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Climate Change and Permafrost

Permafrost is an important part of our environment and plays an important role in maintaining the stability of many ecosystems around the world. Below are a few brief descriptions of how climate change has contributed to the melting of permafrost and the associated impacts on different aspects of ecosystems.

This alpine valley is entirely above the tree line

Freshet in Pangnirtung, Nunavut -f

Fresh Water Supplies

Permafrost plays and integral role in the regulation of fresh water supplies in the arctic and high alpine regions . Three general ground water systems found in permafrost regions include: Supra-permafrost, intra-permafrost and sub-permafrost . Supra-permafrost system involves the water that is present above the frozen ground layer . Intra-permafrost water system involves the water present within channels or holes that run through the frozen ground layer . Supra-permafrost water systems exist below the frozen layer of earth . Together, these systems regulate and support aquifer water supply as well as above ground fresh water sources such as lakes and streams . When permafrost melts many freshwater lakes drain into the newly exposed soil below . The surrounding ecosystems are affected as arctic lakes provide important habitat for migratory waterfowl, ungulates such as moose and many aquatic species . Fresh water evaporation also occurs as permafrost melts . When the frozen ground disappears, associated surface air temperatures increase causing increased evaporation of fresh water supplies. Increased ground surface temperature also increases the rate of spring glacier melt . This associated increase in freshet causes water to run over soil and into muskeg areas where the water stagnates and becomes acidic . Once the acidified water enters into aquatic systems, it impacts the associated ecosystem .

Plants

There is a strong interdependence between permafrost and vegetation in permafrost regions . The melting of permafrost has a significant effect on soils, such as the moisture content and the availability of nutrients. Permafrost functions to serve terrestrial ecosystems; when permafrost thaws it decreases the amount of species that can grow in the low temperatures and high moisture soils . The effects that thawing permafrost has on vegetation greatly depends on the depth of the regions active layer . In some regions the thawing of permafrost leads to increased soil drainage and in others it leads to increased soil moisture; both causing changes to the dominant species in an area . In areas where the thawing permafrost causes increased soil drainage, wet plant species like Kobresia tibetica and Kobresia humilis decrease and drought plants such as Poa annua and Agropyron cristatum begin to take over . Unfortunately the decreased soil moisture leads to the disappearance of Alpine meadows and creates Alpine deserts .As Ice-rich permafrost regions begin to thaw the terrestrial ecosystems turn to aquatic or wetland ecosystems . Due to this process “wet sedge meadows, bogs, thermokarst ponds and lakes are replacing forests” . In Alaska the permafrost degradation has caused a decrease in birch forests by 25% . Permafrost degradation in the lowlands of Alaska has caused tussock (grass)-tundra communities to turn into shrub-tundra communities . Shrubs and woody plants are extending their northern ecological range and encroaching on lichen-dominated ecosystems .

Lichen-covered tree, Tresco

Tussocks - geograph.org.uk - 452055

As a result, the amount of lichens found in the affected areas decrease . This affects the entire ecosystem, as lichens are a vital food source for caribou that are commonly found in arctic regions . The degradation of permafrost and its effects on vegetation is a complex and intricate cycle; thus far the thawing permafrost has two major effects on vegetation: 1. Permafrost thaw in ice-rich soils equates to a loss of terrestrial ecosystems and an increase in aquatic or wetland ecosystems. 2. Permafrost thawing in the upland regions results in improved soil drainage leading to the alpine meadows undergoing a transformation to either shrub communities or drought communities .

Permafrost - ice wedge

Soil Sustainability

Permafrost is integral to soil stability in arctic regions . Melting permafrost causes the surrounding soil to become unstable and settle . As permafrost melts, surrounding lakeshore destabilization takes place . Consequently, bank materials slump into the lakes decreasing oxygen concentration . As a result, water temperature increases which allows bacteria to flourish . The abundant bacteria produce carbon dioxide and methane gas causing the lakes and ponds to produce a significant source of greenhouse gas . This increased methane release is further amplified as melting permafrost exposes previously buried soil. Methane and carbon dioxide stored in the organic matter seep into the atmosphere and contribute further to the climate change problem . Similar to lake shore destabilization, meting permafrost causes bank materials to slump into river water which causes sedimentation of fish bearing streams and adversely effects habitat and health of salmon and other aquatic species . Settlement of surface soil associated with melting permafrost leads to significant infrastructure instability and damage to roads, bridges, buildings, homes, pipelines and airstrips in affected areas .

Further Information

• Arctic methane release
• Alpine plant
• Alpine flora
• Climate of the Alps
• Drunken trees
• International Permafrost Association
• Permafrost Young Researchers Network
• Permafrost carbon cycle
• Azimuth