POPULATION AND ECOSYSTEMS
he world's polar regions are its least populated areas. But while Antarctica has no permanent residents, the Arctic has more than 3.7 million inhabitants from eight countries. The prime environmental influences come from outside, whether long-distance tourism or long-distance pollution. But these same influences are also crucibles for new forms of international cooperation. [Add]
The Arctic region -- defined as the ice-covered Arctic Ocean and surrounding tundra -- has a rich history of semi-nomadic communities living off its meagre resources of fish, marine mammals, caribou, berries and mushrooms. These communities live largely in harmony with their environment, creating little pollution and managing their resources sustainably.
Indigenous communities are now outnumbered by migrants from the south in most parts of the region except Greenland and Nunavut (though the Russian migrant population in Siberia is declining). Nonetheless, they remain vibrant societies and are gaining self-governance, culminating in 1999 with the creation of the world's newest autonomous territory, Nunavut in northern Canada . [Add]
The Arctic's specialized ecosystems and animals, adapted to the cold and dark, are particularly vulnerable to the accumulation of toxic contaminants such as heavy metal, hydrocarbons and persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and pesticides, that accumulate in body fat. Some pollutants have local sources: PCBs leaking from old Canadian military equipment and Siberian oil pipelines and metal refineries, for instance. But levels of most POPs can only be explained by long-range movement from lower latitudes. They reach the region via rivers flowing north into the Arctic, particularly from Siberia; via sea ice transporting contaminants from the coast; via global ocean currents; and by the strong south to north air flows, particularly from Europe.
The cold Arctic air is believed responsible for "capturing" and then depositing passing air pollution, including POPs and mercury, through a process known as "global distillation". The long marine food webs are extremely efficient at increasing the concentrations of such toxins so that birds and animals at the top of the chain receive large doses. Heavy metals such as cadmium and mercury, and POPs such as PCBs, all bioaccumulate in this way. The build-up is made more acute because many of the toxins accumulate in fats, the main food of many polar animals. As a result, studies suggest, polar bears are dying after imbibing PCBs in their mothers' milk .
The local people, at the top of the food chain, are among the most heavily exposed populations in the world to such pollutants, which reach dangerous concentrations in the flesh of whales, seals and other mammals. Approaching 17 percent of Greenlanders have potentially harmful levels of mercury in their blood, mostly from eating whale and seal meat. A typical traditional meal of these foods may sometimes exceed maximum daily allowed doses of mercury, PCBs and other toxins. Thus the contaminants directly threaten customary ways of life and cultural traditions. [Add]
Arctic ecosystems are particularly vulnerable to contamination, taking a long time to recover. Oil, for instance, breaks down only very slowly in the cold and dark. The oil spill from the Exxon Valdez in Alaskan waters in 1989 left 36 000 seabirds and 3 000 sea otters dead and a legacy that lasted far longer than it would have in warmer regions.
Arctic ecosystems have also accumulated radioactive isotopes spread through the atmosphere following the atmospheric testing in the 1950s, and the Chernobyl nuclear accident in Ukraine in 1986. While levels of fallout in the Arctic were no higher than elsewhere, Arctic lichens absorbed large amounts of caesium-137. The lichen is the staple diet of animals such as reindeer, which are eaten by humans. As a result, Arctic inhabitants typically have five times as much of the isotope in their bodies as people to the south, and some reindeer herders have levels 300 times higher. Herders of northern Scandinavia have been prevented from eating and selling reindeer meat because of the fallout from Chernobyl. [Add]
Landuse threats to Arctic ecosystems have historically been small, but they do exist. Norwegian reindeer herds have increased threefold since 1950, exhausting lichen cover over an area of several hundred thousand square kilometers. Overgrazing has contributed to severe erosion of the loose volcanic soils in Iceland, and commercial forestry has fragmented the Siberian boreal forests . [Add]
The Arctic was an important theatre of the Cold War, providing remote sites for military installations and weapons tests, and hiding submarines beneath the sea ice. In the future, its economic role is likely to grow. Long-standing metal smelting in Siberia and coal mining in the far-north island of Svalbard are being joined by oil exploitation in Alaska and the Barents Sea, and plans to reopen the old shipping route north of Norway and Russia. Since the end of the Cold War, the eight Arctic nations have come together to discuss their shared environment. Besides creating nature reserves in the region, they have taken the lead in pushing through a protocol to an existing United Nations convention, curbing 16 POPs in Europe and North America, and have spurred negotiations for a global treaty. [Add]
Many of the human-induced environmental threats in the Arctic do not occur in the largely unpopulated Antarctic, where economic activity has declined since the great sealing and whaling expeditions of the 19th century. The main pursuit is now science. The continent has 35 permanently occupied bases, with the oldest, the Argentinean Orcadas base, having been continuously inhabited since 1904. The fastest growing activity is tourism, which now brings more than 10 000 people there annually, mostly by cruise ship.
A certain amount of economic activity is also concentrated on fisheries, and there is concern about large-scale overfishing, particularly of the Patagonian toothfish, which makes up by far the largest share of the finfish catch in the region. In contrast to the rich marine life in the nutrient-filled waters of the Southern Ocean, the largely ice-covered continent has few land species. [Add]
Beyond the immediate threat of human activity, the polar regions are falling prey to global threats: notably climate change and the thinning of the ozone layer. The Arctic has lost around 5 percent of its sea ice in the past two decades , and land ice could follow. Recent modelling studies suggest that a warming of 3 degrees C would be sufficient to melt the entire Greenland ice sheet, raising sea levels worldwide by 7 meters over a thousand years or more .
Warming is already threatening the survival of polar bears around Hudson Bay, because the sea ice from which they hunt is disappearing. And the additional ultra-violet radiation streaming through the Antarctic ozone hole each southern spring is believed to be killing large numbers of fish eggs and larvae floating on the surface of the Southern Ocean by damaging their DNA. It also kills an estimated 15 percent of the phytoplankton in parts of the ocean . [Add]