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Animals
Related Links
Arctic Climate Impact Assessment 
North Pacific Climate Regimes and Ecosystem Productivity (NPCREP) project (PDF, 2 pp., 141 KB, About PDF)
IPCC Working
Group II, Fourth Assessment Report, Chapter 5, Ecosystems, their Properties, Goods and Services, 2007 [PDF, 62 pp., 929 KB, About PDF]
Mammals | Invertebrates and Insects | Birds | Fish | Reptiles and Amphibians
Mammals
Mammals, with the notable exceptions of whales and dolphins, are primarily terrestrial (land-dwelling) animals that inhabit diverse areas of the Earth. Mammalian responses to rising temperatures and other climate changes are also diverse. Many small mammals are coming out of hibernation and breeding earlier in the year than they did several decades ago, while others are expanding their ranges to higher altitudes. Some show trends toward larger body sizes, probably due to increasing food availability and higher temperatures. On the other hand, reproductive success in polar bears has declined due to melting Arctic sea ice (IPCC, 2007).
In 2004, the Arctic Climate Impact Assessment (ACIA)
summarized some of the effects of warming temperatures on animals and their
habitats in polar regions, including parts of Alaska. Polar bears, seals,
migratory birds, caribou and reindeer are all experiencing changes that could
have dramatic effects on their species and the ecosystems they inhabit (ACIA,
2004).
For example, polar bears are dependent on sea ice to hunt seals and to move from one area to another. Polar bears are unlikely to survive as a species if there is an almost complete loss of summer sea-ice cover, which is projected to occur before the end of this century by some climate models. The seals that polar bears hunt are also unlikely to be able to adapt to an absence of summer sea ice, because they give birth to and nurse their pups on the ice and use it as a place for resting.
According to the ACIA, caribou and reindeer populations could decline because of their dependence on tundra for vegetation. As tundra vegetation zones continue to move northward with the changing climate, the caribou and reindeer could have a more difficult time finding food and raising their calves.
Invertebrates and Insects
Invertebrates represent 97 percent of all animal species. Though most invertebrates are very small, their influence on their surroundings can be enormous. Bees, moths, ants and other insects, for example, perform a critical role in the life of seed plants by transferring pollen. Insect pollination is particularly important for production of certain fruits, nuts and vegetables.
Climate change could have both positive and negative impacts on invertebrates and insects. Recent warming in Alaska, for example, has caused spruce budworms to reproduce further north. Spruce budworms are the most widely found and most destructive pests to coniferous (evergreen) trees in the western United States. The Kenai Peninsula in south-central Alaska experienced a massive outbreak of spruce bark beetles (another serious insect pest) in the 1990s, causing 10-20 percent mortality of trees (IPCC, 2007).
In addition, a range shift toward the poles (northward in the Northern Hemisphere)
or to higher elevations has occurred among many invertebrates that are
considered pests or disease organisms. According to the Arctic Climate
Impact Assessment , the spruce bark beetle increased its presence in unprecedented
numbers in the Kenai Peninsula in Alaska and the Yukon in Canada in the 1990s,
killing thousands of acres of trees over a period of less than a decade (ACIA,
2004).
Butterflies’ habitat ranges in North America have shifted northward and in elevation as temperatures increased. In some cases, such as the Edith’s Checkerspot Butterfly, local populations have become extinct in the southern portion of their range. (IPCC, 2007).
Birds
Birds
are an important part of many functioning ecosystems because of their roles
in seed dispersal, pollination, and as both predator and prey. Scientists
have observed that birds
are breeding and laying their eggs earlier and that migratory species have altered their wintering and/or critical stopover habitats. For example, warmer springs have led to earlier nesting for 28 migrating bird species on the east coast of the U.S. (IPCC, 2007).
The Arctic Climate Impact Assessment has
stated that the timing of bird arrival in the Arctic may no longer coincide
with the availability of their insect food sources (ACIA, 2004).
Important breeding and nesting areas are projected to decrease sharply as
trees shift their range northward, invading tundra areas. As sea level rises,
more tundra area, and thus more habitat for birds and their prey, will disappear.
This could eventually affect the success or failure of the breeding of several
hundred million birds that migrate to the Arctic each summer, which in turn
could determine the population sizes of birds at lower latitudes.
Just as the changing climate could impair the extent to which a bird’s life cycle is synchronized with its food supply, warming temperatures could affect other ecological processes that are also vital to ecosystem health. Pollination, seed dispersal, and pest control by birds are dependent on careful timing of bird arrival, atmospheric temperature and other climate-related factors, and therefore could be disrupted as the climate changes (IPCC, 2007).
