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Geo: ELSS > Arctic Tundra > Flashcards

Arctic Tundra Flashcards

1
Q

How much does temperature range by in the Artic Tundra?

A

From -30C to 10C

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2
Q

How does temperature influence the water cycle in the Artic Tundra?

A

Thawing of permafrost occurs in summer when temperatures are above 0°C increasing meltwater and reducing ice storage.
As permafrost melts evapotranspiration can occur and the biomass store can grow in summer.
Lots of water stored in cryosphere

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3
Q

How does permeability influence the water cycle in the Artic Tundra?

A

Permafrost acts as an impermeable layer reducing infiltration or percolation
Reduces the groundwater store in winter and increases overland flow.
In summer percolation occurs in soil moisture storage and flows increase.
Igneous rock formations have a dense crystalline structure that further reduces permeability.

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4
Q

How does relief influence the water cycle in the Artic Tundra?

A

A flat relief due to ice sheets create a thermokarst landscape.
Little GPE reduces surface runoff and increases infiltration creating a boggy landscape.
There is an increase in the surface store of water in alas lakes.

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5
Q

What is the rate of processes in the Artic Tundra water cycle compared with the Amazon Rainforest?

A 
Evapotranspiration = slower
infiltration = slower
percolation = slower
surface runoff = slower
Precipitation = slower
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6
Q

What are the sizes of water stores in the Artic Tundra compared with the Amazon Rainforest?

A 
Atmosphere = smaller
biosphere = smaller
groundwater = smaller
cryosphere = larger
surface water store = larger
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7
Q

What biomes does Tundra lie between

A

Ice and Snow, Needleleaf forest

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8
Q

How does precipitation change over the course of the year in the Artic Tundra?

A

It remains low - slightly higher in the summer months

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9
Q

Why is the tundra so cold?

A

Because for 8-9 months there is a negative heat balance, due to its latitude.
Low insolation

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10
Q

What are the key stores of the water cycle in the Artic Tundra?

A
  • Small stores of moisture in the atmosphere due to low temperatures that reduce absolute humidity
  • Limited groundwater and soil moisture stores.
  • Accumulation of snow and river/lake ice during winter months. Melting of active layer and snow in the summer results in sharp increase in river flow.
  • Extensive wetlands, ponds, and lakes on the Tundra surface during summer
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11
Q

What are the physical factors affecting the carbon cycle in the Artic Tundra

A
  • Vegetation and organic matter in soils
  • Temperature
  • Mineral composition of rocks
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12
Q

What are the key flows of the water cycle in the Artic Tundra?

A
  • Low rates of evapouration: low temperatures and insolation mean ground is often frozen
  • The permafrost is a barrier for infiltration, percolation, recharge, and groundwater flow.
  • Low annual precipitation (50-350mm)
  • Limited transpiration because of the sparse vegetation cover (short growing season)
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13
Q

How does vegetation and organic matter in soils influence the carbon cycle in the Artic Tundra?

A
  • Lack of insolation reduces the biomass store.
  • Majority of carbon is stored as partly decomposed plant remains in permafrost.
  • Low photosynthesis and respiration.
  • When decomposition occurs in waterlogged environments bacteria respire anaerobically releasing methane instead of usual CO2 aerobically.
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14
Q

How does temperature influence the carbon cycle in the Artic Tundra?

A
  • Rapid decomposition in summer months as bacteria rely on heat making decomposition a slower process. - - Photosynthesis, respiration and the tundra biomass store increase in summer as plants require sunlight. -
  • Ocean gas exchange and soil storage of carbon increase in winter.
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15
Q

What is the annual NPP for the Artic Tundra?

A

The average annual NPP is less than 200gcm2.

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16
Q

How did the mineral composition of rocks influence the carbon cycle in the Artic Tundra?

A
  • Lack of soil nutrients (nitrogen) limits plant growth reducing biomass and evapotranspiration, respiration and photosynthesis.
  • Groupings of igneous rock around Baffin Bay with some sedimentary rock in the North.
  • Sedimentary rock is a larger store of carbon and due to rock being hidden away by the permafrost there is little metamorphism.
  • Less carbon released from the lithosphere to the atmosphere due to limited lithification, degassing or other processes in the slow carbon cycle.
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17
Q

What are the key features of the biosphere in the Artic Tundra?

