Extreme Environments
Extreme Environment: relatively inaccessible areas that tend to be viewed as inhospitable to human habitation, though they do provide opportunities for settlement and economic activity
Clod & high altitude environments
Polar, glacial, periglacial & high mountains in nontropical areas
Hot, arid environments
Hot deserts and semi-arid areas
Distribution of Extreme Environments
Cold and high altitude environments → uneven distribution
Northern hemisphere → periglacial belt
Located towards the north and south poles where insolation is low
Desert and Semi-Arid environment
Covers ⅓ of the earth's surface
Generally located around the tropics
Due to permanent high-pressure systems that limit rain formation
Both environments
The angle of incidence: the angle at which light strikes the surface of the Earth
The greater the latitude, the less sunlight the area receives
Sun’s rays strike the surface at a lower angle near the polar
Atmospheric circulation
Hot air near the equations rises and moves toward the poles
At around 30 degrees latitude → air pushed downwards due to the Ferrel Cell’s Wind Circulation
Ferrel Cell’s Wind Circulation: Driven by temperature differences, cool polar air masses, and warm subtropical air masses converge, pushing each other upwards along their meeting line around 60 and 70 degrees north and south.
Creates high pressure in the tropics
Cold air at poles is very dense → dense → creates high pressure + low-temperature environments
Reflection and Scattering
Reflection: most of the heat that reaches the surface in polar areas is reflected into space due to the shiny surfaces of ice caps and snow
Scattering: there is a greater thickness of atmosphere near the polar than at the equator that the sun’s ray must penetrate → more energy is reflected and scattered
Due to location sun rays enter the atmosphere in polar areas at an oblique angle → gasses absorb more heat and light, so less reaches the surface
Length of Daylight Hours
On equator → length of days is the same throughout the year (day = 12 hours, night = 12 hours)
Further from equation → more variation
Summer → more daylight
Winter → night lasts longer
Altitude
The higher in the troposphere (first layer of the atmosphere), the lower the temperature
Lapse Rate: the rate at which temperature drops
Caused by adiabatic cooling
Adiabatic Cooling: the cooling of an air parcel as it rises adiabatically in the atmosphere
Offshore Currents
Many deserts are on the west coast where the water is cold
Winds blow parallel to the coasting & push surface water towards the sea
Cold water draws upwards (upwelling) to replace surface water
The air’s capacity to hold moisture is diminished
Rainshadow Effect
Rising air at the slope of the mountain towards the wind cools and loses moisture
Descending air on the other side of the mountains warms up → decreasing its relative humidity → causing it to be dry
Climate
Low temperatures all year around
Mountain environments
a large amount of rainfall → due to relief rain
Low rainfall → rain shadow area
High diurnal temperature ranges → Underlying rock weakens due to extreme freezing
Can easily lead to avalanches
Relief
Steep and rocky terrain which is mostly inaccessible
Young mountains have steep gradients and weak rock structures
The area is a frequent risk for rockfall and mass movement
Slope Aspect: the direction that a slope faces
Northern hemisphere (most of highest mountains) → slopes face south
Get more sunshine for longer periods of time
Causes difference in vegetarian and land uses than northern aspect
Altitude and Biosphere
Mountain areas have vertical series of bands of vegetation
Altitude affects temperature
As animals need vegetation for food → distribution is also along the altitude zones parallel to vegetarian
The number of species declines with increasing altitude
Tectonic hazard
Tectonics uplifts → mountain ranges
Still ongoing → creates constant instability
Areas around are affected by earthquakes
Wealthy countries → build earthquake-proof structures
Climate
Moist defects
Generally low amount of rainfall
Rainfall Variability
Very high for arid regions
Varies from year to year
Diurnal Fluctuations
Arid regions generally have a large diurnal temperature range
Deserts near the sea have a moderating effect
Seasonal Fluctuations
Equatorial deserts: little season changes in temperatures
Subtropical deserts & mid-latitude deserts: great variation between winter and summer temperatures, especially in high altitudes
Wind
Arid regions are typically windy
Sparse vegetation
More air movements
Lack of frictional drag from trees
Connection can also cause heavy winds
Sun heats the ground and dry air above, which expands and rises, with cooler air coming in to replace
Wind removes moist air → increases evapotranspiration
Flash floods
Normally deserts may have irregular flash floods
Typically have unstable terrain
Waterlogged solid → deteriorates vegetation growth and causes solifluction → unpredictable terrain change
Solifluction: seasonal freeze-thaw action upon waterlogging topsoils which induces downslope movement
Difficult to source liquid water & insulated pipes to carry them
Short growing season → outsources food
Roads ice frequently
Frost heave can cause damage
Ice Heaves: sheets of ice that push against each other or the shoreline. They form when ice sheets expand due to rapid temperature fluctuations. Thermal expansion of the ice occurs when a rapid increase follows a period of very cold weather in temperature
Have great diurnal temperature variations
Think and weak soil → no fertility for agriculture & harsh winds
Generally low rainfall
Steep topography → accommodating infrastructure and communication is difficult to build and maintain
Altitude increases → decrease in air density, water vapor → dehydration, carbon dioxide, and boiling point of water → difficult to cook
Frequent avalanches → destroy settlements
Lack of water and precipitation
No freshwater → impossible to farm and maintain livestock
Use chemical weathering to achieve finer soil
Great diurnal temperature variations
extremely high during the day and extremely cold during the night
Extreme temperatures limit vegetation growth
Glacial advancements and retreats
