Geography- Cold Environments

OCR AS geography cold environments

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Reasons why environments are cold

  • high latitude 
    • high latitudes are colder than lower latitudes because they receive less solar radiation as the sun's energy hits the earth at more of an angle at high latitudes so it is spread over a larger area
  • high altitude 
    • high altitudes are colder than lower altitudes because air temperature decreases with increasing altitude. less of the sun's energy reflected back from the earth is trapped at higher altitudes, making it colder. lower air pressures higher up also means temperatures drop. it gets between 6'C and 10'C colder for every 1000m you go up
  • They're in the middle of continent. 
    • the middle of continents are cold because they're far away from the sea. In the summer, the land heats up quickly and the sea heats up slowly. In the winter, the land cools quickly and the sea cools slowly. So, in winter the sea warms the land near the coast but not the interior- called continentality
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More causes of cold environments

Less water vapour

  • cold air can't carry water vapour
  • the moisture won't be evaporated so will form ice
  • water vapour acts as a greenhouse gas
  • at the poles there is less water vapour in the atmosphere so less warmth is trapped by the clouds so the heat is lost into space

Fewer daylight hours

  • lack of heat energy getting to the surface due to the tilt of the earth
  • means for 6 months of the year there is not much sunlight reaching the earth so water doesn't evaporate but freezes

Lots of ice

  • makes cold air sink which pushes on the ground creating high pressures, this spreads out causing cold winds and blizzards
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More causes of cold environments

Reflection

  • the white ice reflects the sunlight instead
  • darker colours absorb the heat
  • the whiter and more compact the ice the most reflection
  • 20% reflected by vegetation
  • 10% reflected by ocean water
  • 85%-90% reflected by snow

Sun Angle

  • makes atmospheric length longer
  • reflection higher
  • the air colder with less moisture
  • and the daylight hours fewer in winter
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Single cell atmospheric circulation

  • Air at equator rises into the atmosphere
  • the air at the poles sinks so the air that is pulled back from the ozone layer by gravity fills in where the cold air has sunk
  • air cools as it approaches the poles
  • the moisture in the air condenses by the tropics
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Glacial climates

  • found at high altitudes and high latitudes
  • areas of land permanently covered by ice
  • very cold and dry (antarctic temperatures -10'c at coast to -40'c on ice sheet summit)
  • cold winds blow out from the centre to the coast- katabatic winds
  • winter temperature= -70'c to -25'c
  • summer temperature -40'c to -2'c
  • found at high latitude:
    • e.g. the antarctic ice sheet and greenland ice sheet
    • both entirely above 60' latitude
  • found at high altitudes
    • found in Himalayan mountains even though its low latitude because its the highest mountain range
    • glaciers even form at latitudes close to the equator
  • even though it can be really cold on low altitude land in the middle of continents there's not enough snow
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Periglacial climates

  • have significant cover of snow and ice but not all year round e.g. scadinavia
  • temperature is frequently or constantly below freezing but not covered by ice, contain a layer of permafrost on or below the surface
  • high latitudes
    • e.g. the northern parts of asia, north america and europe
    • receive relatively small amounts of insolation due to low angle of the sun
  • high altitudes
    • periglacial conditions exist around ice masses in mountain ranges
    • found on high altitude plateau areas e.g. the tibetan plateau in asia
  • in the interior of land masses, periglacial conditions exist at lower altitudes and lower latitudes because of the effect of continentality e.g. siberia
  • albedo- they reflect a lot of solar radiation (average absorption is 40-90% in dark soils and 10-20% on snow and ice
  • precipitation levels are low- due to cold air unable to hold moisture
  • affected by high pressure conditions which reduces rainfall- in arctic rainfall declines away from oceans as travels westerly loses moisture
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Polar environments- Arctic (north pole)

  • cold because it exists at a high latitude
  • can be defined either by the Arctic circle (66'N) or by the 10'C July isotherm (areas north of this line have an average temperature below 10'C in july, the hottest month)
  • area around the north pole is made up of sea ice,
    • sea ice shrinks in summer leaving open sea
    • refreezes in winter
  • much of the Arctic polar environment is made up of the northern land areas of Asia, North America and Europe
  • land-based polar environments can include glacial environments e.g. Greenland ice sheet and periglacial environments e.g. northern Russia
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Polar environments- the antarctic (south pole)

  • high latitude cause it to be cold
  • the Antarctic Circle (66'S latitude) doesn't go all the way around the land mass of Antarctica though, so the polar environment around the south pole is defined as 10'C January isotherm
  • some of the Antarctic polar environment is also cold because it's at a high altitude- ice so thick in some places its reaches an altitude of 4000m
  • the interior of Antarctica is also cold because of the effect of continentality- the centre is hundreds of kilometres from the warming effect of the oceans
  • a large area around the antarctic land mass is made up of sea ice
    • area of sea ice changes throughout the year, shrinking in summer and refreezing in winter
  • the land based polar environment includes glacial environments e.g. Antarctic ice sheet 
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Mountain (upland) climates

  • were once covered in ice but now free of snow and ice
  • landforms formed during the cold periods continue to exert an influence over people's lives in the area
  • upland areas may remain periglacial e.g. Alps and Himalayas are high enough to still have ice caps
  • they are cool- lose about 1'C for every 100m 
  • they are wet- mountainous areas often cause relief of orographic rainfall
  • they are above the treeline- treeline= limit of the area that trees can grow
  • can exist at any latitude
    • e.g. alpine conditions exist along much of the rocky mountains in North America which run north to south from above 50' to around 30' latitude
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The lake district

