For decades, Arctic permafrost has functioned as a massive natural storage system, effectively trapping carbon-rich organic material beneath frozen ground and slowing the release of climate-warming gases. However, new experimental research from the University of Leeds reveals that this system may be far more vulnerable than previously understood. As temperatures rise and frozen soils begin to thaw, the physical properties of permafrost change in ways that significantly accelerate the movement of gases into the atmosphere, potentially amplifying climate change.
The study shows that thawing Arctic permafrost can become between 25 and 100 times more permeable than when it is frozen. This means gases such as carbon dioxide and methane—both potent greenhouse gases—can move much more freely through the soil. Permafrost regions globally store an estimated 1,700 billion tons of carbon, which is roughly three times the amount currently present in the atmosphere. As warming intensifies, the release of even a fraction of this stored carbon could create a powerful feedback loop: rising temperatures lead to thawing, thawing releases greenhouse gases, and those gases drive further warming.
To better understand this process, researchers conducted controlled laboratory experiments rather than relying solely on field observations. They gradually warmed permafrost samples from -18°C to +5°C, carefully measuring how gas flow and permeability changed at each step. One of the most important findings was that permeability does not increase gradually. Instead, the most dramatic changes occur near the freezing point, between approximately -5°C and 1°C. This temperature range is critical because many Arctic regions frequently hover within it, meaning even small increases in temperature can trigger disproportionately large changes in gas movement.
This discovery highlights a crucial physical mechanism that complements the more commonly discussed biological processes in permafrost thaw. While previous research has focused on microbial activity breaking down organic matter and producing greenhouse gases, this study emphasizes that the structure of the soil itself is changing. As Arctic permafrost thaws, it develops cracks, channels, and reorganized pore spaces that allow gases to escape more easily. This structural transformation effectively turns the ground into a more efficient pathway for emissions, accelerating the rate at which gases reach the atmosphere.
The implications extend beyond climate alone. The researchers also point to the potential for increased movement of radon, a naturally occurring radioactive gas associated with higher cancer risks. As permeability rises, radon could travel more easily through thawing soils, posing additional health concerns for communities in Arctic and sub-Arctic regions.
Overall, the findings suggest that Arctic permafrost is not just a passive carbon reservoir but an active and dynamic system that can rapidly respond to warming. By becoming significantly more permeable during thaw, it may transform the Arctic into a faster and more intense source of greenhouse gas emissions. This creates a self-reinforcing cycle that could accelerate global climate change, underscoring the urgency of understanding and mitigating permafrost-related risks as temperatures continue to rise.