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Subsistence makes an important contribution to livelihoods in many isolated rural communities in Alaska, especially but not exclusively for native peoples. While subsistence is practiced to gather food, subsistence resources and the activities associated with their harvest also make important contributions to health, culture, and identity.
Subsistence hunting and fishing have been significantly harmed by present climate changes, through stresses on fish, marine mammals, and wildlife driven by permafrost thawing, sea ice retreat, and ecosystem shifts. While some specific subsistence resources are likely to grow more abundant (e.g., salmon near the northern limit of their range), the stresses are likely to grow more intense, even in the near term. Potential climate-change impacts on Alaska's wildlife both direct and indirect -- through changes in their habitats and food sources -- are likely to be both positive and negative, although all impacts are speculative at this time due to uncertainties in climate change projections.
The Arctic tundra is an important and sometimes critical habitat of international importance, particularly for migratory birds and caribou. Over time, a synchronicity has evolved between plant development and animal exploitation of available food to ensure survival. However, continued climate change could threaten this interaction by, for example, mismatches in the timing of plant growth and the arrival of migratory species. Weather station data for Alaska suggest that spring is arriving earlier, with earlier snow disappearance and warmer temperatures triggering earlier plant growth and development. Alaska's growing season is beginning earlier and lasting longer, with warmer summer days extending growth termination from August into September. Local weather records show that the growing season in Alaska has lengthened by more than 14 days since 1950. A longer growing season could or could not benefit wildlife, and could be particularly detrimental to those whose migration patterns would not allow them access to vegetation during its most nutrient-rich stage.
Moreover, changes in temperature can impact the type of vegetation that grows in this region. For example, Nome is now surrounded by tundra that depend on cool summer days, but its number of warmer summer days is increasing and approaching the threshold that would foster tall shrub and tree development. Should its vegetation change, wildlife that depends on traditional tundra vegetation could be impacted.
Because the Arctic tundra habitat cannot move northward in response to climate change, as can other ecosystems, due to the Arctic Ocean bordering this region, it is likely that the tundra will shrink by as much as one to two thirds globally. There are at least three present or potential actions that will contribute to shrinkage or changes in the tundra ecosystem in Alaska. One comes from a consistent prediction of global biogeography models that the northern edge of the boreal forest will advance into the tundra. Second, and already occurring, is that recovery of major deposits of oil and natural gas in the Arctic region impact the state's sensitive tundra environment. Finally, over time, and with warming temperatures, Alaska's tundra can become an increasingly important source of carbon dioxide and methane -- greenhouse gases that contribute to accelerated climate warming. If the tundra become a source of greenhouse gases, this is an example of a positive feedback in the Earth system -- that means that warming will trigger release of stored gases that will contribute to more warming.
Warming in the Arctic tundra, projected to be the largest temperature change in our nation, also could be enhanced by the melting of vast expanses of ice and snow cover, which play a crucial role in reflecting solar radiation. This is of concern for two reasons: the exposed land will enhance absorption of heat (because dark earth absorbs more than white ice or snow) and loss of ice and snow cover allows plants increased exposure to harsh weather events and ultraviolet-B (UV-B) radiation. Exposure to UV-B radiation can trigger changes in plant chemistry that reduce the quality of plants for herbivores as well as affect the reproductive ability of the plants.
Present and potential environmental, social, and economic impacts are discussed below. Social and economic impacts, closely connected, are addressed jointly. Discussion concludes with strategies that might be helpful in addressing present and potential affects on Alaska's wildlife and subsistence economies.
Projected environmental affects of warmer temperatures include increased soil thawing depth and greater nutrient availability -- a set of impacts that bodes well for some tundra plants and the animals that depend on them and poorly for others. Second-order affects, such as changes in community structure and ecosystem interactions, also might occur, but whether these impacts would be positive or negative is difficult to predict and would need to be considered on a species-by-species basis.
