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OCR A Level Geography > The Arctic Tundra > Flashcards

Flashcards in The Arctic Tundra Deck (70)
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1
Q

How big is the Arctic tundra?

A

8 million km2

2
Q

What countries/regions is the Arctic tundra in?

A

Canada, Alaska, Siberia

3
Q

Where does the Arctic tundra extend to/from?

A

from the northern edge of the boreal coniferous forest to the Arctic Ocean

4
Q

What is the southern limit of the Arctic tundra?

A

the 10 degrees July isotherm

5
Q

For how many months does the tundra have a negative heat balance (average temperatures below freezing)?

A

8 or 9 months

6
Q

For how long is the ground frozen?

A

permanently

7
Q

How much permafrost thaws in the summer?

A

top metre

8
Q

What happens in winter?

A

the sun remains permanently below the horizon and temperatures reach -40

9
Q

Why is there low biodiversity?

A

few plants and animals have adapted to the extreme environment

10
Q

What plant is not present?

A

trees

11
Q

What is the annual preciptiation?

A

low - 50-350mm

12
Q

what form is most of the precipitation?

A

snow

13
Q

why is there low humidity

A

the cold

14
Q

why is there little transpiration

A

sparse vegetation and short growing season

15
Q

why is there low evaporation

A

the Sun’s energy is used to melt snow and most surface water is frozen

16
Q

what is permafrost a barrier to?

A

infiltration and percolation = limited groundwater stores

17
Q

what accumulates in winter

A

snow and ice

18
Q

why does river flow increase in summer

A

snow/ice and active layer melt

19
Q

why are there wetlands in summer

A

permafrost limits drainage of melted ice

20
Q

how much carbon does the tundra contain

A

1600 Gt

21
Q

what slows decomposition

A

low temperatures

22
Q

how much more carbon is there in the soil than the above ground biomass

A

5X

23
Q

what do long daylight hours in summer allow for

A

rapid plant growth

24
Q

what is the NPP

A

200 g/m2/year

25
Q

what is the biomass

A

4-29 tonnes/ha

26
Q

what do plants input to the soil during the growing season

A

carbon-rich litter

27
Q

the activity of what increases in summer, and what does this release

A

microorganisms - CO2 via respiration

28
Q

What are a source of CO2 and CH4 in winter

A

pockets of unfrozen soil

29
Q

what is the effect of insulating snow

A

microbes can carry out some decomposition

30
Q

what may global warming do to the tundra

A

make it a carbon source. But increases in plant growth may take in more CO2

31
Q

what is the effect of temperature on water storage

A

average temperatures below freezing so water is stored as ice

32
Q

what forms when the active layer thaws

A

pools and lakes

33
Q

why is drainage poor

A

the permafrost

34
Q

what carbon cycle process does the cold prevent

A

evapotranspiration

35
Q

from what does evapotranspiration occur in summer

A

pools and vegetation

36
Q

what are low all year

A

humidity and precipitation

37
Q

what lies under the tundra

A

ancient rock

38
Q

what has reduced the ancient rock to a gentle plain

A

weathering and erosion

39
Q

what does the gentle plain of the tundra cause

A

impedes drainage and causes waterlogging in the summer

40
Q

what is carbon mainly stored as

A

partly decomposed plants in the permafrost

41
Q

what factors limit plant growth

A

low temperatures, no liquid water, little nutrients

42
Q

what are low due to limited plant growth

A

NPP and photosynthesis

43
Q

what compensates for the short growing season

A

long daylight hours

44
Q

what are the results of low temperatures and water logging on the carbon cycle

A

slow decomposition and respiration

45
Q

what size is the flow of CO2 to the atmosphere in the tundra

A

small

46
Q

why do rock porosity and mineral composition have little influence on the carbon and water cycles

A

the impermeability of the tundra

47
Q

when and where was oil and gas discovered in the tundra

A

Prudhoe Bay - 1968

48
Q

why is it difficult for oil and gas industries to function in the tundra

A

extreme cold
long periods of darkness
poor accessibility

49
Q

what was oil and gas production in the tundra driven by

A

high global energy prices and the US government’s policy to reduce dependence on oil imports

50
Q

by the early 1990s the North Slope of Alaska accounted for how much of the USA’s domestic oil production

A

1/4

51
Q

how much USA oil does the North Slope of Alaska contribute to today

A

6%

52
Q

why has oil and gas production in Alaska declined

A

high production costs and growth of the US oil shale industry

53
Q

why does the melting of the permafrost make flooding more likely

A

increases run off and river discharge

54
Q

what process increases because summer wetlands are becoming more extensive

A

evaporation

55
Q

what is the effect of mining sand and gravel

A

artificial lakes that disrupt drainage and cause furhter melting

56
Q

what human activity disrupts drainage

A

road construction

seismic explosions to prospect for oil and gas

57
Q

what human activity reduces run off

A

abstracting water from creeks and rivers

58
Q

why is the permafrost melting

A

construction and infrastructure diffusing heat
dust reducing albedo so more sunlight absorbed
removal of insulating vegetation cover

59
Q

what gasses does melting release

A

CO2 and CH4

60
Q

how much CO2 is estimated to be lost due to melting

A

7-40 million tonnes a year

61
Q

what human activities in the tundra input CO2 to the atmosphere

A

gas flaring and oil spills

62
Q

what is the result of loss of vegetation on the carbon cycle

A

reduces photosynthesis so less CO2 fixed by plants

63
Q

what process in the carbon cycle increases due to melting

A

decomposition

64
Q

why does tundra vegetation take decades to recover

A

slow growing

65
Q

what management strategy goes under roads to prevent melting

A

insulated ice and gravel pads

66
Q

what management strategy allows cold air to circulate beneath structures

A

elevate buildings and pipelines on piles

67
Q

what management strategy allows oil and gas to be accessed several km from the drilling site, and why is this good

A

drilling laterally - less construction sites are needed

68
Q

what management strategy means that fewer exploration wells are needed

A

more powerful computers detect oil and gas remotely

69
Q

what management strategy is used on the Trans-Alaska pipeline

A

refrigerated supports

70
Q

why are the management strategies also pragmatic

A

melting permafrost causes widespread damage to buildings and roads