Lessons from high-resolution satellite case studies for global-scale models of biomass burning: An approach for assessing the component of net deforestation linked with fire

Besides fossil fuel emissions, the largest anthropogenic flux of carbon to the atmosphere stems from tropical deforestation. One of the most important tools used to clear land is fire, but it remains uncertain what fraction of the net deforestation flux is lost as direct fire emissions as opposed to onsite or offsite decomposition of slash and non-merchantable timber. Most of the uncertainty can be attributed to the large temporal and spatial variations in burned areas, fuel loads, and how much of the fuel is actually combusted in the process of land clearing. This variability is especially large in areas undergoing rapid deforestation, where frequently burning pastures and grasslands often border fire prone closed canopy tropical forest. Here we investigate the links between net deforestation and fire in three active biomass-burning areas: the southern Amazon, southern Africa, and southern Borneo (Kalimantan). In each area, these links are explored using MODIS 250m satellite data of fire activity and vegetation characteristics. Results demonstrate the need to preserve spatial variability of fire processes when aggregating site level data to regional or global level; they also reveal how interannual variability in precipitation affects the rate of deforestation, which is then shown to be one of the main drivers of interannual variability in the growth rates of many atmospheric trace gases.