arctic tundra Flashcards
The Arctic Tundra
- occupies 8 millionkm^2
- in Northern Canada, Alaska and Siberia
- extends from Northern edge of boreal coniferous forest to artic ocean and southern limit approximates the 10(oc) July isotherm (climatic limit of tree line) - climate severe and becomes more worse with latitude - 8/9 months, his negative heat balance with av tep below freezing
The Arctic Tundra
- ground permanently frozen, with only top metre or so thawing in the summer
- permafrost lies under much of tundra
- in winter, sun remains under horizon for several weeks, temps can plunge below -40
- long daylight hours in summer provide some compensation for growing season mean annual precipitation low
The Arctic Tundra
- few plants and animals adapted to extreme environment
- biodiversity low and apart from few dwarf species
- treeless in southern areas (low arctic), conditions less severe and vegetation provides continuous ground cover
- in north (high arctic), plant cover discontinuous with extensive areas of bare ground
The Arctic Tundra - The Water Cycle
- low annual precipitation (50-350mm), most snow
- small stores of moisture in atmosphere owing to low temps with reduce absolute humidity
- limited transpiration due to sparseness of vegetation and short growing season
- low rates of evaporation: much of suns energy in summer expended melting snow so ground temp remains low and inhabit convection
The Arctic Tundra - The Water Cycle
- surface and soil frozen for most of the year
- limited groundwater and soil moisture stores - permafrost barrier to infiltration, percolation, recharge and groundwater flow
- melting of snow in uppermost active layer in spring and summer -> increase of river flow
- wetlands, ponds, lakes during summer -> temp store of liquid due to permafrost which impedes drainage
The Arctic Tundra - The Carbon Cycle
- permafrost vast carbon sink
- contains 1600GT
- accumulation of co2 due to low temp which slow decomposition of dead plant material
- carbon in tundra soil x5 when above-ground biomass
The Arctic Tundra
- occupies 8 millionkm^2
- in Northern Canada, Alaska and Siberia
- extends from Northern edge of boreal coniferous forest to artic ocean and southern limit approximates the 10(oc) July isotherm (climatic limit of tree line) - climate severe and becomes more worse with latitude - 8/9 months, his negative heat balance with av tep below freezing
The Arctic Tundra
- ground permanently frozen, with only top metre or so thawing in the summer
- permafrost lies under much of tundra
- in winter, sun remains under horizon for several weeks, temps can plunge below -40
- long daylight hours in summer provide some compensation for growing season mean annual precipitation low
The Arctic Tundra
- few plants and animals adapted to extreme environment
- biodiversity low and apart from few dwarf species
- treeless in southern areas (low arctic), conditions less severe and vegetation provides continuous ground cover
- in north (high arctic), plant cover discontinuous with extensive areas of bare ground
The Arctic Tundra - The Water Cycle
- low annual precipitation (50-350mm), most snow
- small stores of moisture in atmosphere owing to low temps with reduce absolute humidity
- limited transpiration due to sparseness of vegetation and short growing season
- low rates of evaporation: much of suns energy in summer expended melting snow so ground temp remains low and inhabit convection
The Arctic Tundra - The Water Cycle
- surface and soil frozen for most of the year
- limited groundwater and soil moisture stores - permafrost barrier to infiltration, percolation, recharge and groundwater flow
- melting of snow in uppermost active layer in spring and summer -> increase of river flow
- wetlands, ponds, lakes during summer -> temp store of liquid due to permafrost which impedes drainage
The Arctic Tundra - The Carbon Cycle
-carbon mainly stored as partly decomposed plant remains in the permafrost.
-low temperatures and low availability of liquid limits plant growth. Short growing season and NPP low.
-Low temps slow decomposition and respiration and the flow of C02 into the atmosphere.
The Arctic Tundra - Oil and gas production and water cycles in Alaska
- north slope of Alaska, is vast wilderness of tundra
- oil and gas here discovered in Prudhoe bay in 1968
- development of industries a challenge: harsh climate with extreme long and cold periods of darkness in winter- > permafrost and melting of the active layer in summer, remoteness and poor accessibility -> and fragile wilderness of great ecological value
The Arctic Tundra - Oil and gas production and water cycles in Alaska
- production went ahead, driven by high global energy prices and US governments policy to reduce dependence on oil imports
- investments in pipelines, roads, oil production plants e.g. in 1970s and 80s
- by 1990, accounted for 1/4 US domestic oil production - today, 6%, though alaska still an important oil and gas province, due to high production costs and oil production in other parts of USA
The Arctic Tundra - Effect of oil and gas production on the carbon cycle
-impacts permafrost- its highly sensitive to changes in thermal balance, where this has been disrupted, permafrost melts releasing CO2 and methane. ( estimated C02 loss estimated from 7-40M tonnes/ year.
-Gas and oil spillages also emit CO2.
-Destruction of vegetation- reduction in photosynthesis and the uptake of CO2.
The Arctic Tundra - Effect of oil and gas production on the water cycle
- melting of permafrost and snow cover increases run off and river discharge making floods more likely - summer: wetlands and lakes more extensive, increasing evaporation
- strip mining of sand and gravel creates artificial lakes which disrupts drainage and exposes to more melting - water abstracted from creeks and rivers e.g.
- building of ice roads in winter reduce localised run off
strategies to reduce the impact of development on the water and carbon cycles
1) refrigerated supports- used on the pipeline to stabilize temperature of permafrost
strategies to reduce the impact of development on the water and carbon cycles
2) insulated ice and gravel pads- roads and other infrastructure can be on insulated ice or gravel pads- protecting permafrost from melting
strategies to reduce the impact of development on the water and carbon cycles
buildings and pipelines elevated on piles- infrastructure elevated allows cold air to circulate beneath, reducing melting permafrost.
