Mapping past human land use using archaeological data : A new classification for global land use synthesis and data harmonization

In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, linking archaeologists with climate modelers, biodiversity conservation workers and initiatives. This study was undertaken as part of the Past Global Changes (PAGES) project (and its working group LandCover6k), which in turn received support from the U.S. National Science Foundation, Swiss Academy of Sciences and the Chinese Academy of Sciences. The work of global-scale coordination, database development, and the work of land use groups around the world was supported with workshop grants from Past Global Change (PAGES) and the Human and Biosphere Commission of INQUA (the Global Holocene Land Use - HoLa - International Focus Group and related projects). Additional funding was provided by the University of Chicago, the University of Pennsylvania, and the many institutional and personal sources of support for travel and time that allowed the many participants in this project to contribute their expertise and enthusiasm to this critical effort. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.'