A
  • Low growing perennial plants
  • Few trees except for dwarf birch
  • Ground level species dominate - mosses, lichen, heather, bilberry.
  • Low levels of biodiversity and biomass
  • Slow growth rate
  • Fragile - vulnerable to damage
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18
Q

What is permafrost?

A

Permanently frozen ground for 2 years in a row

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19
Q

How is carbon stored in permafrost?

A

It is frozen in the form of organic matter

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20
Q

What is the positive feedback loop in the Artic Tundra related to permafrost?

A

As the climate warms, more permafrost melts, and this means more greenhouse gasses are released. This then warms the climate more and the cycle repeats.

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21
Q

How may the artic tundra react to a warming climate in a negative feedback loop?

A

There will be more plants growing at the surface due to warmer conditions and these may absorb lots of the carbon released.

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22
Q

What is a negative feedback loop?

A

Negative feedback loops return a system (the carbon cycle) back to a dynamic equilibrium after a shift away.

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23
Q

What is a positive feedback loop?

A

Positive feedback loops amplify any change in a system to shift it increasingly far from equilibrium.

24
Q

What does the fact that most of the artic tundra is waterlogged mean?

A

The decomposition that occurs in tundra pools and lakes is anaerobic and therefore produces methane (CH4) rather than carbon dioxide (CO2) which is released into the atmosphere.

25
Q

Why is methane being released into the atmosphere worse than carbon dioxide?

A

methane is 84 times more potent over a 20 year timescale than CO2 in the atmosphere - it has a much more significant warming effect.

26
Q

Why is the artic tundra waterlogged?

A
  • Permafrost prevents infliltration

- flat relief means there is no surface runoff

27
Q

What are distinctive features of the carbon cycle in the artic tundra?

A
  • Accumulation of carbon is due to low temperatures that slow decomposition of dead plant material
  • Flux of carbon is concentrated in the summer, because plants grow rapidly in the short summer
  • Tundra biomass is small (ranging between 4 and 29 tonnes/ha
  • During the growing season plants input carbon rick litter into the soil
  • Activity of micro-organisms releases CO2 and CH4 as decomposition occurs in unfrozen soil (mainly in summer)
  • In the past, the tundra has been a carbon sink, but the warming climate has led to concerns that the tundra may become a carbon source
28
Q

How much carbon is stored in permafrost globally?

A

1600GT

29
Q

How much more carbon is stored in the soil in the artic tundra than the biomass?

A

5 times more

30
Q

How does the ocean impact the artic tundra carbon cycle?

A
  • Cold temperatures in the Arctic increase the efficiency of carbon transfer from the atmosphere to the ocean by diffusion.
    • Arctic Ocean is 3% of the Earth’s oceans, but removes 5 to 14% of the Earth’s ocean carbon uptake
31
Q

How long has most carbon been locked in permafrost in the Artic Tundra?

A

500,000 years

32
Q

How do vegetation changes and forest help the artic tundra become a carbon sink?

A
  • CO2 levels rise and drop in the atmosphere due to changing levels in vegetation as a result of the seasonal variations in conditions.
  • Observations show that evergreen shrubs and trees are migrating northwards due to the warming. These species store more carbon than the sparse vegetation they are replacing.
  • Increases in vegetation will increase the absorption of carbon from plants due to the process of photosynthesis, there will be more vegetation as temperatures rise.
33
Q

How do wet soils help the artic tundra become a carbon sink?

A
  • If the soil is sufficiently saturated with water then the bacteria do not have sufficient access to oxygen and can’t metabolise the carbon.
34
Q

How does ocean absorption help the artic tundra become a carbon sink?

A
  • The artic ocean could absorb 20% more carbon than previously predicted by the end of the 21st century
  • As the ocean absorbs more carbon the pH decreases
  • Warmer oceans store less carbon, so the cooler Artic Ocean is still able to hold a lot of carbon.
  • Seagrasses cover less than 0.2% of the ocean floor, but store 10% of the carbon. However, 30% of historical cover has been lost at a rate of roughly 1.5% a year.
35
Q

How does the feedback loop created by melting permafrost help the artic tundra become a carbon source?

