The Distribution of Extreme Environments (SL IB Geography)

What is an extreme environment?

• Extreme environments are places that are considered inaccessible and very hard for human life to survive in
• Some areas can provide opportunities for development and economic activity 
  • They can have rich mineral deposits such as oil, gas, gold, etc. 
  • However, exploiting these resources is costly 
• Population densities are low in these areas
• Harsh conditions make it difficult to obtain and maintain energy and food supplies
• Many Indigenous peoples are abandoning traditional lifestyles 
• Examples of extreme environments include:
  • Deep ocean trenches
  • Hyper-arid deserts (cold or hot)
  • Salt lakes
  • Volcanoes
  • Mountain plateaus, etc

Distribution of cold and high-altitude environments

• These environments include:
  • Polar regions
  • Glacial areas
  • Periglacial areas
  • High mountains in non-tropical latitudes
• Cold areas are mostly found at high latitudes (66° north and south of the equator), such as the polar regions and arctic tundra
  • These areas are also known as cold deserts because of:
    
    • Low levels of precipitation
    • Poor soil conditions
    • Low levels of vegetation
• Cold environments are also found at high altitude, such as the Himalayas and the Andes

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Distribution of cold and high-altitude environments

• The distribution of cold environments can be divided into polar, glacial, periglacial and high-mountain areas
• Polar environments are found where levels of solar radiation are very low
  • Located in high-latitudes within the Arctic and Antarctic circle (from 66.5° to 90° N and S)
  • They are the coldest places on Earth 
  • Examples include the Poles, Greenland and northern Canada
• Glacial
  • Found at higher latitudes and altitudes, with high levels of precipitation
  • Found at the edges of polar ice sheets and mountain glaciers 
  • Ice remains throughout the year
  • Examples include the Andes, Himalayas and Franz Josef Glacier, New Zealand
• High-mountain (non-tropical) 
  
  • Also referred to as alpine
  • Found at high latitudes and altitudes of over 3 000 m, where snow and ice remain throughout the year with a cooler climate and seasonal coverage of snow at lower altitudes
  • Examples include the Himalayan and Tibetan mountain ranges in Asia, the Rockies and the Andes in the Americas, and the New Zealand Alps
• Periglacial or tundra environments are found at the fringes of permanent glaciated areas
  • Either at high-altitude mountain regions or high-latitude polar regions
  • Mainly located in the northern hemisphere due to a lack of land mass in the southern hemisphere 
  • These areas account for a third of the Earth's surface

• Hot desert and semi-desert areas stretch across 30% of Earth's land surface
• They are home to approximately 20% of the world's population
• Deserts have high levels of aridity
• They are defined as:
  • Semi-arid areas receive between 250 and 500 mm of precipitation per year
  • Arid regions receive 25–250 mm per year
• Four main factors influence distribution:
  • Arid areas are located along the mid- and low-latitudes of the Tropic of Cancer and the Tropic of Capricorn
    • These are stable, subtropical high-pressure areas
    • Semi-arid areas lie along the margins of these arid areas; for example, the Sahara desert is an arid area and the Sahel would be classified as a semi-arid area
  • Continentality
    • The further the distance from the sea, the more moisture is lost before reaching the area, such as the Turkestan desert situated in central Asia
  • Rain-shadow
    • Some areas are located in the shadow of mountain ranges, such as the Atacama Desert, which is alongside the Andes
    • Precipitation falls on one side of the mountain, keeping the adjacent side dry
  • Cold ocean currents
    • Cold ocean currents limit the amount of moisture held in the air
    • Usually located on the western coasts, such as the Namib desert, Africa, this is due to the cold Benguela Current running up the west coast of Africa

Distribution of arid and semi-arid regions; note that most semi-arid regions fringe arid areas