Unstable Ground: Unstable Ground: A Socio-Ecological Impact A Socio-Ecological Impact
Assessment of Permafrost thaw Assessment of Permafrost thaw in Alaskain Alaska
Prepared By:
Greg Hencir, Ben Janes, Rhys Probyn, Emily Wellington
Presentation OverviewPresentation Overview
What is PermafrostWhat is Permafrost Why does permafrost thaw?Why does permafrost thaw? What happens when permafrost What happens when permafrost
thaws?thaws? What can we do to mitigate the What can we do to mitigate the
effects of thawing permafrost?effects of thawing permafrost?
What is Permafrost?What is Permafrost?
““Permafrost is defined on the basis of temperature, as soil or Permafrost is defined on the basis of temperature, as soil or rock that remains below 0°C throughout the year, and forms rock that remains below 0°C throughout the year, and forms when the ground cools sufficiently in winter to produce a when the ground cools sufficiently in winter to produce a frozen layer that persists throughout the following summer”frozen layer that persists throughout the following summer”
Natural Resources Canada: Earth Sciences SectorNatural Resources Canada: Earth Sciences Sector
““Permafrost is a term used to describe permanently frozen Permafrost is a term used to describe permanently frozen ground”ground”
Richard D. Seifert, University of Alaska FairbanksRichard D. Seifert, University of Alaska Fairbanks
What is Permafrost?What is Permafrost?
Source: Natural Resources Canada
Where is Permafrost?Where is Permafrost?
The pan-arctic area of the Northern HemisphereThe pan-arctic area of the Northern Hemisphere
Continuous Permafrost Zones (CPZ) Continuous Permafrost Zones (CPZ)
Discontinuous (DPZ)Discontinuous (DPZ)
Sporadic (SPZ) Sporadic (SPZ)
Isolated (IPZ)Isolated (IPZ)
Where is Permafrost?
Source: International Permafrost Association
Permafrost FormationPermafrost Formation
Estiated Depth:Estiated Depth: 440m in Barrow, Alaska440m in Barrow, Alaska 600m in the Canadian 600m in the Canadian
Arctic IslandsArctic Islands 1493m in the northern 1493m in the northern
Lena and Yana River Lena and Yana River basins in Siberiabasins in Siberia
Source: U.S. Army Corps of Engineers
Permafrost ThawPermafrost Thaw
Thawing since the last Glacial Maximum, Thawing since the last Glacial Maximum, approximately 20,000 years agoapproximately 20,000 years ago
Roughly 10 to 12°CRoughly 10 to 12°C temperature increase since temperature increase since thenthen
Presumably take centuries or even millenias to Presumably take centuries or even millenias to completely thaw, nevertheless the upper few completely thaw, nevertheless the upper few meters containing the most ice volume will thaw meters containing the most ice volume will thaw the soonest and have the greatest impactthe soonest and have the greatest impact
Environmental Environmental ImplicationsImplications
Modes of degradationModes of degradation
Riverbank Riverbank slumpingslumping
Uneven surfacesUneven surfaces Thermokarst Thermokarst
wetlandswetlands Cryoplanation Cryoplanation
terracesterraces Small Small
lakes/collapse bogslakes/collapse bogsUnstable permafrost embankment (ACIA 2005)
Uneven surfacesUneven surfaces
Thermokarst wetlandsThermokarst wetlands
Cryoplanation terracesCryoplanation terraces
Cryoplanation terraces
Small lakes & collapse scar Small lakes & collapse scar bogsbogs
New groundwater flow systems New groundwater flow systems develop as a result of thawingdevelop as a result of thawing
Upper part of an Upper part of an organic peat mat, organic peat mat, Yukon-Tanana Yukon-Tanana Uplands ->Uplands ->
Upland bogs could Upland bogs could dry out; dry out; accelerated accelerated decomposition of decomposition of peat -> GHG peat -> GHG emissionsemissions
Greenhouse gas emissionsGreenhouse gas emissions
Carbon StorageCarbon Storage For thousands of years photosynthetic For thousands of years photosynthetic
productivity in permafrost zones has productivity in permafrost zones has outweighed decomposition.outweighed decomposition.
As thaw period and depth increaseAs thaw period and depth increase Microbial respiration of stored hydrocarbons Microbial respiration of stored hydrocarbons
into methane and carbon dioxide increase. into methane and carbon dioxide increase. Decomposition of such materials will Decomposition of such materials will
exacerbate thaw and drastically alter current exacerbate thaw and drastically alter current permafrost environments. permafrost environments.
