Effects of ‘Zombie’ Fires on Western Canada’s 2024 Wildfire Season

Communities in Western Canada have been bracing for the 2024 wildfire season with a sense of urgency for months now. The cause? Overwintering or ‘zombie’ fires that burn slowly beneath the snow.

These flameless smoulders are kept alive because of the peat moss that covers the forest floor and the thick layer of snow insulating them from the cold. Peat moss is made up of decomposed organic materials from peat bogs, a type of wetland commonly found in western Canada. Peat moss naturally holds large quantities of water, but warmer weather conditions cause the moss to dry and act as a super fuel that keeps the zombie fires burning.  These fires can reignite when the snow melts and they are again exposed to air. Zombie fires are at an increased risk of reignition due to a combination of climate change driven factors, including warmer-than-usual winter conditions, reduced snowpack, quicker ice melt, and less spring rain, resulting in spring drought conditions. Taken together, these factors have led to the premature onset of wildfire season.

After a record-breaking 2023 season in British Columbia, which saw 18.5 million hectares of land burned in wildfires and a surge in the number of large ‘mega fires’ (i.e., fires that burn more than 100,00 acres or 40,500 hectares of land), hopes for a quieter and less destructive 2024 are slimming. On top of the zombie fire phenomenon, the World Meteorological Organization recently confirmed that the 2023-2024 winter period was the warmest Canadian winter ever recorded.

According to BC Wildfire Services, last year’s season resulted in: 

-An estimated 208 evacuation orders, which affected approximately 24,000 properties and roughly 48,000 people; and

-An estimated 386 evacuation alerts, which affected approximately 62,000 properties and roughly 137,000 people.

When a property is affected by a wildfire (or a structural fire), the 30 Forensic Engineering team is frequently asked to perform smoke contamination and/or indoor air quality assessments. These assessments determine the extent of the impacts and if they pose a threat to human safety.

Since 2021, we have completed 34 wildfire and smoke contamination assessments in Alberta, British Columbia, and the Northwest Territories.  A reoccurring trend is that regions with increased and severe wildfire activity are likely to have elevated background levels of combustion by-product (i.e., soot, ash, and char concentrations) compared to regions with low wildfire activity. This consideration is imperative when discussing pre-loss conditions and developing remediation strategies.  

Business owners that complete proactive pre-loss risk assessments to determine baseline combustion by-product concentrations could save days of lost time and tens of thousands of dollars in smoke remediation costs if their property is affected by structural or wildfire smoke. Further, business owners can be prepared for poor indoor air quality and increase worker safety by implementing precautions such as carefully planned HVAC maintenance and operation schedules and the placement of air scrubbers to move air and filter the fine smoke particulate. 

With the 2024 wildfire season now underway, communities in BC and Alberta are already beginning to experience evacuation alerts. It is imperative that western Canadians do what they can to prevent wildfires initiated by human activity. Residents of Western Canada can play a role in reducing the growth of wildfires by adhering to fire bans and reporting fires to the provincial wildfire reporting centre. In BC, the public can also use the ‘Report a Fire’ function in the BC Wildfire Services app.

If your property has been impacted by smoke contamination from a wildfire or structural fire, or if you are interested in a proactive pre-loss risk assessment, please don’t hesitate to reach out to us.

Feature image via Sonja Leverkus: Zombie Fires’ burning at an alarming rate in Canada (