  • 34 miles across
  • its features are as a result of periods of glaciation 
  • most recent ended 10,000 years ago include
    • U-shape valleys which are now filled with lakes
    • glacier cirques, typically filled with tarns
    • higher fells are rocky with lower fells being open moorland
    • much of the land is often boggy due to high rainfall
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Glaciers are systems

Inputs

  • snow (form precipitation or avalanches)
  • condensation of water vapour form the air
  • sublimation of water vapour from the air directly to ice crystals
    • sublimation- involves a direct change of state from a gas to a solid without passing through the liquid stage
  • Bits of rock collected when the glacier carves away at the landscape, and rocks that have fallen onto the glacier from above

stores

  • main store= ice
  • meltwater is a small part of the glacier, can be found on, in or below ce
  • glaciers also carry debris (rocks, gravel and sand)
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Glaciers are systems

Outputs

  • outputs are the losses from a glacier
  • ice can melt and flow out of the glacier as meltwater
  • surface snow can melt and evaporate
  • ice and snow can sublimate to water vapour
  • snow can be blown away by strong winds
  • with glaciers that end at the sea, blocks of ice fall from the front of the ice mass into water creating icebergs
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Glacial Budget

=the balance between a glaciers inputs and outputs

  • accumulation is the input of snow and ice into the glacial system
  • ablation is the output of water
  • glacial budget is the balance between accumulation and ablation over a year- it shows whether the volume of water in the glacial system has increased or decreased, determines whether the glacier advances or retreats
  • more accumulation in the upper part of the glacier called zone of accumulation
  • get more ablation in the lower part of the glacier called zone of ablation
  • place where accumulation and ablation are equal is called the glaciers equilibrium point
  • if there's more accumulation than ablation= positive regime- glacier grows and advances
  • if there's less accumulation than ablation= negative regime- glacier retreats
  • same amount of ablation and accumulation glacier stays the same
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Glacial budget changes....

Throughout the year

  • you get more ablation during warmer times of the year-ice melts when warm
  • during the colder moths there is more accumulation than ablation
  • over the year, this might balance out
    • the glacier advances in winter but retreats in summer, so overall the volume of water in the glacier stays the same

Over several years...

  • global temperature change over long periods of time affect the glacial budget
  • temperatures in the 19th century were colder than in the 18th century so in general there was more accumulation than ablation meaning that glaciers advanced because they had a positive regime
  • in the 20th century global temperature increased so glaciers tended t have a negative regime and retreated
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Formation of glaciers

  • snow settles, has loose, fluffy, snowflakey consistency at this point
  • the weight of more snow falling on top turns the snow into a denser, more granular kind of snow called firn
  • air is squeezed out, and particles of ice are compressed together by the continuing accumulation of snow and ice
  • water also melts and refreezes in the air spaces, making the ice more dense
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warm-based glaciers

glaciers can be classified according to the temperature of their base:

  • warm-based glaciers
    • base is warmer than the melting point of ice
    • it is warmer because of the heat from friction caused by the glacier moving
    • or because of geothermal heat from the earth
    • the ice at the bottom of the glacier melts and the meltwater acts as a lubricant making it easier for the glacier to move downhill
    • ice at the surface also melts if the temperature reaches 0'C and meltwater moves down through the glacier, lubricating it even more, lots of movements means lots of erosion
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Cold-Based Glaciers

  • cold-based glaciers
    • the base is cold- temperature well below the ice's melting point so there's very little melting
    • ice is frozen to the bottom of the valley so there is little movement
    • there's hardly any melting on the surface either
    • means that cold-based glaciers don't cause very much erosion at all
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processes in cold environments- weathering

mechanical- no change in state, just disintegrates usually as a result of temperature change

  • freeze-thaw- water gets into cracks and expands 9% when it freezes
  • wet/dry- glacial clays crack up in cold dry winters
  • pressure release- as glaciers melt

chemical- change in state just decomposes usually following snow melt

  • solution/ carbonation- limestone dissolves more rapidly in cold temperatures
  • acid action- especially if snow is polluted
  • hydrolysis- water reacts with minerals to produce clays

biological- by plants and animals (usually in search of water, nutrients or shelter)

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Glacial processes

  • Basal sliding- meltwater underneath glacier allow the glacier to slide over the ground- main way warm based glaciers move
  • there's more melting around bits of rock protruding from the valley floor because there's more pressure on the ice, meltwater can refreeze downstream of the obstruction where there's less pressure
  • glaciers move in an arc shape when they're in a hollow- rotational flow
  • internal deformation- where the ice bends and warps to flow downhill, caused by ice crystals shifting past each other
    • way cold-based glaciers move
  • at the head of a glacier the valley is steep so there is strong gravitational force pulling the ice downwards, making the ice move quicker, creating more tension causing the ice to fracture into thick layers this layers slip downwards- extensional flow
  • lower down the glacier the ice is moving slowly because the valley is less steep. faster the ice from the head of the glacier pushes down on the slower ice and compresses it, high pressure causes the ice to fracture into layers and the layers slip forwards- compressional flow
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Speed of Glacier

  • main things that determine the speed at which a glacier flows is gradient of the valley floor, thickness of the ice and the temperature at the base of the glacier
  • the steeper the valley, the faster the glacier will flow
  • the thicker the ice the faster it will flow
  • in a warm based glacier thicker ice exerts more pressure on the valley floor causing more melting making it flow faster
  • in a cold based glacier thicker ice means there's more internal deformation which makes it flow faster
  • the warmer the base of the glacier the faster it will flow
  • ice moves faster nearer the glacier's surface than at the base- friction at the base slows the glacier down
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Glaciers crack as they move down the valley