Glacier: Slow-moving mass of ice formed by accumulation and compaction of snow on mountains or near poles
Although solid, behaves like thick liquid and flows at an extremely slow rate under gravity
Glacial system → balance of inputs (accumulation of snow, avalanches, debris, heat), storage (ice, meltwater, moraine), and outputs (losses due to ablation: melting, sublimation, evaporation)
Ablation: all methods by which the glacier can lose mass. In this zone, there is a net loss in mass when outputs are greater than inputs
If accumulation > ablation → glacier avances
If accumulation < ablation → glacier retreats
If accumulation = ablation → glacier is steady
Glacier will have a positive regime when supply is greater than loss → thicken and advance
Glacier will have a negative regime when wasting is greater than supply → thin out and retreat
Natural Desertification
Desertification: the process by which deserts expand into semi-arid areas or become more intense
Variations in rainfall/drought/increased aridity can cause deserts to expand or retrace
Glacial erosion
Plucking
Occur at the base of the glacier
As ice moves, meltwater seeps into joints and freezes to the rock → ripped out when the glacier moves
Can be used for abrasion
Abrasion
Debris carried by the glacier scrapes and scratches the rock
Finer material will smooth out the rock → producing gently sloping landforms
Factors affecting glacial erosion
Relative hardness of particles and bedrock
Most effects abrasion: har particles + soft bedrock
Ice thickness
Greater the thickness → greater the vertical pressure → more effective abrasion
Basal water pressure
Basal water pressure may lift the glazier above the level of particles that the base, reducing the among of the brain
Sliding of basal ice
Faster the rate of basal slides → greater the rate of abrasion
Movement of debris towards the glacier base
If particles at the glacier base are not renewed → become polished → less abrasion
Debris particle size and shape
Large and angular debris abrade much more effectively than small and round debris
Landforms produced by glacial erosion
Cirque: an oval-shaped depression in the side with a steep back wall and a rock lip
Arete: narrow, knifed-edged ridge
Pyramidal peak: pointed peak with radiating aretes
Glacial trough: steep-sided u-shaped valley
Hanging valley: tributary glacier left high above the main valley
Truncated sur: steep cliff-like valley sides
Rock steps: stepped long profile in a glacial trough
Ribbon Lake: long narrow lack in glacial trough
Cirque lake: small, deep, circular lake
Roche Moutonné: ice-smoothed rocks with steeper side facing down-valley
Striations: rocks scaled with parallel scratches
Freeze-thaw: the process by which the freezing of water puts pressure on rocks (especially jointed rocks). Only occurs when the temperature fluctuates above and below freezing points are there are cycle of strain and release
Mass Movement
Frost Heave: the expansion of fine-grained soils such as silts and clays to form small domes. Results from the direct formation of ice.
The thermal conductivity of stones is greater than spil so they are underneath the stone become colder → ice crystals form
The crystals force the stones above them to rise
Solifluction: Common when surface sediments are poorly drained and saturated with water. Occurs when tyres are above zero and free liquid water is available in the action later
In winter, water freezes in the soil, causing expansion and secretion of individual soil particles
In spring, the ice metals and water flows downhill
Water cannot filtrate the soil due to permafrost → flows over and caries the segregated soil particles and deposits them further down
Frost creep: type of solifluction that occurs because of frost heaving and thawing
Starts with the freezing of the surface ground, angling particles at right angles. As ice thaws in the warm season, contracting surface drops particles in elevation due to gravity → particles move slightly downslope
Rockfalls: occur when fragments of rock break away from a cliff face from freeze-thaw weathering
Permafrost: permanently frozen subsurface
To be classified as permafrost must be frozen for at least 2 years
Commonly occurs in periglacial environments
Types of permafrost
Continuous
Discontinuous
Sporadic
Thermokarst: irregular, hummocky terrain with marshy or lake-filled hollows created by the disruption of permafrost's thermal equilibrium
Pingos: dome-shaped isolated killed with interrupt flat tundra plains. Form as a result of movement and freezing of water under pressure
Open-system pingos: forms when the source of water is a distance elevate the source
Closed-system pingos: forms when the supply of water is local and permafrost expands
Often form on site of small lakes where water is trapped by freezing from above
Mechanical weathering
Salt crystallization: a form of weathering which causes the decomposition of rock by the solution of salt, causing chemical and physical changes in the rock
Disintegration: a form of weathering where the grains of rock become loose and fall out, leaving a pitted surface
Occurs in deserts with lar diurnal temperature ranges
Erosion
Water
Exogenous rivers: rivers that have their source in wetter environments and then flow through a desert
Endorheic Rivers: rivers that drain into an inland lake or sea
Ephemeral rivers: Rivers that flow seasonally or after a storm and tend to have high discharges and sediment levels
Wind
The movement of sediment is crashed by drag and lift forces, also known as suspension, but are reduced by particle size and friction
Deflation: Progressive removal of fine material by the wind leaving behind larger materials
Abrasion: sandblasting action acted by materials as they are moved by alteration
Saltation bouncing of sand particles by wind forces
The process smooths away rock close to the ground
Landscape features in hot arid environments
Formed by deposition
Dunes: develops when sans Grania, moved by saltation and surface creep, are deposited
Form around large rocks, which hold the main part of the dune in place
Formed by wind erosion
Yardangs: extensive ridges of rock. They are separated by troughs, and have an alignment similar to the prevailing winds.
