B.C.’s worst-ever wildfire season in 2023 appears to have carried over into 2024.
The mild and dry fall and winter have created perfect conditions for a record number of so-called “zombie fires.”
“Zombie fires” ignite and burn during the wildfire season, then go dormant over the winter period before reigniting again the following season in the spring, according to experts. They burn deep underground and remain undetected for a considerable amount of time before re-emerging.
Many parts of B.C. had lower-than-average rain in the fall and the ground did not become saturated enough to extinguish them.
The fires can continue to burn underneath the snowpack and can then pose a new danger come the spring.
John Davies, a senior wildfire management specialist with Forsite Consultants, said “zombie fires” can also be known as holdover fires.
He said they are seeing a lot of these fires in northern B.C.
“The ecosystems out there have very deep, dark duff depths with is basically just decomposing vegetative or woody biomass,” Davies said.
“They have a very, very deep organic layer. That’s what makes it possible for these fires to burn underground is that they have lots of fuel, so this decomposing vegetative matter, and they have oxygen, and so they just burn subsurface.”
Davies said the fire can burn slowly through the vegetative matter until the spring comes and it can move back up to the surface and become visible once again.
He said “zombie fires” can become a concern when they are burning near an edge that does not have a fireguard and they have access to unburned fuel.
Dr. Lori Daniels, a professor and Koerner Chair in Wildlife Coexistence with the Faculty of Forestry at UBC said they are watching these fires closely as the province heads into the spring.
“Our concern is that in the spring, when it warms up again, you get warm, dry days and it’s typically on a breezy day where you get a bit of wind fanning those flames that we get these zombie fires popping up to the surface and beginning to burn again as a surface fire and beginning to spread through the forest,” she said.
“So BC Wildfire and other wildfire agencies across Canada will be on high alert this spring watching for those zombie fires on the edges of those very large fires that burned all across our country last summer.”
Last week, the province reported the snowpack is at 61 per cent of normal with the South Coast mountains recording only 30 to 47 per cent of seasonal averages.
This well-below-normal snowpack is raising concerns about drought heading into the spring and summer months.
Daniels said a couple of examples of “zombie fires” include the Horse River Fire, which forced the evacuation of Fort McMurry on May 1, 2016. That fire was not declared out until August, 2017.
She said some of the bigger fires in B.C. have also taken more than a year to be declared out because parts of them burn underground as “zombie fires.”
On Dec. 31, 2023, there were more than 100 fires still burning around the province.
Daniels said when hot and dry conditions are present in the spring dip, that is when the fires become a concern.
“There’s a gap between when the snow melts and when the broadleaf trees produce their leaves and create shade and cooler temperatures in more humid conditions,” she said.
“That window between snow melts, and the broadleaf trees are producing their leaves is called the spring dip. It’s a period when there’s concern about new fires starting or those ‘zombie fires’ emerging to the surface and causing problems. So we’ll be on high alert as the snow melts this spring into the summer conditions.”
Daniels added that climate change means the province is seeing these hot and dry conditions earlier and, in some places, year-round.
“More extreme temperatures and drought in the summertime are all contributing to both the size of the fires, the intensity of the fires and the chances that they’ll continue to smolder through the winter.”