This assessment report quantifies the everincreasing material flows required to build, maintain and operate the cities, transport systems, food supply and energy systems on which today’s world depends. The importance of understanding these flows is twofold. There are very important environmental impacts related to the mobilization of materials for use in economic activity. Large-scale change in land use and forest cover accompanies the extension of agriculture, timber production and in some cases mining and energy extraction. Impacts associated with increasing agricultural outputs include large-scale land degradation via erosion, salinization and acidification which can accompany the extension of cropping into marginal lands or the intensification of inputs on existing arable land.
Credit: UNEP International Resource Panel.