The strata are vertical
Zeugens: tabular masses of resistant rock separated by trenches where the wind cuts vertically through the cap into the underlying soft rock
The strata are horizontal
Rock petals: formed by exposed isolated rocks in the series when a more resistant layer of sedimentary rocks sits above a softer layer
The lower softer rock erodes faster than the higher, more resistance-rich
Oases: fertile spots in the desert where water is found. Formed where natural depressions are deep enough to cut into water table
This leads to semi-permanent water is available near the surface
Formed by water erosion
Wadis: dry river channels that are generally steep-sided and flat-bottomed. May have formed during flash floods or during wetter pluvial periods in the Ice Age when the runoff collected from sheet flood becomes concentrated into deep ravines
Measea: Plateau-like featured with steep-sides
As the mesa is reduced in size by cliff retreats, it rains its flat top and altitude
Buttles: a smaller version of mesas, representing the final stage of erosion before the resistance rock is finally eroded
Agriculture in Arid Areas
Benefits: The environment offers an abundance of heat and sunlight, favoring a lengthy growing season. If water is available, farming can be an opportunity. Opportunities include:
Nomadism
Settled farming with groundwater
Irrigation next to rivers and oasses
Increased use of drought-tolerant species
Challenges and possible solutions: The area is dominated by the lack of fresh water, too much sunlight and heat, low rainfall seasons, alien waters, strong dry winds, poor soil structure, overgrazing, and poor transport. All arid and semi-arid have negative water balance (outputs from evapotranspiration and stores of water exceed this input from precipitation
Soil is arid due to low rainfall and high evapotranspiration
Soil is infertile due to:
Low organic content
Generally thin with few minerals
Lack of clay
Soluble salts in soil which can be toxic to plants
Irrigation access
Not all areas have access to irrigation
To the areas that do, problems include salinization, depletion of groundwater, pollution, and less access to water elsewhere
Salinisation Risk
May occur in areas where the water table is close to the surface & annual precipitation is less than 250 mm
In poor drainage locations (ex. Valleys and basins), surface water evaporates and leaves behind large amounts of salts
Saline soils adversely affect the growth of more crops
Reduces rate of water uptake by roots
Sustainability
Agriculture in arid and semi-arid environments can be made more sustainable by:
Reducing her size and pressure on the amount of limited vegetation
Use solar panels to produce energy
Plant vegetation
Use more efficient types of irrigation
Building check dams to collect water
Using more salt-tolerant plants
Mineral extraction
In extreme environments: opens up opportunities for poorly developed regions, employ opportunities, and can generate significant income from exports
In cold environments: resource development can improve, but can put the environment under pressure and create conflict
Due to inaccessible, there is a high cost of attracting workers
Fragility Of periglacial areas
The limited ecosystem is highly susceptible to interference
Low temperature limits decomposition, which can lead to pollution (especially oil)
Frost heave
Can lift piles for oil pipelines and structure out of the ground → need to be embedded deeper which is expensive
Resource nationalism
Governments tend to assert control of natural resources in their territory and conflict with the interest of multinational corporations
In arid environments: huge potential for development and generate large earnings for countries that develop them
Due to inaccessibility, there is a high cost of attracting workers and protecting people from extreme heat and aridity
Politics
Risk of intruding on rights of Indigenous people
Environmental impact
The movement of people and vehicles can introduce exotic species
Mines can be a major source of dust pollution linked to respiratory disease
Open-pit mining can expose dangerous chemicals and contaminated groundwater
Popular destinations due to scenery, rare species, pristine landscapes
Mountain environments have a low carrying capacity and are easily damaged by human impact because of this erodible soil and vegetation
tourism opportunities may be linked to scenery, wildlife, indigenous culture and outdoor pursuits.
create jobs, provide income for workers,
Challenges include extremes of temperature, accessibility, water shortages and a lack of resources to sustain tourism.
The impacts on the natural environment include mass movement, erosion, land degradation, hazards, aesthetic changes, water shortages, waste, introduction of exotic species and habitat removal.
Desertification
Desertification: Land degradation in humid and semi-arid areas (not including non-desert (arid) areas)
Involves the loss of biological and economic productivity and it occurs where climatic variability (especially rainfall) coincides with unsustainable human activities.
Causes
Desertification can be a natural process intensified by human activities. All areas affected by desertification are marginal and have highly variable rainfall, except rainforests desertified by inappropriate farming techniques.
Natural causes
Temporary drought periods of high magnitude and long-term climate change towards aridity.
