4.3.3. Food and Fiber Production
Summary: Significant impacts on agriculture are likely, including crop and
pasture performance increases from CO2 rises; mixed effects of temperature rises;
changes in soil fertility; changes in quality of grain and pasture nutrition;
shifts in the suitability of districts for particular crops, such as kiwifruit;
and possibly increased problems with weeds, pests, and diseases.
Impacts will vary widely from district to district, crop to crop, and decade
to decade. Grain crops may gain in the first few decades because of the immediate
beneficial effect of higher CO2, but that advantage may be eroded as the delayed
rise in temperature becomes greater and reduces the grain-filling period. In
Australia's warm low latitudes, some crops are near their maximum temperature
tolerance and are likely to suffer increasingly as the temperature increases.
The possibility of overall decreased rainfall in Australia would negatively
affect rangeland pastoralism and irrigated agriculture (which is a major source
of production). Any changes in global production, and hence international food
commodity prices, would have major economic impacts.
Farming in the region is well adapted to dealing with variability and change
through a variety of natural and market factors-for example, by means of plant
breeding, diversification, seasonal climate prediction, and so forth. Such techniques
are likely to be sufficient to adapt to climate change over the next few decades;
in some cases these techniques may facilitate expanded production. As the time
horizon extends, however, the changing climate is likely to become less favorable
to agricultural production in Australia, leading to a long-term increase in
Production forestry will be affected by changes in tree productivity; forest
operational conditions; and pests, weeds, disease, and wildfire incidence. The
net impact is not clear. The longer time to reach maturity results in a relatively
large exposure to financial loss from extreme events, fire, or any rapid change
in climate conditions.
A number of climate sensitivities have been identified for fisheries, but
the impacts cannot be predicted with any confidence. It appears that freshwater
and near-shore fisheries will be more affected than open-ocean fisheries. The
principal adaptation option is scientifically based integrated fisheries management
and coastal zone management.