by Abby Metzger and Nancy Steinberg

Erica Fleishman propped herself up in the bucket seat of the small airplane so she could see the Oregon landscape below. One of the plane’s windows was open to allow a filmmaker to take footage, making communication with the other two passengers and pilot impossible. Brand new to the Pacific Northwest, Fleishman had never seen most of the places below from the ground, but even so, she knew they were changed beyond recognition. From decades of work elsewhere in the West, she knew that wildfires will do that. Smoke still lingered in the air.

It was October 2020, and the worst wildfire season to hit the state of Oregon in decades was, thankfully, winding down. Fleishman had joined the faculty at Oregon State University a few months earlier as the new director of the Oregon Climate Change Research Institute. Today she had been invited to fly over some of the burned areas.

“The forested places that burned were intellectually really interesting in terms of the patchiness,” Fleishman says. “But then, you look down and see strange, light-colored squares and realize, ‘oh my gosh, those are concrete pads where homes used to be,’ and that was terribly sobering.”

< Erica Fleishman

All tolled, more than a million acres burned in Oregon, the second-highest in one season in recorded history. Eleven Oregonians lost their lives, and thousands of structures, including many homes, were destroyed. Fires burned from eastern Oregon to the McKenzie River Valley to coastal Lincoln County — marking the landscape and our memories for years to come.

Even before the flames were doused and the damage was fully surveyed, questions swirled like smoke. Why was this fire season so bad? Was it poor forest management? Was it climate change? Is this the new normal?

Image: painting by Trey Phillips

As Fleishman explained again and again to media outlets and seminar audiences last fall, a confounding tangle of variables was at work. Some were decades-long trends, while others felt almost like bizarre one-off events. A closer look at some of the drivers of the 2020 fires, as well as of those in the past, reveals more about climate change’s effects on Oregon wildfires and might tell us something about what the future has in store.


As you have likely heard, fires are a natural part of western ecosystems, even a necessary ecological process. Oregon landscapes have always been affected by fire, but wildfire patterns, frequency and severity have changed in the 150 years since Europeans arrived in the West.

Before European settlement, most forest fires were ignited by lightning strikes. “There is very little evidence that [indigenous people] had any effect on the fire regimes of the forest,” says Julia Jones, Distinguished Professor of geography in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State. “Although the Native peoples did migrate seasonally from the [Willamette] Valley up into the mountains, they occupied specific parts of the landscape, particularly wide, low-elevation valleys, and flat broad ridges, such as the upper ridges of the H.J. Andrews Experimental Forest.” In other words, they had no need to set fire to dense forests — that’s not where they spent their time.

Julia Jones >

European settlers, traveling west, brought new ignition sources with them, in the form of campfires. “In the 1850s or so, Europeans began to arrive across the Cascades on the Santiam Wagon Trail, and some of their campfires escaped and blew westward into the forest,” Jones says. “So, we had a new ignition source in forested landscapes.”

Today, ignition sources are more diverse: Lightning strikes and campfires continue to cause fires, but sparks from cars driving by dry roadway vegetation, discarded cigarettes, and, importantly, downed power lines add to the list.

In the early 1900s, as fires became more common near human settlements, suppression became more common as well, Jones says. Suppression had a significant downside: It allowed fuels for fires to build up in some ecosystems. “When a fire eventually came along,” Jones points out, “it was likely more difficult to control and burned at a much higher severity.”

So, ignition and suppression have changed over time and may have contributed to the disastrous fire season of 2020. But Jones also notes that summers have been getting warmer and drier in Oregon, which brings us to the question of the impact of long-term climate trends and their role in the 2020 fire season.


Scientists are clear: It is likely that some long-term climate-related factors contributed significantly to the 2020 wildfire season, particularly the September conflagrations. As Larry O’Neill, associate professor and Oregon’s state climatologist, puts it, climate change “set the table” for more acute and unusual factors to make a terrible impact.

Aridity: It's not just for deserts

Aridity is a measure of dryness that incorporates a range of variables, including precipitation, temperature, humidity and even winds. Trends in all of these parameters have led to increasing aridity.

For example, O’Neill explains, “Gradually increasing temperatures have increased evaporation, sucking needed moisture out of the plants and soil.”

Fleishman adds, “Dry vegetation burns more easily than vegetation that has more moisture. Fuel moisture level is a key variable in controlling how fires spread.” A 40-year decline in summer precipitation has reduced humidity as well. During the Labor Day 2020 fires, humidity was extraordinarily low in many areas of Oregon, 10-12% in Salem, for example.

Precipitation deserves an especially close look. In western Oregon, we think of ourselves as living in a damp environment. But climate change seems to have caused critical shifts in precipitation patterns. When water falls as snow in the winter, the mountains store that snow and then slowly release it as snowmelt into our watersheds throughout spring and summer. As temperature has increased, we are receiving less snow and more rain in winter, which reduces streamflow and therefore water availability in the warmer months.

You've heard of flash floods ...

In addition to these long-term trends in aridity, climate reared its head in distinct ways in 2020, again setting the stage for the fire season.

For one thing, Oregon experienced what is called a “flash drought” in August and September. O’Neill says: “Around middle to late August and early September, we had one of the warmest periods on record in a lot of Oregon, creating a flash drought. This is basically where you have a heat wave that can last a couple of weeks, and it rapidly evaporates off any remaining moisture. In this case, climate change exacerbated typical summertime drying, and was a contributing factor in creating the flash drought.”