Overgrazing
Vegetation is lost through grazing and trampling by large numbers of livestock.
Overgrazed lands become more vulnerable to erosion as compaction of the soils reduces infiltration (increasing surface runoff) and trampling increases wind erosion.
Fencing leads to severe localized overgrazing while boreholes and wells cover the water table, leading to soil salinization.
Overcultivation
This leads to diminishing returns (yield decreases every season) and so to maintain the return on agricultural investment, the area of growth must be expanded.
Reducing fallow periods and introducing irrigation help to maintain output, but contribute to further soil degradation and erosion by lowering soil fertility and promoting salinisation.
Deforestation
Occurs where land has been cleared to extend the area of cultivation and in the surrounds of urban areas for firewood.
The loss of vegetation cover increases rainsplash erosion and the absence of root systems allows for easy soil removal by wind and water.
Climate change
Soils exposed to degradation as a result of poor land management could become infertile as a result of climate change.
Climate change may exacerbate desertification through alteration of spatial and temporal patterns in temperature, rainfall, solar radiation and winds.
Arctic region
As ice caps are melting, a military race between the US and Russia competing for its extremely valuable resources
The region is opening up two major shipping lanes, and oil and gas reserves are worth trillions of dollars.
If the Arctic region continues to melt and open up vital shipping lanes, there must be international cooperation to provide security and rescue elements for commercial shipping.
Oil conflicts in the Middle East
Conflicts over oil are the result of long-standing historical disputes, which have developed into the desire to control valuable oil and natural gas assets.
The economic world has become energy-centric, and access to energy resources provides strength and power for some countries, whereas lack of resources leads to vulnerability for other countries.
Countries with surplus energy reserves, and the ability to export energy, often have a disproportionate influence on the world stage.
ISIS: A Sunni extremist group that controls large parts of western Syria and northern Iraq. ISIS controls key oil-producing areas of Syria and oil-refining facilities in Iraq. This, in part, allows it to pay for its military. Such conflicts make it difficult for countries that depend on Middle Eastern oil.
Sustainable development: New technology and sustainable developments in extreme environments
Sustainable development: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs. They should fulfil needs, in particular the essential needs of the world's poor, but are restricted by limitations imposed by the state of technology and social organization on the environment's ability to meet these present and future needs.
Solar power
A completely renewable resource which has non-direct pollution during electricity generation and requires little maintenance.
However, there are high initial costs for solar plants and it is limited in that power cannot be harnessed at night or in countries with low annual hours of sunlight
Desalination
The removal of salts and minerals from seawater and soil.
Due to high energy input, the costs of desalinating seawater are generally higher than the alternatives, but alternatives are only sometimes available and depletion of reserves is a problem in certain locations.
The main criticism regarding desalination and the use of reverse-osmosis technology is that it costs too much.
Aquaponics
An integrated form of farming that enables farmers to increase yields by growing plants and farming fish in the same closed freshwater system.
Mimics natural processes and enables waste to be efficiently reused.
Climate change and EEs
The impacts and management of global climate change in extreme environments, including adaptation by local populations
Climate change impacts on arid environments:
Food security
As temperatures rise, evaporation levels will increase and reduce precipitation effectiveness.
Environmental hazards such as floods and droughts will become more common in arid areas like the Sahel, disrupting agricultural systems
reduce food production and availability and increase prices, food insecurity and hunger.
Poverty will exacerbate the impacts of climate change in these areas.
Local adaptation strategies by Senegal:
Improving soil fertility by the careful use of fertilizers
Improving the efficiency of irrigation systems and pest control
Adopting water and soil conservation techniques using baguettes (stone rows) to reduce run-off on slopes
Developing the Great Green Wall of the Sahara and the Sahel Initiative (GGWSSI), that is, a massive line of trees across the southern Sahara and Sahel to combat the combined effect of resource degradation (deforestation and soil erosion) and drought/desertification
Coping strategies for water shortages
Adaptations to water shortages include:
Increased mobility (the traditional way)
Management of size and composition of herds
Exchange of livestock and livestock products
Increased use of drought-tolerant species
Utilization of wild species and tree crops
Windbreaks to reduce wind erosion of bare soil
Irrigating with silt-laden river water to restore soil
Dune stabilization using straw bales and xerophytic plants
Land enclosure to reduce wind erosion
Climate change impacts on cold environments
Any increase in temperature is likely to have a greater impact in areas where the mean annual temperature is only a little below the freezing point.
risk of degradation and the development of thermokarst (subsidence).
Benefits
The warming climate has made minerals that were once locked in ice accessible.
Farming may become more productive as net primary productivity increases and the length of the growing season increases.
Consequences
Many settlements are located at river mouths, river confluences or islands.
Melting permafrost, coastal erosion, increased flooding and a rise in sea level due to climate change will take a toll on buildings, ports, bridges and roads.
This will increase the number of climate refugees as well as death tolls from unpredictable sea ice.
life in cold extreme environments will become more expensive (e.g. snowmobiles must take longer routes, and buildings are weakened by melting permafrost).
People relying on fishing will either have to go further to catch or alter to take into account changes in species composition.
