Our Natural Resources at a Glance - Climate
- Australia is a dry continent where rainfall is unreliable compared with Europe and North America.
- Recurring droughts and floods are a natural feature of the landscape.
- The Australian continent has a number of distinct climatic zones, broadly: the summer dominant tropics and sub tropics to the north; the Mediterranean climates to the south; the arid and semi arid regions in the middle of the continent; and areas of high rainfall on coastal fringes and in the ranges of the east of Australia.
- Agricultural land use is heavily influenced by this climatic regime. Generally, the tropical north is suited to grazing (principally cattle) as well as the production of fruit and sugarcane.
- The major land uses in the sub-tropical and Mediterranean climates in the south are cereal cropping as well as sheep and cattle grazing.
- The Murray-Darling Basin in the south-east of the continent has a large irrigation infrastructure, supporting the production of fruit, vegetables, rice and many other intensive agricultural activities.
- Agriculture in the arid zone involves extensive grazing, where sheep and cattle are reared at relatively low densities of less than one sheep per 10ha.
- The higher rainfall zones are suitable for dairying, as well as more intensive grazing enterprises that produce meat.
Seasonal rainfall zones
- Australia’s diverse climatic regime creates many opportunities and risks for agriculture. Producers are always planning to avoid losses by protecting themselves against drought, as well as capitalising on good years.
- Recurring drought means that downturns in agricultural production occur from time to time, resulting in loss of crops, downsizing of the national sheep flock and cattle herd and reduced water allocations for irrigators.
- The high levels of production in good years provide commodities for both the domestic and international markets.
- Extreme climatic events are an inherent risk of agricultural production in Australia.
- Historical climatic records are now sufficiently reliable to profile climate variability over the whole of Australia with a degree of confidence.
- This information may be used to plan and manage agricultural production systems according to the nature of the variability in any region. The extent to which it is possible to mitigate the effects of extreme climatic variations, in particular drought, depends to a large extent on their predictability.
- In the long term, knowing the extent of climatic variability allows a rational approach to risk management.
The 2002–03 drought
- There is a relationship between sea surface temperature in the Pacific and Indian Oceans and climate effects in some parts of Australia. Awareness of this allows more active management of agricultural systems.
- Predictions may give useful guidance up to nine months in advance, but only for certain parts of Australia and depending on the time of year. Elsewhere, current predictive schemes are no better than chance.
- Irrigated agriculture activities can face considerable risks from climate variability. Irrigated producers may actually face a higher risk of ‘exposure’ to failure in drought than some dryland producers, who have a number of production options available to them.
- Appropriate frameworks to manage water in the future may become crucial if long-term climate change results in more frequent and/or severe droughts.
Index of reliability of long term annual rainfall
- Climate change projections for Australia are consistent with the trends identified in global level studies.
- Based on modelling by the CSIRO, surface average annual air temperatures are expected to rise between 0.8 to 1.4oC by 2030, with rainfall shifting by ± 10% over the same period. It is expected that these trends will double by 2070.
- Predicting the likely effects of climate change is complicated because increased carbon dioxide boosts plant growth and changes water use efficiency, while projected changes in climate can offset or enhance these benefits.
- Ecosystems that are particularly vulnerable to climate change include coral reefs, arid and semi-arid habitats in southwest and inland Australia and Australian alpine systems.
- Human systems vulnerable to climate change include agricultural production, particularly in southwest Western Australia, Victoria and the alps, water supply, settlements and infrastructure in regions exposed to cyclones, floods and storm surges and areas subject to spread of disease vectors.
- The opportunities to adapt to climate change via new crops, industries and management practices will vary by region.
- Potential negative effects include: reduced wheat production from reduced rainfall reliability, increasing suitability ranges for diseases and pests, reduced milk yield due to heat stress in dairy cattle, increased irrigation requirements for the sugar industry, and reduced fruit yield and quality through a reduction in chilling temperatures in some cases.
- Potential positive effects include: increased plant production in northern Australia and reduced incidence of frost damage in southern Australian fruit crops.
- Water resource use is likely to be the key natural resource management issue directly influenced by climate change.
Rainfall change predictions
Comparison of 9 models predicting winter (April to October)
rainfall in 2050 compared to the 30 year mean from 1960-90
Climate variability: www.bom.gov.au
Climate change: www.csiro.gov.au
Climate change: www.ago.gov.au
...At a Glance
Australia - Our Natural Resources | Foreword | Overview | Water | Climate | Soils | Land Use | Vegetation | Social | Biodiversity | Pests | Government Initiatives | Data and Information sources | Acknowledgements