Every winter, e.g. snow blankets in Alaska and northern Canada, wildfires are extinguished, and peace prevails – especially on land. Underneath all that white noise, some fires continue to spread on the floor, chewing carbon dioxide, depending on their duration. When spring arrives and the cold climate is disrupted, the “overwintering” fire erupts on the ground — which is why scientists call it a zombie fire.
Now new analysis in the newspaper Nature they describe their initial quantity, and indicate the potential causes for the fire to return. Using satellites and ground reports, researchers developed a method that can detect the location of a fire for more than 10 years – all – burnt in Alaska and the Northwest Territories of Canada, frozen in snow, and left for the summer. Basically, he connected the burning scars with nearby areas where a new fire broke out later. (He judged cases that would have been as if they had been struck by lightning, as well as approaching people as if they had been accidentally caused). It was estimated that between 2002 and 2018, the resulting volcanoes accounted for 0.8% of all landfills in these countries. This sounds like a small thing, but one year it became known: 2008, when one zombie fire was really responsible for getting 38 percent of all the burning sites.
Such a eruption could be a signal of things to come from the Arctic with extreme heat. Although 2008 was a very bad year, it was not in vain. Rather, it was part of the culture in which the zombie fire started. “They often appear in hot weather and in large fires,” says Rebecca Scholten, an electronics scientist at VU Amsterdam Research University, the lead author of the new paper. “And really, this is what we can show has increased over the last 40 years.” For example, the catastrophic fires of 2009 and 2015 in Alaska, and 2014 in the Northwest Territories, caused excessive fires in late spring.
The northern soils are full of peat, the dead plants are especially adequate ventilation. When a wildfire burns around the Arctic, it also burns around this area. As long as the top fire consumes the oil, the fire peat continues to spread under the soil, moving down and around. In research, Scholten and colleagues found that this could happen after the summer, as this causes the plants to dry out, thus burning more. “When they burn too much, they can get very hot in the soil,” says Sander Veraverbeke, a VU scientist at Amsterdam. “And the harder it burns, the more likely it is that the fire will go out. Even in the fall of winter, or in the cold of winter, water does not penetrate deep into the soil to suffocate it.
Then spring comes and the ice returns. The hot spot could explode, searching for more vegetation to burn on the edge of the original wound. “Basically, when the snow melts, we already have dry oil,” says Scholten.
This is exactly what he thinks happened in 2008 and in some years I have burned the zombie fire. A huge fire was burning on the ground, which gave them a chance to survive the winter. And researchers think that this is growing more and more. “We are really showing that the big fire years, associated with the summer, have been on the rise since 1975, and we hope that this will continue,” says Veraverbeke. “This will also help keep the fire from becoming too hot.”
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