While the coronavirus distracts the world, a new foe has stealthily taken over Siberia, enveloping the taiga despite efforts to eliminate it.
The term “zombie fires” gained popularity last year when the Russian subarctic experienced an intense heat wave during the first half of 2020. Temperatures up to 38˚C and melted permafrost and created damaging wildfires.
Everyone sighed in relief when winter blanketed the region in a thick layer of snow. Little did they know that fires continued to brew beneath the snow! Seemingly impossible, right? But this week, videos showed parts of Siberia still burning from the last summer’s stubborn fires.
Satellite image of Siberia’s fires in July 2020. Photo: NASA
Zombie fires occur when fire from the previous season consumes carbon-rich plant material under the snow in winter. Highly flammable vegetation such as grass moss, shrubs, and peat insulate the fire, which either continues to burn or later reignites when the ground thaws.
Few realize that arctic permafrost contains a third of the world’s carbon-rich soil. This ancient permafrost stores thousands of years of carbon — fuel. Lightning usually ignites the fires in the first place. Burning peat is particularly destructive, because its greater heat melts permafrost and oxidizes the underlying peat, emitting destructive greenhouse gases. Burning peat releases more than 100 times carbon than a traditional wildfire.
Zombie fires in Alaska. Photo: Western Arctic National Parklands
There is no easy way of putting out a zombie fire. In 2008, firefighters in the United States pumped 7.5 billion litres of water into an area ravaged by zombie fires but had to wait months to see if it worked.
Researchers at the Imperial College London in the UK found a better solution. A non-toxic suppressant combines water and a “wetting” agent meant to increase the penetration of water in the soil. The suppressant let the water low evenly through the soil, and the fire died by 40 percent. Without this even distribution, the fire does not die out properly.
Here is an example of a zombie fire that still burned at -30˚C.
