Tundra and Polar Areas

At the very top and bottom of the world are vast expanses of wind swept, treeless land. Almost all of Antarctica and much of the Arctic is permanently covered with a thick layer of ice.  

The polar regions of the world are always cold because at these high latitudes, the sun never rises far above the horizon, and its rays only glance across the earth. What little solar energy does manage to reach the surface is reflected back into space by the bright white ice.

The Arctic

Beyond the arctic ice however, is a large area of tundra. The arctic tundra encircles the North Pole and extends south to the edge of the boreal forest.

The tundra has an unusually dry, cold climate. Winters here are long and dark, with the sun barely rising above the horizon for weeks. The average winter temperature is -34C (-30F). During the short summer, the sun shines nearly 24 hours a day and temperatures can reach 12C (54F). The growing season ranges from 50-60 days. Known as a cold desert, only 15-25 cm (6-10”) of precipitation falls annually, most of it in the form of snow. Throughout the year, incessant winds of 30-60 km/hr (48-97 mph) roar across the treeless landscape.

The most limiting factor to life in the tundra is permafrost – ground that is frozen year round. All biological activity takes place in the upper few inches above the permafrost. Soil is permanently frozen, so trees with their deep root systems are unable to grow.  There are still a surprising number of hardy plants that have adapted to the cold climate. About 1,700 kinds of shrubs, sedges, mosses, liverworts and lichens grow here, along with 400 varieties of flowers. All of the plants are low-growing to keep out of the wind, and their roots form a dense mat near the surface. They are insulated from the bitterly cold winter temperatures by the snow cover.

The tundra is a carbon sink – an area that takes in more carbon dioxide from the atmosphere than it releases. During the short polar summers the plants take in carbon dioxide, sunlight and water in the process of photosynthesis. While plants in other parts of the world give off carbon dioxide when they die and decompose, the colder temperatures of the tundra means there is no decomposition, and plant remains thousands of years old have been found in the permafrost.

The permafrost also prevents water from seeping into the ground. Water remains on the surface throughout the summer, freezes in winter and reappears the next year, augmented by snow fall. The paradoxical result is a large number of ponds, bogs and sloughs in an area with minimal precipitation. Colder temperatures also inhibit evaporation, which would deplete water sources.

 All this surface water provides an excellent home for aquatic insect larvae. Hoards of black flies, deer flies, mosquitoes and no-see-ums provide a ready food source for millions of migrating birds who go north to breed and raise their young each year. Mosquitoes survive the extreme winter temperatures by producing an anti-freeze like compound in their blood that allows them to survive winter under the snow.

Surprisingly, there are 48 land animal species in the tundra – shrews, hares, rodents, wolves, foxes, bears, deer, musk=oxen and wolverine among them. Animals have adapted to survive long cold winters and raise young quickly in the summer. They have compact bodies with short limbs to conserve heat; many are insulated with thick layers of fat or blubber, and have dense layers of fur to trap air next to the skin.  Many species hibernate in the winter, and most birds retreat to the south for the winter. Animals burrow into snow whenever possible to avoid endless icy winds and take advantage of the insulting properties of snow.

The tundra is fragile, unforgiving environment. Animals and plants that live here live on a precarious edge and the smallest stresses can bring about their destruction.

The Antarctic

Most of the world’s tundra is located in the northern hemisphere, as the colder Antarctic temperatures produce a larger area of permanent ice cover.

The ecological stability of the Antarctic is based on the presence of ice. Any change in the environment that reduces the amount of ice would irreversibly modify the entire ecosystem. Rises in ocean temperatures break up coastal ice, endangering seals, penguins and krill, which graze on the algae attached to the ice.

The Antarctic ecology is dominated by the sea. Tiny shrimp-like crustaceans called krill live in the top 45 metres (150 ft) of the ocean in their countless billions. Krill are the center of the Antarctic Ocean’s food web, providing the bulk of the diet for blue whales, fur seals, penguins, albatross and fish. The current intensity of human fishing for krill, combined with heating of the ocean from a thinning ozone layer, could lead to an overall decline in their population, which would have repercussions all the way up the food chain

In this coldest of the world’s habitats, animals that survive here have some outstanding adaptations. The most famous inhabitants of Antarctica - Emperor penguins – have developed a co-operative behavioural strategy for survival during the unceasing icy winds. Huddling together in the thousands to keep each other warm, individuals constantly take turns to stand on the exposed fringes before returning to the heat in the interior of the group. Emperor’s do not build nests, but keep their single egg off the ice by holding it on top of their feet, underneath the warm skin flap of the parent bird.  

Life in the frigid oceans also requires special adaptations. The protective guard hair of a fur seal may have up to 50 or more soft hairs growing from the follicle to help trap air next to the body. Like animals in the northern polar areas, sea mammals in the Antarctic oceans also have an extra layer of fat and thicker fur.

• Atmospheric transportation of pollutants is now global – PCB’s have been found in the fat of Antarctic penguins; pesticides and industrial effluents in arctic animals
• Right whales - so called by early whalers because they gave the longest whalebones and thickest blubber – have been hunted nearly to extinction. They mate in the seas off Patagonia in bays now threatened by oil and gas development.
• The Alaskan Oil Pipeline was built across a caribou migration route. In some places it has been raised to allow the caribou to pass under, but its construction has melted permafrost along its length.  Oil exploration and extraction have also disturbed permafrost in many areas. When the sun hits tire tracks it causes the permafrost to melt, causing erosion and bigger ruts which eventually turn into gullies. As the Arctic permafrost melts, plant mass decomposes, returning carbon dioxide to the atmosphere and reversing the carbon sink effect
• Pollution from mining and oil drilling in the Arctic has polluted the air, lakes and rivers
• More people moving to the tundra to work the mines and oil rigs have created towns and more roads, which disrupt seasonal movements of large animals, and bring them into close contact with humans. Rubbish left from Antarctic explorers that wasn’t carried out takes so long to decompose in the frigid temperatures that mountains of it are piling up
• Higher temperatures in the Arctic are drying up onds that have been home to aquatic wildlife for millennia. The year 2006 was 3.5C (37F) warmer than the past 30 year average, causing high evaporation of ponds on Ellesmere Island, which have been monitored since 1983.