Climate change presents a great threat to agriculture in Western Australia. Industries reliant on natural resources will be the first to suffer the adverse impacts of a rapidly warming world.

Humans are producing unsustainable levels of greenhouse gas emissions from the burning of fossil fuels (like oil and coal) and the clearing of land. This is leading to an unnatural build up of these gases in the atmosphere, and a rapid warming of the earth, that is disrupting our climate system Unless action is taken to dramatically reduce greenhouse gas emissions, there could be a global average temperature increase of up to 5.8 oC.
(Intergovernmental Panel on Climate Change 2001)

The CSIRO’s recent predictions for temperature increases are set out in the map below. One study predicts warming for southern Western Australia by 2050 to be 1.3-3.2 oC (Allan & Hunt 1999). This apparently small increase in the average can have a big impact on seasons and climatic conditions.

This warming over next 50 years will result in:

• a decrease in available water resources;
• higher temperatures;
• a reduction of area of arable land;
• a reduction in crop and livestock quality and output

While there may be some benefits for some crops, the overall impact of climate change will be negative.

Australia’s relatively low latitude makes it particularly vulnerable through impacts on its scarce water resources and on crops presently growing near or above their optimum temperatures. (Basher and Pittock 1998)

One message is clear, climate change will fundamentally change agricultural production in Western Australia.

Rural communities, businesses and their representatives must assess the strength of current planning and policies dealing with climate change and agriculture. To do so, the causes and effects of climate change need to be fully understood throughout the community in terms of economic, social and landscape change.

The summary presented in this report intends to give an indication of the impacts of climate change on agriculture in Western Australia, based on published scientific studies.

Ranges of average annual warming (C) for around 2030 and 2070 relative to 1990. Shaded bars show changes for areas with corresponding shades in the map.

Continued at top of page 2 --->

Climate change and temperature
By 2030, temperatures in Western Australia will be 0.4-2 oC higher than they were in 1990. If greenhouse gas emissions continue to increase, the higher temperature estimate is more likely to occur. By 2070, temperatures
in Western Australia will be 1.0-6.8 oC higher (again depending on what happens with greenhouse gas emissions in the coming decades). If emissions continue
to increase, farmers in WA will be facing extreme temperature increases at the upper end of the scale of the predictions.

Competition for an already over-allocated water supply will increase the price of agricultural production and place further stress on rivers and ground water systems supporting arable lands.

Climate change, soils and water
Climate change will decrease the area of arable lands currently used for agricultural production in Western Australia.

It is expected that a decline in soil moisture content will result from higher evaporation rates due to the increases in surface temperature, coupled with lower rainfall. This
will have detrimental impacts for agriculture and water supplies in Western Australia.
(Allan & Hunt 1999)

The mean increases in drainage of 6-27mm/year represent a substantial potential change in landscape hydrology, which is likely to increase risks of salinisation in areas not yet affected, and increase rates of salinisation in areas already affected.
(Howden 1999b)

The CSIRO predicts average decreases in annual water balance from lower rainfall and increased evaporation rates. By 2030, there may be decreases in moisture balance of up to 160mm, and up to 500mm by 2070, leading to greater moisture stress for Australia.
(CSIRO 2001)

Climate change and water
Water is predicted to become scarcer because crucial winter rainfall is likely to decrease. Competition for an already over-allocated water supply will increase the
price of agricultural production and place further stress on rivers and ground water systems supporting arable lands.

By 2100 it is predicted, in most climate change models, that winter-spring rainfall will decrease between 10-30%
(Allan & Hunt 1999). However, recent studies by CSIRO suggest that there could be a 20% drop in annual rainfall over the southwest by 2030, and a 60% drop by 2070.
(CSIRO 2001)

Impacts on agricultural sectors

Beef cattle
The frequency of heat stress in Australian beef cattle increased by 40% from 1957 to 1996, and is estimated to increase by a further 138% by the year 2050 because of climate change.
(Howden 1999a)

Howden (1999a) predicts that an initial increase in temperature and atmospheric CO2 will increase pasture growth, live-weight gains and improved financial outcomes on the rangelands. However, increases in heat stress, water consumption, possible changes in grass distributions, and increased soil water logging and salinity, especially in marginal grazing lands, will offset the initial advantage.
(Howden 1999a)

Continued start of page 3, below on left.

Wheat
The overall impact of climate change on wheat yields is likely to be negative. Increases in temperature, and reduction in rainfall, will outweigh the benefit of increased CO2 levels. Wheat yields are expected to decrease with warming beyond 2 oC, and with the expected reduction in rainfall as CO2 increases (Howden 1999b). Also, the predicted increase in CO2 levels is expected to reduce grain protein (or nitrogen) by 4-14%. These changes are likely to be significant in downgrading grain quality, representing a reduction in one to two quality classes.
(Howden 1999b)

Orchards and vineyards
Vineyard and orchard enterprises that need chilling to produce a quality product may find adaptation to higher temperatures difficult. There are land constraints in moving operations further south or to higher areas in Western Australia.
(Whetton et al. 2000)

Farm forestry
Forestry production will be affected by changes in carbon dioxide levels, temperature and rainfall. If carbon dioxide levels increased, but there was no impact on rainfall, tree growth would increase. However, a dramatic reduction in rainfall in Western Australia, combined with a likely increase in fire frequency, would offset any benefits.
(CSIRO 2001)

What can be done?
The vulnerability of Western Australia's agriculture will be determined by community, individual and institutional readiness to help avoid climate change, and to adapt to it.

