Arctic Tundra (physical And Human Factors That Affect The Carbon And Water Cycle Flashcards
Water cycle specific to the tundra
Low annual precipitation ( 50-350 mm of snow)
Low moisture in atmosphere = low temps and lower humidity
Short growing season and sparse vegetation = limited transpiration
Most of the suns energy id used to thaw the active layer of the permafrost keeping ground temps low and convection is inhibited
Permafrost being a barrier to infiltration and percolation, recharge and groundwater flow = limited groundwater and soil stores.
Winter - accumulation
Spring - ablation and permafrost active layer thawing ( top m) = immediate increase in river flow with extensive wetlands, ponds and lakes holding the temporary storage of water which impedes drainage
Carbon cycle specific to the tundra
Large carbon sink - 1600gt of carbon
Low temps = slow decomposition of plant and animal material = accumulates carbon
6 x more carbon in tundra soils than above ground mass
Active layer thaws = increase in the carbon flux conc
Small biomass ranging between 4 and 29 tonnes per hectare based on the density of ground cover due the NPP being lower than 200 grams /m2 / year
Plants put carbon rich litter in the soil
Increased decomposition releases carbon dioxide to the atmosphere by respiration
Pockets of unfrozen soil and water release methane
Permafrost is meant to be a carbon sink but due to the climate warming it is becoming a carbon source
Although, the carbon budget is arguably still in balance due to the increase temperatures stimulating plant growth and therefore sequestering more carbon but could put a strain on fertility.
Physical factors affecting the flows and store in the water cycle
Temperature,relief and rock permeability
Water is stored as ground ice in the permafrost due to temperatures being below freezing at -40 degrees Celsius
Short summer the active layer thaws and liquid water on the surface
Forming of meltwater pools and shallow lakes
Poor drainage and limited infiltration due to the permafrost
Limited evaporation and transpiration due to sub-zero temperatures
Lack of liquid water = limited growth
Evaporation, in the summer only takes place in saturated soils,vegetation
Low humidity and the precipitation is sparse
Water logging due to minimal relief and the chaotic glacial deposits
Undulating land under the tundra due to million of years of erosional weathering
Low permeability due to permafrost and crystallised rocks
Seasonal changes in the carbon cycle
Decomposed plant remains locked away for the past 500,000 years
Small biomass = growing season of 3 months
Long hours of daylight = better growing season due to more light needed for photosynthesis.
Impact of developing oil and gas on the water cycle
Melting permafrost and snow = increases overland flow and river discharge making flood risk increase
Summer = wetlands, ponds and lakes are extensive which increases evaporation
Strip mining of sand and gravel creates artificial lakes which disrupt drainage and expose permafrost for further melting
Drainage networks are disrupted by road construction and seismic explosions as a means of extracting oil
Water extracted from creeks and rivers for industrial use - reduced overland flow
Oil and gas impacts on the carbon cycle - causing permafrost to melt
Carbon is highly sensitive to change in the thermal balance
construction and the operation of oil and gas installations, settlements and infrastructure diffusing heat directly into the environment
Deposition of dust on roadsides creating darkened surfaces therefore increasing absorption of sunlight
Removal of the vegetation cover insulating the permafrost
Background
8 million km 2 - extends from the northern edge of the boreal coniferous forest to the Arctic Ocean
North - extensive areas of bare ground as there are more severe artic conditions, few plant species = low biodiversity
South - less severe conditions so there is full ground cover
Southern limit is 10 degrees Celsius July isotherm - climatic climate of the tree - limit of growth
8-9 months of the year the tundra has a negative heat balance with average monthly temps below freezing
Only active layer of permafrost melts in the summer
Several weeks of the winter = -40 degrees Celsius due to the sun being below the horizon
Physical factors affecting the flows and stores in the carbon cycle
Decomposed plant remains locked away for the past 500,000 years
Small biomass = growing season of 3 months
Lower temperatures and water logging slower decomposition, respiration and co2 is released into the atmosphere
Long hours of daylight = better growing season due to more light needed for photosynthesis.
Seasonal changes in the water cycle
Water is stored as ground ice in the permafrost due to temperatures being below freezing at -40 degrees Celsius in the winter
Short summer the active layer thaws and liquid water on the surface which is forming of meltwater pools and shallow lakes
Poor drainage and limited infiltration due to the permafrost
Limited evaporation and transpiration due to sub-zero temperatures
Lack of liquid water = limited growth
Evaporation, in the summer only takes place in saturated soils,vegetation
Low humidity and the precipitation is sparse
Water logging due to minimal relief and the chaotic glacial deposits
Undulating land under the tundra due to million of years of erosional weathering
Low permeability due to permafrost and crystallised rocks
Dynamic equilibrium
A system having unrepeated average states through time.
Continuous inputs,outputs and variable stores of energy and materials
Short term = water or carbon will fluctuate each year.
Eg, heavy rainfall could add more water to the system raising the water table , drainage to from springs lowers the table back to normal levels= negative feedback loop
Eg, burning fossil fuels increases the co2 in the atmosphere but also stimulates photosynthesis in plants, removing excess co2 from the atmosphere and restoring equilibrium = negative feedback loop
Oil and gas impacts on the carbon cycle - what is the consequences of permafrost melting
Releases co2 and methane
Estimated co2 losses from permafrost vary from 7 to 40 million tonnes/year and methane losses range from 24,000 to 114,000 tonnes/year
Oil and gas impacts on the carbon cycle
Gas flaring and oil spillages release co2 to the atmosphere
Destruction of the tundra reduces photosynthesis and its uptake of co2 from the atmospheric store
Thawing of the soil increases microbial activity, decomposition and release of co2
Slow growing nature of the tundra means regeneration and recovery from damage takes decades ( 50 years)
Management strategies to moderate the impact on the carbon and water cycle
Insulated ice and gravel pads
Buildings and pipelines elevated on piles
Drilling laterally beyond beyond drilling platforms
Powerful computers to detect oil and gas bearing geological structures remotely
Refrigerated supports - eg, built into the trans Alaskan pipeline
