Closing Thoughts

Climate change is fundamentally changing ecosystems and their fire conditions. The 2023 fire season, still active during the workshop, highlighted the urgency of developing and implementing solutions to address wildland fires. While the focus of the workshop was on improving understanding to ultimately reduce greenhouse gas (GHG) emissions from wildland fires, many workshop participants emphasized the importance of balancing mitigation efforts that are climate effective, socially inclusive, and ecologically appropriate. Key to the consideration of how direct and indirect (i.e., climate change-driven) human influences on GHG emissions from wildland fires may impact efforts to reach net-zero emissions, several speakers highlighted that the reduction of GHG emissions from anthropogenic sources could be critical for slowing the impacts from climate change on fires and ecosystems.

A key theme highlighted throughout the workshop was the importance of not only learning from current and historic practices of Indigenous peoples, but also centering Indigenous voices and leadership in all stages of fire management. Many participants emphasized that engaging local communities who live in and manage these systems and benefit from land use is a critical part of identifying and implementing appropriate intervention strategies. Colonial policies of fire suppression have disrupted historical land use and cultural practices, and today, communities largely do not have the opportunity to reintroduce fire to the landscape and steward their lands. Discussions highlighted opportunities to shift the current regime of fire management to allow fires of choice and reduce GHG emissions, including reintroducing cultural burning and cultural land management practices.

Workshop discussions centered on ecosystems particularly impacted by climate and land use changes where historical fire regimes and the carbon balance have been disrupted. Discussions were organized about three global biomes—temperate, Arctic/boreal, and tropical—with the recognition that ecosystems are heterogeneous and diverse in their ecological conditions, culture, and landscape resilience.

In temperate forest systems, both direct and indirect (i.e., climate change) human-driven changes to the fire regime are threatening carbon stocks, or carbon carrying capacity. Changes in the frequency or intensity of fires have impacted the ability of these systems to regenerate or regrow vegetation that historically served a self-regulating function. In the western U.S. dry, temperate ecosystems in particular, a century of fire suppression has led to dense forests that have likely exceeded their carbon carrying capacity with an elevated risk of high-severity fire. Today’s conditions are very different from historic landscapes where there were lower-density forests and carbon stocks that had frequent lower-severity fire. Fuel and landscape management solutions will likely be important going forward, including cultural burning, prescribed burning, active management of wildfire, and mechanical fuel reduction.

Increases in the frequency and severity of wildland fires due to climate change in the Arctic and boreal regions is threatening the large amounts of carbon that have been stored for decades or centuries as permafrost. Burning in boreal systems is dominated by combustion of belowground carbon. As fire severity in these systems increases, it will decrease the net primary productivity of boreal forests, thin the organic layer on the ground, warm soils, and lead to faster decomposition and turnover of biomass—a cycle that will continue and could lead to permanent permafrost (carbon) loss after fire.

Arctic and boreal systems are warming more rapidly than global average temperatures; however, reducing emissions from future fires is challenging because these are very large areas with low population density and limited infrastructure. Within the boreal, there are large regional differences in flammability, carbons stocks (e.g., permafrost, peat), and fire risk. Responding to massive and accelerating changes in the boreal may involve large investments in people and response mechanisms. Global science and policy collaboration and funding may be needed to substantially reduce emissions across the Arctic and boreal region. Solutions in the boreal may involve a mix of approaches, including targeted suppression of early-stage fires in carbon and Yedoma permafrost–rich coniferous habitats, cultural burning, post-fire seeding to accelerate recovery, and in some geographies, stopping the suppression of broadleaf species to reduce fire spread, which may include economic incentives to utilize broadleaf species as part of the bioeconomy. However, there are trade-offs in the reduction of conifer habitats that are important for some endangered species and for trapline users.

In tropical peatland systems, rapid large-scale land use change—from agriculture and land clearing—has drained peatlands making them more vulnerable to fire. Natural climate variability (e.g., El Niño–Southern Oscillation) can amplify fire activity in these regions and increase GHG emissions. In tropical peatland systems where human activities have disrupted the ecosystems, water management to re-wet and maintain higher water tables in peatlands and land management that protects systems that are burning frequently for agriculture could reduce GHG emissions and protect ecosystems. However, fire in many tropical and subtropical ecosystems is essential for food security, so it is important to balance livelihood security with fire prevention. Tropical forests are also at increasing risk due to changes in the three drivers of fire in these systems: fuels, ignitions, and climate. Reducing deforestation could be the most effective strategy to manage wildfire risk.

In Australia, where there is a mix of ecosystem types, low-intensity burning early in the fire season can reduce high-intensity, late-season fires and their emissions in the northern tropical savannas. On the other hand, in temperate forests in Australia, ignition management together with strategic applications of prescribed burning, could reduce emissions from wildfires.

To implement the suite of fire and land management strategies discussed throughout the workshop, several participants highlighted that investments in resources—including for workforce and capacity—would be useful. Speakers noted the difference between cost-effective (i.e., cost per ton of mitigation) and low-cost solutions, and pointed to an increase in resource allocation that may be important to match the scale of mitigation required.

However, the use of carbon markets to finance fire management could disincentivize overall reductions in emissions.

Several speakers identified opportunities to advance observational and modeling tools to improve understanding of current and future fires and their associated GHG emissions. Given the complexity of fuels across all types of landscapes, some participants highlighted a goal to better characterize the total mass, physical structure, and chemical and water dynamics of fuels. Relatedly, better characterization of fire behavior and fuel consumption—including the spatial variation and moisture content—could improve both observation- and model-based GHG emission estimates. From a carbon emissions perspective, there is a gap in accurately characterizing prescribed, small, and cooler (e.g., surface, nighttime, peat) fires, and emissions from duff, peatlands, and permafrost. Continuous, consistent satellite observations also have a role to play, and high-resolution geostationary observations and trace gas retrievals are an opportunity to improve understanding at higher spatial resolutions.

In addition to observations, there are diverse mechanisms that represent fire ignition, spread, suppression, and extinction in models where decisions are made about the process-level detail to represent fire at large scales. Model representations of vegetation–fire feedbacks are particularly important for predicting future fires. For example, in tropical savanna systems, interactions between fire, carbon dioxide, shrubs, and grass may have a positive feedback on emissions. To build confidence in projections of wildland fires and their emissions, participants discussed the importance of evaluating how well models simulate observed spatial patterns, annual cycles, interannual variability, and long-term trends of fire and land cover. Additionally, accurately simulating succession could be an important test of the ability of dynamic vegetation models to capture fire processes.

Another accounting mechanism important for decision making is the reporting of inventories of national GHG emissions by countries as part of international agreements. This reporting by design focuses on direct human (anthropogenic) emissions and removals. Emissions from wildland fires, if they occur on unmanaged lands or on some managed lands, are not accounted for as part of national inventories; on the other hand, prescribed fire emissions are always accounted for. Countries—including the United States, Canada, and Australia—are working to reduce uncertainties of national wildfire emission estimates, particularly by expanding inventories into managed and unmanaged forests. However, some participants highlighted the importance of being realistic about the limitations of the land sector to increase or even maintain current carbon sinks as climate impacts increase.

The enthusiastic participation of the academic, governmental, private, practitioner, and Indigenous communities in the workshop demonstrated the energy around improving understanding and finding solutions to reduce GHG emissions from wildland fires. Participants discussed opportunities to shift the current regime of management toward carbon-focused management that could increase the resilience of ecosystems to store carbon. This moment of increasing vulnerability to wildfires is a chance to turn attention toward the diverse set of available regionally differentiated, ecosystem-appropriate mitigation strategies.