New Study: Fuel Reduction Likely to Increase Carbon Emissions

Bark Beetles in the Black Hills

Thanks to Matthew Koehler for finding this’s an interesting review paper. Here’s a summary from Science Daily:

Forest Health Versus Global Warming: Fuel Reduction Likely to Increase Carbon Emissions

Forest thinning, such as this work done in the Umpqua National Forest in Oregon, may be of value for some purposes but will also increase carbon emissions to atmosphere, researchers say. (Credit: Photo courtesy of Oregon State University)

ScienceDaily (Dec. 20, 2011) — Forest thinning to help prevent or reduce severe wildfire will release more carbon to the atmosphere than any amount saved by successful fire prevention, a new study concludes.

There may be valid reasons to thin forests — such as restoration of forest structure or health, wildlife enhancement or public safety — but increased carbon sequestration is not one of them, scientists say.

In research just published in Frontiers in Ecology and the Environment, Oregon State University scientists conclude that even in fire-prone forests, it’s necessary to treat about 10 locations to influence fire behavior in one. There are high carbon losses associated with fuel treatment and only modest savings in reducing the severity of fire, they found.

“Some researchers have suggested that various levels of tree removal are consistent with efforts to sequester carbon in forest biomass, and reduce atmospheric carbon dioxide levels,” said John Campbell, an OSU research associate in the Department of Forest Ecosystems and Society. “That may make common sense, but it’s based on unrealistic assumptions and not supported by the science.”

A century of fire suppression in many forests across the West has created a wide range of problems, including over-crowded forests, increased problems with insect and pathogen attack, greater risk of catastrophic fire and declining forest health.

Forest thinning and fuel reduction may help address some of those issues, and some believe that it would also help prevent more carbon release to the atmosphere if it successfully reduced wildfire.

“There is no doubt you can change fire behavior by managing fuels and there may be other reasons to do it,” said Mark Harmon, holder of the Richardson Chair in Forest Science at OSU. “But the carbon does not just disappear, even if it’s used for wood products or other purposes. We have to be honest about the carbon cost and consider it along with the other reasons for this type of forest management.”

Even if wood removed by thinning is used for biofuels it will not eliminate the concern. Previous studies at OSU have indicated that, in most of western Oregon, use of wood for biofuels will result in a net loss of carbon sequestration for at least 100 years, and probably much longer.

In the new analysis, researchers analyzed the effect of fuel treatments on wildfire and carbon stocks in several scenarios, including a single forest patch or disturbance, an entire forest landscape and multiple disturbances.

One key finding was that even a low-severity fire released 70 percent as much carbon as did a high-severity fire that killed most trees. The majority of carbon emissions result from combustion of surface fuels, which occur in any type of fire.

The researchers also said that the basic principles in these evaluations would apply to a wide range of forest types and conditions, and are not specific to just a few locations.

“People want to believe that every situation is different, but in fact the basic relationships are consistent,” Campbell said. “We may want to do fuel reduction across much of the West, these are real concerns. But if so we’ll have to accept that it will likely increase carbon emissions.”

Note from Sharon: I like the fact that they state:

There may be valid reasons to thin forests — such as restoration of forest structure or health, wildlife enhancement or public safety — but increased carbon sequestration is not one of them, scientists say.

I think it’s just an illustration (if true as generally as the authors claim) that climate change makes what used to be considered a simple problem of “protecting the environment” more complex. As in coal versus natural gas.

I also think carbon cycling is by far one of the most complex and difficult to explain concepts we have dealt with since I have been working in this arena. I think it’s because you have to look at it over a long timespan, and each action you do leads to both some release of GHGs (at different rates) and some opportunity for sequestration on the area where the release has happened. Further, not doing things can in some cases lead to tree death of overstocked stands (say, by beetles) which could lead to either quick release through fires or slower release by the use of forest products or the logs just lying there and releasing carbon. I often think a diagram of release by scenario over time would be really helpful to visualize and understand. Clearly there are a number of assumptions associated with the likelihood of different scenarios, and sensitivity analysis of these assumptions would also be helpful.

Here’sa link to the study.


  1. Thank you for posting this.

    Sharon’s skepticism and that certain healthy reservation around jumping to conclusions is always good, but there comes a point in which a vast of body of research (including papers which I’ve previously cited on NCFP and which featured Mark Harmon prominently) get treated by Sharon in a peculiarly dismissive fashion. (I will not repost them for this reason, but post others.)

    The thing is, the research in this area is well established, and getting reinforced to a significant degree as time goes on. In contrast to this extensive body of research, recently the Society of American Foresters also elected to reveal their biases by ignoring that vast body of evidence. (We should expect a healthy reaction to that in JAF)


    Hudiburg TW, Law BE, Wirth C, Luyssaert S (2011). Regional carbon
    dioxide implications of forest bioenergy production. Nature Climate

    Abs: Strategies for reducing carbon dioxide emissions include
    substitution of fossil fuel with bioenergy from forests1, where carbon
    emitted is expected to be recaptured in the growth of new biomass to
    achieve zero net emissions2, and forest thinning to reduce wildfire
    emissions3. Here, we use forest inventory data to show that fire
    prevention measures and large-scale bioenergy harvest in US West Coast
    forests lead to 2–14% (46–405 Tg C) higher emissions compared with
    current management practices over the next 20 years. We studied 80
    forest types in 19 ecoregions, and found that the current carbon sink
    in 16 of these ecoregions is sufficiently strong that it cannot be
    matched or exceeded through substitution of fossil fuels by forest
    bioenergy. If the sink in these ecoregions weakens below its current
    level by 30–60 g Cm-2 yr-1 owing to insect infestations, increased
    fire emissions or reduced primary production, management schemes
    including bioenergy production may succeed in jointly reducing fire
    risk and carbon emissions. In the remaining three ecoregions,
    immediate implementation of fire prevention and biofuel policies may
    yield net emission savings. Hence, forest policy should consider
    current forest carbon balance, local forest conditions and ecosystem
    sustainability in establishing how to decrease emissions.

