Senator Merkley On The Wrong Side Of Thinning Controversy

Clearcut and thinning near Susanville, CA failed to halt the spread of the Dixie Fire. Photo George Wuerthner

I recently got a message from Oregon Senator Merkley announcing that he supported more thinning and logging of our forests to reduce large wildfires.

The irony is that logging/thinning is a primary source of Greenhouse Gas Emissions (GHG) that is contributing to climate warming which ultimately is driving large fires.  U.S. emissions from logging are up to 10 times that of wildfires and insects. For example, the wood products industry contributes to approximately 35% of the GHG emission in Oregon, more than the total contribution of the transportation sector.

Promoting logging under the guise that this will reduce large fires is counterproductive. Since climate warming is the primary driver of large wildfires (not fuels), adding to anything that increases drought, high temperatures, low humidity, and wind only contributes to more wildfires.

The nearly dried-up Wickiup Reservoir near Bend, Oregon reflects the regional drought promoting wildfires. Photo George Wuerthner

There is good paleo climatic studies showing a correlation between severe drought conditions and wildfire. Is it no surprise that the West is experiencing some of the worse drought conditions in centuries, and there are large fires occurring.

Furthermore, we have abundant evidence that thinning and other “fuel reductions” like prescribed burning fail under extreme fire weather conditions. And extreme fire weather conditions are the only situations that count since nearly all large blazes occur only under such climate/weather circumstances.

Thinning can also increase wind penetration and drying of fuel, thus actually enhance fire spread.

It doesn’t matter if thinning or prescribed burning might work under low or moderate fire conditions since fire occurring under these conditions typically self-extinguish or are quickly suppressed.

What burns in a forest fire are fine fuels like needles and small branches. The snags left behind store carbon as does the roots below ground and any charcoal that results from a fire. Photo George Wuerthner

Another factor ignored by proponents of thinning and other fuel reductions is that logging releases GHG emissions now. Still, even forests charred by high severity fires continue to store carbon in snags, roots, and charcoal buried in the soil. So logging the forest today contributes to greater CO2 emissions when we must reduce these emissions.

The red line marks the perimeter of the Milli Fire. The numerous light areas on the right side of the satellite photo are within the fire perimeter are clearcuts and thinned sites which obviously did not halt the spread of the fire. 

To justify more logging, Merkley cited the 2017 Milli Fire near Sisters, Oregon, as an example of how effective thinning was by asserting fuel treatments “saved” Sisters.  It is questionable if thinning treatments “saved” Sisters. An air photo of the fire perimeter shows that most of the area burned had been previously logged. In other words, it had already experienced significant “fuel reduction” to no effect on the spread of the Milli Fire. Furthermore, the Milli fire burned through two recent previous burns: the Black Crater and Pole Creek blazes—which area also essentially “fuel reductions.”

If fuel reductions are the key to stopping the advance of fires, why didn’t all these other previous fuel reductions “save” Sisters?

The progress of the Millie Fire. Sisters is in the upper right hand of the map.  The green areas indicate the path of the fire early in the event, while the brighter colors indicate the fire spread due to wind which pushed the blaze into the Three Sisters Wilderness. 

I can’t rule out fuel reductions as the proximate cause of the halt of the fire’s march towards Sisters. Still, another explanation that proponents of thinning never mention is how changing weather influenced the fire. When the fire advanced towards Sisters, the wind shifted directions blowing the blaze back westward on the previously burned areas and into lava fields in the Three Sisters Wilderness. The shift in wind direction is a more likely explanation for why Sisters was “saved.”

But even if thinning ultimately did “save” Sisters, a few exceptions do not invalidate the generalization that fuel reductions are ineffective under extreme fire weather conditions.  For instance, some 75% of the Bootleg Fire that burned across more than 400,000 acres in southern Oregon during the summer of 2021 had experienced previous logging/thinning/prescribed burning.

In the foreground is a clear-cut, is an extreme form of fuel reduction that did not preclude the blaze from charring trees in the background.  Dixie Fire, California. Photo George Wuerhner 

The same for most of the acreage influenced by the 900,000-acre Dixie Fire that raced across northern California. And lest we forget, the Labor Day 2020 blazes that burned the western slope of the Oregon Cascades sprinted through with the many clearcuts on private commercial lands.

The aftermath of the Camp Fire, a wind-driven blaze, that previous clearcuts, hazardous fuel reductions, and even two previous fires did not halt the fire spread. Photo George Wuerthner 

And the 2018 Camp Creek blaze that took out 19,000 homes and structures in Paradise, California, burned through numerous clearcuts, hazardous fuel treatments (i.e., thinning), prescribed burns, and two previous fires (fuel reduction).

The point is that the timber industry and its allies in “collaboratives” continue to promote “fuel reductions” as the solution despite numerous examples of its failure to halt blazes occurring during extreme drought, low humidity, and high temperatures, and high winds. All these fire weather conditions are exacerbated by climate warming. And logging/thinning only contributes to more warming.

Salvage logging (post-fire logging) removes large snags that are critical for wildlife. Rim Fire, California. Photo George Wuerthner

Furthermore, logging isn’t benign. It releases carbon, removes biomass (the logs that are wildlife habitat), spreads weeds, increases roads which are a significant source of sedimentation in streams, disturbs sensitive wildlife. Plus, most human ignitions occur along roads, thus constructing more roads, even “temporary roads,” can promote more wildfires.

Since only a small percentage of fire actually encounter fuel reductions, we don’t get the presumed benefits of thinning and fuel reductions but we get the negative impacts of logging.

I don’t blame Merkley for misunderstanding fire ecology. However, it’s unfortunate that he listens to folks who have a vested financial interest in promoting logging.

The foundations of homes burned by the  2007 Angola Fire by South Lake Tahoe. Most homes are ignited by wind-driven embers. The area around this subdivision had been “thinned” just six months before, but the homes were not treated and many structures burned to the ground. 

Fuel treatments to the degree they are utilized should be strategic and focused primarily near communities and homes. Typically fuel treatments more than 100 feet from a structure provide no additional protection.

Old-growth ponderosa pine like this one in Yosemite NP, CA stores tons of carbon. We should protect all public forests from logging as carbon reserves. Photo George Wuerthner 

Rather than promote more logging of our public lands, we should set aside all of these lands as carbon reserves and stop the leakage of CO2 that results from “fuel treatments.”





  1. Karl Avatar

    Another great article.
    I emailed it to a friend, that is a Merkley-staffer.
    Thanks for your hard work on delivering the “other side” of the issues of land conservation.

  2. Charles Fox Avatar
    Charles Fox

    The only way to save the forests is to destroy them. With all that “thinning” where is the next cohort of trees supposed to come from?

    The Forest Service “manages” trees by cutting them down. What else does this agency really know how to do? It would take some kind of change in consciousness for the FS to ever do anything else. It doesn’t appear that changing their mindset is part of their agenda.

  3. rastadoggie Avatar

    The Forest Service needs to educate, sign, close and enforce Big Rec impacts (the newest extractive industry): rampant illegal mountain bike trail building, illegal motorized use and illegal ne’er do well and vanlife residency with its resulting poop, trash and campfires out of control. But this obsession with “must cut” overstocked forests (that they’ve created with logging) and mega-funding from no nothing politicians takes up all of the agency bandwidth. My Forest does no education on anything else but has extensive blah, blah, blah and even cartoons and videos about thinning to save us all from natural wildfire.


George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner