Climate change impacts on Australia’s rangeland livestock carrying capacity: A review of challenges

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This report reviews the current state of knowledge in terms of assessing the impacts of climate change on livestock carrying capacity (LCC) in Australian rangelands, particularly concentrating on northern Australia. The report is based on two previous publications (McKeon 2006, McKeon et al. 2009) and documents the importance of livestock carrying capacity as a driver of rangeland productivity and resource condition.

We reviewed calculation procedures using climate and pasture attributes to calculate long-term carrying capacities from simulated forage production in northern Australia. We evaluated current trends in climate variables that affect forage production and indicated that trends in rainfall were likely to be exacerbated/amplified, in terms of forage production and other components of the grazing system. We reviewed recently released climate change projections and identified regions of agreement and disagreement with current trends. We documented modelling capability in terms of calculating the impact of climate change on rangeland systems and identified a number of ‘known uncertainties’, in particular, the impacts of increasing carbon dioxide and the possible role of trees in rangeland systems.

We used simulations of forage production to investigate combinations of changes in rainfall, temperature and carbon dioxide. We found that increases in temperature and carbon dioxide have strong but opposing effects. The magnitude of the opposing effects emphasises the importance of addressing uncertainties in estimating the impact of climate change. We briefly reviewed a range of other issues associated with climate change, such as mitigation, monitoring the impact of climate change on forage production, developing adaptation options, assessing vulnerability and response, managing uncertainty of future rainfall using seasonal climate risk assessment, and a risk-averse approach in using climate change projections.