  • stresses and strains cause cracks called crevasses to form in the glacier
  • stress can be caused by extensional and compressional flow, calving or tension between the ice attached to the valley sides and back wall and the rest of the glacier
  • the tension caused by the glacier pulling away from the ice attached to the back wall produces a big semicircular crevasse at the back of the glacier called the bergschrund
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Glaciers

='rivers of ice'

carry out erosion, deposition and transportation

e.g. madison boulder in new hampshire USA is a glaciar erratic

glaciers load comes from materials falling onto the glacier as a result of mass movements and weathering as well as erosion

load melts glaciers erode the land

glaciers erode because they are mobile and contain material at the base and sides

little erosion happens in polar glaciers because they are too static by lots of erosion happens in warm based glaciers

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Glacier erosion- plucking

Glaciers erode the valley floor and sides by plucking and abrasion

  • Plucking:
  • in the contact with rocks surfaces can thaw slightly and refreeze around rocks protruding from the valley sides and floor. when the glacier moves forward it plucks the rocks away from the valley sides and floor
  • the more fractured and broken the bedrock the more plucking occurs
  • involves downward pressure caused by the weight of the ice and downhill drag as the ice moves, slow enough for meltwater to freeze onto obstacles
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Glacier erosion- abrasion

Abrasion:

  • debris carried along by the glacier can scrape material off the walls and floor
  • the larger and more angular the load the greater potential for erosion
  • the coarser material will scrape, scratch and groove the rock leaving striations and chatter marks
  • finer material smoothes and 'polishes' rock
  • observing abrasion is difficult because it involves digging tunnels through a glacier to gain access to basalt cavities
    • best results by Boulton's (1974) work on the breidamerkurjokull glacier in Iceland
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Meltwater Erosion

-shapes the valley floor

  • Glaciers can produce huge quantities of meltwater, making streams that are powerful enough to erode the valley floor and sides by normal fluvial (river) processes
  • solution, suspension, saltation, traction

the amount and rate of erosion is increased in areas of less resistant rock, and if the glacier is thick or if it's moving quickly it's also increased if there's lots of debris or if the debris is made of resistant rock

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Weathering

Weathering also contributes to the shaping of the glacial valley

  • frost shattering breaks rocks off the back and side walls of the valley
  • Meltwater from snow gets into cracks in the valley walls and then freezes- when it freezes it expands, so exerts pressure on the rock and bits of the rock get broken off
  • these bits of rock often fall onto, or into the glacier
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Glaciers transport debris

  • glaciers carry large loads of debris- this is material that the glacier has gathered by plucking, or bits of rock that have been broken off the back wall or valley sides and fallen onto the glacier
  • debris ranges from fine sediment to huge boulders
  • there are three main ways debris is transported
    • supraglacial material- carried on top of the surface
    • englacial material- carried within the body of the glacier
    • subglacial- moved along at the base of the glacier
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Glaciers depositing their load

  • the unsorted mixture of material deposited by the glacier is called till, it includes everything from massive boulders to pebbles and clay, glaciers drop any size of till anywhere
  • lodgement till is spread onto the valley floor beneath the ice by moving glaciers
  • ablation till is dropped by a glacier when it melts, the till is mainly deposited close to the glacier snout because this is were most ablation happens- the glacier drops debris as the ice around the debris melts
  • till points in the direction that the glacier is flowing
  • till is often deposited as landforms called moraines
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Formation of Cirques/ corries

  • Glaciers normally form on one side of a mountain peak- side that gets least sun and the coldest winds where there's most acculation and least ablation
  • snow collects in hollows and turns to ice causing nivation
  • basal sliding (rotational flow) with abrasion and plucking deepen the hollow into a corrie (a bowl-shaped hollow)
  • when the ice in the hollow is thick enough it flows over the lip and downhill as a glacier
  • frost shattering and plucking steepen the back wall of the corrie also adds to the supply of debris
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Glacial erosion landforms

  • Arete= a steep-sided ridge
    • it's formed when two glaciers flow in parallel valleys.
    • The glaciers erode the sides of the valley, which sharpens the mountain ridges in between them
  • pyramidal peak is a pointed mountain peak with at least three sides 
    • it forms when three corries form back to back
    • e.g. the Matterhorn
  • A horn is an isolated upstanding mass of rock 
    • e.g. Cir Mhor on the isle of Arran
  • Glacial troughs (U-shaped valleys)
    • steep sided valleys with flat bottoms 
    • formed by the erosion of V-shaped river valleys by glaciers. 
    • As the glacier erodes through the V-shaped valley it makes them deeper and wider
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Glacial erosion landforms

  • Hanging Valleys are valleys formed by tributary glaciers
    • they erode the valley floor much less deeply because they're smaller than the main glacier
    • when the glaciers melt, the valleys get left at a higher level than the glacial trough formed by the main glacier
    • get waterfalls from hanging valleys into the main glacial trough
    • e.g. County Mayo in Ireland
  • Truncated spurs
    • formed when ridges of land (spurs) that stick out into the main valley are chopped off (truncated) as the main valley glacier moves past
  • Valley steps
    • steps in the glacial trough
    • form when the glacier erodes the valley floor more deeply
    • happens when another glacier joins it or where there's less resistant rock
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Glacial erosion landforms

  • Tarns are lakes that form in cirques/corries after a glacier has retreated
  • Ribbon lakes are long, thin lakes that form after a glacier retreats
    • form in dips caused by erosion of bands of less resistant rocks or behind dams of debris left by the glacier
  • fjords are long, deep inlets that form when a valley that's been eroded by a glacier is flooded by sea level rise after the ice has melted
    • long profile showing a greater degree of erosion at the source of the fjord compared to the mouth
    • mouth of the fjord is often marked with a sill or threshold
    • e.g. Sogne fjord in Norway has maximum depth of over 1300m but its mouth is only 200m
  • A roche moutonnee is a resistant mass of rock on the valley floor
    • the upstream (stoss) side is smooth, because it was smoothed by abrasion as the glacier went over it
    • the downstream (lee) side is steep and rough where the glacier plucked at it
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Moraines

