With the recent rain and cooling, the wildfire season is essentially over for the Pacific Northwest.
In terms of acreage, 2026 has been one of the most prolific wildfire years of the past decades.
Considering the past 50 years, it was the leading wildfire year in Oregon and number two or three in Washington State. Most of the major fires were started by a limited number of lightning "storms".
But now, the key point.
The great majority of the wildfire acreage occurred in grass and range vegetation, not forests.
Importantly, grass and range fires have little to do with global warming and climate change.
To demonstrate all of this, let's begin by examining the areas burned this year, using graphics from the U.S. Forest Service (below, pink shading shows the fire area this year )
Massive fire area in Oregon. Nearly all in the grassy/range areas of the eastern side of the state.
In contrast, essentially no fires over western Oregon, west of the Cascade crest. One of the lowest wildfire years on record for the western side of the state.
Like Oregon, western Washington has also escaped wildfires this year (see below), and for the same reason: a lack of strong easterly wind events. Most of the wildfire area in Washington State has been in grass and range vegetation, but some of the fires have extended into trees on the slopes of local terrain (e.g., the Little Giant Fire)
What about the origins of the fires in the two states?
According to the U.S. Forest Service, the vast majority of fires were ignited by humans (e.g., arson, power lines, debris burning). The major acreage fires were nearly all started by lightning.
By simple inspection of the graphics, it is clear that grass/range vegetation, not trees, has dominated the 2026 fires in the Pacific Northwest.
Asking various AI systems to compare the satellite-based fire areas to satellite-based land use provides similar answers. In Oregon, the dominance of light vegetation is overwhelming (see below), with three-quarters of the fires in grass and brush. For Washington State, they estimate about 60% coverage by light vegetation.
Examining the fires manually, looking at BOTH satellite assets and surface imagery, it is apparent that the satellite approach underplays the availability and importance of light vegetation. To illustrate, below is an image from a "forest" area within the very large Sinlahekin fire of north-central Washington.
There may be some trees, but grasses and low shrubs dominate. I have looked at dozens of other areas in both states, with similar results.
Based on my review, I would suggest that at least 80% of the Oregon wildfire area this summer was in light vegetation and at least 70% of the fire area in Washington.
Thus, this year was mainly a problem of flammable light fuels that dry quickly (hours to days) and are always dry enough to burn by July in our region.
Modest global warming over time was not a factor in the flammable conditions at the start of summer.
Furthermore, our region has been invaded by non-native, highly flammable grasses and light shrubs. These are human-forced vegetation changes that greatly enhance fire potential.
And with decades of fire suppression, our forests have become unusually dense and full of debris, and thus highly vulnerable to wildfires
In addition, the region has extperience downward trend in lightning. So global warming is not forcing more lightning ignitions.
The bottom line is that human-forced global warming had very, very little to do with the major Northwest fires this summer, and those claiming a connection are providing problematic information to the public.
Let’s face it, human Idiocracy is really the current existential threat; fireworks into dry hills in Chelan etc; I know AI will get us eventually, but us hu-mans not doing ourselves any favors with the environment and especially with wildfires.
ReplyDeleteThe Chelan Hills fire is a stark reminder that we need to leave fireworks for the professionals. Fireworks should be banned for consumer use. They are simply too dangerous to be used by anyone less than a fireworks professional.
DeleteWhat percent of biomass burned was caused by lighting-started fires?
ReplyDeleteI believe you have miss-characterized the nature of the fires in Eastern Washington for this year. You imply they were largely grass/rangeland fires where some burned up into forest areas. This may be true of the large Colville Indian Agency fire, but the 3 Queens fire, the Little Giant Fire, the several fires in the north Cascades and Pasayten Wilderness, and the Sinlahekin fire all started with lightning strikes in the forest areas. Only in the Sinlahekin fire did the fire spread east into grass/shrubland areas but a larger percentage of that fire and the other fires mentioned were in the forest areas.