< Larry O'Neill

The eight-week period from mid-July to September 10 was the third warmest and third driest period in the Cascade Range in the past 42 years, according to a report co-authored by O’Neill for the Climate CIRCulator blog. The flash drought contributed to extremely dry soils and vegetation by early September.

Easterly winds (Those winds though)

Oregonians who experienced the 2020 wildfires will likely remember the winds at the tail end of summer. Warm, dry air careened eastward at speeds typical of severe winter storms.

“It was definitely in the 99.9% of fastest winds for that date,” says O’Neill.

Those winds can be partially explained by a meteorological pattern called an Omega block. As the name suggests, the pattern resembles the Greek letter Omega, with the round part representing a high-pressure ridge that hung off our coast, and the “feet” representing a low-pressure system. This blocking pattern contributed to strong, dry, easterly winds that stretched from the Canadian border into northern California. The easterly winds whipped up fires already underway and ignited new ones by toppling power lines.

By themselves, the winds were indeed unusual, but scientists are starting to look at the interacting effects of two or more variables — called a compound extreme. Independently, the easterly winds and dryness were highly unusual but not unprecedented. Yet the extent to which these two things coincided had never before been recorded. It was the perfect punch.

All together now

Many things aligned during the 2020 wildfires. Decades of management practices that favored fire suppression. New human sources of ignitions. A warmer and drier landscape with more burnable fuels. Seasonal conditions and strange weather patterns — not to mention more people living in harm’s way.

Looking back, scientists can safely say that long-term changes and extreme weather played a part in the 2020 wildfires. If climate change and the slow drying of the West set the dinner table, the 2020 conditions served the main course. The twinning forces ignited powerful wildfires that jumped rivers and roads, razing towns and closing recreational areas.

OCCRI Director Erica Fleishman offers a pointed summary. “If the vegetation is dry and there’s a spark with extremely high winds, a fire is going to go. It’s pretty much just get the heck out of the way and hope for the best. Nothing is going to stop it.”


As forests and debris smoldered, those who still had homes emerged from days of staying inside to avoid hazardous air and wondered what world they had just stepped into. Oregonians rubbed their burning eyes, started to sweep up the ash and asked the all-important question: Can we expect more of the same?

The short-term answer is that 2021 is shaping up to be a high-risk fire season. As early as April, much of western Oregon was under a red flag warning for critical fire weather conditions. A streak of rainless, warm and windy days felt eerily like summer.

“[The fire] warning was months earlier than normal,” Larry O’Neill says.

Thankfully, aside from the southern Oregon Cascades, 2021 saw normal mountain snowpack, partially refilling our precious water bank account. But northwest Oregon received only a little more rain this year compared to last. According to preliminary statistics, Oregon recorded its second driest spring since 1895. This means much drier soil and fuel.

“Since spring was historically dry, 2021 has the potential to be another tough and long fire season in much of Oregon, particularly in central and southern Oregon,” O’Neill says. “Compounding this situation in these regions is that they’re into the second consecutive year of severe-to-extreme drought.” In recognition of these conditions, as of July parts of Oregon were placed in an above-normal fire category by the National Interagency Fire Center.

As for those easterly winds, some scientists have proposed a much-debated hypothesis that they could become more frequent with climate change. But Fleishman says the data do not support this: “By and large, there is no good evidence right now that those types of wind events are going to become more frequent.”

The long-range view is also sobering. According to the Fifth Oregon Climate Assessment, area burned and fire frequency are projected to increase substantially over the next 50 to 100 years, first on the drier side east of the Cascade Range, and eventually in the western Cascade Range. Fires may also become more severe, depending on fire management practices and how vegetation and weather vary with climate change.

As a result, the dialog is shifting from how to prevent forest fires, like in the heyday of Smokey Bear, to how to live in a world with increased fire risk.

“Going forward, we have to act as if this will now be a regular occurrence,” O’Neill says.

“Going forward, we have to act as if this will now be a regular occurrence."

In October of 2020, CEOAS geographer Julia Jones visited a burned area in the McKenzie River watershed. Her visit nearly coincided with Erica Fleishman’s flight to survey the sobering destruction from above. But up close and on the ground, Jones saw something different. Already, trees were making leaves. Cones were alive. It was a stunning reminder of nature’s resiliency, which can be hard to remember in the afterglow of all that burned.

Jones also looks to the power of societal resilience, noting that abrupt changes in human behavior have occurred throughout the history of the Pacific Northwest. For example, the logging that occurred after the early 1900s was once considered essential for fire suppression. Then, in the 1990s, the pendulum swung the other way, and logging in the old growth forests declined sharply.

“It seems that abrupt shifts are more likely in human societies than they are in ecosystems,” Jones says. “So, the question really is, how will human behavior change in response to this one summer? What will be different?”

"The question really is, how will human behavior change in response to this one summer? What will be different?”

Going forward, maybe this is the question we should be asking ourselves — not whether this could happen again, but what will we change?

If we can navigate between longing and loss, between defeat and actually doing something — maybe everything.


Created with images by Pexels - "dawn dusk electricity" • jameswheeler - "british columbia canada fir" • uzumeti - "fire koster heat" • Ylvers - "forest fire fire burning" • TemperateSage - "forest rays god rays"