Is the world running out of metal?
Researchers studying supplies of copper, zinc, and other metals have warned that at present rates of usage, even the full extraction of metals from the Earth's crust and extensive recycling may not meet demand.The research, published in the January edition of the Proceedings of the National Academy of Sciences, suggests the environmental and social consequences of metals depletion become clearer from studies of metal stocks - in the Earth, in use, and in landfills - instead of tracking the flow of metal through the economy in a given time and region.
"There is a direct relation between requisite stock, standard of living, and technology in use at a given time," said Robert Gordon, one of the Yale University researchers conducting the study. "We therefore offer a different approach to studying use of finite resources, one that is more directly related to environmental concerns than are the discussions found in the economics literature."
Using copper stocks in North America as a starting point, the researchers tracked the evolution of copper mining, use and loss during the 20th century. Then the researchers applied their findings and additional data to an estimate of global demand for copper and other metals if all nations were fully developed and used modern technologies.
According to the results, all of the copper in ore, plus all of the copper currently in use, would be required to bring the world to the level of the developed nations for power transmission, construction and other services and products that depend on copper.
For the entire globe, they estimate that 26% of extractable copper in the Earth's crust is now lost in non-recyclable wastes. For zinc, that is 19%.
At present, prices don't reflect these losses as supplies are still large enough to meet demand.
However, the researchers believe that scarce metals such as platinum, face risk of depletion this century due to a lack of suitable substitutes in devices such as catalytic converters and hydrogen fuel cells. In addition, the average rate of metals use per person continues to rise so even more plentiful metals may face depletion risks in the future.
"This is looking at recycling on a broader scale," said Cynthia Ekstein, the NSF officer who oversees the Yale award. "This is looking at the metal lifecycle from the cradle to the grave."
The study required collaboration between experts in metallurgy, economics, industrial ecology and international studies.