Extreme Environment: relatively inaccessible areas that tend to be viewed as inhospitable to human habitation, though they do provide opportunities for settlement and economic activity
Clod & high altitude environments
Polar, glacial, periglacial & high mountains in nontropical areas
Hot, arid environments
Hot deserts and semi-arid areas
Distribution of Extreme Environments
Cold and high altitude environments → uneven distribution
Northern hemisphere → periglacial belt
Located towards the north and south poles where insolation is low
Desert and Semi-Arid environment
Covers ⅓ of the earth's surface
Generally located around the tropics
Due to permanent high-pressure systems that limit rain formation
Both environments
The angle of incidence: the angle at which light strikes the surface of the Earth
The greater the latitude, the less sunlight the area receives
Sun’s rays strike the surface at a lower angle near the polar
Atmospheric circulation
Hot air near the equations rises and moves toward the poles
At around 30 degrees latitude → air pushed downwards due to the Ferrel Cell’s Wind Circulation
Ferrel Cell’s Wind Circulation: Driven by temperature differences, cool polar air masses, and warm subtropical air masses converge, pushing each other upwards along their meeting line around 60 and 70 degrees north and south.
Creates high pressure in the tropics
Cold air at poles is very dense → dense → creates high pressure + low-temperature environments
Reflection and Scattering
Reflection: most of the heat that reaches the surface in polar areas is reflected into space due to the shiny surfaces of ice caps and snow
Scattering: there is a greater thickness of atmosphere near the polar than at the equator that the sun’s ray must penetrate → more energy is reflected and scattered
Due to location sun rays enter the atmosphere in polar areas at an oblique angle → gasses absorb more heat and light, so less reaches the surface
Length of Daylight Hours
On equator → length of days is the same throughout the year (day = 12 hours, night = 12 hours)
Further from equation → more variation
Summer → more daylight
Winter → night lasts longer
Altitude
The higher in the troposphere (first layer of the atmosphere), the lower the temperature
Lapse Rate: the rate at which temperature drops
Caused by adiabatic cooling
Adiabatic Cooling: the cooling of an air parcel as it rises adiabatically in the atmosphere
Offshore Currents
Many deserts are on the west coast where the water is cold
Winds blow parallel to the coasting & push surface water towards the sea
Cold water draws upwards (upwelling) to replace surface water
The air’s capacity to hold moisture is diminished
Rainshadow Effect
Rising air at the slope of the mountain towards the wind cools and loses moisture
Descending air on the other side of the mountains warms up → decreasing its relative humidity → causing it to be dry
Climate
Low temperatures all year around
Mountain environments
a large amount of rainfall → due to relief rain
Low rainfall → rain shadow area
High diurnal temperature ranges → Underlying rock weakens due to extreme freezing
Can easily lead to avalanches
Relief
Steep and rocky terrain which is mostly inaccessible
Young mountains have steep gradients and weak rock structures
The area is a frequent risk for rockfall and mass movement
Slope Aspect: the direction that a slope faces
Northern hemisphere (most of highest mountains) → slopes face south
Get more sunshine for longer periods of time
Causes difference in vegetarian and land uses than northern aspect
Altitude and Biosphere
Mountain areas have vertical series of bands of vegetation
Altitude affects temperature
As animals need vegetation for food → distribution is also along the altitude zones parallel to vegetarian
The number of species declines with increasing altitude
Tectonic hazard
Tectonics uplifts → mountain ranges
Still ongoing → creates constant instability
Areas around are affected by earthquakes
Wealthy countries → build earthquake-proof structures
Climate
Moist defects
Generally low amount of rainfall
Rainfall Variability
Very high for arid regions
Varies from year to year
Diurnal Fluctuations
Arid regions generally have a large diurnal temperature range
Deserts near the sea have a moderating effect
Seasonal Fluctuations
Equatorial deserts: little season changes in temperatures
Subtropical deserts & mid-latitude deserts: great variation between winter and summer temperatures, especially in high altitudes
Wind
Arid regions are typically windy
Sparse vegetation
More air movements
Lack of frictional drag from trees
Connection can also cause heavy winds
Sun heats the ground and dry air above, which expands and rises, with cooler air coming in to replace
Wind removes moist air → increases evapotranspiration
Flash floods
Normally deserts may have irregular flash floods
Typically have unstable terrain
Waterlogged solid → deteriorates vegetation growth and causes solifluction → unpredictable terrain change
Solifluction: seasonal freeze-thaw action upon waterlogging topsoils which induces downslope movement
Difficult to source liquid water & insulated pipes to carry them
Short growing season → outsources food
Roads ice frequently
Frost heave can cause damage
Ice Heaves: sheets of ice that push against each other or the shoreline. They form when ice sheets expand due to rapid temperature fluctuations. Thermal expansion of the ice occurs when a rapid increase follows a period of very cold weather in temperature
Have great diurnal temperature variations
Think and weak soil → no fertility for agriculture & harsh winds
Generally low rainfall
Steep topography → accommodating infrastructure and communication is difficult to build and maintain
Altitude increases → decrease in air density, water vapor → dehydration, carbon dioxide, and boiling point of water → difficult to cook
Frequent avalanches → destroy settlements
Lack of water and precipitation
No freshwater → impossible to farm and maintain livestock
Use chemical weathering to achieve finer soil
Great diurnal temperature variations
extremely high during the day and extremely cold during the night
Extreme temperatures limit vegetation growth
Glacial advancements and retreats
