This text is taken from our newsletter “Le Courrier de la Planète” of June 28, 2022. Click here to subscribe.
The witness of a colder era is about to disappear in Gaspésie: the permafrost of Mont Jacques-Cartier.
This frozen body, under the summit of the mountain which culminates at 1268 meters, is a rarity in southern Nunavik. Soil, rock and water stay below zero year-round — but not for very long. By 2030, the atmospheric temperature will be too high to maintain this glacial remnant, according to geomorphologist Daniel Fortier, a permafrost specialist.
Notice to vacationers who will visit the highest peak of the Chic-Chocs this summer: the typical tundra landscape they will see there is endangered, as are the glaciers of the Rocky Mountains, which are retreating year after year.
“People will be able to tell their children: when I came here, it was tundra. And when they return there with them, it will be shrubs and small trees, says Mr. Fortier, who is a professor at the University of Montreal. Unfortunately, there will be no more permafrost, no more woodland caribou or rare tundra plants. »
Snow, a crucial variable
Mr. Fortier has been going to the summit of Mont Jacques-Cartier since 2009 to download the temperature readings recorded by a probe installed in 1977. It was his predecessor at UdeM, James Gray, who, suspecting that permafrost was there , had secured funding to raise a drill to the top of the mountain. The team had dug a 29 m hole and slipped a cable fitted with thermometers into it. This equipment confirmed the presence of permafrost.
Not all Chic-Choc peaks are capped with permafrost. In order for the biting cold of winter to penetrate the ground, too much snow must not accumulate there. “Snow is like insulation,” explains Mr. Fortier. The very aerodynamic profile of Mont Jacques-Cartier, in the shape of a dome, means that it is very exposed to the winds and that in winter, no more than 30 cm of snow cover the ground.
Mount Logan, at the extreme west of the Parc de la Gaspésie, probably also harbors permafrost: workers who wanted to plant a telecommunications tower there have already encountered frozen ground in the middle of summer. Mount Albert, an imposing massif popular with hikers, does not however hide permafrost.
The frozen volume of Mont Jacques-Cartier extends over a thickness of 45 m. A sort of huge ice cube, this permafrost refrigerates the summit in summer. Its presence is not essential to the tundra vegetation, but greatly favors it. In addition, ice in the interstices between the underground rocks makes the soil more impermeable, which prevents water from percolating and the surface from drying out in summer.
Chemical erosion during thawing
For researchers like Mr. Fortier, mountain permafrost is a “sentinel” of climate change. Its evolution, very slow, flattens short-term temperature variations and only reflects trends persisting for several years.
The analyzes carried out by Mr. Fortier and his team suggest that in a decade, the permafrost of Mount Jacques-Cartier will become “relic”, that is to say, it will enter a shrinking phase. It will take a few more decades to see it completely disappear.
The only island of flora that overlooks Mont Jacques-Cartier will suffer, but also the fauna, such as the caribou, which depends on these tundra species. In addition, the melting of the underground ice will cause chemical erosion of the rocks, which will release substances into the water. “We will see cascading effects on all species,” predicts Mr. Fortier.