Modelling the effects of Climate Change and Deforestation on Fire Risk in Tropical Borneo

Fire in the peatlands and forests of Borneo is a significant environmental issue, with far reaching social and climatic consequences. The KaLi project aims to better understand fire risk in the Kalimantan region of Indonesia, and this part of the project focusses on the climatic risk. While fire severity and frequency are generally expected to increase with climate change, the unique climate and geography of Indonesia and the island of Borneo create heterogenous patterns of change. We ran simulations of RCP8.5 with and without deforestation using regional climate model RegCM4 with boundary conditions from a range of CMIP5 model simulations. These simulations provide high-resolution climate simulations that show the relative contribution of climate change and deforestation to the climatic risk of fire using the Fire Weather Index.

We find that climate and fire risk from climate are significantly affected by both climate change and deforestation, though not to the same extent. The surface temperature in the multi-model mean RCP8.5 simulation increases by ~4 degrees, and deforestation further increases the temperature by ~2 degrees. The climate effects of both RCP8.5 and deforestation are affected by the altitude. Precipitation, in particular, is higher above 500m in the deforestation scenario. Both deforestation and RCP8.5 increase the fire risk according to the Fire Weather Index. Deforestation causes a smaller increase than RCP8.5, but is locally controllable in a way that the carbon emissions causing climate change are not. These high-resolution simulations provide a guide to the most vulnerable areas of Borneo from climatic increases in fire risk, and complement efforts to understand the social aspects of fire risk that are a part of the KaLi project.