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 vulnerability.
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.
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