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geography: glaciation > unit one: glaciers system and the impact of climate change. glacial environments and their distribution > Flashcards

unit one: glaciers system and the impact of climate change. glacial environments and their distribution Flashcards

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1
Q

what is a glacier?

A

a moving body of water

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2
Q

where are glaciers found?

A

in cold areas of high altitude and latitude

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3
Q

why are glaciers important?

A
  • 1/3 of population rely on them for drinking water
  • tourism
  • recreation
  • irrigation
  • hydroelectric power.
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4
Q

what are the inputs of a glaciers?

A
  • accumulation zone, where snow falls at high altitudes which increases the mass
  • avalanches and wind blown snow add mass
  • de-sublimation (steam to ice)
  • dirt zones (where ice is forced upwards
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5
Q

what are the outputs of a glacier?

A
  • ablation zone, where melting occurs due to increased temperatures and run off
  • deformation due to solar energy
  • sublimation (ice to steam)
  • decay of ice, moving blocks into the ocean
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6
Q

what is the line of equilibrium?

A

marks the zone where glacier accumulation is balanced with glacier ablation over a 1 year period (where ice forms)

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7
Q

are the inputs above or below the line of equilibrium?

A

above

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8
Q

are the outputs above or below the line of equilibrium?

A

below

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9
Q

what is glacier mass balance?

A

the difference between inputs and outputs

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10
Q

what is a positive mass balance? (zone of…)

A

inputs > outputs

… accumulation

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11
Q

what is a negative mass balance?
(zone of…)

A

inputs < outputs

… ablation

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12
Q

is ablation or accumulation greater in the summer and why?

A

ablation > accumulation
more output

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13
Q

is ablation or accumulation greater in the winter and why?

A

ablation < accumulation
more input

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14
Q

How does ice form from snow in the zone of accumulation?

A

1) snowflakes fall, these contain air and have a low density
2) as more snow falls, pre existing snow compacts
3) snow that becomes compacted experiences freezing in the winter and thawing in the summer = firn/neve ice (composed of ice crystals separated by air passages)
4) in summer, meltwater percolates (moves down vertically) into firn
5) firn refreezes and the snowpack becomes increasingly dense
6) no. of years later, successive layers of snow and firn accumulate to a depth of 20m

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15
Q

what is a glacial period?

A

colder periods

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16
Q

what is the mass balance like in a glacial period?

A

positive mass balance which leads to long term growth of glaciers

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17
Q

what is an interglacial period?

A

warmer periods

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18
Q

what is the mass balance like in a interglacial period?

A

negative mass balance leads to long decay and the retreat of the glacier

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19
Q

what was the name of the last glacial period and what area did it cover?

A

devensian - covered most of northwest europe

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20
Q

what is the quaternary period?

A

a geological period representing the last 2.6 million years

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21
Q

what is an epoc?

A

smaller glacial/interglacial periods within a geological period

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22
Q

what was the last epoc called?

A

holocene

23
Q

what is present day earth’s orbit like?

A
  • 365 1/4 days
  • axis = tilted towards sun
  • angle = 23.5 causing seasonal variation in climate
  • axis changes between the tropics of cancer and capricorn
24
Q

what are the milankovitch cycles?

A

1) stretch (eccentricity) of orbit
2) axis tilt (obliquity)
3) wobble (precession)

25
Q

what is stretch (eccentricity)?

A
  • time frame = 100,000 years
  • shape of the orbit e.g circular or oval
  • this affects the amount of solar radiation that reaches the Earth
26
Q

what is axis tilt (obliquity)?

A
  • time frame = 41,000 years
  • over the last million years, tilt has varied between 22.1 and 24.5
27
Q

what is the effect of axis tilt (obliquity) on climate?

A
  • makes seasons milder
  • warming winters / cooling summers
  • allows snow and ice at high altitudes to build up into ice sheets
28
Q

What is wobble (precession)?

A
  • time frame = 25,771.5 years (26,000)
  • affects the position of the seasons on orbit
29
Q

what do feedback mechanisms do to glacial mass balance systems?

A

they can either amplify or diminish changes in the system

30
Q

what can positive feedback do?

A

amplify changes in the glacial budget

31
Q

how does positive feedback affect glaciers?

A
  • cooling leads to further cooling -> meaning snow and ice cover increases meaning it raises the surface albedo (reflectivity) of the Earth’s surface.
  • more solar energy is reflected back
32
Q

how does positive feedback loop operate when milankovitch cycle starts cooling?

A

cooling of climate > ice cover increases > increase in light/reflective surface > global albedo increases > increased reflection of isolation

33
Q

what can negative feedback do?

A

reduce/diminish changes in the glacial budget

34
Q

how does negative feedback affect oceans?

A

warming can also lead to cooling e.g disruption to the thermohaline ocean current circulation

35
Q

how can warming lead to the development of interglacial periods?

A

warming leads to increased temperatures > arctic sea melts > darker surfaces revealed > albedo is reduced (less reflective surfaces) > increased absorption of solar radiation

36
Q

how does thermohaline ocean circulation work?

A
  • low density freshwater drains to into north atlantic
  • high density saline warm north atlantic drifts, ocean current forced to descend further south
  • warmth from north atlantic drift ocean current shut off to north west europe, reducing temperatures
37
Q

what is solar forcing?

A

refers to energy released by the sun - solar output linked to solar spots

38
Q

what are solar spots?

A

areas of high solar output which fluctuate on an approx. 11 year cycle

39
Q

is solar forcing a long-term or short-term cause of climate change?

A

short-term

40
Q

when was the little ice age?

A

between 1645 and 1715

41
Q

what was the little ice age known as?

A

the ‘maunder minimum’ occurred with low levels of solar output

42
Q

what happened during the little ice age

A
  • sea ice expanded far south making it impossible to ship things to Iceland and greenland
  • baltic sea and river thames froze over
  • increased amount of permanent snow in high altitude areas of Scotland
43
Q

how do volcanic eruptions affect climate change?

A

explosive eruptions propel sulfur dioxide and ash into the atmosphere, where they reflect incoming solar radiation therefore can cause cooler conditions and lead to global cooling

44
Q

are volcanic eruptions long-term or short-term cause of climate change?

A

short-term

45
Q

what is meant by an anthropogenic factor?

A

human activity/ factors

46
Q

what different human activities affect climate change?

A

agriculture, deforestation, fossil fuel usage

47
Q

how has human activity affected climate change?

A

has lead to the increase in concentration of greenhouse gases in the atmosphere resulting in the increase of global temperatures

48
Q

how much has the average temperature increased since 1880?

A

1.2 degrees

49
Q

What is present day ice cover like?

A

glaciers cover more than 10% of Earth’s land surface
(stores 75% of freshwater)

50
Q

how is present day ice cover different to ice cover 10,000 years ago?

A
  • sea ice has retreated further north
  • U.K, Norway, Finland and Sweden no longer covered in ice
  • sea levels rising, affects coastlines
51
Q

why are glaciers found at high altitudes?

A

because there is an increase of accumulation due to higher temperatures

52
Q

what is an example of a high altitude glacial location?

A

the alps

53
Q

why are glaciers found at high latitudes?

A

there is a bigger surface area, which means the solar energy is spaced out, less absorbed in one spot

54
Q

what is an example of a high latitude glacial location?

A

the arctic

geography: glaciation (9 decks)

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