‘Zombie fires’ and the burning of fire-resistant vegetation are new features driving Arctic fires, with strong consequences for the global climate, according to a study by an international team of scientists. This year’s wildfire season in the Arctic began two months earlier and was unprecedented in its extension.
“It is not only the amount of burned area that is alarming,” says Merritt Turetsky, from the University of Colorado in Boulder (United States), who adds: “There are other trends that we notice in the satellite data that tell us how it is changing the Arctic fire regime and what this means for our climate future“.
Scientists argue that the experience of indigenous peoples and other local communities are essential to understand and manage this problem global. The study, published in the journal Nature Geoscience, identifies new features of the recent Arctic fires.
One is the prevalence of remnant fires, also called ‘zombie fires’. The fire of a previous growing season can smolder in carbon-rich peat underground during winter and then reignite on the surface as soon as the weather warms up in spring.
“We know little about the consequences of the remaining fires in the Arctic, except that represent a boost in the climate system and it may mean that severe fires in one year set the stage for more fires next summer, “explains Turetsky.
The second feature is the new appearance of fires in fire resistant landscapes. As the tundra in the far north becomes hotter and drier, vegetation types that are not normally considered combustible begin to catch fire: dwarf shrubs, reeds, grass, moss, and even surface peat. Wet landscapes like swamps and salt marshes too become vulnerable to burns.
The consequences of this new fire regime could be significant for the Arctic landscape and peoples and for the global climate. More than half of the fires detected this year in Siberia occurred north of the Arctic Circle, in the permafrost and with a high percentage of ice on the ground.
This type of permafrost retains huge amounts of carbon from ancient biomass. Climate models do not take into account the rapid thawing of these environments and the consequent release of greenhouse gases, including methane.