Glacier: Slow-moving mass of ice formed by accumulation and compaction of snow on mountains or near poles
Although solid, behaves like thick liquid and flows at an extremely slow rate under gravity
Glacial system → balance of inputs (accumulation of snow, avalanches, debris, heat), storage (ice, meltwater, moraine), and outputs (losses due to ablation: melting, sublimation, evaporation)
Ablation: all methods by which the glacier can lose mass. In this zone, there is a net loss in mass when outputs are greater than inputs
If accumulation > ablation → glacier avances
If accumulation < ablation → glacier retreats
If accumulation = ablation → glacier is steady
Glacier will have a positive regime when supply is greater than loss → thicken and advance
Glacier will have a negative regime when wasting is greater than supply → thin out and retreat
Natural Desertification
Desertification: the process by which deserts expand into semi-arid areas or become more intense
Variations in rainfall/drought/increased aridity can cause deserts to expand or retrace
Glacial erosion
Plucking
Occur at the base of the glacier
As ice moves, meltwater seeps into joints and freezes to the rock → ripped out when the glacier moves
Can be used for abrasion
Abrasion
Debris carried by the glacier scrapes and scratches the rock
Finer material will smooth out the rock → producing gently sloping landforms
Factors affecting glacial erosion
Relative hardness of particles and bedrock
Most effects abrasion: har particles + soft bedrock
Ice thickness
Greater the thickness → greater the vertical pressure → more effective abrasion
Basal water pressure
Basal water pressure may lift the glazier above the level of particles that the base, reducing the among of the brain
Sliding of basal ice
Faster the rate of basal slides → greater the rate of abrasion
Movement of debris towards the glacier base
If particles at the glacier base are not renewed → become polished → less abrasion
Debris particle size and shape
Large and angular debris abrade much more effectively than small and round debris
Landforms produced by glacial erosion
Cirque: an oval-shaped depression in the side with a steep back wall and a rock lip
Arete: narrow, knifed-edged ridge
Pyramidal peak: pointed peak with radiating aretes
Glacial trough: steep-sided u-shaped valley
Hanging valley: tributary glacier left high above the main valley
Truncated sur: steep cliff-like valley sides
Rock steps: stepped long profile in a glacial trough
Ribbon Lake: long narrow lack in glacial trough
Cirque lake: small, deep, circular lake
Roche Moutonné: ice-smoothed rocks with steeper side facing down-valley
Striations: rocks scaled with parallel scratches
Freeze-thaw: the process by which the freezing of water puts pressure on rocks (especially jointed rocks). Only occurs when the temperature fluctuates above and below freezing points are there are cycle of strain and release
Mass Movement
Frost Heave: the expansion of fine-grained soils such as silts and clays to form small domes. Results from the direct formation of ice.
The thermal conductivity of stones is greater than spil so they are underneath the stone become colder → ice crystals form
The crystals force the stones above them to rise
Solifluction: Common when surface sediments are poorly drained and saturated with water. Occurs when tyres are above zero and free liquid water is available in the action later
In winter, water freezes in the soil, causing expansion and secretion of individual soil particles
In spring, the ice metals and water flows downhill
Water cannot filtrate the soil due to permafrost → flows over and caries the segregated soil particles and deposits them further down
Frost creep: type of solifluction that occurs because of frost heaving and thawing
Starts with the freezing of the surface ground, angling particles at right angles. As ice thaws in the warm season, contracting surface drops particles in elevation due to gravity → particles move slightly downslope
Rockfalls: occur when fragments of rock break away from a cliff face from freeze-thaw weathering
Permafrost: permanently frozen subsurface
To be classified as permafrost must be frozen for at least 2 years
Commonly occurs in periglacial environments
Types of permafrost
Continuous
Discontinuous
Sporadic
Thermokarst: irregular, hummocky terrain with marshy or lake-filled hollows created by the disruption of permafrost's thermal equilibrium
Pingos: dome-shaped isolated killed with interrupt flat tundra plains. Form as a result of movement and freezing of water under pressure
Open-system pingos: forms when the source of water is a distance elevate the source
Closed-system pingos: forms when the supply of water is local and permafrost expands
Often form on site of small lakes where water is trapped by freezing from above
Mechanical weathering
Salt crystallization: a form of weathering which causes the decomposition of rock by the solution of salt, causing chemical and physical changes in the rock
Disintegration: a form of weathering where the grains of rock become loose and fall out, leaving a pitted surface
Occurs in deserts with lar diurnal temperature ranges
Erosion
Water
Exogenous rivers: rivers that have their source in wetter environments and then flow through a desert
Endorheic Rivers: rivers that drain into an inland lake or sea
Ephemeral rivers: Rivers that flow seasonally or after a storm and tend to have high discharges and sediment levels
Wind
The movement of sediment is crashed by drag and lift forces, also known as suspension, but are reduced by particle size and friction
Deflation: Progressive removal of fine material by the wind leaving behind larger materials
Abrasion: sandblasting action acted by materials as they are moved by alteration
Saltation bouncing of sand particles by wind forces
The process smooths away rock close to the ground
Landscape features in hot arid environments
Formed by deposition
Dunes: develops when sans Grania, moved by saltation and surface creep, are deposited
Form around large rocks, which hold the main part of the dune in place
Formed by wind erosion
Yardangs: extensive ridges of rock. They are separated by troughs, and have an alignment similar to the prevailing winds.