=the name for different formations of till deposited by a glacier as it melts

there are 3 different types of moraine:

  • Lateral moraine is deposited where the sides of the glacier were
  • Medial moraine is deposited in the centre of the valley where two glaciers converge (two lateral moraines join together)
  • Terminal moraine builds up at the end of the glacier and is deposited as semicircular hillocks of till

Till= all the stuff that the glacier leaves behind- unsorted boulders, stones and clay

moraine is the name given to particular formations of till

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Till

Till can also be deposited as hills called Drumlins

  • Drumlins are half-egg shaped hills of till, up to 1500m long and 100m high
  • upstream (stross) end is wide and tall
  • downstream (lee) end is narrow and low
  • may be egg shaped because the till got stuck around rock of a little hill sticking out into the glacier
  • may be that an original mound of till got streamlined when the ice re-advanced over it
  • drumlins often form in groups
  • drumlins in the Ribble Valley in Lancashire 
  • also a hole bunch of drumlins under water level in clew bay, Ireland
  • a drumlin faces the opposite way to a roche moutonnee
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erratics

=boulders that have been carried a long way by glaciers

  • erratics are rocks that have been picked up by a glacier or an ice sheet, carried along and dropped in an area of completely different geology
  • e.g in the yorkshire dales at Norber, loose black silurian rocks sit on top of while carboniferous limestone

there are erratics in eastern england that were originally picked up by an ice sheet in norway and carried all the way to england in the ice ages

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Fluvioglacial Processes

meltwater streams erode the landscape

  •   when glacial ice melts, water runs out and forms streams of meltwater, warm-based glaciers retreating produce lots of meltwater
  •  surface meltwater filters through the glacier (e.g. through crevasses) and flows through tunnels underneath the glacier, before running out of the snout of the glacier 
  •  meltwater streams cause erosion in the same way as normal rivers but they cause more erosion than rivers of the same size
  • because the pressure of the ice means the meltwater streams flow very quickly so they can carry lots of material that erodes the landscape
  • meltwater streams form deep troughs in the landscape called meltwater channels. because meltwater streams have a lot of erosive power, the meltwater channels they produce are very wide and deep. after the glacier has retreated, the deep meltwater channels are left with very shallow streams running through them. 
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Fluvioglacial deposits

Glacial meltwater carries a large load of sediment of various sizes

  • meltwater streams deposit their load on the valley floor as they flow away from the glacier
  • meltwater streams are often braided- split into lots of mini streams that cross over each other
    • because when the meltwater is flowing more slowly (e.g. in winter, when the amount of meltwater is lower) they can't carry its load - so it deposits sediment on the ground and splits into two streams to get round it
  • there's a difference between glacial deposition features formed by glaciers dropping debris as they melt and fluvioglacial deposition features formed by meltwater carrying debris and depositing it away from glaciers
  • fluvioglacial deposits are sorted
    • fine sediment is separated from the larger sand, which is separated from the gravel
    • glacial deposits are unsorted
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fluvioglacial- Outwash plains and kettle holes

an outwash plain= a layer of gravel and clay that forms in front of where the snout of the melting glacier used to be, meltwater flows out of the glacier and carries the sediment with it

  • sediments on outwash plains are sorted into layers
    • gravel gets dropped first because its heavier than sand and clay so forms the bottom layer
    • clay is dropped last and gets carried furthest away from the snout because it's the lightest sediment thus forming the top layer of the outwash plain
  • blocks of ice that have broken off from the front of the glacier can get surrounded and partly buried by the fluvioglacial deposits when the blocks of ice melt they leave holes in the outwash plain called kettle holes
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fluvioglacial- Eskers

Eskers= long, winding ridges of sand and gravel that run in the same direction as the glacier.

  • they're deposited by meltwater streams flowing in tunnels underneath the glacier, when the glacier retreats and the stream dries up, the load remains as an esker. 
  • eskers show you where the glacial tunnel used to be
  • e.g. trim esker in ireland
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fluvioglacial- Kames

  • kames are mounds of sand and gravel found on the valley floor
    • meltwater streams on top of glaciers collect in depressions and deposit layers of debris
    • when the ice melts the debris is dumped on the valley floor
    • lots of kames and other features at the margins of the retreating breidamerkurjokull glacier in south east iceland
  • Kame terraces are piles of deposits left against valley wall by meltwater streams that run between the glacier and the valley sides
    • look like lateral moraine, but they're sorted into layers- meltwater streams deposit their heaviest loads first, so kame terraces have gravel at the bottom and sand on top
    • e.g. along the edges of valleys in the lammermuir hills in eastern scotland
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fluvioglacial- Lakes

called proglacial lakes

  • can form in front of glaciers
  • e.g. when the flow of meltwater streams gets dammed by the terminal moraine
  • as meltwater streams flow into a proglacial lake, they slow down and deposit their sediment on the ice
  • these deposits are known as deltas, when ice melts these deltas are dumped on the valley floor, forming delta kames
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fluvioglacial deposits continued

the melting (wasting) of ice results in the formation of meltwater streams:

