Tundra

The earliest human settlers of Arctic and tundra regions were probably the Yenisey Ostyaks of western Siberia and the Yukaghirs and Chukchi of eastern Siberia. Early inhabitants of northern Scandinavia and the White Sea region were among the first settlers of Arctic Europe, while North American Native Americans may have spread into the far north of the New World thousands of years before the Inuit. Later waves of settlers included the Finns of northern Scandinavia, the Nenets of northern Russia, and the Tungus and Yakuts of eastern Siberia. These were nomadic peoples, initially hunters, latterly herdsmen, who became increasingly dependent on following the great herds of reindeer on their migrations. About 20 ethnic groups now inhabit Arctic areas of Russia including the Yakut of the Lena River basin, the Tungus of the region east of the River Yenisey, the Yukaghir between the Indigirka and Yana Rivers, and the Chukchi of the extreme north-east of Siberia. The Chukchi are believed by many to have given rise to the Aleuts and Inuits whose descendants still live in semi-permanent settlements in Canada, Alaska, and coastal areas of Greenland.

Because of the harsh climate, long, dark winter months, and low productivity, the impact of humans on Arctic tundra ecosystems has been relatively mild until recently. However, exploitation of oil, coal, and minerals (such as nickel, iron, apatite, gold, tin, mica, tungsten, lead, zinc, and molybdenum) in the last few decades has resulted in a number of undesirable effects. Low productivity coupled with peaty soils that are easily compressed during the summer thaw renders the tundra very sensitive to heavy vehicles. Traffic has led to local erosion in many areas, particularly those targetted for oil extraction. Lines to guide engineers taking seismic readings have also been bulldozed across the tundra at regular intervals causing extensive damage. Even where this damage does not lead to erosion, the slow-growing tundra vegetation may take many years to recover. Environmental organizations have pointed out these negative effects and forced many companies active on the tundra into developing landscape management and wildlife conservation plans. Many access and distribution roads are now constructed on thick cushions of gravel up to 2 m (7 ft) deep to prevent melting of the permafrost, movement of the soil, and the initiation of erosion.

A less predictable consequence of oil-prospecting and extraction is the threat of oil spillage from the distribution network, particularly from ocean-going tankers. In 1989, 250,000 barrels of oil spilled from the tanker Exxon Valdez causing extensive pollution of coastal habitats and the death of large numbers of sea birds. The long-term effects of the spillage, if any, are the subject of continuing research.

The construction of long pipelines to carry oil across the North American tundra has led to some disruption of caribou movements as herds are prevented from following their traditional seasonal migration routes. The growing human presence in the region, however, has led to a marked reduction in the density of wolves, a benefit to the caribou population that traditionally suffers heavy losses to these predators. However, an increase in caribou numbers could lead to overgrazing of tundra vegetation and degradation of the typical plant communities. Striking a balance between caribou, wolves, and the perceived threat to human and domestic populations will require careful planning and population management.

Radioactive pollution from nuclear testing and reactor accidents is also a cause of considerable concern. Dust ejected from the failing Chernobyl nuclear power station in 1986 (see Chernobyl Accident) contained large amounts of radioactive caesium, which was washed out of the atmosphere and subsequently accumulated in the snow and ice of Greenland and other Arctic lands at such high levels that it can still be detected in the accreting ice masses of glaciers. The uptake of radioactive material and other chemical pollutants by slow-growing lichens has had severe repercussions, for these plants are a major source of food for reindeer and caribou which, in turn, are hunted and eaten by indigenous people. Consumption of food contaminated with radioactive substances may increase the risk of developing diseases such as cancer and may also contribute to the risk of birth defects. The slow turnover of nutrients by the relatively unproductive tundra vegetation suggests that the problems of radioactive contamination and its accumulation in food chains will be acute for many years to come.

There is also concern about the release of chemicals such as chlorofluorocarbons (CFCs) into the atmosphere and the effect on the ozone layer at polar latitudes. The major concern at the moment is the large ozone hole that opens over the southern polar landmass of Antarctica each spring, permitting increases in ultraviolet radiation possibly to levels that may endanger living organisms in places such as Australia and New Zealand. Although small temporary holes have been detected over the Arctic and caused some concern, the ozone layer at northern latitudes appears to be much more resilient than in the south. The issue of chemical contamination of the upper atmosphere and the effects on the ozone layer at both poles is the subject of continuing monitoring and research.