The strata are vertical
Zeugens: tabular masses of resistant rock separated by trenches where the wind cuts vertically through the cap into the underlying soft rock
The strata are horizontal
Rock petals: formed by exposed isolated rocks in the series when a more resistant layer of sedimentary rocks sits above a softer layer
The lower softer rock erodes faster than the higher, more resistance-rich
Oases: fertile spots in the desert where water is found. Formed where natural depressions are deep enough to cut into water table
This leads to semi-permanent water is available near the surface
Formed by water erosion
Wadis: dry river channels that are generally steep-sided and flat-bottomed. May have formed during flash floods or during wetter pluvial periods in the Ice Age when the runoff collected from sheet flood becomes concentrated into deep ravines
Measea: Plateau-like featured with steep-sides
As the mesa is reduced in size by cliff retreats, it rains its flat top and altitude
Buttles: a smaller version of mesas, representing the final stage of erosion before the resistance rock is finally eroded
Agriculture in Arid Areas
Benefits: The environment offers an abundance of heat and sunlight, favoring a lengthy growing season. If water is available, farming can be an opportunity. Opportunities include:
Nomadism
Settled farming with groundwater
Irrigation next to rivers and oasses
Increased use of drought-tolerant species
Challenges and possible solutions: The area is dominated by the lack of fresh water, too much sunlight and heat, low rainfall seasons, alien waters, strong dry winds, poor soil structure, overgrazing, and poor transport. All arid and semi-arid have negative water balance (outputs from evapotranspiration and stores of water exceed this input from precipitation
Soil is arid due to low rainfall and high evapotranspiration
Soil is infertile due to:
Low organic content
Generally thin with few minerals
Lack of clay
Soluble salts in soil which can be toxic to plants
Irrigation access
Not all areas have access to irrigation
To the areas that do, problems include salinization, depletion of groundwater, pollution, and less access to water elsewhere
Salinisation Risk
May occur in areas where the water table is close to the surface & annual precipitation is less than 250 mm
In poor drainage locations (ex. Valleys and basins), surface water evaporates and leaves behind large amounts of salts
Saline soils adversely affect the growth of more crops
Reduces rate of water uptake by roots
Sustainability
Agriculture in arid and semi-arid environments can be made more sustainable by:
Reducing her size and pressure on the amount of limited vegetation
Use solar panels to produce energy
Plant vegetation
Use more efficient types of irrigation
Building check dams to collect water
Using more salt-tolerant plants
Mineral extraction
In extreme environments: opens up opportunities for poorly developed regions, employ opportunities, and can generate significant income from exports
In cold environments: resource development can improve, but can put the environment under pressure and create conflict
Due to inaccessible, there is a high cost of attracting workers
Fragility Of periglacial areas
The limited ecosystem is highly susceptible to interference
Low temperature limits decomposition, which can lead to pollution (especially oil)
Frost heave
Can lift piles for oil pipelines and structure out of the ground → need to be embedded deeper which is expensive
Resource nationalism
Governments tend to assert control of natural resources in their territory and conflict with the interest of multinational corporations
In arid environments: huge potential for development and generate large earnings for countries that develop them
Due to inaccessibility, there is a high cost of attracting workers and protecting people from extreme heat and aridity
Politics
Risk of intruding on rights of Indigenous people
Environmental impact
The movement of people and vehicles can introduce exotic species
Mines can be a major source of dust pollution linked to respiratory disease
Open-pit mining can expose dangerous chemicals and contaminated groundwater
Popular destinations due to scenery, rare species, pristine landscapes
Mountain environments have a low carrying capacity and are easily damaged by human impact because of this erodible soil and vegetation
tourism opportunities may be linked to scenery, wildlife, indigenous culture and outdoor pursuits.
create jobs, provide income for workers,
Challenges include extremes of temperature, accessibility, water shortages and a lack of resources to sustain tourism.
The impacts on the natural environment include mass movement, erosion, land degradation, hazards, aesthetic changes, water shortages, waste, introduction of exotic species and habitat removal.
Desertification
Desertification: Land degradation in humid and semi-arid areas (not including non-desert (arid) areas)
Involves the loss of biological and economic productivity and it occurs where climatic variability (especially rainfall) coincides with unsustainable human activities.
Causes
Desertification can be a natural process intensified by human activities. All areas affected by desertification are marginal and have highly variable rainfall, except rainforests desertified by inappropriate farming techniques.
Natural causes
Temporary drought periods of high magnitude and long-term climate change towards aridity.
