Characteristics of 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

Reason for Distribution

• 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

Cold Environments

• 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

Arid Environments

• 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

Characteristics of Extreme Environments

Cold & High Altitude Environments

• 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

Desert and Arid Environments

• 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

Challenges for Human Habitation

Cold and High-Altitude Environments

Cold Environment

• 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

High Altitude Environment

• 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

Desert and Arid Environments

• 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

Changing Distributions of Extreme Environments

• 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

Physical Processes and Landscapes

Glacial Processes and Landscapes

• 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

Periglacial Processes and Landscapes

• 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

Periglacial Landscapes Features

• 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

  • 

Physical Processes in Hot Arid Environments

• 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

    • 

Managing the Future of the Environment

• 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

Tourism in Extreme Environments

Cold Environments

• 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

Arid Environments

• 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.

Future of Extreme Environments

• 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.

Access to Resources In Extreme Environments

• 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.