24 Jan 2014 --- Up to 849 million hectares of natural land nearly the size of Brazil may be degraded by 2050 should current trends of unsustainable land use continue, warns a report by the United Nations Environment Programme (UNEP) to be presented today by the UN at the World Economic Forum in Davos, Switzerland. The need to feed a growing number of people globally has led to more land being converted to cropland at the expense of the world's savannah, grassland and forests.