Carbon farming co-benefits optimization in south-eastern Australian rangeland

Global efforts to combat climate change have motivated the adoption of carbon farming as one strategy for reducing greenhouse gas emissions. Carbon farming has gained traction in southeast Australian pastoral areas, largely driven by an Australian Commonwealth payment for carbon abatement scheme known as the Emission Reduction Fund (ERF). However, the ERF focuses solely on carbon storage and overlooks the additional co-benefits from carbon farming. This study explores the potential for optimizing land use in carbon farming to maximize co-benefits while maintaining financial returns and carbon storage benefits. Four different scenarios were analysed for our Western Division, New South Wales (NSW) study area. A baseline least-cost scenario that maximizes total economic return, and two co-benefit scenarios that examine the potential impacts of prioritizing biodiversity or land degradation resistance. A final balanced co-benefit scenario explored the trade-offs between land degradation resistance and biodiversity co-benefits. All three co-benefit scenarios impose constraints requiring financial returns and carbon storage to be above baseline scenario levels and allow a 10 % increase in budget consistent with a premium for co-benefit outcomes. The headline results show a fourfold increase in biodiversity priority score and a 230 % increase in land degradation resistance score without reducing landholder returns. The total economic return remained at similar values since the constraints were set to zero sacrifices, while the carbon abatement showed a 10 % increase in three co-benefit scenarios. This increase in total carbon abatement was achieved across the greater land area due to a nearly two-fold higher abatement potential of selected cells in the least cost scenario compared with the other co-benefit scenarios. Overall, the results illustrate the considerable potential to improve co-beneficial outcomes without losses in carbon storage or landowner returns and lay the groundwork for including such benefits in carbon markets. This emphasizes the necessity of strategic resource allocation and mindful consideration of objectives and constraints for better carbon farming outcomes. The research highlights how better co-benefits from carbon farming can be aligned with global efforts to address climate change while promoting additional ecosystem services as carbon farming co-benefits.