One Hundred Years of Fire Suppression Narrative Challenged

Roberts Fire near Glacier National Park, Montana. Photo George Wuerthner 

A few weeks ago, I attended a panel discussion about wildfires. All the panelists and the moderator suggested that large mega fires resulted from fuels that had attained unnatural levels due to a “hundred years of fire suppression.”

The idea that fire suppression is responsible for large wildfires is engrained in the fire narrative. For instance, a recent article in Anthropocene Magazine declared: “A century of aggressive suppression of wildfires has starved many western U.S. forests, including California’s, of the low-intensity fires that once shaped these forests thanks to lightning strikes and intentional fire starting by the region’s Indigenous inhabitants.”

Numerically most fires are small and seldom burn much acreage. Photo George Wuerthner 

The standard narrative is that frequent low-severity burns (where most trees survive) kept fuels low; thus, there were few large blazes. Numerically, most fires were always small, seldom burning more than a few acres, but as a result, they had little real influence on most fire regimes and fuel loads.

So common is this assertion that most advocates of “active forest management” (read logging and prescribed burning) seldom examine the underlying assumptions.

The influence of fire suppression may be more a consequence of climatic conditions than human endeavors.

Ponderosa pine at lower, drier locations were often influenced by low-severity, high frequency fire. But even ponderosa pine, especially at higher, moister locations, occasionally burns at high-severity. Photo George Wuerthner

The only forest type that “may” have been influenced by fire suppression are dry forests like ponderosa pine. But livestock grazing, not fire suppression, is the more likely factor that accounts for reduced wildfires in these forests. However, even ponderosa pine experiences high-severity blazes at times.

However, proponents of 100 years of fire suppression seldom acknowledge that ponderosa forests’ low-severity, high-frequency fire regimes” seldom apply to other major plant communities.

Aspen, as well as nearly all other plant communities in the West, tend to burn at longer fire rotations often of centuries, and when they do, they naturally burn at high-severity. Photo George Wuerthner 

Most plant communities of the West typically experience long fire rotations of many decades to hundreds of years without any significant fire. This includes spruce-fir, lodgepole pine, juniper-pinyon, sagebrush, chaparral, aspen, west-side Douglas fir, and many other plant groups.

Indian cultural burning was primarily localized in influence around village settlements such as the Yosemite Valley, however, the majority of wildfire in even Yosemite NP was influenced by climate rather than human burning. Photo George Wuerthner 

Proponents of Indian cultural burning suggest that frequent blazes set by Native Americans every few years kept fuels low so that large blazes were uncommon. However, long-term charcoal and pollen studies document that large, high-severity wildfires have always been a natural part of Western landscapes. The influence of Indian burning was primarily of a local nature, not a landscape scale feature.

Graphic showing the episodic nature of large wildfires in Yellowstone National Park.

Plus, we have evolutionary evidence for this. Up to 50 bird species are more common or even dependent black-backed woodpecker on high-severity wildfires sites.

Sagebrush in the Trout Creek Mountains, Oregon. Sagebrush can not tolerate frequent fires, and disappears if burned too frequently. It has long fire rotations up to 400 years. If Indian cultural burning was a major influence on plant communities there would be no sagebrush. Photo George Wuerthner 

Many plants are poorly adapted to frequent fires. Sagebrush, for instance, has fire rotations of up to 400 years. If Indians regularly burned sagebrush at 1-5 year intervals, we would not have significant amounts of sagebrush nor sagebrush-dependent species like sage grouse, pygmy rabbit, and sage sparrow.

Pondorosa pine existed for millions years before humans colonized NA and kept them “healthy” by cultural burning. Photo George Wuerthner 

Proponents of Indian cultural burning low severity fires kept forests healthy. But one must ask how did such forests like ponderosa pine which evolved 55 million years ago survive all those years before humans colonized the continent?

The other problem with the 100 years of fire suppression mantra is that statistics on wildfire demonstrate that its effectiveness was marginal at best. Climatic conditions explain variation in wildfire acreage burned better than human fire exclusion.

Prior to WW11 almost all fire suppression was done by a few men riding horses and mules around in remote wilderness. Their ability to influence fire spread was mininal. Photo George Wuerthner 

First, before World War 11, fire suppression consisted of a few men riding mules around in remote wilderness areas armed with shovels and axes. Their influence on wildfire starts and spread was insignificant.

Statistics bear this out. Between the early 1900s and late 1930s, tens of millions of acres of forest were charred by wildfire annually.

The aftermath of the 1910 Burn charred up to 3.5 million acres–was fire suppression really successful a hundred years ago? 

