Greg Hencir, Ben Janes, Rhys Probyn, Emily Wellington Unstable Ground: A Socio-Ecological Impact Assessment of Permafrost thaw in Alaska Prepared By: Greg Hencir, Ben Janes, Rhys Probyn, Emily Wellington

Presentation Overview What is Permafrost Why does permafrost thaw? What happens when permafrost thaws? What can we do to mitigate the effects of thawing permafrost?

What is Permafrost? “Permafrost is defined on the basis of temperature, as soil or rock that remains below 0°C throughout the year, and forms when the ground cools sufficiently in winter to produce a frozen layer that persists throughout the following summer” Natural Resources Canada: Earth Sciences Sector “Permafrost is a term used to describe permanently frozen ground” Richard D. Seifert, University of Alaska Fairbanks

What is Permafrost? Source: Natural Resources Canada

Where is Permafrost? The pan-arctic area of the Northern Hemisphere  Continuous Permafrost Zones (CPZ)  Discontinuous (DPZ)  Sporadic (SPZ)  Isolated (IPZ)

Where is Permafrost? Source: International Permafrost Association

Permafrost Formation Estiated Depth: 440m in Barrow, Alaska 600m in the Canadian Arctic Islands 1493m in the northern Lena and Yana River basins in Siberia Source: U.S. Army Corps of Engineers

Permafrost Thaw Thawing since the last Glacial Maximum, approximately 20,000 years ago Roughly 10 to 12°C temperature increase since then Presumably take centuries or even millenias to completely thaw, nevertheless the upper few meters containing the most ice volume will thaw the soonest and have the greatest impact

Environmental Implications

Modes of degradation Riverbank slumping Uneven surfaces Thermokarst wetlands Cryoplanation terraces Small lakes/collapse bogs Unstable permafrost embankment (ACIA 2005)

Uneven surfaces

Thermokarst wetlands

Cryoplanation terraces

Small lakes & collapse scar bogs

New groundwater flow systems develop as a result of thawing Upper part of an organic peat mat, Yukon-Tanana Uplands -> Upland bogs could dry out; accelerated decomposition of peat -> GHG emissions

Greenhouse gas emissions Carbon Storage For thousands of years photosynthetic productivity in permafrost zones has outweighed decomposition. As thaw period and depth increase Microbial respiration of stored hydrocarbons into methane and carbon dioxide increase. Decomposition of such materials will exacerbate thaw and drastically alter current permafrost environments.

Additionally… Northward movement of forested zone Increased ions concentrations in small upland lakes (Ca, Mg, Sulfate) Leading to potential increases in productivity / shifts from ultra-oligotrophic state More water in freshwater ecosystems, increased survival of freshwater and sea run fish.

Permafrost and human infrastructure Effecting the “basis of regional and national economic growth” Foreseeable increase in permafrost thaw will have major effects on: Transportation Roads, Railways, Airports Building Residential, utility, economy

“No ground to stand on” Tundra travel More Geohazards Increasing road hazards & damage Shorter travel season More Geohazards Landslides, Debris & mud flows Subsidence

“No ground to stand on” Railways shift and bend Airport runways crack and subside Hillsides erode out from under buildings

Causes of permafrost degradation and techniques for mitigation Can’t control how climate change impacts permafrost Can control how what we build impacts permafrost Passive insulation techniques Active cooling techniques Can also control how we plan for construction Permafrost avoidance Structures that can change Cheap building materials Permafrost removal

Case Study: Alaska’s institutional management of permafrost construction Has continuous and discontinuous zones Highway systems: <5,000 miles of paved roads Avoidance Continual rehabilitation—cheap pavements Insulating materials in roadbed Railroad system: 611 miles, completed in 1923 Continual maintenance (ballast dropping) Trans-Alaska Pipeline System (TAPS) Pipe heated to facilitate flow In thaw stable areas, pipe buried (and refrigerated) In other areas, Vertical Support Members (VSMs) free to move Frequent monitoring

Case Study: Qinghai-Tibet Railway permafrost engineering 695 miles of track, $4.1 billion, >5,000m More than 300 miles of permafrost Half of permafrost high risk: high mean temperature, high ice content, or both Cooling techniques Crushed rock embankments Ventilation ducts Shading boards

Conclusions Thawing of permafrost could make soils more stable for future building In mean time, construction strategies in permafrost zones need to consider: Costs of continual maintenance vs. initial cost of advanced engineering solutions How rapidly can permafrost thawing be expected to occur? Lifetime of these solutions—what will happen to Q-T railway in long term climate change model?