Moreover, warmer temperatures can initiate chain reactions -- positive and negative -- that would affect several levels of nutrition available to wildlife. For example, warmer water could increase freshwater primary productivity, leading to more fishes for more birds to feed on. Yet, on Alaska's coast, warmer and fresher water could result in unpredictability and dilution of the spring blooms, resulting in less available food for waterfowl. Further, a rise in sea level could affect breeding locations by inundation.
As the examples above suggest, not all of Alaska's wildlife would be compromised by climate change. Indeed, all birds, migratory or seasonal, would likely benefit from warmer temperatures, even if only marginal increases occur. They would expend less energy to maintain a constant body temperature, resulting in better survival. Insects could respond well to ecosystem changes and proliferate, supporting insect-eating birds. Also, any lengthening of the ice- and snow-free season would contribute positively to the survival chances of waterfowl, such as loons, swans, and raptors.
However, the increased frequency of storm events that could accompany climate change could harm birds through physiological effects and loss of available food. Bird migration, breeding, and survival of the young depend on the orchestration of several well-timed events. The disruption of these events as a result of climate change could endanger the survival of some bird species.
Snow depth is an important factor for the survival of small mammals and caribou, with decreases in snow depth likely to jeopardize the overwintering and survival of at least the small mammals. Ice-coating, caused by freezing rain on snow surfaces and winter foliage not covered by snow, can affect the large mammals by the unavailability of forage, whereas small mammals are endangered by a build-up of carbon dioxide under the ice. Snow cover is also important in the distribution of lichens, an important food source for caribou. Should food sources for caribou be compromised, caribou range could spread to reindeer areas, increasing competition for food sources in those areas. Also, caribou calving is linked to vegetation produced during early snowmelt, and there is a concern that that relationship could be disrupted should the timing of the snowmelt change. For example, the immature flowers of the tussock-forming cotton grass are a nutrient-rich, critical food source for calving. In the warm spring of 1990, the cotton grass had already passed its most nutrient-rich state before the migratory porcupine caribou herd arrived for calving, raising serious concern for the short-term stability of the caribou herd specifically and for wildlife, in general, when coupling the food availability/animal exploitation process.
As discussed in impacts to Alaska's forests, warm, dry conditions in Alaska would favor the proliferation of insects. The harm insects present to forests has been discussed; should such damage occur, loss of forests would compromise the habitat for many of Alaska's wildlife species.
In the last three decades, conditions already have resulted in an increase in forest fires; a further increase in fires could lead to more early successional vegetation favored by moose, beavers, Arctic hares, sharptailed grouse, and other wildlife species. Fires also could limit the lichen supply in spruce forests, creating a shortage of winter food for caribou. Past tundra fires have occurred during periods of above-normal temperatures and below-normal precipitation, conditions that could increase during part of the year in Alaska. Further, tundra vegetation, particularly lichens, so important to the winter grazing of caribou and moose, are slow to recover after fires.
Wetland habitats will likely increase through extensive thawing of permafrost and ground subsidence. However, some Arctic tundra ponds and lakes are expected to lose water or completely dry up, which would result in the loss of established lake habitat. Of special concern is the deep-water, overwintering habitat that is critical to the survival of Arctic freshwater fish. Those habitats could be enhanced or lost -- it is not possible to determine which will occur at this time.
Many aspects of the climate change already occurring, and its consequences for forests, marine ecosystems, permafrost, and sea ice discussed above, are already causing multiple serious harms to subsistence livelihoods. Many populations of marine mammals, wildlife, and seabirds have been reduced or displaced. Reduced snow cover, a shorter river ice season, and thawing of permafrost all obstruct travel to harvest wild food. Declines in some fish stocks have harmed subsistence as well as commercial harvesters.
