The Arctic is experiencing warming at over double the rate of the global average due to climate change. This is leading to major changes for northern communities dependent on permafrost, endangering infrastructure, transportation, energy systems, and the sociocultural stability of these areas.
Permafrost constitutes the continuously frozen layer of soil that covers about a quarter of the Northern Hemisphere's land surface. This ground is shielded from atmospheric conditions by an active layer of topsoil that often supports vegetation, thawing each year and refreezing in the winter months. Infrastructure elements including roads, airports, and railways, along with other structures not artificially heated, are constructed over permafrost regions. The impact on the Arctic's infrastructure from thawing permafrost, diminishing sea ice, and changes in water flow is more significant than may be initially perceived.
Climate change poses the following challenges for geotechnical engineering in permafrost areas:
- Rising temperatures: As temperatures rise, permafrost thaws, leading to ground instability. Thawing causes subsidence, settlement, and deformation of structures built on permafrost.
- Reduced bearing capacity: Permafrost provides stability to structures by acting as a load-bearing layer. As it thaws, bearing capacity decreases, affecting the safety and longevity of buildings, roads, and other infrastructure.
- Thermokarst and erosion: Thawing permafrost can create thermokarst features such as sinkholes, slumps, and pits that accelerate erosion. These processes undermine the stability of foundations and embankments.
- Infrastructure vulnerability: Existing infrastructure including roads, pipelines, and buildings in permafrost regions faces increased risk of damage due to ground movement. This causes repair and maintenance costs to rise, impacting budgets and sustainability.
- Snow accumulation and ponding: Infrastructure alters local snow distribution. Increased snow accumulation near structures insulates the ground, preventing it from freezing as deeply. This exacerbates thawing and affects stability.
Current methodologies may not accurately predict when infrastructure will fail due to the lack of specific emphasis on permafrost degradation in their calculations; enhanced models are needed to evaluate potential hazards more reliably. Ongoing evaluation and surveillance of permafrost characteristics, such as ice composition, temperature, grain size and salinity, improve the precision with which engineers can spot variations and plan for adaptive strategies. With this in mind, the value of resilient infrastructure design and active community involvement is growing.
To counteract the repercussions of climate change in these areas, engineers have a variety of strategies at their disposal:
Adaptive design: Engineers modify infrastructure designs to account for permafrost thaw, including the use of thermosyphons (heat exchangers) to stabilize foundations by maintaining a frozen layer.
Insulation: This helps prevent heat transfer from buildings to the ground. This can mean increasing the thickness of existing insulation or using frost-resistant materials and frost blankets.
Ground improvement: Permafrost can be stabilized by injecting grout or other materials to enhance load-bearing capacity. This reinforces the ground and prevents subsidence.
Elevated foundations: Minimizing settlement and deformation can be achieved by raising structures above the ground on pilings or stilts, reducing their contact with thawing permafrost.
Monitoring and early warning systems: Sensors can be deployed to monitor ground temperature, settlement, and stability. Early warnings allow for timely interventions.
Climate-resilient materials: Using materials that withstand freeze-thaw cycles and ground movement is crucial. Concrete additives, geotextiles, and frost-resistant steel can enhance durability.
Land use planning: Engineers are collaborating with urban planners to avoid building in high-risk areas. Zoning regulations consider permafrost vulnerability.
Climate change has also created a carbon feedback loop. Permafrost typically remains frozen for at least two consecutive years, often for millennia. It contains vast amounts of organic matter, which, when thawed, becomes accessible to microbes. These microbes decompose the organic material, releasing greenhouse gases like carbon dioxide (CO₂) and methane (CH₄) into the atmosphere. Methane is particularly concerning because it is about 25 times more effective at trapping heat in the atmosphere than CO₂ over a 100-year period. This release of greenhouse gases further warms the climate, leading to more permafrost thaw—a classic positive feedback loop.
Arctic wildfires have become more frequent and intense due to rising temperatures and drier conditions. These fires release significant amounts of CO₂ from burning vegetation and contribute to permafrost thaw by removing the insulating layer of vegetation and exposing the soil to warmer temperatures. The thawed permafrost then releases more greenhouse gases, perpetuating the cycle.
Other feedback loops include:
- Ice-Albedo Feedback: As ice and snow melt, they reveal darker surfaces like ocean water or land, which absorb more solar radiation. This increases local temperatures, leading to more ice melt.
- Water Vapor Feedback: Warmer temperatures increase evaporation rates, adding more water vapor to the atmosphere. Since water vapor is a potent greenhouse gas, this amplifies warming.
- Tipping Points: These feedback loops can push the climate system toward tipping points—thresholds beyond which significant and often irreversible changes occur. For example, the complete loss of Arctic summer sea ice or the large-scale thawing of permafrost could lead to rapid and uncontrollable climate changes.
The thawing of permafrost poses risks to ecosystems, communities, and global climate stability, and understanding these feedback loops is crucial for predicting future climate scenarios and implementing effective mitigation strategies. Hatch’s engineers are using advanced models to predict infrastructure performance under changing conditions and partnering with our clients to help them implement these tools and strategies. Contact us for additional information and to learn more about the ways we’re safeguarding infrastructure and maintaining the stability of the built environment in Arctic regions.
