7. The Future of Agriculture in the Murray-Darling Basin

The data presented in this chapter indicate the critical importance of agriculture in the MDB, for the Basin itself and for Australia as a whole. In many respects, the Basin is not an ideal environment for many agricultural activities. In particular, the unpredictable weather and seasonal conditions make farming difficult, especially in terms of the availability of moisture. This situation is now further complicated by likely climate change. Higher temperatures and changes to ‘normal’ rainfall patterns (the amounts and seasonality) would inevitably result in changes to the distribution of crop and livestock production.

Generalised best estimates for climate change in the Murray-Darling Basin suggest a small (5-10%) decrease in rainfall in the northern summer-dominant rainfall areas of the Basin, and a larger decrease (10-20%) in rainfall in the southern MDB (Beare and Heany 2002). Kokic et. al. (2005) indicate that wheat yields in the MDB will, under the worst case scenario, decrease by 5-15 per cent.

Research is in progress to assess possible impacts of climate change on dryland and irrigated agriculture in the MDB.

It has been hypothesised that projected losses in runoff and streamflow will be offset by increases by yield per hectare caused by increased levels of carbon dioxide in the atmosphere. However, the impact of increasing carbon dioxide on many crops remains unknown. It is thought that higher temperatures will have a negative impact on crops that require vernalisation in winter, such as stone and pome fruits. Higher temperatures may also negatively affect dairying due to relative losses in milk production during increased warmer months.

Because climate change is expected to affect different regions of the MDB differently, it is difficult to generalise about the impact of climate change on dryland grazing and cereals. Research suggests that tropical animal parasites can shift further south under climate change (White et al 2003). Beef and sheep production generally increases with stable or increasing rainfall, and drops with significant decrease in rain.

It is suggested that climate change may be beneficial to wheat production in the Wagga Wagga area and further west near Dubbo and Moree. However, the impact of climate change on many production and environmental issues such as salinity is not yet fully understood. Clearly, sustainable management, land use and land cover change interactions are complex under climate change, and adaptation at a regional scale will be more difficult.