The Role of Soil Carbon Sequestration as a Climate Change Mitigation Strategy: An Australian Case Study

Soil carbon sequestration (SCS) is a key priority in the Australian government's Long-Term Emissions Reduction Plan. Under the government's Emission Reduction Fund (ERF), farmers are encouraged to change to a management practice that will increase their soil carbon (C) stock and earn Australian Carbon Credit Units (ACCUs). The projections of net C abatement nationally range from 17 to 103 Mt carbon dioxide equivalent annually up to 2050. This huge range reflects the uncertainties in achieving net SCS due to biophysical constraints, such as those imposed by the paucity and variability of Australian rainfall and the difficulty of measuring small changes in soil C stock. The uptake by farmers is also uncertain because of compliance costs, opportunity costs of a practice change and the loss of business flexibility when a farmer must commit to a 25-year permanence period. Since the program's inception in 2014, only one soil C project has been awarded ACCUs. Nevertheless, an increase in soil C is generally beneficial for farm productivity. As a voluntary C market evolves, the government is expecting that farmers will sell their ACCUs to businesses seeking to offset their greenhouse gas emissions. The risk is that, in buying cheap offsets, businesses will not then invest in new energy-efficient technologies to reduce their emissions at source.