Overgrazing
Vegetation is lost through grazing and trampling by large numbers of livestock.
Overgrazed lands become more vulnerable to erosion as compaction of the soils reduces infiltration (increasing surface runoff) and trampling increases wind erosion.
Fencing leads to severe localized overgrazing while boreholes and wells cover the water table, leading to soil salinization.
Overcultivation
This leads to diminishing returns (yield decreases every season) and so to maintain the return on agricultural investment, the area of growth must be expanded.
Reducing fallow periods and introducing irrigation help to maintain output, but contribute to further soil degradation and erosion by lowering soil fertility and promoting salinisation.
Deforestation
Occurs where land has been cleared to extend the area of cultivation and in the surrounds of urban areas for firewood.
The loss of vegetation cover increases rainsplash erosion and the absence of root systems allows for easy soil removal by wind and water.
Climate change
Soils exposed to degradation as a result of poor land management could become infertile as a result of climate change.
Climate change may exacerbate desertification through alteration of spatial and temporal patterns in temperature, rainfall, solar radiation and winds.
Arctic region
As ice caps are melting, a military race between the US and Russia competing for its extremely valuable resources
The region is opening up two major shipping lanes, and oil and gas reserves are worth trillions of dollars.
If the Arctic region continues to melt and open up vital shipping lanes, there must be international cooperation to provide security and rescue elements for commercial shipping.
Oil conflicts in the Middle East
Conflicts over oil are the result of long-standing historical disputes, which have developed into the desire to control valuable oil and natural gas assets.
The economic world has become energy-centric, and access to energy resources provides strength and power for some countries, whereas lack of resources leads to vulnerability for other countries.
Countries with surplus energy reserves, and the ability to export energy, often have a disproportionate influence on the world stage.
ISIS: A Sunni extremist group that controls large parts of western Syria and northern Iraq. ISIS controls key oil-producing areas of Syria and oil-refining facilities in Iraq. This, in part, allows it to pay for its military. Such conflicts make it difficult for countries that depend on Middle Eastern oil.
Sustainable development: New technology and sustainable developments in extreme environments
Sustainable development: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs. They should fulfil needs, in particular the essential needs of the world's poor, but are restricted by limitations imposed by the state of technology and social organization on the environment's ability to meet these present and future needs.
Solar power
A completely renewable resource which has non-direct pollution during electricity generation and requires little maintenance.
However, there are high initial costs for solar plants and it is limited in that power cannot be harnessed at night or in countries with low annual hours of sunlight
Desalination
The removal of salts and minerals from seawater and soil.
Due to high energy input, the costs of desalinating seawater are generally higher than the alternatives, but alternatives are only sometimes available and depletion of reserves is a problem in certain locations.
The main criticism regarding desalination and the use of reverse-osmosis technology is that it costs too much.
Aquaponics
An integrated form of farming that enables farmers to increase yields by growing plants and farming fish in the same closed freshwater system.
Mimics natural processes and enables waste to be efficiently reused.
Climate change and EEs
The impacts and management of global climate change in extreme environments, including adaptation by local populations
Climate change impacts on arid environments:
Food security
As temperatures rise, evaporation levels will increase and reduce precipitation effectiveness.
Environmental hazards such as floods and droughts will become more common in arid areas like the Sahel, disrupting agricultural systems
reduce food production and availability and increase prices, food insecurity and hunger.
Poverty will exacerbate the impacts of climate change in these areas.
Local adaptation strategies by Senegal:
Improving soil fertility by the careful use of fertilizers
Improving the efficiency of irrigation systems and pest control
Adopting water and soil conservation techniques using baguettes (stone rows) to reduce run-off on slopes
Developing the Great Green Wall of the Sahara and the Sahel Initiative (GGWSSI), that is, a massive line of trees across the southern Sahara and Sahel to combat the combined effect of resource degradation (deforestation and soil erosion) and drought/desertification
Coping strategies for water shortages
Adaptations to water shortages include:
Increased mobility (the traditional way)
Management of size and composition of herds
Exchange of livestock and livestock products
Increased use of drought-tolerant species
Utilization of wild species and tree crops
Windbreaks to reduce wind erosion of bare soil
Irrigating with silt-laden river water to restore soil
Dune stabilization using straw bales and xerophytic plants
Land enclosure to reduce wind erosion
Climate change impacts on cold environments
Any increase in temperature is likely to have a greater impact in areas where the mean annual temperature is only a little below the freezing point.
risk of degradation and the development of thermokarst (subsidence).
Benefits
The warming climate has made minerals that were once locked in ice accessible.
Farming may become more productive as net primary productivity increases and the length of the growing season increases.
Consequences
Many settlements are located at river mouths, river confluences or islands.
Melting permafrost, coastal erosion, increased flooding and a rise in sea level due to climate change will take a toll on buildings, ports, bridges and roads.
This will increase the number of climate refugees as well as death tolls from unpredictable sea ice.
life in cold extreme environments will become more expensive (e.g. snowmobiles must take longer routes, and buildings are weakened by melting permafrost).
People relying on fishing will either have to go further to catch or alter to take into account changes in species composition.