Is global burned area declining due to cropland expansion? How much do we know based on remotely sensed data?

The global extent of the amount of burned area seems to have changed substantially in the last two decades. Discussions regarding the main force behind the current trends have dominated research in recent years, with several studies attributing the global decline in wildfires to socio-economic and land-use changes. This review discusses the uncertainties and limitations of remotely sensed data used to determine global trends in burned areas and changes in their potential drivers. In particular, we quantify changes in the amount of burned area and cropland area and illustrate the lack of consistency in the direction and magnitude of the trend in cropland land cover type specifically within sub-Saharan Africa, the region where data show a strong trend in the amount of burned area. We state the limitations of remote-sensed fire and land cover products. We end by demonstrating that based on the currently available data and research methods applied in the literature, it is not possible to unequivocally determine that cropland expansion is the primary driver of the decline in fire activity.