change. Since the Industrial Revolution, we have emitted half a trillion tons of carbon into the atmosphere. That is the amount of carbon we would release if we piled up and burned all living things—all the redwoods, termites, blue whales, and bacteria. We make more carbon dioxide (CO2; the dominant anthropogenic greenhouse gas) than all our other products combined: about 32 billion tons of it in 2020. CO2 is the primary product of humanity—the thing we make the most of. There have been stunning advances in renewable energy, especially solar, which has plummeted in cost more than 90% over the past ten years. We now have plausible and proven pathways to 100% carbon free energy that will cost less than what we are paying now [41]. We need to electrify everything (transportation, manufacturing, heating, and agriculture) and simultaneously clean up our electrical production. Heat pumps, batteries, solar panels, pumped hydro, electric vehicles… Call your legislator today and ask them to support the rapid deployment of these transformative technologies. They are the ones who can hold our utilities (which are monopolies by design) accountable. Make sure your next car is electric. Switch out your natural gas furnace and water heater with a heat pump. These investments will save you money in the long-term, clean the air (saving some 11 million lives annually [42]), and reduce climate change. We are poised not only to meet the goal of limiting warming to 1.5°C, we can beat it. We need to get back to the Holocene as quickly as we can.

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