With increasing frequency, lightning is observed well beyond the Arctic Circle, where it was previously very rare. Today, they represent a new risk of triggering fires in the Arctic.
Thunderstorms and lightning far beyond the arctic circle
In the Arctic landscape, if there is one thing you rarely see, it is lightning. However, with temperatures rising three to four times faster in this region of the globe, the presence of warm and humid air is more and more frequent: the result is conditions conducive to the formation of thunderstorms and the production of lightning.
Chris Vagasky has observed this. He is a meteorologist and an expert in the Vaisala Global Lightning Network lightning detection system.
“In 2021, we detected 7,000 lightning strikes in total. This was almost twice the combined number of lightning strikes detected in the previous nine years. This is a significant number at these latitudes and even beyond 80 degrees North. »
— Chris Vagasky, meteorologist, Vaisala
Chris Vagasky is a meteorologist and expert in weather detection systems. eclairs at Vaisala
In the summer of 2019, lightning was detected just 50 kilometers from the North Pole, a latitude at which lightning has never been detected. In Alaska, in the Canadian Arctic, as in Siberia, lightning is less and less rare.
Des lightning was detected very close to the North Pole.
As Alex Young, an American meteorologist in Fairbanks, Alaska, points out, it is partly the improved detection capability that explains why there are more lightning strikes. Lightning detection systems in the Arctic have mainly been developed over the past ten years, which makes comparisons beyond this period more difficult.
That said, meteorologists at high latitudes observe changing climate conditions. Alex Young reports more severe weather events than usual in recent years in Alaska. This warm weather, beyond the Arctic Circle, is no stranger to the intensification of fires in these regions.
Alex Young is a meteorologist with the US National Weather Service in Fairbanks, Alaska.
In the summer of 2022, Alaska and Siberia experienced some of their most severe fire seasons. And lightning can play an important role in starting some fires. Researchers like Sander Veraverbeke of the Free University of Amsterdam have studied the sites of these recent fires in Siberia.
“The majority of fires are started by humans, but in remote Arctic regions, the spark plug is lightning. Almost all fires inside the Arctic Circle are triggered by lightning.
— Sander Veraverbeke, Professor of Climate and Ecosystem Studies, Free University of Amsterdam
As the forest and the tundra dry out, with rising temperatures, the ignition capacity increases and it would be, according to Sander Veraverbeke, the combination of drier materials on the ground and the number of lightning strikes that would lead to more ignitions in the far north.
Sander Veraverbeke is Professor of Climate and Ecosystem Studies at the Free University from Amsterdam.
With the intensification of fires in summer at very high latitudes, a curious phenomenon has also been observed the following winter. Fires that persist incognito in the depths of the bog and burn slowly all winter long, under the snow. We nicknamed them zombie fires.
< p>“Lightning-triggered fires occur mostly at the summer solstice in June. But with these phantom fires that last all winter, the sites flare up again as soon as the snow has disappeared. As a result, the fire season starts earlier. »
— Sander Veraverbeke, professor of climate and ecosystem studies, Free University of Amsterdam
This is what the researcher's team recently observed in Siberia. Satellite images show that, very early in the spring, the fire started around the edge of a site burned the previous summer before gaining ground throughout the summer.
Very early in the spring, the fire is active around the edge of the area burned the previous summer.
< p class="e-p">How to explain that these fires which run under the snow are not extinguished in contact with the water resulting from the melting of the snow? Jennifer Baltzer, professor and Canada Research Chair in Forests and Global Change at Wilfrid Laurier University in Ontario, explains that these fires do not systematically melt all the snow on top of them.
Following intense fires in summer, some fires persist all winter under the snow. They are nicknamed “zombie fires”.
These bogs are a super insulator. If you have a fire consuming deeper layers of this bog, it will be isolated from the snow and cold above. These insulating properties help keep this fire active, says Jennifer Baltzer.
In the summer of 2022, Jennifer Baltzer led a team of researchers in the Northwest Territories to survey areas recently devastated by fires and try to better understand the nature and scope of these winter fires (zombie fires). Among other things, they wanted to measure the impact of these fires on carbon emissions.
If the fires reach great depths, is there a risk of consuming carbon old and release it into the atmosphere? This is one of the questions we ask ourselves, says Jennifer Baltzer.
Jennifer Baltzer is a professor and holder of the Canada Research Chair in Forests and Global Change at Wilfrid Laurier University in Ontario.
Rising temperatures, increased lightning and fires, and additional carbon dioxide emissions are a vicious circle from which the Arctic will not be able to escape.
The report by André Bernard and Vincent Laurin is broadcast on the show Discovery Sundays at 6:30 p.m. on ICI Radio-Canada Télé.