Nedal Nassar

Advisor: Thomas Graedel


Metals are vital to modern society. Shelter, transportation, and communication are all dependent on metals and their alloys. Indeed, it is difficult to think of a facet of human society that does not incorporate metals in one form or another. Human reliance on metals is not a new phenomenon. What is new is the rate at which humans are extracting, processing and using metals. The exponential increase of metal utilization that has been witnessed over the last century has lead to a significant shift of metal stocks from the lithosphere to the anthroposhere. This shift of materials from lithosphere to the built environment raises important social, economic and environmental questions such as “Should we be concerned about the long-term availability of metals?”, “Is it possible to recycle our way to sustainability?”, and “Are cities the mines of the future?” These and other questions cannot be answered in any meaningful way unless quantity of metals that in use is quantified.

Several in-use stock quantifications can be found in literature on a global, regional, and city level but few provide spatially explicate results – an aspect that can often be essential for resource management. A recent study by Rauch (2009) published in the Proceedings of the National Academy of Sciences utilized spatially resolved GDP data along with DMSP nighttime lights data to provide the first spatially resolved in-use stock estimate for four metals on a global scale.

The analysis conducted by Rauch was for a single year (year 2000). While obtaining a snap-shot in time is valuable, with the continued increase in metal utilization it is equally important to understand how these stocks change over time. Utilizing recently radiometerically-corrected nighttime lights data, this study aims at developing global in-use stock estimate for four metals (Copper, Iron, Zinc, and Nickel) for several years (1995, 2000, and 2005). The results of the study will depict where the stocks for these metals have changed and by how much on a global basis. The study will also provide in-use stock estimates for jurisdictions (including regions, countries, and cities) for which no estimates were previously available.