Protecting new markets: quantifying the risks to new carbon markets from invasive species and prioritising areas for immediate action

Financial mechanisms such as offsets are one strategy to abate greenhouse gas emissions. However, in the case of carbon offsets, if the carbon is released due to intentional or unintentional reversal through environmental events such as fire, the financial liability to replace lost offsets will likely fall on the provider. In order to manage this risk, an understanding of the spatial and temporal distributions of threats is needed. We use the case study of savanna burning, an approved greenhouse gas abatement methodology under the Carbon Farming Initiative in Australia, to examine the risks posed by high biomass invasive grasses, such as gamba grass (Andropogon gayanus Kunth), to carbon markets in northern Australia. We focus our analysis on the threat of gamba grass to savanna burning due to its documented impacts of increased fuel loads and altered fire regimes. We build on an initial assessment of the spatial and financial extent to which gamba grass poses a risk to savanna burning programs in northern Australia. We estimate the costs and benefits of three gamba grass management scenarios. The management scenarios prevent up to ~100,000 ha in new infestations which is a substantial return on investment in weed management. Our analysis demonstrates how the use of spatial spread modelling of gamba grass can be used in conjunction with a financial assessment of risk to identify infestations of highest priority for control.