Sea level rise can cause loss of wetlands in coastal areas, where some waterfowl spend the winter months. Sea level is rising along most of the U.S. coast, and around the world, and is projected to continue rising throughout this century. In locations where the wetlands cannot move inland due to topography or human development, these important habitats may be lost and the ecosystems in which they exist forever changed (IPCC, 2007).
Fish
Fishing
is highly valued in the U.S. as both a commercial enterprise and as a recreational
sport. According to the IPCC, certain fish
species are becoming less abundant worldwide.
Fish populations and other aquatic resources are likely to be affected
by warmer water temperatures, changes in seasonal flow regimes, total flows,
lake levels, and water quality. These changes will affect the health of
aquatic
ecosystems, with impacts on productivity, species diversity, and species
distribution (IPCC, 2007).
Stream habitats are projected to decline across the U.S. by 47 percent for coldwater, 50 percent for cool-water, and 14 percent for warm-water species. In the southern Great Plains, summer water temperatures already approach the limits for survival of many native stream fish (IPCC, 2002). An 8°F increase in average annual air temperature is projected to eliminate more than 50 percent of the habitat of brook trout in the southern Appalachian Mountains. The Northern pike, which spawn in flooded meadows in early spring and whose young remain in the meadows for about 20 days after hatching, would be especially affected by low spring water levels. Higher winter temperatures have been observed to decrease the survival rate of the eggs of yellow perch (a coldwater species). On the other hand, one study found that higher winter temperatures (by 2ºC) were beneficial for rainbow trout. However, the same temperature increase in summer caused negative effects (IPCC, 2007).
Changes in the geographic distribution of ocean fish stocks have been linked to climate-ocean system variations such as the El Niño events. Fluctuations in fish abundance increasingly are regarded as a biological response to climate-ocean variations, and not just as a result of over-fishing and other human factors. Climate change can compound the impact of natural variation and fishing activity and make marine life management more complex. For example, scientists have observed that elevated temperatures have increased mortality of winter flounder eggs and larvae and lead to later spawning migrations. As oceans warm, tuna populations are predicted to spread toward currently temperate regions (IPCC, 2007).
Currently, NOAA is conducting the North Pacific Climate Regimes and Ecosystem Productivity (NPCREP) (PDF, 2 pp., 141 KB, About PDF) project in the eastern Bering Sea and the Gulf of Alaska. This geographic region was selected for initial climate and ecosystems studies due to its importance for living marine resources (Alaskan fisheries account for approximately 50 percent of the US commercial fishery landings), model predictions that climate change will be most severe at high latitudes, and many indications that environmental conditions are already changing in these regions.
Reptiles and Amphibians
The ability of reptiles and amphibians to adapt to changes in climate depends in part on their ability to move to more suitable habitat. A European study found that most reptile and amphibian species could expand their ranges in a warmer climate if dispersal were unlimited, but if they were unable to disperse then the ranges of nearly all species (more than 97 percent) would become smaller (IPCC, 2007).
In the mountainous cloud forests of Costa Rica, the base of the clouds has been climbing in altitude as the climate warms. Researchers have found a strong connection between declines in the frequency of mist days and declines in amphibian populations (IPCC, 2007).
Impacts of climate change on coral reefs and mangroves may affect sea turtles and crocodiles. Increases in the severity of tropical storms could also affect sea turtle populations. Hurricane Emily in 2005 destroyed 1,500 sea turtle nests along the Mexican coast (IPCC, 2007).
In North America, many amphibians, such as some species of frogs and salamanders, lay their eggs in temporary pools that form in early spring after snowmelt. If a warmer climate causes ponds to dry earlier in the season, amphibian populations could suffer (IPCC, 2007).
References
- Arctic Climate Impact Assessment (ACIA), 2004: Impacts of a Warming Arctic:
Arctic Climate Impact Assessment . Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA, 144 pp.
- IPCC, 2007: Climate Change 2007: Impacts, Adaptation, and Vulnerability . Contribution of Working Group II to the Third Assessment Report of the
Intergovernmental Panel on Climate Change [Parry, Martin L., Canziani, Osvaldo F., Palutikof, Jean P., van der Linden, Paul J., and Hanson, Clair E. (eds.)]. Cambridge University Press, Cambridge, United Kingdom, 1000 pp.
- IPCC, 2002: Climate Change and Biodiversity (PDF, 86 pp., 1008 KB, About
PDF) [Gitay, Habiba, Suarez, Avelino, Watson, Robert T., and Dokken, David Jon, eds.]