As the temperature rises, the frozen groundwater begins to melt, resulting in greenhouse gas emissions, which accelerate global warming.
The Stortalen Plateau is a vast charcoal swamp surrounded by snow-capped mountains. The strange smell of rotten eggs disturbs the fresh air of the Swedish Far North. We are in the Arctic, about ten kilometers from the small town of Abyssinia, where global warming is three times faster than anywhere else in the world.
Planted in swamps, a pod that looks like a space capsule reveals the undoubted importance of this place lost on the edge of the world. Here, scientists study the melting frozen groundwater, geographically known as permafrost (or permafrost).
Long-locked, greenhouse gases in permafrost are released today. Between methane (CH4) and carbon dioxide (CO2), permafrost contains about 1,700 billion tons of organic carbon, almost twice the amount of carbon already in the atmosphere. Methane lasts 12 years in the atmosphere, compared to centuries for carbon dioxide, but it has 25 times more powerful greenhouse effect than CO2. Scientists warn: Permafrost melting is a “time bomb” for climate.
The vicious circle
In the 1970s, “when researchers began to explore these landscapes, these pools did not exist,” said Keith Larson, coordinator of the Center for Research on the Impact of Global Warming at the Swedish University of Ume at the Abisco Scientific Research Station.
Permafrost – soil that has been permanently frozen for two consecutive years – extends beneath a quarter of the land in the Northern Hemisphere. In Abyssinia, it was ten meters thick and dates back thousands of years. In Siberia, it is more than a kilometer deep and hundreds of thousands of years old.
As the temperature rises, the permafrost begins to melt. Bacteria in the soil Emissions of carbon dioxide and methane, greenhouse gases, which break down biomass stored in frozen soil, accelerate global warming. A strong vicious circle.
Not far from Abyssinia, in the Storflaket swamp, researcher Margaret Johansson has been recording permanent ice melting for 13 years, noting that the “active” layer is increasing every year. “Since measurements began in 1978, it has grown 7 to 13 centimeters thick every ten years,” explains the geophysicist from the Swedish University of Lund. “This freezer, which keeps plants frozen for thousands of years, stores carbon, which thickens the active layer.”
The point of no return?
Scientists at the United Nations Intergovernmental Panel on Climate Change (IPCC) have warned that permafrost could melt “significantly” if CO2 emissions were not reduced by 2100. The average annual temperature in the Arctic has risen by 3.1 degrees Celsius in half a century, compared to 1 ° C on the planet as a whole, the Arctic Observatory and Evaluation Program warned in May (Amap).
Can permafrost reach this critical threshold, a climate “tipping point” where CO2 and methane emissions are inevitable and irreversible ecosystems, with the risk of disrupting the entire planetary system, as defined by the IPCC?
For example, scientists are concerned about the Amazon rainforest becoming savannah or the disappearing glaciers of Greenland and western Antarctica. “If all of the frozen carbon escapes (from permafrost), it will almost triple the concentration of carbon in the atmosphere,” says Gustaf Hugalius, an expert on carbon and permafrost cycles at the University of Stockholm.
The main problem is that the melting of permanent ice and the release of carbon will continue even if all human emissions are stopped immediately.
Mistakes on the ground
In Abisco, you can already see signs of permafrost melting. Here, faults in the ground and small landslides are revealed. There, the telephone poles tilted under the impact of ground movements.
In Alaska, 85% of the land area is permafrost and roads are destroyed. In Siberia, entire cities have begun to crumble as foundations have slipped. In Yakutsk, the world’s largest city built on permafrost, houses had to be demolished.
According to a draft report by IPCC experts on the effects of global warming to be released in 2022, melting permanent frost across the Arctic could affect two-thirds of infrastructure by 2050. More than 1,200 cities and villages, 36,000 buildings and four million people will be affected.
Threat to Paris motives
Scientists warn that greenhouse gases emanating from permafrost threaten the objectives of the Paris Agreement. The signatories to the 2015 agreement have pledged to control global warming “well” to +2 ° C, if possible +1.5 ° C, compared to the pre-industrial period to achieve neutral carbon in the middle of the century.
According to the latest results of the IPCC, humanity should not emit more than 400 billion tons of CO2 to get a two-thirds chance of not exceeding 1.5 C. Given the current emissions, our “carbon budget” risks running out in a decade.
But a study by the U.S. National Academy of Sciences warns that this allocation of carbon emissions, which can accept potential and unpredictable “sudden” emissions of greenhouse gases from natural sources in the Arctic, is “not fully taken into account.”
In its last report in August, the IPCC raised the question and noted that “additional warming will increase permafrost melting”. Acting now will have a further impact on the melting speed of permafrost, Keith Larson insists. While “we have no way to control the permafrost thawing rate” does not mean “we must not give up on moving away from fossil fuels or changing our way of life on this planet”.
Rising temperatures in the Arctic have already caused irreversible changes. “We have been raising deer here for at least 1,000 years,” says Thomas Kuhmunen, a member of the Sami community in the north of Sweden.
The snow, which freezes throughout the winter, constantly melts and freezes, forming a hard layer that prevents reindeer from reaching their main food, lichen. Today deer find it difficult to find enough to eat. Like other breeders, Thomas Kuhmunan had to send his flock to graze on a much larger area than before.
“Often in the forest we send them to pastures, which our ancestors only used as a third choice,” the breeder insists. In their draft report to be released in 2022, IPCC experts are concerned about the changes facing reindeer herders in the far north.
The former is the highest peak
At a distance of 70 km, on the spectacular southern peak of the Kepnekis Massif, Ninis Rosquist was able to see with the naked eye the annual warming that is taking place in the Arctic. The 61-year-old glacier expert climbed the mountain that day to place the antenna in fresh snow to measure altitude.
Even before she gets the answer, she knows that the glacier, located 150 kilometers north of the Arctic Circle, is less than its last arrival. Since the 1970s, the summit has lost more than 20 meters and its GPS stands at only 2,094.8 meters. Two years ago, the peak lost its title of Sweden’s highest peak.
“In the last 30 years, it has melted faster than ever and in the last ten years it has melted even more,” explains a professor at Stockholm University. Especially the summer was unusually hot. Northern Norway, Sweden and Finland recorded 30 to 35 ° C peaks again this summer.
In South America and the Himalayas, tens of thousands of people depend on the seasonal melting of glaciers for drinking water and irrigation. As for Greenland, the sea level rises to seven meters in its ice, not to mention western Antarctica.
There is a lesson to be learned from the Arctic, many researchers believe: some of these ecosystems are not already under human control.