Kari Greer / U.S. Forest Service- Pacific Northwest Region
Taylor Creek and Klondike Fires, Rogue-Siskiyou National Forest, Oregon, 2018

2020 was a memorable year for wildfires. Images of burning forests appeared everywhere on social media and attention-grabbing headlines dominated news cycles all over the world. Heading into the 2021 fire season, two big questions loom in everyone’s minds, so we checked in with some fire experts at UW Environment to ask: Are fires getting worse over time? If so, what compounding factors are in place?

Let’s start by examining the components that contribute to wildfires, also referred to as the “fire triangle.” Firstly, fires need fuel. This can either be brush, grass, trees, vegetation, and even fallen or dead vegetation — anything that could be burnable biomass. Secondly, fires need some sort of ignition, whether human induced or as the result of lightning. Lastly, the weather conditions need to be right: hot and dry, with winds assisting the fire in its spread.

Fuel, both its makeup and behavior, are different on the east side and the west side of the Cascades.

Many forests on the east side contain the classic pine trees in an open forest system. Fire is no stranger to these forest systems, which have naturally burned every ten to thirty years throughout their evolutionary history. Forest systems here exist in drier conditions, which increases the likelihood of burning year to year. The east side not only has forests, but also a variety of other systems conducive to burning. “A lot of area burned east of the Cascades is not in forests, but actually in sagebrush or grassland,” said Climate Impacts Group Climate Adaptation Specialist Crystal Raymond

Moving to the west of the Cascades, the climate is typically colder in the summer and wetter, and the forests are made up of Douglas fir, hemlock and cedar with fire cycles in the hundreds of years. Historically, fires in these forests occur less frequently, with a given patch of forest sometimes not burning for 500 years or more. However, when the weather conditions are extremely dry and perhaps most importantly, windy, fires can thrive. Because the weather conditions are critical to fire events, forests west of the Cascade Crest can remain unburned for many human generations’ lifetimes and have the opportunity to accumulate biomass, which is why it becomes a concern when the right weather conditions align for fires.

Following European colonization of North America, fire management techniques like fire suppression and fire exclusion removed or prevented a lot of fires that would have otherwise occurred. Fire suppression refers to a management technique of trying to put out a fire as soon as it starts. This not only dampens the fire that is occurring but it also excludes the fire from spreading to other areas where it would’ve burned. Fire exclusion is a broader term referring to the attempted removal of fire from landscapes using fire suppression techniques; most frequently through human-caused fire managed by Native Americans. 

“In our current context today, fire management includes many approaches,” says School of Environmental and Forest Sciences’ Assistant Professor Brian Harvey. “Fire carries some risk to society, so suppressing it when needed to protect resources and human lives, safety and property is important. But while suppression in some cases is the right thing to do, use of prescribed fire and letting other fires burn naturally is an important piece to the puzzle of forest management. Fire has always, and will continue to play a major role in these forested landscapes—the forests are very fire adapted. Minimizing societal damage from fire means that we’ll need to continue to be better fire adapted.”

The effects of past fire suppression are not felt equally across our forests in the Northwest. Fire suppression and exclusion eliminates the natural, periodic removal of vegetation in forests that are adapted to frequent fire in forests east of the Cascades, allowing them to build up more fuel on the forest floor, which can lead to forest conditions ripe for uncharacteristically severe fire.  West of the Cascades, forests burn less frequently and naturally build up more fuel, thus are not as impacted by fire suppression and exclusion. Native American tribes have for very long times practiced a lot of prescribed burning, especially in drier forests. Prescribed burns are used as a land management practice to clear underbrush and eliminate growing biomass.

“It is important to acknowledge Native American burning,” said Raymond. “Fire suppression is a very Euro-centric practice. Native Americans were using burning as a very active management practice, and one that is often overlooked when talking about the role of fires on both sides of the state.”

The intensity of and damage a big fire can do not only depends on the fuel load, but also a warming climate and its proximity to population centers. 

“The strongest driver of fire area burned are the climate drivers that make fire possible — warm, dry conditions lead to more fire activity,” says Harvey “A lot of area that is burning is not necessarily doing a lot of harm to human life, and sometimes the biggest fire years in terms of area burned aren’t the most damaging to human life. Other years, we see a relatively quieter fire year in terms of area burned but they cause a lot of societal damage because of where those fires are located.”

When discussing wildfire, many metrics contribute to how massive a fire year is, ranging from the location of fires and the proximity to infrastructure to total area burned. Our fire experts agree that the ingredients for fire are plentiful and abundant across the Western U.S. High biomass ecosystems (some at a natural level, some at a level higher than what is recorded historically) means fuel to burn, ignitions on landscapes are plentiful, and warm dry conditions are becoming more and more abundant to drive big fire years. History has proven that these conditions correspond with big fire events.

Raymond urges communities, especially those close to forest areas, to treat the fires season like preparing for any other natural disaster. “We need to recognize that we do get fires in western Washington and Oregon, and when they happen they can be big and severe. Start thinking now about evacuation and community response, and plan for it like you would an earthquake. How are you going to find each other and recover after a wildfire? Having these plans in place can really make a difference in the recovery process post fires.”