  • on the ice surface (supraglacial streams)
  • within the ice (englacial streams)
  • beneath the ice (subglacial streams)
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Periglacial- permafrost

permafrost= permanently frozen ground

  • top layer can melt in the summer (active layer) 20-25% of Earth's land surface is permafrost
  • areas of permafrost can be continuous (all the ground is frozen) or discontinuous (only patches of the ground are frozen
  • for discontinuous permafrost to form the mean annual temperature needs to be below 0'C for at least 2 years
  • for continuous permafrost to form the mean annual temperature needs to be below -5'C
  • the layer of permafrost is impermeable 
  • if the temperature gets above 0'C in the summer the active layer melts, but the water can't go anywhere causing the active layer to become waterlogged and will easily flow wherever there's a gradient- flow called solifluction
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Ice wedges

  • when temperatures drop very low in winter, the ground contracts and cracks form in the permafrost called frost contraction
  • when temperatures increase in spring, the active layer thaws and meltwater seeps into the cracks
  • the permafrost layer is still frozen, so the water freezes in the cracks- the ice-filled cracks formed in this way are called ice wedges
  • frost contraction in following years can re-open cracks in the same place, splitting the ice wedge, more water seeps in and freezes, widening the ice wedge. the ice wedge gets bigger each time this happens

ice wedge= a crack in the ground formed by a narrow or this piece of ice that measures from 3-4m wide extending downwards into the ground, during winter months freeze thaw weathering causes water to expand

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Frost Heave

  • 1. water freezing in the ground can make humps on the surface
  • 2. when the active later freezes in the winter, ice forms in a lens shape
  • 3. in fine grained soil (like silt or clay) the ice lifts (heaves) up the surface layers of soil- frost heave
  • 4. ice lenses also form underneath stones because stones lose heat faster than the soil around them, so when temperatures drop it's colder beneath the stones
  • 5. as the ice lenses expand, they push the stones upwards towards the surface of the ground. the ice lenses underneath the stones stop the stones from slipping back down. if the ice thaws, fine material fills in the space where the ice was, so the stones don't fall down. eventually the stones rise above the surface of the ground

frost heave occurs when soil expands and contracts due to freeze thaw process this damages plant roots and causes cracks in the pavement, damages the foundations of buildings

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Patterned ground

sometimes stones on the surface of the ground are arranged in circles, polygons or stripes= patterned ground, formed in two ways:

  • stones can get pushed to the surface by frost heave, once they reach the surface they roll down to the edges of the mounds that have formed, so they form circles around them, if the mounds are on a slope, the stones roll downhill and form lines
  • frost contraction causes the ground to crack in polygon shapes. the cracks get filled in with stones, forming polygon patterns on the surface
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Nivation makes hollows deeper

  • when snow gets into a hollow in the ground, it can increase the size 
  • the temperature in the periglacial environments often fluctuates around 0'C, so a lot of freezing and thawing happens- when the temperature's above 0'C the snow melts, and when it's below 0'C, the water refreezes as ice
  • every time the ice freezes, it expands so frost shattering eventually breaks bits off the rock at the base of the hollow. when the snow melts, the meltwater carries the broken bits of rock (debris) away
  • slopes collapse because they're waterlogged and they've been eroded- the material is washed away by meltwater
  • eventually the hollow become deeper and wider. the processes that cause this are collectively called nivation and the hollows formed by these are nivation hollows, they can be the beginning of cirques
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Pingos

  • a pingo is a conical hill with a core of ice, can be as large as 80m high and about 500m wide
  • two types of pingo: open-system and closed-system
  • open-system pingos:
    • form when there's discontinuous permafrost
    • groundwater is forced up through the gaps between areas of permafrost (from unfrozen layers lower down)
    • the water collects together are freezes, forming a core of ice that pushes the ground above it upwards
  • closed-system pingos:
    • form in areas of continuous permafrost where theres a lake at the surface so the area beneath them remains unfrozen
    • when the lake dries up, the ground is no longer insulated and the permafrost advances around the area of unfrozen ground. the water eventually freezes and creates a core of ice that pushes the ground above it upwards
  • if the ice core thaws the pingo collapses, leaving behind a pond surrounded by ramparts
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Solifluction lobes

formed when waterlogged waterlogged soil slips down a slope due to gravity

forms u-shaped lobes

solifluction produces lobe formations where one section of the soil is moving faster than the soil around it e.g. because its on steeper ground, so it flows down further to create a tongue shape

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Dry valleys

  • during periglacial periods limestone and chalk become impermeable due to permafrost
  • rivers flowed over their surface
  • spring melt from glaciers give high erosion at the end of periglacial periods normality returns and valleys are left dry

e.g. devils dyke near brighton

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Misfit streams

  • a stream that is far too small to have eroded the valley which the stream occupies 
  • the  shape of valley may also be inconsistent with a typical valley that has been eroded by water 
  • when a period of glaciation modifies the landscape by creating glacial troughs the rivers occupy such valleys after the ice has retreated they are not in proportion to the size of the valley 
  • e.g. misfit streams near loch ness
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blockfields and scree

blockfields:

  • large angular blocks created by freeze-thaw action
  • good examples found in snowdonia national park, wales

Scree

  • debris from a glacier scraping along side and mountain creating more debris
  • scree slopes are composed or large quantities of angular fragments of rock
  • e.g. the slopes at westwater in the Lake District, they have an angle of rest which is the angle which the slope is stable and no further mass movements occur, about 25"
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Coombe and head deposits

  • coombe deposits= chalk deposits found below chalk escarpments in southern england
  • head deposits= more common below outcrops of granite on dartmoor
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loess

=deposit laid down by wind

consists mostly of unstratified, structureless silt but also includes angular and sub-angular pieces

from glacial deposit

very fine (like flour) and is transported by wind and susceptible to wind erosion

e.g. sides of Mississippi river alluvial valley are a classic example

also in the chinese loess they form steep, high cliffs when eroded by rivers

the source of the material is glacial abrasion, frost cracking, salt weathering and fine particles picked up from outwash deposits

