Metal Stocks in Society – Scientific Synthesis - UNEP

Executive SummaryThe continued increase in the use of metalsover the twentieth century has led to a substantialshift from geological resource baseto metal stocks in society. Such a shift raisessocial, economic, and environmental issuesthat require quantifying the amount of stockof “metal capital” utilized by society. Thisreport reviews the relevant literature on thistopic. From a compilation of 54 studies, it isclear that a reasonably detailed picture of inusestocks and in-use lifetimes exists for onlyfive metals: aluminium, copper, iron, lead,and zinc, and in only two cases have spatialstock allocations been performed. Limiteddata suggest that per capita in-use stocks inmore-developed countries typically exceedthose in less-developed countries by factorsof five to ten. Sparse but potentially usefulin-use stock information exists for nineteenother metals. There is a little informationon stocks in government repositories, andessentially none on stocks in “hibernation”,in tailings repositories, in industrial stockpiles,or in landfills, nor on typical in-use lifetimesfor almost the entire periodic table ofthe elements. Outflows from in-use stocks,potentially useful for determining future ratesof reuse, can currently be reliably estimatedonly for aluminium, copper, iron, and lead.This is the first of six reports on the stocksand flows of metals, the last of which willdraw upon the first five to address criticalityand policy options related to the sustainabilityof metals.