A
  • Artic tundra air temperature has risen twice as fast as the rest of the world - has risen by 0.6C in the past 3 decades
  • Warmer temperatures means that soils that may have been frozen for thousands of years begin to decompose and release their carbon.
36
Q

How much have average temperatures in permafrost risen by in the Artic Tundra since the 1980s

A

5.5C

37
Q

How do forest fires help the artic tundra become a carbon source?

A
  • Forest fires are on the rise in the tundra releasing stored carbon and potentially offsetting the impact of increased plant growth
  • ## Arctic wildfires emit 35% more CO2 so far in 2020 than for whole of 2019 - about 205 megatonnes emitted in June and July alone as Siberia hit by heatwave.
38
Q

When is it estimated that the Artic Tundra will become a carbon source?

A

It has been estimated that to net carbon emissions from permafrost ecosystems to the atmosphere, possibly by the middle of the 21st century.

39
Q

How many tonnes of Carbon are store underneath the artic tundra?

A

1,000bn

40
Q

Alaska - HI - How does increased snow and permafrost thawing impact the water cycle in the AT?

A

o The oil and gas industries increase melting of permafrost and snow as poorly insulated infrastructure and heat from gas flaring diffuses to the ground and raises local temperatures, creating an urban heat island effect.
o This increases surface runoff and therefore increases river discharge.

41
Q

Alaska - HI - How is increased surface runoff impacting the water cycle in the AT?

A
  • Increased surface runoff making flooding more likely. Lakes and rivers have a larger surface area as a result which increases evaporation, transferring water that has been stored in frozen permafrost and soils long-term to the atmosphere.
42
Q

Alaska - HI - How do artificial lakes influence the water cycle in the AT?

A

o Strip mining of aggregates (sand and gravel) for construction creates artificial lakes which disrupt natural river drainage networks and further expose permafrost to thaw.
o Road construction and seismic explosions used to prospect for fossil fuels further disrupt these networks.

43
Q

Alaska - HI - How does abstraction of water influence the water cycle in the AT?

A

o Water is abstracted from creeks and rivers for industrial use and the building of ice roads in winter, which reduces surface runoff and therefore reduces the amount of water stored on the Earth’s surfaces as the atmospheric store increases.

44
Q

Alaska - HI - How does increased atmospheric storage of water influence the water cycle in the AT?

A
  • Low annual precipitation is a key aspect of Alaska’s climate.
  • A greater store of moisture in the atmosphere due to increased evaporation will increase precipitation levels as cold temperatures mean that little water can be stored here for long.
45
Q

Alaska - HI - How does increased permafrost permeability influence the water cycle in the AT?

A

o Permafrost creates low permeability as it is a barrier to infiltration, percolation, and recharge and groundwater flow. These processes increase as permafrost thaws and allows the ground to become more permeable.
o As more water is freed from being frozen and can infiltrate the ground, soil moisture storage and groundwater storage increase. The presence of more water in the ground increases throughflow and groundwater flow, as temperatures continue to increase and permafrost continues to melt, because there is now more liquid water.

46
Q

Alaska - HI - How does increased melting influence the water cycle in the AT?

A

o Melting releases water that has been locked away in storage long-term, such as in permafrost, and therefore its movement through processes increases. As a result of human activity in these industries, the water cycle in Alaska is becoming more mobile.

47
Q

Alaska - HI - How does increased localised thawing of permafrost influence the carbon cycle?

A

o Permafrost is a major carbon store in the tundra and is sensitive to temperature changes. The construction and operation of oil and gas installations and infrastructure with poor insulation diffuses heat to the ground; the slightest change in temperature increases the depth of the active layer.
o Dust deposition alongside roads darkens the snow surface, increasing insolation.
o The removal of vegetation reduces cover from insolation by increasing the area exposed to it, and also removes a vital layer of insulation for the permafrost.
o These activities collectively increase the rate and expanse of permafrost thaw, releasing CO2 and methane gases to the atmosphere and depleting this store.
o The North Slope loses approximately 7 to 40 million/tonnes/year of CO2 from permafrost thaw, and 24,000 to 114,000 tonnes/year of methane (CH4).

