12.1. The Australasian Region
Australasia is defined here as Australia, New Zealand, and their outlying tropical
and mid-latitude islands. Australia is a large, relatively flat continent reaching
from the tropics to mid-latitudes, with relatively nutrient-poor soils, a very
arid interior, and rainfall that varies substantially on seasonal, annual, and
decadal time scales, whereas New Zealand is much smaller, mountainous, and mostly
well-watered. The ecosystems of both countries contain a large proportion of
endemic species, reflecting their long evolutionary history and isolation from
other land masses. They have been subject to significant human influences, before
and after European settlement 200 years ago.
The region's climate is strongly influenced by the surrounding oceans.
Key climatic features include tropical cyclones and monsoons in northern Australia;
migratory mid-latitude storm systems in the south, including New Zealand; and
the ENSO phenomenon, which causes floods and prolonged droughts, especially
in eastern Australia.
The total land area is 8 million km2, and the population is approximately
22 million. Much of the region is very sparsely populated; most people (85%)
live in a relatively small number of coastal cities and towns. Both countries
have significant populations of indigenous peoples who generally have lower
economic and health status. The two countries have developed economies and are
members of the Organisation for Economic Cooperation and Development (OECD);
unlike other OECD countries, however, their export trade is dominated by commodity-based
industries of agriculture and mining.
12.1.2. Previous Work
The Australasian chapter (Basher et al., 1998) of the IPCC Special Report
on Regional Impacts of Climate Change (RICC) (IPCC, 1998) provides an extensive
assessment of likely climate change impacts and adaptation options for Australia
and New Zealand, based on work published until early 1998. That report concludes
that Australia's relatively low latitude makes it particularly vulnerable
through impacts on its scarce water resources and crops that presently are growing
near or above their optimum temperatures, whereas New Zealanda cooler,
wetter, mid-latitude countrymay gain some benefit from the ready availability
of suitable crops and a likely increase in agricultural production with regional
warming. Nevertheless, a wide range of situations in which vulnerability was
thought to be moderate to high were identified for both countriesparticularly
for ecosystems, hydrology, coastal zones, settlements and industry, and health.
Indirect local impacts from possible climatically driven changes in international
conditionsnotably commodity prices and international tradealso was
identified as a major issue in the 1998 report, as well as by the New Zealand
Climate Change Programme (1990). Key points from Basher et al. (1998) follow.
Climate and Climate Trends: Climate trends were reported to be consistent
with those in other parts of the world, with mean temperature increases of as
much as 0.1°C per decade over the past century, a faster increase in nighttime
than daytime temperatures, and sea level rising an average of about 20 mm per
decade over the past 50 years. Increases in average rainfall and the frequency
of heavy rainfalls were reported for large areas of Australia.
Climate Scenarios: Australian scenarios reported for 2030 exhibited
temperature increases of 0.3-1.4°C, uncertain overall rainfall decrease
of as much as 10%, and more high-intensity rainfall events. Projected changes
for 2070 were about twice the 2030 changes. New Zealand projections included
similar temperature increases, as well as stronger westerly air flow, with resulting
precipitation increases in the west and decreases in the east.
Water Supply and Hydrology: Possible overall reduction in runoff, with
changes in soil moisture and runoff varying considerably from place to place
but reaching as much as ±20%, was suggested for parts of Australia by
2030. Sharpened competition was expected among water users, with the large Murray-Darling
Basin river system facing strong constraints. Enhanced groundwater recharge
and dam-filling events were expected from more frequent high-rainfall events,
which also were expected to increase flooding, landslides, and erosion. A reduced
snow season was expected to decrease the viability of the ski industry, although
it would provide seasonally smoother hydroelectricity generation in New Zealand.
Ecosystems and Conservation: Significant potential impacts identified
on Australasian land-based ecosystems included alteration in soil characteristics,
water and nutrient cycling, plant productivity, species interactions, and ecosystem
composition and function, exacerbated by any increases in fire occurrence and
insect outbreaks. Aquatic systems would be affected by changes in runoff, river
flow, and associated transport of nutrients, wastes, and sediments. These changes
and sea-level rise would affect estuaries and mangroves. Australia's coral
reefs were considered to be vulnerable to temperature-induced bleaching and
possibly to sea-level rise and weather change.
Food and Fiber: Direct impacts on agriculture from CO2 increases
and climate changes were expected to vary widely in space and time, with perhaps
beneficial effects early in the 21st century, followed by more detrimental effects
in parts of Australia as warming increases. Any changes in global production
and hence international food commodity prices would have major economic impacts.
The net impact on production forestry from changes in tree productivity, forest
operational conditions, weeds, disease, and wildfire incidence was not clear.
The impact on fisheries could not be confidently predicted.
Settlements and Industry: Possible changes were noted in the frequency
and magnitude of climatic "natural disaster" events affecting economically
important infrastructure. Likely impacts of climate change were identified on
water and air quality, water supply and drainage, waste disposal, energy production,
transport operations, insurance, and tourism.
Human Health: Increases were expected in heat-stress mortality (particularly
in Australia), the incidence of tropical vector-borne diseases such as dengue,
and urban pollution-related respiratory problems.
Adaptation Potential and Vulnerability: Some of the region's ecosystems
were identified as very vulnerable, with fragmentation and alteration of landscape
by urban and agricultural development limiting natural adaptability. Land-use
management was the primary adaptation option identified. Although coral reefs
were identified as vulnerable, it was suggested that they might be able to keep
pace with sea-level rise.
Techniques that already provide considerable adaptability of agriculture to
existing climate variability may apply to climate change over the next few decades.
However, at longer time horizons the climate was expected to become less favorable
to agricultural production in Australia, leading to increased vulnerability.
Scientifically based integrated fisheries and coastal zone management were regarded
as principal adaptation options for fisheries.
Adaptation options identified for settlements and infrastructure included integrated
catchment management, changes to water pricing systems, water efficiency initiatives,
building or modifying engineering structures, relocation of buildings, and urban
planning and management. Low-lying coastal settlements were regarded as highly
vulnerable to high sea level and storm events. Adaptation options included integrated
coastal zone management (ICZM); redesign, rebuilding, or relocation of capital
assets; and protection of beaches and dunes. New Zealand is exposed to impacts
on its Pacific island territories, including the eventual possibility of having
to accept environmental refugees.
A moderate degree of vulnerability was identified for human health, with adaptation
responses including strengthening existing public health infrastructure and
meeting the needs of vulnerable groups such as isolated communities and the