2.b. CASE STUDY: The Arctic Tundra Flashcards
where is the arctic tundra? what are its characteristics?
Arctic tundra is located in the northern hemisphere, extending from the Arctic Circle down to the coniferous forests of the taiga. and across alaska, canada and some of siberia.
- mean temps of -15 degrees c. For 8/9 months the tundra has a negative heat balance
- its warmest temps during its 3 summer months is 10 degrees c
- winter can get as low as -40
what is the climate like in the tundra?
- mean temps of -15 degrees c. For 8/9 months the tundra has a negative heat balance
- its warmest temps during its 3 summer months is 10 degrees c
- winter can get as low as -40
what is the permafrost? how does this affect the water cycle?
- permanently frozen layer of water and soil [can range from a few centimeters to over 1,500 meters deep]
- underlies much of the tundra
- important to the water cycle
how does this affect the water cycle?
- prevents infiltration further than the active layer into the ground causing 1000s of surface puddles to form in summer as active layer melts.
what is the active layer? how does this affect the water cycle?
- the active layer is a roughly 1m thick layer on top of the permafrost.
- thaws during short summer
how does this affect the water cycle?
- when it thaws the water cannot go down ward due to the infiltratable permafrost below therefoe water sits on the surface in the form of extensive wetlands, ponds and lakes. and due to the flat releif of the tundra this doesnt run off.
water cycle in the Arctic Tundra
- The water cycle in the arctic tundra during wimter is stagnant. (8/9 months of the year)
- 3/4 month of temps above 0 allow for a short growing season of small, low to the ground, sparse vegetation = limited transpiration
- active layer thaws in summer
- low annual precipitation of <100mm/yr most falling as snow
- low amounts of transpiration due to much of the suns energy being expended on melting snow.
- permafrost is a barrier to percolation, infiltration and groundwater flow.
- rivers and lakes frozen in winter accumulate snow and ice, in the summer this and the active layer melts contributing to a sharp uptake in river flow.
physical factors affecting the water cycle in the tundra
temperature, permafrost, low precipitation, and limited vegetation
how does climate in the tundra affect the water cycle?
averages at -15 and down to -40 8/9 months of the year results in most precipitation falling as snow as well as less that 100mm/year. and the permafrost.
the carbon cycle in the tundra
- mostly stored as partly decomposed plant remains locked in the permafrost for at least the last 500,000 years.
- limited vegetation [due to low tems and unavailability of water] leads to the biomass carbon store is relatively small. no photosynthesis during winter due to a lack of water and sunlight, only during 3 months.
- low temps and waterlogging slow decomp, respiration and flow of CO2 to the atmosphere
- permafrost prevents the porosity, permability, or mineral composition of rock having any effect on both the water and carbon cycle.
- perma frost is a vast carbon sink
physical factors affecting carbon cycle in the arctic tundra
temperature, permafrost, vegetation, and soil composition
seasonal changes affecting the cycles
water:
- active layer, lakes, rivers melt = more river flow
- active layer melts = extensive surface water in wetlands, ponds, lakes
- short growing season - small amounts of transpiration
- small amounts of precipitation
carbon:
- short growing season = small amounts of photo synthesis
- permafrost never thaws = lots of carbon locked up
-The thaw of the active layer leads to increased respiration, the activity of microorganisms breaking down organic matter, and the release of CO2 into the atmosphere
oil and gas production in the arctic tundra
North Slope of Alaska there is vast tundra where, in 1968, oil and gas reserves were discovered. Despite the major challenges the conditions of the tundra present production proceeded. Driven by the rising global energy prices and the US govs policy to reduce dependance of oil imports.
Huge investments were made into pipelines, roads , oil production facilities, power lines, power generators which were completed in the 70s & 80s. by the early 90s the North Slope accounted for nearly 25% of the USAs domestic oil production. Although today it is less than 4%, it still remains an important source.
the impacts of the oil and gas industry on the water cycle in the tundra
Oil and gas activities disrupt the fragile ecosystem, leading to increased greenhouse gas emissions, altered drainage patterns, and changes in permafrost, all of which have major implications for both cycles
Thawing permafrost:
Oil and gas operations, including drilling and infrastructure development, can thaw permafrost, This thawing releases stored water, alters drainage patterns, and can contribute to flooding and soil erosion.
Pollution:
Oil spills and other forms of pollution from oil and gas operations contaminate water bodies, impacting water quality and potentially harming wildlife.
Infrastructure:
Roads, pipelines, and other infrastructure associated with oil and gas development can alter natural drainage patterns and increase runoff, potentially leading to increased erosion and water pollution.
Increased Evaporation and Precipitation:
Warming temperatures associated with the melting of permafrost and other climate change factors can lead to increased evaporation and altered precipitation patterns, further impacting water availability and distribution in the Arctic.
Impact on River Systems:
Oil and gas operations can disrupt the natural flow of rivers, especially during the spring thaw, and affect the delicate balance of aquatic ecosystems.
the impacts of the oil and gas industry on the carbon cycle in the tundra
Impacts on the Carbon Cycle:
Increased Greenhouse Gas Emissions:
Oil and gas activities release significant amounts of carbon dioxide (CO2) and methane (CH4), major greenhouse gases, into the atmosphere, contributing to global warming.
Permafrost Thawing:
Thawing permafrost releases large quantities of stored carbon dioxide and methane, which are locked in the frozen ground.
Destruction of Vegetation:
Infrastructure development and other activities can destroy or damage vegetation, reducing the amount of carbon stored in the tundra ecosystem and the capacity for carbon sequestration.
Changes in Decomposition Rates:
Warming temperatures increase the rate of decomposition of organic matter in the soil, releasing more carbon dioxide into the atmosphere.
Changes in Sedimentation:
Increased runoff and erosion caused by oil and gas operations can lead to changes in the amount of organic matter transported to the ocean, affecting carbon storage in marine sediments.
Management strategies in the arctic tundra
- insulated ice and gravel pads
- buildings and pipelines of elevated piles
- drilling laterally beyond drilling platforms
- new tech
- refridgerated supports
insulated ice and gravel pads
insulated ice and gravel pads:
roads + other infrastructure can be built on insulating ice/gravel pads to help prevent the permafrost melting [eg: Spine Road and Prudhoe Bay lies on a 2m thick pad]
elevated piles
building infrastructure ontop of piles allows for airflow to circulate beneath, providing insulation from the heat produced by these infrastructures for the permafrost.
drilling laterally
allow gas and oil to be drilled several km away from the site. Shell has developed the ‘snake drill’ which allows directional drilling across a wide area from one site.
leads to a need for fewer drilling sites/rigs greatly reducing the impact on begetation and permafrost.
computers
more powerful computers can detet oil and gas bearing geological structures remotely so fewer exploration wells are needed = reduced impact on env.
refrigerated supports
refrigerated supports are used on the Trans-alaska pipeline to stabilize temps of the permafrost.