    And there’s;

    Clark J, Sessions J, Krankina O, Maness T (2011). Impacts of Thinning
    on Carbon Stores in the PNW: A Plot Level Analysis. College of
    Forestry, Oregon State University
    “All thinning scenarios on all plots without exception resulted in a
    significant loss of carbon relative to a no-thinning scenario. This
    suggests that the findings may be applicable to other forest types and
    thinning prescriptions”

    and there’s biogenic carbon emissions as they relate to woody biomass combustion for heat and electricity:

    Gunn JS, Ganz DJ, Keeton WS (2011). Biogenic vs. geologic carbon
    emissions and forest biomass energy production. GCB Bioenergy Glob.
    Change Biol. Bioenergy (; p.n/a-n/a).

    Abs: In the current debate over the CO2 emissions implications of
    switching from fossil fuel energy sources to include a substantial
    amount of woody biomass energy, many scientists and policy makers hold
    the view that emissions from the two sources should not be equated.
    Their rationale is that the combustion or decay of woody biomass is
    simply part of the global cycle of biogenic carbon and does not
    increase the amount of carbon in circulation. This view is frequently
    presented as justification to implement policies that encourage the
    substitution of fossil fuel energy sources with biomass. We present
    the opinion that this is an inappropriate conceptual basis to assess
    the atmospheric greenhouse gas (GHG) accounting of woody biomass
    energy generation. While there are many other environmental, social,
    and economic reasons to move to woody biomass energy, we argue that
    the inferred benefits of biogenic emissions over fossil fuel emissions
    should be reconsidered.

    Sharon said:
    “I think it’s just an illustration (if true as generally as the authors claim) that climate change makes what used to be considered a simple problem of “protecting the environment” more complex. As in coal versus natural gas.”

    Coal versus natural gas is a false argument for “protecting the environment”, akin to whether one smokes four, or just two, packs a day. Statistically, they both lead to a higher probability of premature death.

    In regards to carbon emissions, we know what must be done, and in a most urgent fashion, (given the latest COP failure in Durban). But there will always be those skeptics who use their position to bolster arguments (like tobacco smokers) which treat high risk as less important than satisfying personal needs.

    Unfortunately, the difference here is smokers are making personal choices heavily biased by their addictions and thus suffer (mostly) personal consequences. On the matter of national discussions around public lands management and the carbon emissions which result, there are those whose personal biases contribute to profound planetary predicaments.

  2. David- I was not saying anything about bioenergy.. all I was saying was that the study may be framing a question in a way that isn’t realistic..

    “Is thinning a good thing to do vis a vis carbon?”

    My framing would be:

    “1. People thin forests for a variety of reasons not related to bioenergy or carbon- usually to reduce fuels and/or restore to prior fire return intervals.
    2. Given that they are going to thin them anyway, what is the best thing to do with thinned material (or burn vs. mechanically treat) carbonwise and with regard to other environmental and social variables?”

  3. I found a very interesting blog post on global warming by two USFS researchers, Ned Nikolov, Ph.D. & Karl Zeller, Ph.D. USFS Rocky Mountain Research Station, Fort Collins CO, USA.
    Their article is titled “Expanding the Concept of Atmospheric Greenhouse Effect Using Thermodynamic Principles: Implications for Predicting Future Climate Change”
    Judging from their past publications, Nikolov and Zeller have been studying and researching global warming for the past decade. I find their conclusion in the blog post to be interesting, and sure to cause much debate.
    “Earth’s climate is currently in one of the warmest periods of the Holocene (past 10K years). It is unlikely that the Planet will become any warmer over the next 100 years, because the cloud cover appears to have reached a minimum for the present levels of solar irradiance and atmospheric pressure, and the solar magnetic activity began declining, which may lead to more clouds and a higher planetary albedo. At this point, only a sizable increase of the total atmospheric mass can bring about a significant and sustained warming. However, human-induced gaseous emissions are extremely unlikely to produce such a mass increase.”
    I find it surprising that USFS researchers would come up with something that contradicts the “scientific consensus”. I applaud them for taking a fresh look at global warming. They may be right or wrong or a shade in between, but it appears the science is far from settled.

  4. Sharon said “sensitivity analysis of these assumptions would also be helpful.”

    Sensitivity analysis may be helpful, however the study says “our conclusions depend not so much on site-specific parameters but rather on the basic relationships – between growth, decomposition, harvest, and combustion – to which no forest is exempt. [our findings] leaves little room for any fuel-reduction treatment to result in greater sustained biomass regardless of system parameterization.”

    The lesson is that forest restoration projects, especially those involving commercial logging, should not take credit for carbon storage benefits, but should instead find ways to mitigate likely adverse carbon consequences, by for instance leaving significant areas untreated and by retaining most medium-sized and all large trees.

  5. “… retaining most medium-sized and all large trees.”

    This is exactly what the USFS have been doing in Sierra Nevada National Forests since 1993. Our “commercial logging” cuts trees with an average dbh of 14″, leaving all medium and large sized trees above 30″ dbh. Can you say that such fuels treatments don’t have ample medium and longterm carbon benefits by mitigating the inevitable wildfires and bark beetles? I guess that one COULD also say that the manufacturing of solar panels is wildly carbon-negative, if you don’t include their usage by the customer. Some people appear to be ignoring the varied longterm ecological benefits of restoration, including carbon sequestration.

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