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?