ALASKA - Human Activity causing change within a Periglacial Landscape system

How long is the pipeline?

800 miles

Where is the oil extracted and where is it exported? Why?

Prudhoe bay on Alaska’s North Slope to Valdez. Prudhoe bay is frozen over, Valdez is the Northernmost “ice free” port in America.

How many oil barrels does it produce per day?

1.4 million barrels

What is the pipeline called?

Trans - Alaskan pipeline

How much can it adjust in natural disasters?

25 m horizontally, 5m vertically

Why did they build the pipeline in the 70s?

• The price of oil extraction rose exponentially due to the oil crisis in the 1970s. After Arabs quadrupled the price of oil. Arabs prohibited oil exports to the United States and Western Europe, which caused the oil prices to increase to around $12 per barrel More valuable.

• Sedimentary rock on the North Slope (Prudhoe bay), sedimentary rock is needed for extraction of oil. 10 billion barrels worth in Barrow

• America’s need for energy security due to political tensions/conflict in Middle East and Russia

How does human activity impact the flow of material?

• To drill oil effectively, companies must create a stable surface to accommodate equipment from underlying soil. eg. Graven pads (1-2m thick layer)

• These are extracted from streams and river beds which increase the rate at which gravel is transported. EFFECTS EQUILIBRIUM BETWEEN EROSIONAL AND DEPOSITIONAL PROCESSES

  • Hydraulical processes effected: ground water levels fell by more than a m in an area 2km from extraction site

How does this human activity impact flows of energy?

• Release burning of gases: “Flaring” which involves burning a layer of natural gas to get to the oil, which releases C02 into the atmosphere.

  • IMPACT: Can harm wildlife by attracting birds and insects into the flame. Methane + CO2 can be released as greenhouse gases, which can contribute to the enhanced Green House effect

Specific example town in Alaska that is experiencing these effects

Barrow - the most Northern town in Alaska. They are experiencing the urban heat island effect, which saw temps reach 2.2 degrees celsius higher than in surrounding areas. This is caused by domestic heating systems in poorly insulated buildings

The effect of these impacts in changing periglacial landscapes?

Alas - large scale, flat floored, steep sided depressions (5-50m in depth), this is caused by the large scale thawing of ground ice resulting in large scale subsidence (ground sinking)

Solifluction lobes - The constant thawing of the surface, will result in the active layer becoming saturated with meltwater on slopes, resulting in gravity pulling these down slopes as tongue shaped lobes

The effect of these impacts on climate change

Thawing of permafrost - This has a global impact on Greenhouse gas emissions.

• Organic matter, which consists of dead plants and animals, contain lots of carbon.

  • As it begins to thaw due to the Greenhouse effect, it will decay, releasing CO2 and methane into the atmosphere (Global permafrost contained 1,500 billion tonnes of carbon).

Strategies to minimise impacts?

• Pipeline raised above the ground and supported by refrigerants to ensure heat is not conducted into the ground. They are placed in a zig zag route to adjust to ground movements and do not block the migration routes for animals