For instance, in 1910, the Big Burn raced across 3-3.5 million acres of northern Idaho and Western Montana. Indeed, during the 1920s and 1930s, up to 40 million acres were burned annually. And in 1929, an estimated 50 million acres were charred by blazes. By comparison, when 10 million acres burn today, it is considered an enormous wildfire year.

Can anyone suggest that fire suppression was effective if 50 million acres are burning in a year?

The early part of the last century was dominated by extensive drought—remember the Dust Bowl years. We will come back to this in a bit.

The influence of climate on wildfire is seen in this chart. During warm dry periods of the early 1900s there were millions of acres burned. Then mid century 1940-1988 cooler, moister conditions prevailed and fire acreage charred was dramatically reduced. Then with climate warming, from 1988 onward, larger acreages were again occuring. 

It was only after WW11 that fire suppression was possible. Armed with helicopters, air tankers, bulldozers, and smoke jumpers allowed humans to control smaller wildfires. However, these blazes typically burn a few acres and have little impact on the landscapes.

It is again well documented that 95-99% of wildfires are insignificant.

The problem is that we attack these fires and take credit for putting them out when, if we had done nothing, nearly all of them would have self-extinguished without burning a significant acreage.

Old Faithful erupting in Yellowstone. For more than a decade, Yellowstone allowed most backcountry fires to burn without suppression, the vast majority self extinquish without burning more than a few acres. Photo George Wuerthner

This was borne out by an experiment done in Yellowstone National Park. In 1972, the Park Service allowed 235 backcountry fires to burn without suppression. Of these fires, 222 went out alone without burning more than a few acres. Even the relatively few more significant blazes are all self-extinguished. About 76% of fires in Yellowstone never reach more than 0.1 hectares (0.25 acres) in size, and 92% of fires in Yellowstone never burn more than 40 hectares (100 acres).

Was there more fuel in 1988 than 1987 or 1986 when the Park was not suppressing wildfire? And why did 1.4 million acres burn in 1988? The summer of 1988 was the driest and warmest since the park was created. 

Why did so few acres burn in Yellowstone between 1972 and 1987, and then suddenly, in 1988, a million and a half acres in the Greater Yellowstone Ecosystem were charred? Did fuel suddenly accumulate? The likely explanation is human carbon emissions contributed to a climate that grew hotter and drier with prolonged droughts.

Though modern fire suppression efforts have reduced the spread of small fires, they have done little to change the occurrence of large blazes, responsible for nearly all the acreage charred by wildfire annually. Several studies have shown that 1% of large and extreme wildfires are responsible for 90% of the total acreage of wildfires.

What drives large blazes isn’t fuel. You can have all the fuel in the world, but you will not get a significant blaze if you don’t have the right climate-weather conditions. The conditions that create large fires include severe drought, low humidity, high temperatures, and, most importantly, high winds.

Wind-tossed embers are responsible for 90% of the structural losses across the West.

I have visited dozens upon dozens of large blazes across the West, and I know no exceptions to the generalization that climate/weather is the driving force behind significant wildfires.

The recent wet winter in California is a perfect example of the influence of climate/weather on fire. According to state data, California received 141 percent of its average annual rainfall during the most recent water year (2023). The state’s snowpack reached the deepest level recorded in at least 40 years. Not surprisingly, only 317,191 acres have burned in California in 2023 compared to the five-year average of 1,509,952.

Was wildfire suppression so effective after WW11 throughout the 1950s and 1980s that almost no large fires occurred? But suddenly, from the 1990s forward, firefighting became successful.

During the period of 1950-1970s due to cooler and moister conditions, glaciers were growing on Mount Hood, and not surprisingly, fire “suppression” by natural conditions occurred. Photo George Wuerthner 

The answer lies in climate. A review of the overall climate of the last century shows that the early years from 1900 to 1940s were drier than average. We had the Dust Bowl and extensive drought throughout the West. Then during the 1950-1970s, it was so wet and snowy during those years that glaciers in the Pacific Northwest grew more than ever since the Little Ice Age.

Yes, fuels did accumulate during these wet cycles, but that is not abnormal. This yin and yang of climate variation explains most differences between high fire years and when fires burn far less acreage.

All this suggests that the present forest policy of thinning and prescribed burning is more delusional than effective. It may give people the impression that public agencies can preclude large wildfires, but in the face of climate warming, we are experiencing significantly more acreage burning; however, when viewed from a longer temporal scale, what we are seeing is precisely what has occurred in times past when the Earth’s atmosphere was warmer and drier.

In the face of these climatic conditions, the only sensible response is to promote home hardening and to stop building in the Wildland Urban Interface and zone lands. Other presumed “solutions” like logging only enhance fire spread, degrade forest ecosystems, and waste taxpayer funds.