The speed and magnitude of global warming mean that rural communities have to consider a mix of mitigation and adaptation strategies. A strong government policy to
minimise the threat to rural communities and reduce greenhouse gas emissions is urgently needed. Such a policy must include commitments to the following.

Reducing Australia's greenhouse gas emissions from industrial sources

A dramatic reduction in emissions is required on a local and global level to protect agriculture from the worst impacts of climate change. In addition, government
must be lobbied to invest further in the transition to sustainable transport fuels, sustainable electricity generation (solar and wind), and energy efficient machinery and technology.

Scenarios predicting a high level of climate change suggest that wheat cropping would become unviable in Western Australia. (Basher and Pittock 1998)

Including the effects of climate change in all future planning decisions for rural Western Australia

Every policy and planning decision made for natural resources and agricultural planning must seek to reduce the effects of climate change on rural communities.

Increasing funding for research into climate change impacts and mitigation strategies

CSIRO have produced world-class research into the effects of climate change and abatement strategies (such as methods to reduce methane emissions from livestock), however, there is currently very little government-funded research into the impacts of climate change on Western Australia's rural communities.

Rejuvenating river systems

Healthy rivers will be more resistant to the effects of climate change. Water allocations must be planned, especially in irrigation districts, to mitigate the effects of climate change. Environmental flow allocation must be protected to ensure continuing water quality and river health in the future.

Continued at top of page 4 --->

Expanding native vegetation regeneration, and halting land-clearing rates

Current best practice mitigation for salinisation is the reintroduction of native, stabilising ecosystems. A strongly funded and enacted native vegetation strategy to combat salinisation is needed to reduce the vulnerability of salinity-affected farmers in the future. Halting land-clearing rates will also lead to a decrease in greenhouse gas emissions.

For more information Contact:
Conservation Council of Western Australia
(08) 9420 7200

Climate Action Network Australia

Join the Farming and Climate Change network by logging on to: www.cana.net.au/farmer/

Produced with assistance from the Myer Foundation.

References
Allan, R., and Hunt, B. 1999, Climate Change Modelling for the Southern Region of Western Australia, CSIRO Atmospheric Research. Shanghai Draft 21/1/2001, Summary for Policy Makers, IPCC, Shanghai.

Basher, R. E. & Pittock, A. B. 1998, 'Australasia' (Chapter 4), in The Regional Impacts of Climate Change: An Assessment of Vulnerability, Watson, R. T., Zinyowera, M. C., Moss, R. H. & Dokken, D. J., Cambridge University Press, New York.

Bureau of Rural Resources 1989, Rural Industries: Workshop on Climate Change, Bureau of Rural Resources, Canberra.

CSIRO 2000, Inquiry into Global Warming, Submission to the Senate Environment, Communication, Information Technology and the Arts Reference Committee, Canberra.

CSIRO 2001, Climate Change Projections for Australia, Climate Impact Group, CSIRO Atmospheric Research, Melbourne.

Hennessy, K. J. & Clayton-Greene, K. 1995, Greenhouse Warming and Vernalisation of High-Chill Fruit in Southern Australia, climatic Change, 30, 327-348.

Hennessy, P. K., Whetton, P. H., Katzfey, J. J., McGregor, J. L., Jones, R. N., Page, C. M. & Nguyen, K. C. 1998, Fine Resolution Climate Change Scenarios for NSW: 1995-1998, Summary Report, Research undertaken for the NSW EPA, CSIRO Atmospheric Research, Canberra.

Howden, S. M., McKeon, G. M., Reyenga, P. J., Carter, J. O. & Scanlan, J. C. 1999a, Global Change Impacts on Australian Rangelands, Report to the Australian Greenhouse Office, CSIRO Wildlife and Ecology, Working Paper 99/09, Canberra.

Howden, S. M., Reyenga, P. J. & Gorman, J. T. 1999b, Global Change Impacts on Australian Wheat Cropping, Report to the Australian Greenhouse Office, CSIRO Wildlife and Ecology, Working Paper 99/04, Canberra.

Howden, S. M., Reyenga, P. J. & Meinke, H. 1999c, Global Change Impacts on Australian Wheat Cropping: Studies on Hydrology, Fertiliser Management and Mixed Crop Rotations, Report to the Australian Greenhouse Office, CSIRO Wildlife and Ecology, Working Paper 99/13, Canberra.

Howden, S. M., Reyenga, P. J., Meinke, H., & McKeon,G. M. 1999d, Integrated Global Change Impact Assessment on Australian Terrestrial Ecosystems, Report to the Australian Greenhouse Office, CSIRO Wildlife and Ecology, Working Paper Series 99/14, Canberra.

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Intergovernmental Panel on Climate Change (IPCC) 1998, in The Regional Impacts of Climate Change: An Assessment of Vulnerability, Watson, R. T., Zinyowera, M. C., Moss, R. H. & Dokken, D. J., Cambridge University Press, New York.

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Jones, R. & Hennessy, K. 1999, Climate Change Impacts in the Hunter Valley: A Risk Assessment of Heat and Stress Affecting Dairy Cattle, citing Davison et al. 1996, Managing Hot Cows in Australia, QLD Department of Primary Industry, p. 58.

Whetton, P. H., Hennessy, P. K., Katzfey, J. J., McGregor, J. L., Jones, R. N., Page, C. M. & Nguyen, K. C. 2000, Fine Resolution Assessment of Enhanced Climate Change Scenarios in Victoria, Research Undertaken for the Victorian Department of Natural Resources and Environment, CSIRO Atmospheric Research, Victoria.