Wildfire Mitigation, Stranded Biomass Residuals, and Quantifying Counterfactuals

Wildfire is intensifying across the western United States, driven by a century of fire suppression, fuel accumulation, and a warming, drying climate. Larger and more frequent fires bring escalating risks to lives, homes, and ecosystems, while wildfire smoke has become one of the fastest-growing threats to public health in the region, contributing to respiratory and cardiovascular illness and reversing decades of air quality gains in many communities. As these risks grow, so does the urgency of addressing their root causes at scale.

Ecological thinning, the mechanical removal of excess fuels to restore forest resilience, is widely recognized as essential to reducing wildfire severity, yet it remains chronically underfunded and undersupplied with markets for the residue it generates. Absent a viable end use, most of this biomass is disposed of through open pile burning, itself a significant and largely unaccounted source of particulate matter and greenhouse gas emissions. Scaling thinning treatments requires viable outlets for this stranded residue, but doing so credibly depends on rigorously quantifying the counterfactual, or what would have happened to that biomass, and its emissions, absent an intervention. Counterfactuals are notoriously difficult to establish for biomass systems, where outcomes vary widely across space, time, feedstock type, and management context, and where baseline assumptions can make or break the integrity of a carbon or air quality claim.

Since launching in 2020, a particularly severe wildfire year that underscored the scale and urgency of the problem, the Carbon Containment Lab has built its Biologic Program around addressing this challenge through several connected pieces of work. We have developed geospatial models that map where fuels-reduction residue is generated, at what volume, and under what site conditions, allowing us to estimate business-as-usual emissions at landscape scale rather than relying on generic assumptions. We have also directly measured the true cost of business-as-usual disposal, showing that pile burning retains only a small fraction of stored carbon while releasing outsized quantities of particulate matter and black carbon per ton burned.

What remains missing, and what this project prioritizes, is the harder counterfactual question of what would happen to that residue, and its associated emissions, absent intervention, accounting for the heterogeneous, policy-sensitive management decisions that make biomass baselines so difficult to pin down. Below, we describe each of these pieces in more detail, along with how closing the counterfactual gap would let us move from broad estimates to defensible baselines that can support real investment decisions.

Timeline

investigation

Identify locations and quantities of biomass residues generated if Unites States Forest Service accomplishes thinning goals Publish results in whitepaper and as part of Roads to Removal Report

investigation

Quantify the economic costs and greenhouse gas emissions associated with pile burning practices Publish results in peer-reviewed journal and share findings with broad audience

implementation

Regional Model of Counterfactual Practices by Forest Type and Ownership Class

implementation

Develop practical guidance for carbon credit methodologies intending to credit use of wildfire thinning residues

Currently

First, we sized and located the problem.

Through the Forest Inventory and Analysis (FIA) Program, the United States Forest Service (USFS) maintains a network of more than 300,000 permanent forest plots across the country, sampled at a base density of roughly one plot per 6,000 acres and remeasured every five to ten years. Each plot records tree species, diameter, height, and condition for both live and dead trees, along with site-level variables like down woody material, soil characteristics, understory vegetation, and land use.

Stocking level, a measure of how much growing space on a given acre is occupied relative to what the site can support, is calculated from these plot measurements. Comparing current stocking against the stocking level associated with healthy fire regimes shows where forests are overloaded with excess small-diameter material relative to what the land can sustainably carry.

To quantify the size of the waste residue problem, we started with goals set forth by the USFS in their Wildfire Crisis Implementation Plan (2021). In this plan, the USFS committed to treating an additional 50 million acres on top of the 20 million acres already slated for treatment by 2032, bringing the total scope of planned fuels-reduction work to 70 million acres. We used this commitment to define the boundaries of our analysis, then applied FIA-derived stocking and species data, layered with wildfire hazard potential, slope, and proximity to road infrastructure, to identify the 70 million accessible, highest-hazard acres in need mechanical treatment and how much non-merchantable material each acre would yield if brought down to a healthy stocking level.

Published in a whitepaper and as part of the Roads to Removal report, this was an essential step to identifying the locations and quantities of residues that are likely to be generated in the near future. We conservatively estimate that these activities will generate over 1.2 billion bone-dry tonnes (BDT) of low-value waste residues, equivalent to over 2 billion metric tons of carbon dioxide by 2032.

Bivariate graphic of 2050, 70 million acre scenario. Low to high acreage per county (gray to bright pink) and low to high bone dry tons per county (gray to bright blue) are highlighted.

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Second, we measured what business-as-usual costs.

Despite the massive scaling planned for ecological thinning and associated pile burning, there were extremely limited sources describing the processes, costs, and emissions associated with the pile burning business as usual practice. To do this, we combined two data sources: five years of cost records from the USFS's own tracking database (FACTS), and in-depth interviews with 11 Forest Service fire management professionals across California, Oregon, and Washington who plan and run these burns firsthand. We also mapped each interviewee's forest against factors like road access, elevation, and slope to see what drives costs up or down.

