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5.4.3. Responses of Wildlife and Impacts on Goods and Services
Findings indicate that many animals already may be responding to local climatic
changes. Types of changes already observed include poleward and elevational
movement of ranges, changes in animal abundance, changes in body size, and shifts
in the timing of events such as breeding to earlier in the spring. These responses
have been identified by a group of studies from around the world in a variety
of different species (see Table 5-3). Far more information
is available than can be summarized here. More detail on these changes is available
in Hughes (2000) and Price et al. (2000).
5.4.3.1. Changes Exhibited by Animals
Results from most studies that use large-scale data sets provide circumstantial
(e.g., correlational) evidence about the association between changes in climate-related
environmental factors and animal numbers or activities. Circumstantial evidence,
though insufficient by itself, is highly suggestive when multiple studies examining
a myriad of different species on all continents find similar results. Combined
with smaller scale studies, experimental studies, and modeling studies that
examine mechanistic connections between animals and climate change, the weight
of evidence becomes even stronger. Such is the case for wildlife already exhibiting
change related to climate forcings (see Table 5-3).
The information given in the following subsections is a sampling of the types
of studies that have examined the potential impacts of climate change on animals.
The studies were selected for taxonomic and geographic inclusiveness and are
not inclusive of the breadth of range of published studies. Information on more
studies can be found in Table 5-3 and in Price et
al. (2000).
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Box 5-6. Penguins as Indicators of Climate Warming
in Western Antarctic
Midwinter surface air temperatures in the Western Antarctic Peninsula
(WAP) region have increased by 4-5°C over the past 50 years (Smith
et al., 1996b). Studies confirm that the spatial and temporal patterns
of winter sea-ice development in the WAP have changed during this time
in response to rapid warming (Fraser et al., 1992; de la Mare, 1997; Jacobs
and Comiso, 1997; Loeb et al., 1997). Chinstrap (Pygoscelis antarctica)
and Adélie (P. adeliae) penguin populations also have changed during
the past 25 years.
Although these two species are ecologically very similar, with diets
and breeding ranges that overlap in the WAP (Volkman et al., 1980), their
winter habitat preferences are radically different. Adélies are
obligate inhabitants of the pack ice, whereas Chinstraps are ice-intolerant,
preferring to remain in close association with open water (Fraser et al.,
1992; Ainley et al., 1994). The quality and availability of winter habitat
is an essential determinant of survival and therefore a key factor regulating
seabird populations (Birkhead and Furness, 1984). Adélie penguins
have decreased by 22% whereas Chinstrap penguins have increased by more
than 400% over the past 25 years (Fraser and Patterson, 1997; Smith et
al., 1999). This pattern supports the hypothesis that the increasing availability
of open water as a result of warmer winters is favoring the survival of
Chinstraps over the ice-dependent Adélies (see Fraser et al., 1992).
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