Polar Environment (OCR GCSE Geography B)
Revision Note
Written by: Jacque Cartwright
Reviewed by: Bridgette Barrett
Characteristics of the Arctic & Antarctica
The Arctic is an ocean surrounded by land and Antarctica is a continent surrounded by ocean
Most of the Arctic's ice is sea ice, and this varies throughout the year
Melting Arctic sea ice does not raise sea levels, but Antarctica's melting land ice does cause variation in global sea volume
| Arctic | Antarctica |
---|---|---|
Location | Region within the Arctic Circle, from 66.5° to 90° north of the Equator | Landmass encompassing the South Pole and mostly south of the Antarctic Circle from 66.5° to 90° south of the Equator |
Climate | Fluctuating between 10° C in summer to -40° C in winter Annual precipitation is less than 500mm per year | Colder than the Arctic with average summer temperatures of -28°C - coastal regions are warmer than the interior but winter temperatures have reached as low as -90°C (Vostok research station) Annual precipitation inland is 50mm and 200mm at the coast |
Features | The ocean is surrounded by continents and large islands, with drifting sea pack ice that extends in winter and icebergs. Ice reaches heights of 3m in places Mountainous regions on land, with areas covered in permanent ice and snow Includes the treeless, permafrost, tundra region where only the surface layer of the soil thaws each summer | Antarctica is a continent covered by a permanent ice cap ice and surrounded by the Antarctic Ocean Mountains up to 3794km high with the Transantarctic Mountains running across the whole continent Ice reaches thicknesses of 4.5km in places In winter, Antarctica almost doubles in size due to freezing seawater |
Flora | Arctic region - lichen and mosses Tundra - sedges, grasses, low-growing shrubs and small flowering plants such as the Arctic poppy | Mostly lichen and some mosses Phytoplankton in the ocean |
Fauna | Whales, seals, fish, wolves, caribou/reindeer, polar bears and birds such as the Snow Goose - all are specifically adapted to live in the harsh Arctic | No indigenous terrestrial mammals Penguins, seals and whales rely on the sea for their food and land provides a habitat for breeding |
Soil | Thin and poor quality, with very few plants Underlying rock weathers slowly due to low temperatures Permafrost sits below the active layer and remains frozen all year round The active layer melts in the summer months and ranges from 20-100cn To prevent damage to the permafrost, buildings are built on stilts | Antarctic soils can be loose, soft, and sandy or frozen, hard, and rocky Very little organic matter to support more than mosses or lichens |
Location of the Arctic, Tundra, and Antarctica
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: The top layer of soil thaws producing boggy and waterlogged land
Winter: Frozen soil and long, dark winters
Animals need to adapt to cold, dry, snowy conditions, as well as wet summers
Adaptations of Animals and Plants to Cold Environments
Animal | Plant |
---|---|
Some animals hibernate to conserve energy and survive the winter, e.g. Arctic ground squirrels hibernate for 7-8 months of the year and can survive even if their body temperature drops below freezing. | Most plants become dormant to survive the cold, dark winters |
Animals are well-insulated e.g. thick fur like polar bears or blubber like seals. This reduces the amount of energy they have to use to keep warm. | Plants are small and round-shaped to provide protection from the wind. |
Many birds migrate to warmer areas during winter – Arctic terns live in the Arctic during the northern hemisphere summer and then fly to the Antarctic for the southern hemisphere summer. | 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. |
Many animals have white coats in winter for camouflage – this helps predators sneak up on prey, and for prey to hide in the snow. Arctic hares are white, which makes them harder for predators to spot against the snow. | The warmer, wetter summer is very short, so most plants have adapted to a growing season of just 50-60 days. They are very bright and vibrant to attract as many insects as possible for pollination. |
Many animals have physical adaptations, such as short legs: round, squat bodies: layers of fur and insulating blubber. The Musk Ox grows two layers of fur. Warm air is trapped in the shorter layer. The longer layer is over 60cm long. Its hooves are large and hard, allowing it to break the ice and drink the water beneath. | Many plants use underground runners or bulbs instead of seeds to reproduce because the growing season is so short. |
Interdependence in Polar Environments
The living (biotic) and non-living (abiotic) components in cold environments are closely linked
Both are fragile and easily damaged
If one component changes, the others are affected
They are 'inter-dependent' on each other for survival
The low biodiversity of the cold, dry climate means this interdependence is fragile and easily disrupted or damaged
If temperatures increase (e.g. due to global warming) more sea ice melts in the summer
Animals such as seals and polar bears rely on sea ice for breeding and hunting
So, if it disappears these animals are threatened
Other examples of interdependence include:
Antarctica has very few plants, making phytoplankton in the sea the most important producers and form the basis of the food chain
Phytoplankton > krill > fish > penguins
Phytoplankton rely on the nutrient-rich sea currents rising to the surface from deep waters
If this didn't happen the whole ecosystem could collapse
Plant cover is low causing plants to grow slowly but also to decompose slowly
This makes the soil low in nutrients, further reducing the ability for further growth
Herbivores, like reindeer, rely on plants like mosses to survive, but they also provide nutrients to the soil through their dung, from eating the plants
Plants also rely on herbivores to help them reproduce as animals spread seeds through their dung and on their fur
Carnivores, like wolves, will follow the herbivores as they search for vegetation
The tundra in summer, has greater plant cover, allowing surface plants to absorb heat from the sun and preventing the permafrost below from thawing
The permafrost provides water and diluted nutrients for plants and any damage to the permafrost will cause it to melt, leading to flooding and stopping plant growth
It also releases trapped greenhouse gases (methane) – leading to increased global warming, and changes to the climate of cold environment, threatening plants and animals as a cycle
Interdependence of cold environments
Human activity is causing global temperatures to rise, affecting the permafrost
A warming permafrost allows previously frozen flora and fauna to begin thawing and decomposing, releasing methane into the atmosphere and further enhancing the greenhouse effect
Increased demands for oil, gas and precious metals increase the pressure on cold environments
Adaptation takes time, but changes to an ecosystem can be fast
Cold environments have very low biodiversity (particularly Antarctica)
Low biodiversity means 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
Worked Example
Outline one way that plants are adapted to the climate in cold environments.
(2 marks)
You will gain credit about one environment only
Max 1 mark for two separate points
No marks will be given for referring to animal adaptation
Responses need to be developed [d]:
Answer
E.g. Most plants become dormant [1] to survive the cold, dark winters [1d] Plants are small/round-shaped [1] to provide protection from the wind [1d]
Most plants have shallow roots [1] because of the layer of permafrost/ice beneath the soil layer [1d]. Leaves are generally small [1] to limit the amount of moisture lost [1d]
Many plants use underground runners or bulbs instead of seeds [1] because the growing season is so short [1d]
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