How to Protect Forest Carbon in a Fire-prone Future | World Resources Institute Wildfire and Forest Carbon

In 2020, the U.S. land sector absorbed the equivalent of about 13% of the country’s greenhouse gas emissions, and most of this CO₂ removal came from forests. Reaching U.S. climate goals, however, will require the land carbon sink, including forests, to remove about 19% more CO₂ in 2030 than it did in 2020. In addition to increasing the capacity of lands to sequester carbon, there is also a need to protect existing carbon stocks. The role of US forests as a carbon sink is not guaranteed in a changing climate: U.S. Forest Service data show that since 1990, forests in Arizona, Colorado, Idaho, Montana, New Mexico and Utah [1] have consistently emitted more carbon than they absorbed. Together, these forests emitted 36.7 million tons (Mt) CO₂e in more than they sequestered in 2019, which is equivalent to the emissions from 7.9 million passenger vehicles driven for one year. This is a result of interconnected factors like drought, large-scale tree mortality from insect infestation, above-average temperatures and high-severity wildfires. These wildfires inflict long-term damage on forest ecosystems, hampering their ability to sequester carbon for decades and creating a dangerous climate-fueled feedback loop.

Western states with dry forests generally run the highest risk of wildfire. But it is likely that wildfire risk could increase in other regions, particularly in southeastern states, as the climate continues to change, further threatening forest ecosystems. In order to protect the carbon that is stored in U.S. forests and enable forest ecosystems to sequester more carbon into the future, there is a critical need for climate-informed management of forest ecosystems. This is also vital to advancing U.S. climate goals, protecting communities from catastrophic wildfire, creating jobs and economic benefits in rural communities and benefiting water quality and ecosystem health. Addressing these urgent needs will require more extensive research and monitoring, the development of markets for products that encourage and reward effective stewardship and the implementation of effective policies.

More severe wildfires lead to rising carbon emissions from forests

Forests in the Western United States have evolved with fire. For thousands of years, wildfires ignited by lightning or by native peoples as a land management strategy helped to clear dead plant matter from the forest understory and reduce competition between tree seedlings. These fires were generally of mixed severity and moderate in size, with large patches of low and medium-temperature fire sweeping through the understory and with small patches of high-temperature fire. Since the early 1900s, however, forest management has been guided by the mandate to suppress fires as soon as they start. As a result, dead biomass, shrubs and saplings now crowd the forest floor, providing fuel for large-scale, high-temperature, severe wildfires that climb into tree canopies and kill large swaths of forest. This dynamic is amplified by the hundreds of millions of trees that have died from drought, rising temperatures, and insect infestations, providing additional fuel for severe wildfire. In California’s Sierra Nevada mountains alone, 129 million trees died from drought and insect infestation between 2010 and 2020. As tree deaths and the number of severe wildfires have increased, so have carbon emissions.

The long-term impact of wildfire on forest carbon depends on three interconnected factors:

1. The environmental and ecological conditions present in a forest, including the number of fire-adapted species and quantity of highly flammable fuel
2. The severity of wildfire that burns the forest
3. The ability of a forest ecosystem to recover after a fire  

Mild and moderate severity fires can result in a temporary forest carbon loss as brush and small-diameter saplings burn. Research shows that healthy forest ecosystems have historically been able to recover the carbon lost from mild and moderate severity burns over the course of 1-2 decades and continue to sequester carbon as plants regrow. Some research suggests that mild to moderate-severity fires may even increase the ability of forest soils to sequester carbon.

The large-scale, high-severity fires now common in Western states, however, have an effect on carbon sequestration that is much larger and more negative in the long-term. High-severity fires that burn hundreds of thousands of acres can kill entire forests of mature trees, releasing stored carbon in both trees and forest soils into the atmosphere. Beyond carbon lost to the atmosphere during the fire, the forest also loses its ability to sequester carbon into the future. Severe fires can destroy seeds that help forests regrow, and increasingly hot and dry conditions can present inhospitable conditions for seedlings. There is strong agreement among scientists that a changing climate will decrease the ability of forests to recover from severe wildfire. Research shows that in some Western forests, severe fires coupled with heat and drought are permanently transforming forests into shrublands, which decreases the ecosystem’s ability to sequester carbon.