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cold environments contain valuable resources

many cold environments contain resources that attract development include:

  • whales, seals and fish 
    • e.g. in northern russia whales and seals are hunted for their skins, meat and blubber, while its fishing industry is one of the largest in the world
  • minerals 
    • e.g. the discovery of gold in canada and alaska triggered gold rushes and led to the establishment of towns based around mining that still exist today
  • oil 
    • e.g. alaska has a lot of oil and over the last few decades oil companies have moved into the area to exploit this resource

cold environments also have attractive scenery- attracts tourists e.g. the number of tourists visiting Antarctica each year has risen from 6700 in 1992 to 4600 in the 2007/ 2008 season

some cold environments have the potential for hydroelectric power production as they have natural lakes at high altitudes. norway currently supplies 99% of its domestic electricity HEP plants

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Fragile ecosystems

fragile ecosystems are ecosystems that struggle to recover to damage

fragile because of the harsh climate:

  • short growing season (when there's enough light and warmth for plants to grow) means that plants don't have much time to recover if they're damaged
    • summers are shorter
    • plant cover is reduced and plant height is shorter
  • the plants and animals are adapted to the cold conditions, so find it hard if their environment changes
  • decay is slow because it's cold, so pollution is broken down very slowly

tundra is a fragile ecosystem found in some cold environments e.g. in periglacial environments

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Tundra

Tundra is found where it's too cold for trees to grow

  • either because of high altitude or high latitude
  • Arctic tundra is found in Greenland, northern Russia and Canada
  • Antarctic tundra is found in islands around Antarctica e.g. South Georgia
  • Alpine tundra occurs in alpine environments
  • vegetation includes shrubs, grasses, mosses and lichen
  • animals found there include seals, penguins, seabirds, hares, foxes, caribou (reindeer) and bear
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Animal life

  • very few species 
    • only 70/8600 birds breed in the Arctic
    • only 23/3200 mammals
  • large numbers of a single species e.g. caribou and lemmings
  • population numbers are cyclical e.g. lemmings have a 3-7 year cycle

adaptations to cold environments:

  • severe climate- low number of species and low mean densities
  • low temperature- high quality insulation, increased metabolic rates
  • snow- life below snow patch for smaller animals, large herbivores favour thin snow
  • short summer- birds migrate, breeding cycle compressed, large clutch/litter size, simple food chain
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soils

  • soils are affected in periglacial environments by permafrost and low temperatures
  • bacterial activity is low and waterlogging sometimes leads to the formation of an acid humus, blue-grey blotchy mud is found due to waterlogging (gleying) this reduces ferric compounds to ferrous compounds as oxygen is lost
  • soil contains angular fragments of rock
  • tundra gleys is the most common soil
  • not all periglacial soils are waterlogged- better drained sites podzols may develop
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Nutrient Cycle

  • the cycling of nutrients is essential for plant growth however in cold environments it can be prohibited by a number of factors;
    • amount of nutrients in soil is limited because the rate of weathering is slow
    • as precipitation levels are low there are few nutrients dissolved in rainfall
    • frozen ground and snow cover can make it difficult for the plant roots to reach and absorb the limited supply of nutrients
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Case study- climate and ecosystems in the Alps

  • Switzerland has an alpine climate. 
  • In summer temperatures reach up to 25'C and in winter temperatures drop between 2-6'C in the valleys but at high altitudes temperatures are well below freezing
    • coldest part is Jura in the north-west particularly in the Brevine valley
  • rainfall varies throughout the country with over 2500mm in Vaud in the south east but in Valais than 530mm of rain fall

Alpine vegetation:

  • high elevations- flowers bloom between april and july whereas at lower elevations growing season is longer
  • adaptations:
  • bright pigments protect from ultraviolet radiation
  • colour attracts insects for pollination
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Case study- climate and ecosystems in the Alps

  • growing close to rocks to avoid trampling e.g. orchids
  • hairs on the leaves to reduce moisture loss
  • waxy coatings to reduce water loss
  • succulents store water
  • growing close to the ground reduces moisture loss from lower wind speeds at ground level
  • as temperature decreases by 1'C for every 100m at an altitude of about 800m coniferous tress replace deciduous trees
    • coniferous trees adapted to photosynthesis at lower temperatures
    • deciduous trees shed there leaves when the temperature gets too low
    • red spruce is the typical tree found in the Swiss Alps
  • trees being affected by acid rain and pollution means that as the forests die back and get thin, the risk of avalanches increases as there is less vegetation to bind the soil
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Case study- climate and ecosystems in the Alps

Animal life

  • animal life in switzerland is under threat because of human activity
  • typical species include the ibex (mountain goat) the chamois (antelop) and the marmot (a gregarious rodent)
  • characteristic birds include the chough and the golden eagle
  • over 80 species are threatened with extinction
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Thermokarst

=forming of landscape due to melting of permafrost ground

refers to the subsidence that occurs as permafrost melts

most common cause of man-induced thermokarst on a landscape is the clearance of the surface vegetation for agriculture and/or construction purposes

three factors control permafrost degration:

  • ice content on underlying permafrost and, in particular, the presence or absence of excess ice
  • thickness and insulating qualities of the surface vegetation
  • duration and warmth of summer thaw period
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man-induced thermokarst

