In their purest form, natural wildfires, most commonly caused by lightning strikes or volcanic activity, are a necessary part of the lifecycle in most ecosystems. They provide a number of important ecological benefits, such as reducing dead vegetation, stimulating new growth, and improving wildlife habitat. Indeed, a variety of plant and animal species depend on wildfires for their very survival.
However, in recent years, numerous countries, including the United States, have experienced significant wildfires that have moved far beyond these ecological benefits, leaving entire communities devastated and vital infrastructure destroyed. For example, over the past year, we have seen record-setting heat contribute to unusually severe wildfires in Europe and Canada, and have heard many in the scientific community assert that climate change is causing more frequent and more powerful extreme weather events. But, as powerful and impactful as these events may be, they alone cannot account for the increase in number and severity of these wildfires.
Unfortunately, there is one glaring factor that is present in a majority of the wildfires that occur today – that is, a majority of these wildfires are no longer naturally caused. In other words, they are no longer wild. The U.S. Forest Service estimates that nearly 85 percent of wildfires in the United States are caused by humans. In fact, a recent study, conducted by 15 universities, looked at wildfire data from 1980 through 2020 and found that well over 90 percent of the wildfires in California alone can be traced back to humans.
The study notes that these fires stem from a number of human activities, including arson, debris burning, smoking, recreational activities, equipment operation, vehicles, power infrastructure, and past land-management practices. However, when combined with dry vegetation and hot temperatures, only a small spark is needed to start a big fire.
Sadly, California is not alone in this regard. Most recently, we have seen the destructive power of these wildfires on the island of Maui and the historic town of Lahaina. Although the cause of these wildfires are currently unknown, it is estimated that over 98 percent of the wildfires in the Hawaiian Islands, which are home to six active volcanoes, including one on Maui, are caused by human activity. In particular, the spread of flammable, non-native grasses and shrubs have created large amounts of easily ignitable materials that when combined with high winds can greatly increase the risk and severity of a wildfire. Approximately 0.5 percent of Hawaii’s total land area burns each year, which is equal to or greater than the proportion burned of any other U.S. state.
While it is a scientific certainty that nature needs wildfires, we cannot deny our role in the unnatural number and severity of wildfires that we see today. Undoubtable, we have seen an outpouring of support and generosity to aid for those communities that have lost so much in the wake of these devastating wildfires. However, equally as important, we need to understand our role and how our actions may cause, and/or contribute to, these often avoidable disasters. As quickly as a spark can ignite, we can take deliberate, small, and equally as important steps to not only extinguish these flames but to prevent them from catching fire at the outset.
 MacDonald Glen, Wall Tamara, Enquist Carolyn A. F., LeRoy Sarah R., Bradford John B., Breshears David D., Brown Timothy, Cayan Daniel, Dong Chunyu, Falk Donald A., Fleishman Erica, Gershunov Alexander, Hunter Molly, Loehman Rachel A., van Mantgem Phillip J., Middleton Beth Rose, Safford Hugh D., Schwartz Mark W., Trouet Valerie (2023) Drivers of California’s changing wildfires: a state-of-the-knowledge synthesis. International Journal of Wildland Fire 32, 1039-1058.