Stretching across North America, tundra comprises half of Canada and much of Alaska. Conditions in Earth's tundra regions may be harsh, but those areas still are vulnerable to environmental damage. While large numbers of humans may not live in the tundra, people can still threaten the tundra's stability and make life more difficult for plants and animals that reside there.
Warming Causes More Warming
Many scientists believe that greenhouse gas emissions cause the Earth's temperature to rise. As tundra warms, permafrost melts and releases methane and carbon dioxide lying beneath the permafrost. Charles Miller, a NASA scientist who studies the tundra, reports that, "Permafrost soils are warming even faster than Arctic air temperatures." He also warns that the release of these gases could upset the carbon balance in the Arctic and make global warming worse.
Effects of Climate Change on Tundra Life
As temperatures rise in the tundra, the amount of summer moisture may decline, resulting in problems such as wildfires and drought. Insect infestations may also increase. Climate change causes an indirect food supply problem in the tundra. As it gets warmer, shrubs in the tundra replace lichens and other vegetation. Lichens are important because caribou eat them. Decreases in the caribou population can reduce the amount of food available for bears and other predators.
The U.S. Environmental Protection Agency reports that closed-basin lakes in Alaska lost significant area during the past 50 years because of increased evaporation and permafrost thawing. Closed-basin lakes do not have streams that can provide them water. When wetlands and lakes shrink in size, wildlife that breed there lose part of their habitat. Reduction in wildlife affects the food supply of Alaska natives who hunt and fish.
Other Environmental Threats
Oil spills can be a problem in tundra regions because it's harder to clean spills around ice floes than it is to clean spills in open waters. Exploring for oil during the winter may disturb animal species such as polar bears and wolverines as well as vegetation. Tourists can also disturb some native species invading animal nesting grounds. Mining for minerals in the tundra harms the environment when people dig holes and disturb the soil; it could take years for vegetation to return when that happens.