  • initial disturbance is often burrow pits- where the material has been removed for road, airstrip or other construction purposes
    • thermokarst processes are rapid
    • typically hummocky relief forms through preferential subsidence along ice wedges
    • stabilisation only begins 10-15 years after the initial disturbance
    • in environments of great summer thaw, the amplitude of the thermokarst mounds is greater, probably reflecting greater thaw depths
  • movement of vehicles over permafrost terrain 
    • if this occurs in summer when the surface has thawed and is soft and wet surface vegetation can be destroyed and deep trenching and rutting can occur
    • tracks favour continued thermokarst development by collecting water and if located on a slope promote gulleying by channelling snowmelt and surface runoff.
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Case study- changes to Europe's permafrost

Permafrost throughout Europe is melting and threatening alpine villages and ski resorts with rockfalls and landslides

  • main areas being monitored include the Murtel- Corvatsch mountain above St Moritx and the Schilthorn above the Muran and Gandeg resorts near Zermatt
  • a borehole sunk above St Moritz in 1986 showed that the ground temperature had risen between 0.5 and 1.0'C by 2000, if the temperature inside the mountain is only -2'C at the moment, then it will not take long to thaw
  • already in switzerland there have been rockfalls, landslides, mudflows, debris and slushflows as the ice has melted and weakened the mountains and are likely to increase in the near future
  • the permafrost and climate in Europe (Pace) organisation has been set up to monitor the creeping effects of climate change on the stability of mountains
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Case study- changes to Europe's permafrost

  • the combination of ground temperatures only slightly below zero, high ice contents and steep slopes make mountain permafrost in Europe particularly vulnerable to even small climate changes
  • research has shown that permafrost exists as far south as Sierra Nevada mountains in Spain
    • although ice was found only at the top of the Sierra Nevasa mountains
    • in more northern parts of europe such as the Alps it was found at 2500m, in sweden it was found at 1500m
    • In Svalbard, in the high Arctic, ice was found at sea level
    • Britain's highest mountains are too low and too close to the warm westerly winds to have permafrost
  • other mountain ranges with permafrost being monitored include the Pyrenees, the Jotunheimen range in Norway and the Abisko range in Sweden
  • Boreholes have also been dug in Svalbard where coal is mined in the permafrost, the mine buildings have their foundations on frozen soil and there are fears that the buildings will settle and fall if the frost melts
  • this could also be serious problem in the higher european ski resorts where foundations of ski lifts and other buildings assume the ground will remain stable
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Development in Cold environments- fishing

  • fishing can disrupt food chains
    • krill fishing in the Southern Ocean is depleting food supplies for whales and penguins
  • overfishing of a species can severely deplete its population, sometimes beyond recovery
    • overfishing of the Patagonian Toothfish in the Antarctic is currently a concern
  • Bottom trawling catches fish by dragging nets along the sea-bed, this disrupts the ecosystem (by reducing light levels through increasing turbidity) and catches other species as well as the target one
    • it's carried out in the Gulf of Alaska, the Greenland Sea and the Barents sea
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Development in Cold environments- Oil extraction

  • oil spills can occur during transport of oil from the area
    • for example in 1989 there was a huge oil spill off the coast of Alaska when the Exxon Valdez oil tanker crashed
    • over 40 million litres of oil spilled into the ocean, and over 250 000 birds and fish were killed
  • oil spills can occur if pipelines leak
    • between 1977 and 1994 there were on average 30 to 40 spills a year from the Trans-Alaska pipeline
    • some of these were caused by intentional attacks and forest fires
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Development in Cold environments- hydroelectric po

  • hydroelectric dams can block the normal migratory path of fish
    • this can prevent them reaching spawning grounds, and so cause fish population to decrease
  • hydroelectric dams also heat up the water, which can endanger fish that are used to colder temperatures
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Development in Cold environments- Tourism and Mini

Tourism

  • large cruise ships increase pollution in the areas (from ships and tourists)
  • tourists and tourism developments (e.g. roads and hotels) disrupt wildlife and damage habitats leading to reduced biodiversity

Mining

  • mining can lead to ground and surface water contamination either by chemicals during mining or by the materials being mined
    • the lead-zinc mine in Maarmorilik (Greenland) was closed in 1990 but lead and zinc are still released polluting nearby fjords
  • produces both solid waste and wastewater that has to be disposed of.
    • in some cases e.g. in the Red Dog Mine in Alaska and the Kubaka mine in Russia, the facilities are not built to deal with the quantities produced and the waste is released into the environment
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Development has affected locals

even though the climate in the tundra is very harsh, native tribes have always lived there

e.g. the inuit people have live in the tundra in parts of Canada, Greenland and Russia- their traditional way of life involves hunting and fishing 

Newcomers from Europe and the US started to take an interest in Tundra areas during the 17th century because of its oppurtunities

  • seals were hunted for their warm fur and oil
  • oil used in lamp oil and to make leather
  • whales are hunted for oil to fuel lamps, make candles and put in margarine

the arrival of the newcomers had a negative effect on the people living in the tundra, because they brought new diseases with them- many of the inuits were infected and died. e.g. in the late 19th century, early 20th century 90% of the Inuvialent were killed by diseases like TB, measles, smallpox and flu

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Development has affected locals

also, an increase in whaling, sealing and fishing in the tundra areas reduced the numbers of whales, seals and fish available for the inuit people to catch

development in tundra areas has had a big impact on the lifestyles in the indigenous people e.g. in canada:

  • aren't enough resources for inuit tribes to support themselves so they have to find paid employment this is difficult as the few job opportunities that exist are taken generally by the more educated white population
  • with unemployment at nearly 50% amongst some of the inuit communities have to rely on government help
  • the change of employment has also led to Inuits living in permanent settlements instead of being nomadic
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Development can be made more sustainable

for development to be sustainable it has to not deplete resources and not cause long term environmental damage for example:

