Lemmen, Carsten (2009): World distribution of land cover changes, model in NetCDF format [dataset]. GKSS Research Center, Geesthacht, Germany, PANGAEA, https://doi.org/10.1594/PANGAEA.737958,

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Supplement to: Lemmen, C (2009): World distribution of land cover changes during pre- and protohistoric times and estimation of induced carbon releases (Répartition mondiale des espaces défrichés à la pré- et protohistoire et estimation des rejets de carbone induits). Géomorphologie : Relief, Processus, Environnement, 4, https://doi.org/10.4000/geomorphologie.7756

The role of Pre- and Protohistoric anthropogenic land cover changes needs to be quantified i) to establish a baseline for comparison with current human impact on the environment and ii) to separate it from naturally occurring changes in our environment. Results are presented from the simple, adaptation-driven, spatially explicit Global Land Use and technological Evolution Simulator (GLUES) for pre-Bronze age demographic, technological and economic change. Using scaling parameters from the History Database of the Global Environment as well as GLUES-simulated population density and subsistence style, the land requirement for growing crops is estimated. The intrusion of cropland into potentially forested areas is translated into carbon loss due to deforestation with the dynamic global vegetation model VECODE. The land demand in important Prehistoric growth areas - converted from mostly forested areas - led to large-scale regional (country size) deforestation of up to 11% of the potential forest. In total, 29 Gt carbon were lost from global forests between 10 000 BC and 2000 BC and were replaced by crops; this value is consistent with other estimates of Prehistoric deforestation. The generation of realistic (agri-)cultural development trajectories at a regional resolution is a major strength of GLUES. Most of the pre-Bronze age deforestation is simulated in a broad farming belt from Central Europe via India to China. Regional carbon loss is, e.g., 5 Gt in Europe and the Mediterranean, 6 Gt on the Indian subcontinent, 18 Gt in East and Southeast Asia, or 2.3 Gt in subsaharan Africa.

Global subsistence style and technological progress for the period 9500 BC to 2000 BC were hindcasted with the Global Land Use and technological Evolution Simulator (GLUES) for 685 land regions of the world. The intensification of subsistence is visible in the transition from hunting-gathering to agropastoral life style in many world regions. This transition is based on an increase of domesticated plant and animal resources and technological progress, and can sustain much higher population densities than the foraging life style.

The advent of agriculture creates an areal demand for growing crops; where the crop area is occupied by forest in potential vegetation estimated with a dynamical global vegetation model (VECODE), the aboveground and belowground carbon pools are reallocated; the net release of carbon to the atmosphere is calculated.

Initial values for each prognostic variable are identical at simulation start (9500 BC), but the background vegetation varies. Vegetation productivity in terms of net primary production (NPP) was derived from Climber-2 climate anomalies on the IIASA database for mean monthly precipitation and temperature and subsequent application of the Miami model.

Data are presented as 50-year averages with time indicating the central year of each 50-year period (i.e. -2425 denotes the period 2450 BC - 2401 BC), and geographically on a half degree grid with latitude and longitude values denoting the central value within each grid cell.

Model data are from sub-project GLUES (Global Land Use and Technological Evolution Simulations on New Paleoclimate data: Quantified impact of Holocene climate change on land use, regional agrarianisation and anthropogenic deforestation with feedback, see: hdl:10013/epic.35233.d001).