Preventing the worst impacts of wildfires requires all-in action

Severe fires can compromise the ability of forest ecosystems to store carbon, threaten communities — especially those in the wildland-urban interface—and damage watersheds that provide drinking water for humans and wildlife. In the face of these threats, it is crucial to manage fire-prone forests to support their climate resilience and adaptation and their long-term ability to sequester carbon and to actively  that have been damaged by wildfire.

Managing forests for wildfire will require all types of landowners and land managers to collaborate to address pressing problems at a landscape scale. Across 11 Western states, approximately one third of the acres with high fire risk are on private or family-owned land and two thirds are on federal, Tribal or public lands.

Increasingly, scientists, landowners and managers, policymakers, and, state and federal agencies are recognizing the urgent need to scale up the implementation of effective forestry strategies that can help lessen the severity and impact of wildfire. Scaling the magnitude of forest treatment to meet the scale of the threat of wildfire will require sustained investment from federal, state, Tribal and local governments, as well as innovative financing mechanisms to support these projects.

To mitigate the risk of severe fire, forest managers can draw from a toolbox of techniques that reduce the load of highly flammable material in forests. These techniques, referred to as ‘fuel load treatments’, include prescribed low-intensity burns; manual or mechanical removal of dead trees, small-diameter trees and brush while leaving large-diameter healthy trees standing; and the creation of fire breaks that can stop the progress of a fire. More research is needed to accurately quantify the short-term (5-10 year) and long-term (10-50 year) carbon impacts of these treatments in different ecosystems. But many studies indicate that while there is an initial loss of carbon, ecologically informed fuel load treatments may protect the carbon stored in forests in the long-term. This only holds true, however, when healthy, large-diameter trees are not harvested in the process of fuel load treatment. These treatments also may help to decrease the rising cost of suppressing wildfires once they have started. In 2021, the Forest Service and Department of the Interior spent a combined $4.39 billion on wildfire suppression, which is almost double the ten-year average. Action to prevent high-severity wildfire also can reduce the need for firefighters to endure brutal and dangerous working conditions to manage fires and can lower the risk of prescribed burns getting out of control.

Because the planning and implementation of these treatments—especially prescribed burning—needs to be tailored to enhance forest health and keep adjacent communities safe, teams of trained professionals are required to conduct treatments. Furthermore, these treatments are often conducted in remote or mountainous areas leading to high costs and labor needs—which can inhibit large-scale treatments. WRI research has found that treatment costs span approximately $200/acre to $1700/per acre, not including project planning and site preparation costs, and treating all high fire-risk forests would require an investment of $30.8 billion over the span of twenty years. The Bipartisan Infrastructure Law makes a vital down payment: it includes $3.3 billion for wildfire risk reduction and $2.2 billion for forest restoration and development of nursery infrastructure. The 2022 Inflation Reduction Act also contains $2.4 billion for fuel load treatment and forest restoration on federal lands, which would contribute to this down payment if the bill were to pass. Additional funding through public-private partnerships like Forest Resilience Bonds and Resilience Funds will, however, be necessary to manage the threat of wildfire at a landscape scale and restore burned ecosystems for decades to come.

Using thinned biomass could reduce emissions and fund forest treatments

In the face of climate change and high costs for fuel load treatments, there is an opportunity to use dead plant matter removed from fuel load treatments to generate funds to support forest management and sequester carbon. Currently, low-market value biomass removed as part of fuel load treatment is often burned in piles onsite because it is cost-prohibitive to transport it out of forests. This means that the carbon stored in the biomass is released into the atmosphere, diminishing the potential positive carbon impact of fuel load treatment.

Because the small-diameter biomass and dead trees removed during fuel load treatments currently have limited market value, they are not widely utilized in products. Where biomass is utilized, it is often incinerated to generate electricity, a process that can negatively impact air quality in surrounding areas. There is the opportunity, however, to develop markets for small-diameter thinned biomass to channel it towards low-carbon or carbon-negative end uses. These include biochar, which can be used to increase carbon sequestration in soils; oriented strand board, a plywood-like building material; or green hydrogen with carbon capture and storage, which WRI research has found to be a key technology for reaching net zero emissions in the U.S. These climate-friendly end uses are currently greatly constrained by the cost of building and retrofitting production facilities and by the lack of a steady and reliable biomass stream to support a market for them. States like Oregon, Washington and California, among others, are already piloting initiatives to incentivize ecologically informed fuel load treatments by developing markets for products generated from thinned biomass. Increased investment in building the infrastructure to create products like biochar or biomass hydrogen, coupled with lifecycle emissions analyses of producing these products, are critical to increasing the climate benefits of fuel load treatments.

