Wildland Fire Smoke and Emissions Decision Support

The Thomas Fire burns in the hills above Los Padres National Forest during a firing operation, December 20th, 2017. USDA Forest Service photo by Stuart Palley.

The largest source of air pollution faced by the American public is wildfire smoke. Reducing wildfire smoke emissions is therefore a concern as the USDA Forest Service continues to follow through on its ambitious 10-year Wildfire Crisis Strategy. This strategy calls for lowering wildfire risk through an unprecedented increase in forest health treatments to reduce “fuels,” meaning anything that can burn, including trees, grasses, leaves, and branches. One way to do this is to conduct prescribed burns.

Many have argued that the smoke emitted from prescribed burning is “worth it” in the sense that these treatments reduce flammable vegetation, leading to smaller or less intense wildfires in the future, thus less wildfire smoke. That said, these trade-offs are hard to weigh because we lack analyses comparing the air quality impacts of prescribed burning to the air quality impacts of wildfire. A team of scientists is going to change this.

“When big wildfires come along, people want to know ‘What if we had done fuel treatments here? Would this wildfire be less intense? Would we be seeing less smoke?’” said Shawn Urbanski, a research physical scientist at the Rocky Mountain Research Station. He is leading an innovative, interdisciplinary, proof-of-concept study that will quantify the potential impact of prescribed fire treatments on future wildfire smoke emissions. “We want to look at the argument that if we’re going to do these prescribed burns and produce this smoke immediately, that there will be a benefit in the long term,” he said.

Urbanski and his team are focusing on landscapes within the Okanogan-Wenatchee National Forest in Washington State. These landscapes were identified in the agency’s 10-year strategy as priorities areas for reducing fuels. The researchers will be collaborating with the people who are making the work happen. “We will be testing different scenarios, so we will be working with land managers who will help us design them using actual prescriptions. This will allow us to develop scenarios that land managers are interested in,” he said.

By using computer models, the team will assess the probability of different fire size and severity outcomes from different climate scenarios and management strategies, including no management. “Our models will be simulating impacts on the landscape so that we will be able to say: ‘Here are the predicted smoke impacts in a typical year, but also in the 10 percent worst years,’ which are the ones managers are really concerned about – the really impactful outcomes,” said Urbanski.

Being able to weigh the smoke emission trade-offs between prescribed fire and wildfire will be a useful communication tool for gaining public acceptance for prescribed burning as a restoration tool. But Urbanski and his team’s work goes even further.

“The real reason for doing these prescribed fires is not just to prevent smoke emissions but to protect important resources we value and to maintain healthy ecosystems,” Urbanski said. “Our work will also be providing additional information that land managers want to know. For example, land managers on the Okanogan-Wenatchee National Forest have remote areas where they might want to let a wildfire burn and not suppress it as aggressively. We can help them examine alternative management strategies like letting fires burn in those places.”

Objectives

This project will develop a decision support framework for wildland fire smoke emissions that is risk-based. This framework will quantify potential impacts of prescribed fire treatments on future wildfire smoke emissions and allow comparison of emissions between prescribed fire and wildfire.

Expected Products

1) An analysis framework for assessing pollutant emissions and air quality impacts from near-term prescribed fire treatments and potential future wildfires. 

2) A quantitative assessment of potential smoke emissions and air quality impacts associated with prescribed fire treatment scenarios (based on actual prescriptions) and subsequent future wildfires in the Okanogan-Wenatchee National Forest. The analysis will include scenarios without prescribed fire treatments providing baselines to quantify possible net improvements in air quality over a 20-year time horizon. 

3) A geospatial database of simulated daily burned area, fire intensity, fuel consumed, and pollutant emissions for the different land management scenarios. This geospatial dataset can provide pollutant emission input for atmospheric modeling of smoke impacts.

Expected Outcomes

• Demonstration of the proposed modeling framework, the Prescribed Fire Emissions Impact System (PFEIS). 
• Coproduction of scenarios for simulated prescribed fire treatments through collaboration with fuel management planners from Okanogan-Wenatchee National Forest. 
• Trajectories of future greenhouse gas fluxes and forest structure, which will provide information on carbon sequestration and forest health associated with different prescribed fire strategies and the “no-action” scenario. 
• Land managers will be provided with a set of possible future outcomes for burned area, fire probability, fire intensity and pollutant emissions in treated and no-action landscapes.

Metrics of Success

Success can be measured based on the ability of the delivered outputs to address the uncertainty of wildfire and prescribed fire smoke production resulting from large-scale landscape fuel treatments.

Keywords: Smoke, air quality, wildfire emissions, prescribed fire