Assessment of global land availability: land supply for agriculture

We developed a new assessment method of the land supply for agriculture, on a grid scale basis and per region, which takes into account both biophysical, institutional and socio-economic parameters of land availability and suitability for conversion into agricultural production. In many world regions most of the available and suitable land has already been included in agricultural production. Our assessment focuses on the issue of remaining (i.e. potentially available and suitable) agricultural land per region. We first estimated the total available and biophysically suitable land by excluding areas with certain biophysical restrictions (i.e. marginally productive areas, permafrost, steep slopes, wetlands, built-up area). Secondly, we applied institutional parameters of land suitability to exclude protected areas and - in some regions - also intact forests. Thirdly, we used a suitability index to define the potentially available land that is also suitable for conversion to agricultural production from a socio-economic perspective. Subsequently, we subtracted the current agricultural land from the total available and suitable land to derive the remaining (i.e. potentially available and suitable) land per region. As well, we provided the information on the quality and suitability of the available land, based on classes of crop productivity. We also discuss the distribution of global grasslands, in both intensive and extensive agricultural systems, and the effects of this distribution on potentially available land per region. Our results are applicable for global change analysis and modelling. Accurate estimation of agricultural land currently in use influences the possible impact on regional land use change and associated land use emissions from implementation of land-based mitigation schemes, such as REDD, or other policies (e.g. RED).