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The rapid melting of permafrost in the Arctic could double the warming effect produced by greenhouse gases emitted by the soil, which could worsen climate change. That's according to the researchers.
Merritt Turetsky, Canada Research Chair in the Department of Integrative Biology at the University of Guelph, Ontario, could also transform whole landscapes in just a few months, the "sleeping giant" hidden in the tundras of the Canada and other northern regions of the world. and his colleagues argue in a report published in the newspaper Nature.
Research has shown that the Arctic region is currently warming about twice as fast as the global average, resulting in thawing permafrost or frozen soils, often for the first time in thousands of years.
"When the soil temperature exceeds the freezing point, microorganisms break down soil organic matter," the authors wrote. "Greenhouse gases, including carbon dioxide, methane and nitrous oxide – are released into the atmosphere, accelerating global warming."
This is of particular concern as Arctic permafrost contains twice as much carbon as the entire atmosphere, or nearly 1,600 billion tonnes, the researchers say.
"Current models of greenhouse gas and climate emissions assume that permafrost is gradually thawing from the surface down," the authors wrote. "Deeper layers of organic matter are exposed for decades, if not centuries, and some models are beginning to follow these slow changes."
However, this type of research, which focuses on incremental processes, ignores a perhaps even more troubling problem, namely the rapid collapse of permafrost. It is at this moment that several meters of permafrost soil, which holds the soil together, will destabilize in a few days or weeks, instead of a few centimeters a year.
Such a rapid collapse physically modifies landscapes that took millions of years to form – in a matter of months – by subsidence, floods and landslides. Sometimes the land can sink and be flooded with lakes and expanding wetlands. Scientists have even observed hillsides of mostly liquefied hills.
"This abrupt thaw modifies forest ecosystems to thaw lakes and wetlands, resulting in a profound transformation of the landscape that not only impacts carbon feedbacks on climate, but also modifies wildlife habitat", said Miriam Jones, co-author of the States Geological Survey report, said in a statement.
Unlike progressive thawing, a sudden collapse of permafrost more rapidly destabilizes deeper carbon stores and releases more methane, a gas that has a much larger greenhouse effect than carbon dioxide.
"We watch this sleeping giant wake up right in front of our eyes," said Turetsky. "This is happening faster than expected, we show that thaw in the permafrost affects less than 20% of the permafrost region, but carbon emissions in this relatively small region can potentially double the climate return associated with permafrost thaw. "
In addition to the adverse effects on the environment, the sudden thaw also poses a serious problem for Arctic communities. This can make housing unstable or damage infrastructure such as roads and railways. This also has a negative effect on traditional hunting practices, as well as on scientists trying to work in the area.
"We work in areas where permafrost has a lot of ice, and our sites are being destroyed by the abrupt collapse of this ice, not gradually over several decades, but very quickly, on several months or years, "said Turetsky.
Based on their findings, the team made a number of recommendations, including a call for increased monitoring of permafrost in the Arctic, as well as further research on the effects of the thaw on climate change.
"There is an urgent need to make substantial progress on the representation of the effects of the brutal thaw on the carbon cycle in Earth system models," said Dave Maguire, of the University of Alaska Fairbanks, in a statement. communicated. how carbon release from abrupt thaw can affect the implementation of carbon management strategies to control the growth of greenhouse gases in the atmosphere. "
Although the magnitude of the threat posed by thawing permafrost in the Arctic is significant, Turetsky remains optimistic for the future.
"If we can limit human emissions, we can still limit the most dangerous consequences of global warming," she said. "Our window of action is narrowing, but we still have it and we can make changes to save the Arctic as we know it," and the climate of the Earth with it.
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