单项选择题

Coping with Climate Change What we have learned so far about how climate changes is affecting our global environment. Studies show that it adversely affects human and natural systems by reducing biodiversity, impairing biological and chemical cycles and making it more difficult to restore degraded ecosystems. Climate is not the only factor in the deterioration of natural systems. We are making big changes to the landscape, altering land use and land cover in major ways. These changes combined present a challenge to environmental management. Adaptive management is a scientific approach to managing the adverse impacts of climate and landscape change. Nature and Impacts of Climate Change Every week it seems there is an article about global warming in the news media. It may be difficult for some to grasp the big picture of the issue, but in general, climate change has already or is expected to --increase temperatures, particularly in the interior of continents, toward the poles and in winter --boost precipitation (降水量) in wetter areas and suppress precipitation in drier areas --increase rain and decrease snow --lessen peak spring runoff and cause more even year-round flows of water, thereby reducing water availability during summer irrigation and navigation seasons --increase evaporation of water during the summer --enhance the likelihood of lower mean lake levels, drier wetlands, and water shortages, particularly in mountain regions --raise the frequency and magnitude of extreme weather events, such as hurricanes, tornadoes, and floods --raise global sea levels, causing some populated coastal areas to become inundated (被淹没的) --reduce the extent and duration of Arctic sea ice with adverse consequences for marine mammals --increase the loss of glaciers in middle and equatorial latitudes, including premier mountain ecosystems such as Glacier National Park in Montana Global average temperature has increased by about 0.6℃ over the past 100 years, with a major warming upswing in the 1970s. Warming is the result, in part, of rapid increases in emissions of greenhouse gases (GHG), particularly carbon dioxide (CO2), which is a byproduct of the combustion of fossil fuels, such as coal, oil, and natural gas, used for power generation and transportation. When global temperatures rise and precipitation patterns change, it is expected there will be consequences on ecosystems, such as an increase in the spread of exotic species; redistribution of plants, animals, energy, water, and nutrients; alteration of natural processes and the structure and function of ecosystems. Northerly latitudes are particularly vulnerable to climate change. The Arctic Council, an intergovernmental forum for Arctic nations and indigenous people, reported that the northern ice cap is warming at twice the global rate and the Arctic region is expected to warm at two to three times the rate for the rest of the world. Arctic warming will have serious consequences on human and ecology. Nature and Impacts of Landscape Change Landscape change results from natural disturbances and human activities. Natural disturbances include fire, windstorms, avalanches, landslides, tree fall, floods, and insect epidemics. Human activities causing landscape change include conversion of forestland to agriculture, drainage of wetlands, and forest fragmentation from road construction and timber harvesting. Human activities often have a more significant effect on landscapes than natural disturbances because they alter the availability of energy, water, and nutrients to ecosystems; increase the spread of exotic species; accelerate natural processes of ecosystem change; and adversely affect the structure and functioning of ecosystems. Human-induced landscape change has accelerated during the past several decades because of rapid population and economic growth, particularly in countries such as China, India, and Brazil. Landscape change has contributed to a dramatic 1,000-fold increase in species extinction over the past 400 years. On a global basis, nearly 1.2 million km2 of forest and woodland and 5.6 million km2 of grassland and pastureland have been converted to other uses. During the last three centuries, 12 million km2 of cropland were lost. Between 1982 and 1997, 121,000 km2 of non-federal land were urbanized in the United States. More than 90 percent of the land in the lower 48 states has been logged, plowed, mined, grazed, paved, or otherwise modified from previous conditions. Human-induced landscape change significantly affects wildlife. For example, between 1970 and 2000, rural residential development in the Montana and Wyoming portions of the Greater Yellowstone Ecosystem increased 400 percent. Consequently, current and potential grizzly bear habitat on private lands in the ecosystem has been degraded and fragmented. Double-digit growth in residential subdivisions adjacent to the National Elk Refuge in Jackson, Wyoming, has diminished winter range for the 10,000 elk that use the refuge and displaced corridors that elk use to reach summer range in Yellowstone and Grand Teton National Parks. Another example of significant impacts from landscape change is the Crown of the Continent Ecosystem. This ecosystem covers the Rocky Mountains in British Columbia and Alberta, Canada, and western Montana, United States. Here are some specifics: --Most old-growth forests that once existed outside of protected parks and wilderness areas have been harvested. --Many rivers in the region have been altered by hydroelectric power development. --Significant farm, ranch, and forest acreage has been converted to homes and commercial developments. --Lakes and streams have been polluted by agricultural and urban runoff. --Fish and wildlife habitats have been degraded. --Active and proposed energy developments threaten protected areas. --Large areas have been invaded by nonnative species. The desire to preserve the outstanding wildlife (especially large carnivores) and environmental amenities (舒适|) from the negative effects of rapid economic growth and development in the northern Rocky Mountain region prompted creation of the Yellowstone to Yukon Conservation Initiative. The initiative involves 300 conservation organizations and covers an area larger than the states of California and Texas combined, including the Greater Yellowstone and Crown of the Continent Ecosystems. Coping with Climate and Landscape Change Although climate and landscape change has positive effects on human and natural systems, it is expected to have many adverse impacts that deserve attention. Ecosystems have an inherent capacity to resist climate and landscape change, known as ecological resilience (复原能) When this capacity is exceeded, the ecosystem can change in ways that may not be socially and ecologically acceptable. So what can be done Mitigation strategies can reduce ecosystem vulnerability. Mitigation strategies are actions to prevent, reduce, or slow climate and/or landscape change. The Kyoto Protocol to the United Nations Framework Convention on Climate Change, which took effect in February 2005, is a prime example of a climate change mitigation strategy. The protocol commits 36 industrialized countries to curb GHG emissions, especially CO2. Limiting increases in global temperature by 2℃ would require keeping atmospheric concentrations of CO2 below 400 parts per million (ppm). Current concentrations are about 375 ppm. Benefits of the Kyoto Protocol may be limited because it does not include some developed countries, which emit substantial GHGs, and developing countries where rapid population and economic growth is expected to dramatically increase GHG emissions. Other mitigation strategies include increasing the use of alternative energy sources and technologies (clean coal, renewable energy, ethanol, hybrid vehicles, and nuclear power). Although the United States did not sign the Kyoto Protocol, 28 states have programs to curb CO2 emissions, and at least 166 U.S. cities have agreed to apply the Kyoto emission reduction standards to their communities. Other initiatives, like the Apollo Alliance, bring together labor unions, environmental and business groups, and activist organizations with the mission of sharply reducing U.S. dependence on fossil fuels. The alliance is seeking ways to do the following: --power the economy with hydrogen produced from renewable energy resources --implement green construction codes --revitalize urban centers to reduce urban sprawl --determine how industry can store rather than emit carbon into the atmosphere The Apollo Alliance expects to invest $300 billion in new energy technologies and energy conservation over 10 years as a way to eliminate U.S. dependence on foreign oil and create millions of good-paying jobs. These funds would be raised using tax incentives, public bonds, capital strategies, and other mechanisms. The Arctic is warming faster than the rest of the world.