Systemic adaptations to climate change in Western Australian mixed farm systems

Systemic adaptations to climate change in Western Australian mixed farm systems

Australia’s primary industries have historically operated in a highly variable climate. This has
posed significant challenges to production, requiring sound and responsive risk management practices. Climate
change has, and will, introduce even greater challenges. This means that there is a clear need to continue to
assess the opportunities for farmers to improve how they respond to climate variability and changes. We built
representative mixed farm systems (using AusFarm) across climate gradients to investigate likely effect of
climate change and variability and systemic adaptations to explore system’s resilience, to enhance productivity
under climate variability, and change by 2030. We used AusFarm to build mixed farm systems. Model inputs
were derived by consulting with producers and models performance was validated against survey data.
For a climate gradient of 335-215 mm rainfall (Apr-Oct) in Western Australia, we evaluated long term average
effectiveness of changes in planting date, fertilizer application rate, crop and stubble grazing, and stocking
rates (SR) for 2002-2012 as baseline. To assess the impact of climate change, we used two high-emissions
CMIP3 scenarios (A1FI and A2) with high and medium sensitivity and six global climate models projected
climate for 2030. In 2030 and in a relatively medium rainfall region (MR) of the climate gradient, wheat,
barley, canola production changed by +6%, +2%, and -2% on average while meat and wool production
increased by 1% and 2%. In 2030, and in lower rainfall (LR) end of gradient, wheat, barley, canola, and lupine
production changed by -8%, -2%, -11% and -16% while meat and wool production changed by -2% and -4%.
In 2030, GHG emissions changed by -10% for LR and -5% for MR under current management.
In addition to systemic combination of options described above, we evaluated a range of climate adaptation
packages, which were determined in collaboration with stakeholders. These adaptation packages designed
specifically for each region to reduce negative impact and risk of climate change and benefit from likely
opportunities. Alteration of the crop-livestock balance is an adaptation that can compensate negative impact of
climate change by reduction in business risk. These were evaluated through a package with elements of
optimizing area proportions of cropping and pasture either by changing the relative areas of existing crop &
pasture sequences or the relative length of crop & pasture phases, optimizing stocking rate, and adjustments in
livestock joining and sale dates. We designed low-variability to high-intensity mixed farming as adaptation
packages optimised for different risk and return management approaches. Overall, financially optimal systemic
adaptations were projected to offset negative impact of climate change on production and profitability of whole
farm system in 2030 at majority of sites. This would require for practice and land use change to cope with
changes in climate.

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