Studying Permafrost Dynamics in a Warming Climate
Over 25 percent of the Earth’s land surface is permanently frozen, also known as permafrost. High latitude air temperatures have been rising for the last three decades, and this is prompting concern on what the possible impacts will be to thawing permafrost terrain. The Permafrost Research Program at ERDC’s Cold Regions Research and Engineering Laboratory (CRREL) works to better understand the issues, not only for other federal government agencies, but also for states, local entities, and the private sector.
Gauging the Interaction Between the Frozen Earth Environment and Man
Natural and manmade impacts can instigate thaw to permafrost terrain, with resulting changes in permafrost stability, changes in surface and groundwater hydrology, increased carbon liberation, and increased costs to development. CRREL has investigated these impacts since the 1940s, with basic and applied studies benefiting government and the public. As a federal government research entity, CRREL has the ability not only to conduct direct research for unique and difficult problems affecting any facet of society, but also to provide project oversight as an “honest broker,” ensuring the general public’s best interests are met. CRREL collaborates with several universities and other ERDC laboratories, creating strong investigative teams composed of prominent researchers.
In addition, CRREL owns and operates un-paralleled permafrost research facilities at the Alaska Permafrost Research Center (APRC) in Fairbanks, Alaska. The Tunnels Facility, used for sampling and observation, is an underground excavation with over 500 feet of exposure of warm, fine-grained frozen soil and ice. The Farmers Loop Facility is a 135-acre surface plot of boreal forest vegetated permafrost, used primarily for testing and demonstration.
Research that Affects Citizens and States
Designing robust infrastructure for permafrost presents unique challenges to planners, managers and engineers. These challenges range from design and repair of thaw-affected roads, runways and buildings; to understanding how ecosystems will be altered by climate warming. The wide-ranging impact of these problems can create detrimental effects to large government and industry infrastructure and also to homeowners. Recent topics of study include
- Thaw-affected structure remediation
- Expedient non-destructive surveys of permafrost under linear infrastructure
- Paleo-climate reconstruction of late Pleistocene permafrost
- Impacts of fire on the permafrost at military training lands
- An expansion of the Tunnel Facility at APRC was started in February of 2011, creating a new horizontal passage 100 feet in length and parallel to the existing tunnel. The engineering and excavation of Phase I of the New Tunnel was performed by in-house employees and resources and culminated with the installation of an insulated portal structure for thermal protection of the excavation. This new facility, when complete, will expand the Old Tunnel with over 1,000 feet of passageways, creating an enormous gallery for static, warm permafrost studies. The Old Tunnel, excavated in the 1960s with over 500 feet of passageways, has produced more than 70 peer reviewed articles to date on subjects ranging from permafrost and mining engineering to paleontological studies, microbiology, and extra-terrestrial permafrost. It is anticipated that the expanded facility will allow for the volumetric ice and carbon studies and provide a test bed for remote sensing studies.
- In preparation for an upcoming repaving of the 10,000-foot runway at Thule Air Base, Greenland, CRREL was tasked to investigate permafrost thaw mitigation alternatives. A solution was devised to end painting over four million square feet of airfield white, which had been occurring since the late 1950s at considerable manpower and cost.
- Numerous permafrost geotechnical investigations have been conducted for MILCON and other Department of Defense projects in Alaska and Greenland. CRREL possesses subsurface investigative tools and desktop modeling capabilities which, in many cases, have resulted in alternatives that have reduced costs and increased service life of these structures constructed on ice-rich terrain.
Fully understanding the permafrost terrain is key to a successful investigation or study. The CRREL Permafrost Research Program uses several tools and techniques in its explorations:
- Direct Push Technology (DPT) subsurface sampling: Core samples five feet in length and from 2.25 to 3.5 inches in diameter are used on nearly every project allowing for discrete logging and sampling at any depth. This system can also perform air rotary and wet rotary drilling sampling.
- Surface-based geophysics: Earth resistivity (galvanic and capacitive coupled), ground penetrating radar, and conductivity.
- Soil laboratory: Performing grain size analysis, and moisture content, modified Proctor, consolidometer, and long term uniaxial compressive constant strength (creep) testing.
- Desktop modeling with finite element analysis software: This provides the ability to estimate the state of permafrost stability with inputs to the thermal, hydrogeological, and stress regimes. Crucial to these analyses are the effects of man-induced changes.
- Geochemical analytical laboratory: Ion chromatography and isotope analysis.
Force Projection and Sustainment Branch (CEERD-RRH)
US Army Engineer Research and Development Center | Cold Regions Research and Engineering Laboratory