Using producers’ own production and financial data from the Ravensthorpe region, modelling was initially undertaken to assess pasture and livestock production, and enterprise profitability for two prior periods (1970-1999 and 2000-2008) to ensure the models were performing correctly. Modelling was then performed looking ahead to 2030, using 4 different climate scenarios.
A Merino x Poll Dorset lamb production enterprise was examined.
Weather predictions & impacts on production and profitability
Projected weather for the four 2030 scenarios and the impact on livestock production and farm profitability, based on a “business as usual” model for a Merino x Poll Dorset lamb production enterprise at Ravensthorpe are shown below:
- Compared to 1970-1999, over the period 2000-2008
- Rainfall was 5% higher and average maximum temperature was unchanged.
- Profitability of the enterprise was 5% lower
- For 2030:
- The temperature increases are consistent at about 1˚C higher (+5%) but rainfall forecast is more variable ranging from a +15% to – 23%, and averaging a 3% reduction.
- Increased CO2 and temperature will result in an increase in legume content. While this will be positive for animal production, the rate of decline of dry pasture residues over summer may increase, resulting in wind erosion and groundcover limits being reached quicker. This will have ramifications for wind erosion in sandy soils along the coastal sand plains around Ravensthorpe/Esperance.
- At current district average stocking rates (2.5 DSE/ha for Ravensthorpe), profit declined significantly in two climate scenarios with only marginal increases predicted in the other models. On average profit declined by 33%, but with a large range across scenarios (+5% to -90%).
- The results from Ravensthorpe are similar to those found at other locations modelled across southern Australia, but quite different from those from Kojonup.
The impact of adaptations
The following table shows the impact of various adaptations on the profitability of a Merino x Poll Dorset lamb production enterprise at Ravensthorpe
- Because mating time and stocking rate are key profit drivers in this area, these were the main adaptations modelled
- Similar to Kojonup, in 2030 the most profitable approach is to maintain current practices
- Delaying mating by one month and decreasing or increasing stocking rate resulted in decreases in profit
- As a result of the potential for greater erosion over summer, confinement feeding is likely to be an essential component of a sustainable grazing system for producers in these areas.