The Distribution of Extreme Environments (DP IB Geography)

Global Distribution of Cold & High-Altitude Environments

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

Global Distribution of Hot Arid Environments

• 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