Additionally…Additionally…
Northward movement of forested zoneNorthward movement of forested zone Increased ions concentrations in small Increased ions concentrations in small
upland lakes (Ca, Mg, Sulfate)upland lakes (Ca, Mg, Sulfate) Leading to potential increases in Leading to potential increases in
productivity / shifts from ultra-productivity / shifts from ultra-oligotrophic stateoligotrophic state
More water in freshwater ecosystems, More water in freshwater ecosystems, increased survival of freshwater and increased survival of freshwater and sea run fish. sea run fish.
Permafrost and human Permafrost and human infrastructureinfrastructure
Effecting the “basis of regional and national Effecting the “basis of regional and national economic growth”economic growth”
Foreseeable increase in permafrost thaw will Foreseeable increase in permafrost thaw will have major effects on: have major effects on:
TransportationTransportation Roads, Railways, AirportsRoads, Railways, Airports
BuildingBuilding Residential, utility, economyResidential, utility, economy
““No ground to stand on”No ground to stand on”
Tundra travelTundra travel Increasing road Increasing road
hazards & damagehazards & damage Shorter travel Shorter travel
seasonseason
More GeohazardsMore Geohazards Landslides,Landslides, Debris & mud flowsDebris & mud flows SubsidenceSubsidence
““No ground to stand on”No ground to stand on”
Railways shift Railways shift and bendand bend
Airport runways Airport runways crack and crack and subsidesubside
Hillsides erode Hillsides erode out from under out from under buildingsbuildings
Causes of permafrost Causes of permafrost degradation and techniques degradation and techniques
for mitigationfor mitigation Can’t control how climate change impacts Can’t control how climate change impacts
permafrostpermafrost Can control how what we build impacts Can control how what we build impacts
permafrostpermafrost Passive insulation techniquesPassive insulation techniques Active cooling techniquesActive cooling techniques
Can also control how we plan for constructionCan also control how we plan for construction Permafrost avoidancePermafrost avoidance Structures that can changeStructures that can change Cheap building materialsCheap building materials Permafrost removalPermafrost removal
Case Study: Alaska’s Case Study: Alaska’s institutional management of institutional management of
permafrost constructionpermafrost construction Has continuous and discontinuous zonesHas continuous and discontinuous zones Highway systems: <5,000 miles of paved roadsHighway systems: <5,000 miles of paved roads
AvoidanceAvoidance Continual rehabilitation—cheap pavementsContinual rehabilitation—cheap pavements Insulating materials in roadbedInsulating materials in roadbed
Railroad system: 611 miles, completed in 1923Railroad system: 611 miles, completed in 1923 Continual maintenance (ballast dropping)Continual maintenance (ballast dropping)
Trans-Alaska Pipeline System (TAPS)Trans-Alaska Pipeline System (TAPS) Pipe heated to facilitate flowPipe heated to facilitate flow In thaw stable areas, pipe buried (and refrigerated)In thaw stable areas, pipe buried (and refrigerated) In other areas, Vertical Support Members (VSMs) free In other areas, Vertical Support Members (VSMs) free
to moveto move Frequent monitoringFrequent monitoring
Case Study: Qinghai-Tibet Case Study: Qinghai-Tibet Railway permafrost Railway permafrost
engineeringengineering 695 miles of track, $4.1 billion, 695 miles of track, $4.1 billion,
>5,000m>5,000m More than 300 miles of permafrostMore than 300 miles of permafrost Half of permafrost high risk: high mean Half of permafrost high risk: high mean
temperature, high ice content, or bothtemperature, high ice content, or both Cooling techniquesCooling techniques
Crushed rock embankmentsCrushed rock embankments Ventilation ductsVentilation ducts Shading boardsShading boards
ConclusionsConclusions
Thawing of permafrost could make soils Thawing of permafrost could make soils more stable for future buildingmore stable for future building
In mean time, construction strategies in In mean time, construction strategies in permafrost zones need to consider:permafrost zones need to consider: Costs of continual maintenance vs. initial cost Costs of continual maintenance vs. initial cost
of advanced engineering solutionsof advanced engineering solutions How rapidly can permafrost thawing be How rapidly can permafrost thawing be
expected to occur?expected to occur? Lifetime of these solutions—what will happen Lifetime of these solutions—what will happen
to Q-T railway in long term climate change to Q-T railway in long term climate change model?model?