  • National Parks have been set up to allow tourism whilst protecting the environment
    • e.g. Denali national park in Alaska was set up in 1917 and then expanded in 1980 to include a greater area of land
    • cars and private vehicles are banned from the park, so visitors have to travel in park buses on0.
    •  approved routes
    • the most vulnerable parts of the park have no roads avoiding damage
  • fishing quotas have been introduced to limit the number of fish caught and prevent over-exploitation of the resource
    • e.g. in the barents sea
  • oil pipes have automatic shut-off valves in order to minimise oil spills if the pipelines are damaged
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Case Study- Northern Sweden- The Sami

Facts

  • Between 70,000 and 100,000 people in northern Norway, Sweden and Finland.
  • since 1991 had its own parliament
  • two groups- reindeer herders and sea Sami (fishing)

Environmental impacts

  • minimal- migrated with seasons and kept herds in line with carrying capacity
  • increasingly restricted by mining, forest clearance and hydro schemes

Economic impacts

  • low income so many migrate to cities for work
  • few roads or town as tribes were nomadic
  • few services as largely self sufficient
  • subsistence with reindeer supplying most of their needs
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Case Study- Northern Sweden- The Sami

Social impact

  • increasingly absorbed into westernised way of life (only 10% now live off herds)
  • becoming a tourist attraction
  • tribal organization weakened

political impact

  • lost land rights last century so forced out of private forests where reindeer sheltered but now legally protected

Cultural Impact

  • being protected and Sami parliament fosters language and culture
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Case Study- Siberia- Oil

Facts

  • over 600 fields with reserves of 144 billion barrels and 1200 trillion cubic feet of gas- 70% of Russia's output
  • massive expansion since 1990s with pipelines to Europe and China

Environmental impact

  • massive pollution of soil, lakes and groundwater from spills 
    • e.g. 1994- over 50 million gallons and leaking pipelines
  • habitats destroyed by road building, pipe line laying and hunting for food
  • damage to permafrost by pumping --> subsidence

Economic impact

  • urbanisation 
    • e.g. Khanty-Mansiysk Surgut
  • $4.5 billion in tax revenue
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Case Study- Siberia- Oil

Social impact

  • local Khanty and Selkup people lost their reindeer herds and can't migrate due to pipelines= increased depression, Aids, suicide and alcoholism
  • influx of foreign workers

Political impact

  • local village headmen replaced by state or oil company control
  • corruption and violence
  • government see energy as a political power tool

Cultural impact

  • Khanty lost links to their land
  • destruction of sacred places
  • influx of new more westernised workers and cultures
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Case study- recreation and tourism- Antarctica

Facts

  • 80,00 tourists a year expected by 2010

Environmental impacts

  • concentrated round certain bases so concentrated pollution, disturbance of habitats etc
  • tourist ships disturb sea life especially whales (noise, wash and waste)

Economic impact

  • very little as all money spent outside area
  • size of bases is controlled 
  • tourist ships are relatively self-suffiecient 
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Case Study- Antarctica

Social impact

  • minimal as the local population is very small and these people do not live there permanently

Political impact

  • some conflicts due to overlapping claims of control e.g. Uk and Argentina

Cultural impact

  • no existing culture

for extra see more notes

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Case Study- recreation and tourism- Skiing in Swit

Facts

  • Alps to receive 100 million tourists a year, 60% for winter sports

Environmental impact

  • skiers damage trees, kill young shoots and erode surfaces
  • car exhaust fumes kill trees
  • access roads, parking lifts, etc, destroy habitats
  • increased risk of avalanche
  • litter
  • bulldozing of slopes
  • increased water use and sewage disposal
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Case Study- Switzerland

Economic impact

  • creation of jobs (80% of jobs rely on tourism)
  • building of resorts
  • destruction of traditional farming
  • higher incomes but also higher prices
  • improved infrastructure

Social impact

  • local people priced out of their own homes influx of foreign young seasonal workers

Political impact

  • who pays for the infrastructure and damaged environment?

Cultural impact- any traditional culture survives as a tourist attraction

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Case Study- Manage, The Alps

Facts

  • area of 192,000km2 with 13 million people in 6100 settlements
  • 30,000 animal species and 13,000 plant species
  • agreement between 8 countries in 2001

The challenge

  • depopulation in some remoter areas
  • growth of tourism
  • rising 'imported' air traffic (acid rain)
  • increased trans-alpine traffic
  • global warming impacts
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Case Study- Manage, The Alps

Attempts at conservation and/or sustainability

  • draw up inventory of areas and type of damage
  • protect habitats with fences
  • restore forests (use jute netting to anchor seedlings)
  • reduce traffic- direct use of railways
  • soil conservation and restoration of ski slopes
  • environmental education and notice boards
  • controls on tourist buildings- must harmonise
  • water management especially lakes
  • encourage traditional farming
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Case study- conserve, Antarctica ban

Facts

  • area of 14 million km2 with 1000 temporary inhabitants in 50 research stations
  • 1000 plant species; mostly algae and lichens
  • seven countries claim areas but the 1959 antarctic treaty is signed by 46 countries far

The challenge

  • unexploited minerals- coal, oil and iron ore
  • growth of tourism- doubled from 2004 to 2010 estimated around 80,000
  • fishing- 115,000 tonnes a year
  • global warming impacts
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Case study- conserve, Antarctica ban

Attempts at conservation and/or sustainability

  • military activities banned
  • freedom of scientific research and exchange of information
  • nuclear explosions and waste banned
  • all stations open to inspection
  • all territorial claims set aside

also other conventions cover the conservation of flora and fauna (1964) nd a ban on mineral exploitation in 1998

tourism has controlled landing sites and limits on numbers- some areas closed to all activity

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Comments

Polip

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Connor

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Mr A Gibson

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Megan Stewart

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