4.3.1.6. Adaptation and Vulnerability
Adaptations to climate change may be categorized as either "autonomous" adaptations-where
biota and ecosystems respond and change of their own accord-or "planned" or
"conscious" adaptations, undertaken by humans. The primary option for conscious
adaptation measures in respect to near-natural ecosystems is land-use management.
This includes modification of land clearing, forestry practices, fire management,
rangeland animal stocking rates, pest animal management, control of herbaceous
and woody weeds, development of corridors for species migration, resting and
rehabilitating degraded areas, and the consideration of climate change in management
plans for urban, coastal, catchment, and other zones. Implementation of riparian
(riverside) management practices and selective planting of upslope source areas
would mitigate many of the adverse impacts of land development and hydrological
changes on water quality and habitat values of streams, rivers, and ultimately
lake and estuarine habitats. Active manipulation of species generally will not
be feasible in the region's extensive, lightly managed, natural ecosystems,
though in some circumstances-such as for endangered or commercially important
species-relocation to new and more suitable habitats may be desirable and feasible.
Continued research on natural ecosystems also is a necessary, integral part
of adaptation responses. In many instances, our knowledge is insufficient to
provide the guidance sought by managers and policymakers. Routine climatic,
environmental, and ecological monitoring and prediction also are necessary.
In summary, it must be concluded that some of the region's species and ecosystems
are rather vulnerable to climate change because of the likely continued increase
of greenhouse gases; the likely rate of climate change; the fundamental nature
of likely changes to biota and ecosystems; the large proportion of Australasia
affected; the ecological isolation and fragmentation of ecosystems of the region;
existing environmental stresses; and the limited available options for conscious
adaptation.
4.3.2. Hydrology and Water Resources
Summary: The four hydrological situations of most concern to the region
are drought-prone areas, flood-prone urban areas, low-lying islands, and alpine
snowfields. Model simulations suggest changes of as much as ±20% in soil moisture
and runoff in Australia by 2030, with considerable variation from place to place
and season to season and with the possibility of an overall reduction in average
runoff. Water shortages would sharpen competition among various uses of water,
especially where large diversions are made for economic purposes. One study
shows Australia's major Murray-Darling River system facing constraints on existing
irrigation uses and/or harm to the riverine environment. More frequent high-rainfall
events would enhance groundwater recharge and dam-filling events but also would
increase the impacts of flooding, landslides, and erosion. A preliminary study
for an urban area near Sydney showed a tenfold increase in the potential damage
of the "100-year" flood under a doubled CO2 scenario. Water supplies on atolls
and low-lying islands are vulnerable to saltwater intrusion of groundwater from
rising sea levels and to possible rainfall reductions. Reduced snow amounts
and a shorter snow season appear likely and would decrease the amenity value
of the mountains and the viability of the ski industry. The glaciers of New
Zealand's Southern Alps are likely to shrink further.
Adaptation options include integrated catchment management, changes to water
pricing systems, water efficiency initiatives, building or rebuilding engineering
structures, relocation of buildings, urban planning and management, and improved
water supply measures in remote areas and low-lying islands. The financial exposure,
and cost involved in potential adaptations, indicate a high vulnerability with
respect to hydrology.
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