KK10 global scenario

The KK10 historical dataset of anthropogenic land cover change (Kaplan et al., The Holocene, 2011) spans 8000 years, from the dawn of agricultural societies until industrialization (AD 1850). Previous anthropogenic land use datasets used a linear relationship between population and land use, which led to a roughly constant per capita land use area. The KK10 land use scenario, uniquely employs a nonlinear, sigmoidal relationship between population density and human land use (Kaplan et al., Quaternary Science Reviews, 2009) to convert population data into land-use estimates, modulated by a region’s suitability for growing crops and the usability of the land (i.e., more land is used for lesser quality areas and less land is used where high quality land exists). We developed this population density-land use relationship by fitting a sigmoidal relationship to historical forest cover data from several European countries. The equation results in a scenario based on the Boserupian theory of land use change where at low population densities land use expands rapidly until a critical amount of quality land is left. At this point populations begin to intensify land use by increasing labor input and using new technologies and methods, finally decreasing the area of land used per capita. This type of methodology generally results in substantially more anthropogenic land use during preindustrial times than what is depicted previous datasets using a linear population density-land use relationship.