Fire suppression and wildfire intensity

Driving through Jasper National Park in the last few weeks was a sobering experience. The scale of the destruction caused by the Jasper Complex fire is overwhelming. As a result, it was hard not to reflect on the reasons behind the scale of the fire. Climate change and wildfire is one of the more difficult relationships to unpack. There is a general consensus that climate change does increase the risk of fire (e.g., Pandey et al., 2023; Hillayova et al., 2023; Perez-Invernon et al., 2023). But there are a number of different factors that influence this including precipitation, human-nature interface, and even the threat of lightning. One of the factors that impacts this is fire suppression.

Western-based forest management has generally prioritized fire suppression. Even as the role of fire has become better understood in how it provides ecological benefits, the first response to many wildfires is suppression. This has allowed fuel to accumulate within forests. If you have every started and maintained a wood burning fire, you will be familiar with how fuel influences the size and intensity of a fire. More fuel generally means that the fire will be larger. This is what is known as the fire suppression paradox “by putting out a fire today, we make fires harder to put out in the future” (Kreider et al., 2024, Introduction, para. 2).

Using computer modelling, Kreider and colleagues (2024) found that fire suppression had a significant impact on fire severity beyond what would be accounted for by different climate change scenarios. The more intense the suppression approach taken, the more intense the fire severity when a fire does occur. However, not all suppression is created equal.

Obviously, there are some fires that are so severe that suppression is not possible. But inside of that boundary there are two approaches, regressive and progressive suppression. Regressive suppression focuses on stopping low-intensity fires quickly. Progressive suppression, on the other hand, focuses on higher-intensity fires that are still within the range of possible suppression. Perhaps unsurprisingly, regressive suppression has the most significant impact on the severity of later fires. If you suppress all the low-intensity fires, more fuel accumulates in the forest. But, if you focus on higher-intensity fires, the fire reduces the fuel available for future fires. And, it results in a more even distribution of burned areas.

I think that this quote from Kreider and colleagues (2024) sums up what is happening: “The result [of regressive fire suppression] is akin to the over-prescription of antibiotics: in our attempt to eliminate all fires, we have only eliminated the less intense fires… and instead selected for primarily the most extreme events” (Discussion, para. 1). Aside from the consequences of these more extreme fires for humans there are also ecological and biological impacts. Some species are actually fire-dependent, such as lodgepole pine, which has a waxy coating protecting its cones that is removed by wildfires and allows the seeds to germinate. Fire also introduces change and adaptation into the environment, which can better allow it to change in the face of pressures like climate change. The frequency of fire can also impact how quickly resprouting happens with lower fire frequency resulting in slower rates of resprouting (Harrison et al., 2021). Smaller fires happening over longer time periods also tend to increase the stages of succession or the diversity plant species within an area. They create more of a mosaic which then supports greater animal diversity as well.

The time we are currently living in is seeing many different human decisions adding up to create more extreme consequences. Fire is one of these that is complex. It is clear that we need to change our approaches to fire in order to adapt.