The most extreme effects of recent changes on subsistence livelihoods have been from changes in sea ice, which have obstructed hunting of marine mammals. The ice is further from shore, thinner, and present for less of the year. These factors, and the rougher seas encountered in the larger open-water areas between the shore and the ice, have made hunting more difficult, more dangerous, and less productive. Retreat of the ice is also likely to directly harm some species on which subsistence hunters rely, including bearded seals and walrus. Walrus are particularly at risk because they need ice strong enough to hold their weight over water shallow enough that they can reach the bottom to feed. Polar bears need sea ice to hunt seals, and recent ice reductions have been associated with their declining health and birth rate. Projected further large reductions in ice duration and extent could threaten polar bears with extinction.
Some subsistence harvests, such as salmon stocks near the northern end of their range, are likely to benefit from projected climate change. Still, most projected near-term climate changes are likely to intensify existing unfavorable impacts through further loss of sea ice, river ice, and permafrost. In addition, shifts in the composition of tundra vegetation could decrease nutrition available for caribou and reindeer, and invasion of tundra by boreal or mixed forest is likely to curtail the range of caribou and musk-ox. As changes in the cryosphere and both terrestrial and marine ecosystems continue, continuing large changes or displacements of the resources available for subsistence are likely, requiring subsistence communities to make major changes in their practices, or move.
Alaska's 117,000 rural residents are entitled to practice subsistence hunting and fishing on state, federal, and private lands and waters, while urban residents also qualify for subsistence activities on state and private lands. The subsistence harvest by rural residents is about 43 million pounds of food annually, or about 375 pounds per rural resident. The subsistence harvest is largest in the most remote communities, about 500 -- 800 pounds per person annually. Fish comprise 60% of total subsistence food, but there is substantial variation depending on the region: west coast communities rely predominantly on fish, interior ones on fish and land mammals, and northern communities principally on marine mammals.
The links between subsistence harvest and commercial activity are complex. If subsistence food were not available, communities would have to substitute purchased food. With an assumed cost of $3 -- 5 per pound of purchased food, a study of four rural communities with large wild food harvests (590 to 760 pounds per person) found that the cost of replacing the wild food harvest would be $1,800 to $3,800 per person, or 13% to 77% of community per capita income. Moreover, practicing subsistence requires cash income to buy the required equipment, such as guns, boats, and snowmobiles. In one surveyed community (Unalakleet in 1982), the cost of practicing subsistence was about $10,000, nearly half of the mean household income at the time. Consequently, particularly for fishing in coastal communities, the subsistence and commercial harvests can be closely linked: profits from the commercial catch could help pay for required subsistence equipment, and subsistence fish could also be taken during commercial fishing.
Reindeer ranching is an important economic pursuit for Alaskan natives on Seward Peninsula, where it is a cash- and food-producing activity. If climate change results in expansion of caribou range, that could compromise reindeer operations by cross-breeding or by forcing a large proportion of the reindeer herd, traditionally free-ranging, to seek food sources elsewhere. In addition, any significant expansion of forest into the region or productive tundra on Seward Peninsula would contribute negatively to reindeer populations by removing nutrient-rich food.
Tourism in the region is based on consumptive (hunting) and non-consumptive (wildlife viewing, hiking, and sightseeing) use of the land and its wildlife. Climate warming could extend Alaska's tourist season, which is at its peak between June and September.
Subsistence cultures have historically exhibited substantial adaptability to year-to-year fluctuations in abundance of different species by shifting practices and target species, which likely implies some ability to adapt to effects of near-term climate change. Subsistence practices are now both extensively regulated and hotly contested, however, posing challenges to traditional means of adaptation. Moreover, for many subsistence-dependent communities, particularly northern coastal communities that rely on hunting marine mammals, few adaptation options are likely to be available. Consequently, it is possible that projected climate change will overwhelm the available responses. Two options that do exist:
While it is likely that there are no real strategies that can be implemented to respond to large-scale climate impacts on wildlife and their habitats, there could be several strategies that could help in the short term to preserve and protect managed wildlife. They could include:
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