Cold Environments (AQA GCSE Geography): Revision Note

Characteristics of cold environments

• Cold environments have temperatures below 0°C for long periods

•  There are two main categories of cold environments:

  • Polar environments are the most extreme

    • They include Antarctica and parts of the Arctic, such as Greenland, northern Russia, and Canada

  • Tundra environments have permafrost (frozen soil) and short summers.

    • They include northern Canada, Alaska, Iceland, and Siberia

  • The southern hemisphere has little land area and this restricts the tundra to small areas in South Georgia and the Antarctic Peninsula

• Both are fragile and easily damaged

• Together, they make up approximately 35% of the Earth and are found at the higher latitudes 

• Cold environments are only above freezing for 3 months a year

• At the upper latitudes, the sun does not rise or sink for several months of the year

Characteristics of the tundra

Location

• 'Tundra' comes from the Finnish word 'tunturi', meaning 'treeless plain'

• Found mostly in the northern hemisphere, along the Arctic Ocean's edge in North America and Eurasia, and around Greenland

• Small areas are found in South Georgia and the Antarctic Peninsula in the southern hemisphere

Climate

• Winter temperatures can fall to -50°C, while summer temperatures hit 10°C

• The average temperature is between -6°C and -12°C

• There is permanent darkness in winter

• During the summer, the sun never sets

• Precipitation is low, under 380 mm

• Seasons are clearly defined

• There is a lack of permanent ice cover

Soil

• Soil is thin, acidic, and not very fertile

• There is a layer of permafrost, up to 450 m deep, beneath the active soil

• This layer holds large amounts of trapped methane, a greenhouse gas

Plants

• Growing season is short

• No trees grow in permafrost, but small trees appear in warmer, sheltered spots

• Plants grow slowly and stay low

• Grasses, mosses, and lichens are the most common

• Flowering plants have a quick life cycle and are bright to attract insects

Animals

• Diversity is low, but it's higher than in polar regions

• Polar bears, wolves, caribou, snow geese, arctic foxes, and hares are common

• Goats and sheep inhabit mountains

• In summer, insects, birds, and other wildlife appear as the soil layer thaw

People

• Inhabited by approximately four million people

• Large Indigenous population

• Oil and gas workers live in big towns and cities

Characteristics of Polar regions

Location

• Located within the Arctic and Antarctic circle (from 66.5° to 90° N and S)

Climate

• Coldest places on Earth 

• Temperatures very rarely rise above 0°C, with winter temperatures plummeting to -40°C and below

• Precipitation is low, with no more than 100 mm per year

• Winters are long, cold and windy

• Icecaps permanently cover polar regions

• Clearly defined seasons of cold summers and even colder winters

Soil

• Due to the ice sheets that cover them, polar regions have little to no soil

Plants

• Very few plants but some lichens and mosses, are found on rocks

• Warmer coastal regions of Antarctica may see a few grasses

Animals

• Diversity is very low 

• Penguins in the Antarctic and polar bears in the Arctic

• Snowy owls, whales, seals and walruses

People

• Almost uninhabited 

• Indigenous people live in some Arctic regions

• Scientific research for part of the year in Antarctica

Interdependence in cold environments

• Living and non-living things in cold environments are closely linked

• If one part changes, the others change too 

• They are 'inter-dependent' on each other for survival

• The cold, dry climate has low biodiversity, making this interdependence fragile and easy to disrupt or damage

  • If temperatures rise, more sea ice melts in the summer

  • Seals and polar bears depend on sea ice for breeding and hunting

  • If it disappears, these animals face threats

• Examples of interdependence are:

  • Antarctica has very few plants, making phytoplankton in the sea the most important producers and the basis of the food chain

    • Phytoplankton feeds krill, krill feeds fish, and fish feed penguins.

      Phytoplankton depend on nutrient-rich sea currents that rise to the surface from deep waters 

    • If this doesn't happen, the whole ecosystem might collapse

  • Low plant cover causes slow growth and slow decomposition of plants

  • The soil has low nutrients, which reduces its ability to grow

  • Herbivores, such as reindeer, depend on plants like mosses for survival

  • They also enrich the soil with nutrients through their dung after eating the plants

  • Plants depend on herbivores for reproduction because animals spread seeds in their dung and on their fur

  • Carnivores, such as wolves, follow herbivores in their search for vegetation 

• In the summer, the tundra has more plant cover

• This helps surface plants absorb heat from the sun and keeps the permafrost below from thawing

• Permafrost gives water and nutrients to plants

• Damage to permafrost causes it to melt, which leads to flooding and halts plant growth

• It releases trapped greenhouse gases like methane, which increases global warming and alters the climate in cold environments, threatening plants and animals in a cycle

Plant & animal adaptations

• The tundra biome has about 400 varieties of flowers but only 48 different animals

• Plants in the tundra need to adapt to wet summers and dry winters:

  • Summer: Top layer of soil thaws, producing boggy and waterlogged land

  • Winter: Frozen soil and long, dark winters

• Animals need to adapt to cold, dry and snowy conditions, as well as wet summers

Adaptations of animals

• Some animals hibernate to conserve energy and survive the winter

  • For example the Arctic ground squirrels hibernate for 7-8 months of the year and can survive even if their body temperature drops below freezing

• Animals are well-insulated and this reduces the amount of energy they have to use to keep warm

  • e.g. thick fur like polar bears or blubber like seals

• Many birds migrate to warmer areas during winter

  • Arctic terns live in the Arctic during the northern hemisphere summer, then fly to Antarctica for the southern hemisphere summer

• Many animals have white coats in winter for camouflage; the colour helps predators sneak up on prey and allows prey to hide in the snow

  • Arctic hares are white, which makes them harder for predators to spot against the snow

• Many animals have physical adaptations, such as short legs, round squatting bodies, layers of fur, and insulating blubber

  • The Musk Ox grows two layers of fur

  • The shorter layer traps warm air

  • The longer layer is over 60 cm long

  • Its hooves are large and tough, allowing it to break the ice and drink the water beneath

Adaptations of plants

• Most plants become dormant to survive the cold, dark winters

• Plants are small and round-shaped to provide protection from the wind

• Most plants have shallow roots because the permafrost prevents any further growth

• Leaves are generally small, and this limits moisture loss

  • The Caribou Moss has hollow stems and will become dormant until the next rainfall

• The warmer, wetter summer is brief, so most plants have adapted to a growing season of just 50–60 days

• They are usually very bright and vibrant to attract as many insects as possible for pollination

• Many plants use underground runners or bulbs instead of seeds to reproduce because the growing season is so short

Biodiversity issues

• Adaptation takes time, but changes to an ecosystem can be fast

• Cold environments have very low biodiversity (particularly Antarctica) 

• Low biodiversity means that when the population of one species changes, it can affect the population of dependent species; e.g. changes in the number of Arctic hares affect the number of Arctic foxes (their predators)

• Global warming is causing some species to move towards the poles, where it is cooler, to cope with temperature rises elsewhere

• Those species that have already adapted, such as the polar bear, have nowhere else to go and are at risk of extinction