Effects of increasingly variable climates on the productivity and profitability of red meat farms in Tasmania

Rainfed pastures comprise the dominant feed supply of most Tasmanian farms, but such feed is highly susceptible to the vagaries of the climate. Previous studies of the impacts of climate change on the Tasmanian agricultural sector have primarily focussed on productivity, very few concurrently consider productivity and profitability.

The purpose of this study was thus (1) to review the impact of a future, more variable climate on pasture and livestock productivity and profitability, and (2) investigate a range of adaptation options to ascertain potential changes in productivity and profitability.

Effects of climate change in 2050 on pasture-based livestock systems were investigated for two representative beef and sheep farms, the former located at Stanley in north-western Tasmania, the latter in the drier region of the Midlands near Campbell Town. Each farm enterprise was modelled using GrassGro; future climate data was generated from an ensemble of global circulation models (GCMs) based on Representative Concentration Pathways (RCP) 8.5. The approach used to generate the future climates included algorithms to perturb historical climates such that future climate data contained greater variability, including droughts, heat waves and extreme rainfall events while still ensuring alignment with projections from the GCMs.

By 2050, the productivity and profitability of both farms modestly increased. This is a significant result in itself, considering these changes occurred in the absence of any adaptations. Mixed effects of adaptations on productivity and profitability were observed. Increasing the size of mature breeding cows (i.e., genetic intervention) resulted in the greatest positive impact on gross margins (+17%) and productivity (+7%) relative to the 2050 non-adapted treatment. Shifting the date of first lambing to later in the year resulted in the greatest increase in productivity (+6%), but profitability did not increase due the greater amount of supplementary feed required. Selling cattle earlier in the year had a positive impact on ground cover, although productivity (-1%) and profitability (-3%) declined. It is concluded that both regions are likely to remain relatively productive and profitable through to 2050 assuming all other aspects of these systems remain unchanged. With adaptation, beef cattle and sheep farmers in Tasmania may have a geographical advantage relative to hotter, lower rainfall regions on the Mainland.