By Elliot Witscher, 2023 Science Communication Intern 

Over the past few decades, wildfires in the western United States have become more frequent and have burnt a larger area more severely than in the past. The resulting impact on humans and ecosystems is impossible to ignore. At GSA Connects, the Geological Society of America’s annual meeting, in October 2023 in Pittsburgh, Penn., many researchers discussed the impact of wildfire on the environment, human health, and related geologic hazards. 

One presenter, Camille Stevens-Rumann, a professor at Colorado State University, works on studying the impact that repeated wildfires have on ecosystems. Stevens-Rumann became interested in studying post-fire ecosystem changes while working as a wildland firefighter for the U.S. Forest Service after she completed her bachelor’s degree. She says, “I’ve been to all these beautiful places that I watched change, really dramatically, in a matter of minutes. I want to see how they change over the matter of decades.” This desire to watch long-term change was part of her motivation to pursue a Ph.D., and she is now a professor, leading a large lab studying post-fire ecology in Colorado. 

Alexander Gorr, a Ph.D. candidate at the University of Arizona, also studies post-fire processes, specifically working to model debris flows following wildfires. Wildfires increase the risk of flooding and debris flows for several reasons, including loss of canopy and vegetation cover and the fact that burned organic matter in the soil resolidifies post fire, “coating soil particles in a kind of waxy material that makes soil less able to infiltrate water.” When these factors are combined with a rainstorm, water flows across the surface of the ground instead of seeping into the soil. This water will pick up sediment as it moves, and at a certain point it will turn into a debris flow, a fast moving mixture of water and sediment. These debris flows can destroy houses, roads, and bridges, and, Gorr says, “unfortunately it seems every year they take a few lives.” 

Gorr says that one of the biggest misconceptions that he sees about post-fire debris flows is that “the hazard stops with the fire.” After evacuating to avoid a fire, being displaced for a potentially extended period, and finally returning to regular life, “a lot of people think that the hazard is over because the fire is done.” In reality, post-fire debris flows can damage homes and other infrastructure and even become deadly. They are a risk that can exist long after the area initially burns. 

These impacts are especially pronounced in areas that have burned repeatedly in a relatively short period of time. One example Gorr gives is an area near Flagstaff, Arizona, that had wildfires in 2010 and 2022 that both burned the same series of watersheds. In these areas, debris flows and flooding following the second (or third or fourth) burn will be much larger and stronger, potentially impacting a wider geographic area. As these debris flows move soil and organic material away from their original location, trees have an increasingly difficult time growing back, and forests may not fully reestablish, allowing the cycle of debris movement to continue. 

As we move towards a changing future climate, our response to wildfires must change, especially in western states where wildfires are quickly becoming a fact of life. One of the biggest things we can do to improve our relationship with fires, Stevens-Rumann says, “is changing our perspective to fire suppression as the exception” when dealing with forest fires. In areas where fires do not pose an immediate threat to human life or homes, allowing smaller fires to burn will thin out underbrush and other potential fuel that, under fire management policy in the recent past, has built up and allowed for rapid spreads of giant fires. 

Learning to live with the changed landscapes from fires is difficult and painful, yet important for those living in the American west. Stevens-Rumann knows that “it is really hard when you are in a place that you love and are really connected to” and that place is dramatically changed overnight due to wildfires. “It’s hard to accept and figure out how to change the expectations of the system after these big events.” The work of geoscientists like Stevens-Rumann and Gorr is helping create a path to a future where society can live alongside fire and hopefully avoid the devastating effects that are currently impacting people around the world. 

The GSA Science Communication Internship was a program offered at GSA Connects in Pittsburgh, Penn., designed for student attendees interested in science communication as a possible alternative career path.  Interns were paired with GSA’s Science Communication Fellow in order to gain experience in making science clear and exciting, under the tutelage of a professional writer.  Students were assigned to conduct interviews with presenters at the meeting and to compile summaries capturing the significance of the presenters’ work for a non-technical audience.  Media assignments and mentoring were useful learning experiences and exposure opportunities for students seeking to expand their knowledge into geoscientific reporting.