Chris Vagasky has made the observation. He is a meteorologist and an expert in the lightning detection system Global Lightning Network from the Vaisala company.
” In 2021, a total of 7000 lightning strikes were detected. 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. »
In the summer of 2019, lightning is 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.
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.
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 lit by humans, but in remote Arctic regions, the spark plug is lightning. Almost all fires inside the Arctic Circle are triggered by lightning. »
As the forest and 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.
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, under the snow . We nicknamed them
” 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. »
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.
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.
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 to maintain the activity of this fireexplains Jennifer Baltzer.
In the summer of 2022, Jennifer Baltzer led a team of researchers to the Northwest Territories to survey areas recently devastated by fires and try to better understand the nature and scope of these winter fires (zombie fire). Among other things, the researchers wanted to measure the impact of these fires on carbon emissions.
If the fires reach great depths, is there a risk of burning old carbon and releasing it into the atmosphere? This is one of the questions we ask ourselvessays Jennifer Baltzer.
Rising temperatures, more lightning and fires, and additional carbon dioxide emissions are a vicious circle from which the Arctic cannot escape.
The report by André Bernard and Vincent Laurin is broadcast on the program Discovery Sundays at 6:30 p.m. on ICI Radio-Canada Télé.