ReplyDeleteThe Little Giant fire at 172,000 acres is the largest FOREST fire of record for Eastern Washington and the second largest for the state, after the 1902 Yacolt fire. In total, close to 400,000 acres of forest burned this year and this is not a small amount. It was also noteworthy where these big fires started. The 3 Queens, Little Giant and north Cascade fires all started in the usually more moist western sections of the Cascade east slopes, closer the influence of the weather conditions that prevail in western Washington. This was likely aided by the low and early melting snow pack along with the later heat and dryness which led to drier than normal conditions in these areas. This was another warm, dry late spring and summer, similar to most of our recent seasons and this warmth and dryness along with the low snowpack were the key initial conditions leading to this big fire year. I asked for the computation of the 100 and 1000 hour time lag fuels using the Dry Creek RAWS observations, which is close to the starting point of the Little Giant fire. The 100 hour fuel was estimated at 6% and the 1000 hour fuel at 8% on July 15, the date of the fire start. This is considerably drier than the value you claimed in your earlier post that stated these fuel moisture values were not unusually dry. You may be right about a downward trend in lightning storms but it is not the number of storms that is critical in starting fires but their nature and the condition of the fuels. We had dry lightning storms this summer and they ignited many fires in fuels, both grass and timber, that were very dry.
wxman...much of what you state is simply not true. You claim that the Little Giant is the largest fire in eastern WA history..simply false. For example, there was the 2015 Okanogan Complex Fire (304,782 acres): Your claims about the critical nature of snowpack for the fires is clearly false.. My values regarding fuel moisture are all from official sources...cliff
DeleteI claimed that the Little Giant fire was the largest FOREST fire of record in Eastern Washington, not the largest fire. The Little Giant fire started as one lightning fire and spread entirely in a forest environment to 172,000 acres. The Okanogan Complex started as several individual fires which eventually burned together but the fire area west of the Okanogan river stayed separate from the one on the east side of the river so are now considered two separate fires, and the current official largest fire is the 2014 Carlton fire at 256,000 acres. However, both the Carlton fire and the Okanogan Complex contained large areas of grass and rangeland so are not entirely FOREST fires. I stand by my comment that the low, early melting snowpack followed by a lack of rain and extended warm, dry days was a major factor in the Cascade east slope forest fires. Also, the computed 100 hour fuel moisture for Dry Creek RAWS , 6% for July 15, is much drier than the value you presented on your graph, as was also the 1000 hour fuel moisture. You need to explain to me why these values computed from a site close to the Little Giant fire is not as valid as your values which seem to be an average over a larger area.
DeleteI don't think you are correct:
DeleteModern Record Breakers (Conifer & Timber Forests)Okanogan Complex Fire (2015): Scorched 304,782 acres across heavily wooded terrain. It remains the single most destructive forest fire season in modern state tracking, burning dense timber and subalpine forests.Carlton Complex Fire (2014): Burned 256,108 acres primarily throughout the timbered slopes and valleys of the Okanogan and Methow regions. It holds the record as the largest single contiguous wildfire incident in state history.Little Giant Fire (2026): Consumed over 172,000 acres of steep, high-elevation timber forests in Chelan and Okanogan counties.
Furthermore, this was a LOT of the Little Giant fire that really not forest....easy to prove that. A lot of it had burned recently and was comprised of downed logs and light vegetation. The moisture values I showed were from the correction elevation..
A search brought up the following values: 26% of the Carlton fire was classified forest, or about 67,000 acres, the rest grass or shrub land. About 48% of the Okanogan Complex was classified forest, or about 146,000 acres. 88% of the Little Giant fire as forest, or about 151,000 acres. I recently drove up the Entiat valley to view the fire area. Much of what the Little Giant fire burned this year was where the 1970 Entiat fire occurred. I was a fire weather meteorologist on that fire in 1970. After 56 years, new growth was coming back to this area, but it is now mostly burned off again and will have to start over.
DeleteDr. Mass, where did we land on our water reservoir levels and summer "drought"? Curious where the levels historically bottom out for the summer and if we have already started refilling.
ReplyDeleteWay to go Spokane! Good job showing us how it's done.
ReplyDeleteThis raises a couple additional questions:
ReplyDelete1. What is the normal or average percent of acreage burnt respectively in forest and in brush as opposed to forest, and how does that average compare to this year?
2. Forest has far more biomass. Would it not still be true that the forest biomass burnt would still be far more than the range and brush biomass, and wouldn't that be the more important figure for most purposes?
Since our forests have become unusually dense, it sounds like we need to embark on more forest thinning and debris removal projects to reduce the wildfire risk. I hope the state legislature will take up this matter when they return to session in January. It won't do much for federally owned lands. But making these improvements on state owned lands would certainly help.
ReplyDelete