Investment in wildfire risk mitigation treatments and the utilization of thinned biomass have the potential to create jobs and support rural communities. WRI research has found that fuel load treatment and the downstream impacts of biomass utilization could support 49,000 jobs lasting for 20 years in rural communities, mainly in Western states. Federal, state, Tribal and local investment in fuel load treatments, workforce training and the development of markets for thinned biomass can support forest resiliency to wildfire as well as community safety and economic growth.

Federal policy can support the resiliency of the forest carbon sink

In recent years, federal agencies have made commitments to increase ecologically-sound fuel load treatments, prioritizing partnerships and public input in designing and implementing forest management strategies. In a July 2022 memorandum to the U.S. Forest Service, USDA Secretary Vilsack emphasized that the Forest Service must take action to steward the carbon sequestered by forests, including by treating and restoring forest ecosystems to increase their resiliency in the face of wildfire and climate change.

In the near future, the 2023 Farm Bill offers an opportunity to further ensure that federal policy supports forest resiliency. Farm Bill programs including the Collaborative Forest Landscape Restoration Program, the State and Private Forestry Landscape-Scale Restoration Program , the Good Neighbor Authority, the Wood Innovation Grant Program and the Community Wood Energy and Wood Innovation Program offer funding opportunities that support cross-boundary and collaborative fuel load treatments, forest restoration and development of wood products markets. In order to maximize these programs’ impact on forest health, climate and communities, Congress should ensure that the 2023 Farm Bill reflects the following priorities:

1. Support the responsible development of supply chains for climate-beneficial innovative wood products: Competitive grant programs should help to incentivize the utilization of low-market value, small-diameter thinned forest biomass in low-carbon or carbon negative products.
2. Increase funding for research related to forests and wildfire management and increase the coordination and accessibility of data: Federal research funding should be used to assess the immediate carbon and environmental impact of forest health interventions, as well as the impact of treatments on landscapes over time. Federal funding for fuel load treatment and/or post-fire restoration should be accompanied by funding to track work accomplished and long-term outcomes on treated land.
3. Increase the ability of underserved and rural communities, including indigenous communities, to inform and benefit from fuel load treatment and biomass utilization: Grant programs should prioritize projects that provide economic and social benefits to local and underserved communities.
4. Increase meaningful partnership with Tribal communities and incorporate indigenous knowledge and practices of fire usage and forest management wherever possible. Many Tribal communities are on the frontlines of wildfire threat and are under-engaged in planning and executing fuel load treatment on neighboring federal and state lands. Traditional fire and forest management practices are also historically undervalued. All fuel load treatment projects adjacent to Tribal land or on lands of cultural significance should prioritize partnership, informed consent to activities and transparent communication.
5. Improve collaboration among federal and state, community and tribal forest management and increase opportunities for public-private partnership: Federal initiatives, including those funded by the Farm Bill, should be complementary to state and local forest management and wildfire risk mitigation plans. Wherever possible, the USFS should utilize the Good Neighbor Authority, the CFLRP and other mechanisms to contract with states, counties and Tribes to design and implement projects, and these projects should seek to leverage private finance and innovative financing mechanisms to increase the impact of federal funds. Where revenue will be generated from sale of timber or biomass, the USFS should ensure that timber and/or biomass is removed in a manner that supports forest health and ecosystem resiliency and is accompanied by ecosystem restoration.

With support from federal policy and investment, and through partnership with states, Tribes, and communities, the U.S. can start to make fire-prone forests more resilient to the increasing threat of severe fire. These actions can help to protect forest carbon and the many ecosystem services and economic services that forests provide. Forest management can also help the U.S. meet its climate targets; however, the U.S. must also prioritize ambitious and urgent emissions reductions to ensure that climate-related factors like heat and drought do not increasingly exacerbate wildfire severity.

[1] While U.S. Forest Service data suggest that California’s forests were a net carbon sink in 2019, some California state data suggest that California’s forests have become a net carbon source. This uncertainty is due to differing methodologies used to inventory forest carbon.