The results showed pile burning costs more than previously reported: hand-piled treatments averaged around $1,291 per acre and machine-piled treatments around $735 per acre for piling and burning alone. Terrain and road access mattered most, with harder-to-reach, higher-elevation, less-roaded sites consistently costing more. We then used a Forest Service emissions model to show that burning these piles releases nearly 2 million metric tons of CO2-equivalent and thousands of tons of harmful particulate matter every year across just the forests we studied.

To translate these costs into something useful for the carbon removal market, we divided the per-acre disposal cost by the amount of biomass typically produced per acre. This calculation shows the USFS could pay a biomass offtaker $30 to $54 per bone-dry ton, the same amount it currently spends burning that material in the most accessible contexts, and come out budget-neutral. In other words, redirecting the money the government already spends on pile burning could instead fund removal of that wood for carbon storage or other productive uses, at no added cost to taxpayers.

This "avoided-cost subsidy" framing offers a practical, immediately actionable pathway to shift residues away from open-air burning and toward carbon-negative alternatives like biochar, burial, or bioenergy with carbon capture and storage.

Follow the link to access the resulting publication, Assessing costs and constraints of forest residue disposal by pile burning (available open-access or for direct download below).

Key Figures from Barker et al. 2025

Map of National Forests in the study region. Forests included in the study.

Pile burning emissions as simulated using the CONSUME model and study-derived inputs. (A) Indicates emissions ha−1, while (B) indicates annual emissions for the entire study area. These emissions simulations do not include machine emissions associated with cutting and yarding materials, or building piles, only from burning them.

Comparison of CDR Efficiencies (ηCDR) across pile burning as calculated in this study and against four alternative scenarios, including: BECCS, biomass burial, biochar production with agricultural application, and decay.

Next, we are quantifying the evolving biomass counterfactual.

Every carbon credit tied to diverting residue away from pile burning rests on a claim about what would have happened otherwise. If a forest owner would have burned that material regardless, diverting it to storage represents a real, additional reduction in emissions. If they would have hauled it to a mill, chipped it for mulch, or left it in place, the credited reduction is smaller, or in some cases doesn't exist at all. Getting this counterfactual right is what separates a credit that reflects a genuine change in outcome from one that simply pays for something that would have happened anyway.

The trouble is that disposal practice is not uniform. It varies by forest type, ownership class, geography and terrain, and over time, since disposal practice shifts with fuel costs, changing air quality regulations, burn permit availability, and the ebb and flow of state and federal funding for fuels treatment. A counterfactual built from a single average disposal rate, applied uniformly across geography and time, will systematically over-credit some projects and under-credit others.

Getting this right matters directly for the quality of carbon credits generated from wildfire residue diversion. A regionally and temporally resolved counterfactual, reflecting how disposal practice actually varies by forest type, ownership, and place, gives buyers a defensible basis for the reductions they're purchasing and gives project developers a fairer accounting of the value they're creating.

Building this requires several layers of data. Historical treatment and disposal records show what disposal method was actually used at a given site and when. Ownership and land management data identify who controls a given acre and what regulatory or budget constraints they operate under. Remote sensing and satellite-based fire detection can help identify where and when burning actually occurred over time, independent of self-reported records. Regional air quality and burn permit records show where smoke management regulations restrict pile burning and where they don't, which shapes disposal choice as much as cost does. And economic data on mill proximity, road access, and existing biomass markets helps explain why otherwise similar sites end up on different disposal paths. Compiling these data sources, we hope to build a model that reflects how disposal decisions are actually made, forest by forest and owner by owner.

Risks & Risk Mitigation

Treatment Pace and Agency Capacity

The scale of the projected residue opportunity rests on the USFS meeting its treatment targets, and there is real uncertainty about whether current agency capacity can support that pace. Fuels-reduction work depends on a specialized workforce, including foresters, fire management staff, and contract logging and hauling crews, that has struggled with chronic understaffing, budget instability, and difficulty retaining trained personnel in remote areas. Many treatable acres also sit in regions with limited contractor capacity or equipment availability, so even where funding and authorization exist, there may not be enough hands and machinery on the ground to carry out treatment at the pace targets assume. If treatment consistently lags behind stated goals, the volume and timing of residue actually generated could fall well short of current projections, with direct implications for the scale of any carbon or market opportunity.

Counterfactual Uncertainty

The lack of granular, ownership- and geography-specific disposal data makes estimating avoided emissions from residue diversion difficult to defend. To date, most public estimates of pile burning's footprint have relied on aggregated, high-level figures rather than site-specific or owner-specific baselines. The disposal records that do exist are often incomplete, self-reported, or inconsistently tracked across federal, state, and private landholders, and rarely capture how disposal practice shifts with terrain, fuel costs, or air quality regulation over time. This ambiguity makes it hard to credit projects fairly, since sites where pile burning was genuinely likely can end up treated the same as sites where an owner would have found another disposal path regardless.

Partner with us

We're always eager to connect with researchers, land managers, funders, and practitioners working on related challenges. If you have data, ideas, or questions that could sharpen this work, whether on counterfactual modeling, disposal practices in your region, or something we haven't thought of yet, we'd love to hear from you.

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