48
Q

Alaska - HI - How does the transfer of carbon from permafrost to the atmosphere influence the carbon cycle?

A

The release of CO2 and methane from permafrost as it thaws transfers carbon from a long-term store to another from permafrost to the atmosphere.

49
Q

Alaska - HI - How does the removal of vegetation influence the carbon cycle?

A

o These industries degrade and destroy tundra vegetation, of which there are already low levels of biomass. This decreases the amount of carbon stored in vegetation.
o The rate of photosynthesis is therefore reduced as there are fewer plants, meaning that less CO2 is taken up by plants and so more remains in the atmosphere.
o The thawing of soil increases microbial activity because of the warmer temperatures, increasing decomposition and so releasing more CO2 to the atmosphere at a faster rate. The carbon that is stored in the soils is therefore decreased and transferred.
o The slow growth of this vegetation means that regeneration takes decades, so the store will be affected long-term as it cannot be returned until it has grown.

50
Q

Alaska: Full explanation of the climate feedback loop.

A

1) The thawing of permafrost and releasing of CO2, alongside destroying vegetation, gas flaring and oil spillages, are all impacts of these industries and contribute to increasing global temperatures.
2) permafrost melts even more, releasing more carbon to the atmosphere. These greenhouse gases contribute to global warming and cause a climate feedback loop that as temperatures increase, more carbon will be released and increase the temperature again.
3) this means that climate change will continue to damage Alaska’s ecosystem long-term and its effects will be difficult to reverse. This may even result in a thermokarst landscape developing.

51
Q

Alaska: Explanation of drilling laterally managment stategy

A

Explanation:

  • Drilling laterally prevents more infastructure being built and protecting landscapes.
  • Increases productivity 20x

Impact on Water cycle:

  • Fewer exploration sites limit changes in thermal balance of the ground from construction reducing the risk of subsidence/ thermokarst developing.
  • Less Vegetation is cleared from the ground and reduces deepening of the active layer in summer.

Impact on carbon cycle:

  • Limits vegetation being cleared and the area vulnerable to thawing of permafrost.
  • increases the proportion of hydrocarbons recovered from wells.
52
Q

Alaska: Explanation of more power computers management strategy

A

Explanation:
Can detect oil and gas leading to fewer exploration wells.

Impact on carbon cycle:
Limits vegetation being cleared and the area vulnerable to thawing of permafrost.

53
Q

Alaska: Explanation of building houses and pipelines on elevated stilts management strategy

A

Explanation:
- Pipes built up to 3m high and houses 1m high prevents them from moving in contact with the ground.

Impact on water cycle:

  • Stilts prevent thawing of deep permafrost, subsidence and solifluction as cold air can circulate buildings and 80°C oil in pipelines.
  • Sleepers and pumpkin stations prevent and control the spillage of oil onto permafrost.
54
Q

Alaska: Explanation of Utilidors management strategy

A

Explanation:
- Insulated box conduits made of concrete, woods or metal elevated above ground.

Impact on water cycle:
- Limits alterations to the thermal balance of the ground thereby reducing the risk of permafrost melting and subsidence/ thermokarst developing.

55
Q

Alaska: Explanation of insulated gravel pads management strategy

A

Explanation:
- The active layer is removed and replaced with pads typically 1-2m thick for insulation.

Impact on water cycle:

  • Deep permafrost remains insulated from heat being transmitted.
  • Gravel bases are more stable as they dont hold water so there is no more ice to melt close to the surface.
56
Q

Alaska: Explanation of refrigeration pipes management strategy

A

Explanation:
A refrigerated layer is wrapped around the pipe and cooled to the same temperature as the permafrost.

Impact on water cycle:
Limits alterations to the thermal balance of the ground thereby reducing the risk of permafrost melting and subsidence/ thermokarst developing.

Geo: ELSS (4 decks)

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