Page 671 - Environment: The Science Behind the Stories

Amount used per year
Known economic Amount used years of economic if everyone consumed years of economic supply left if
Metal reserves per year supply left at U.S. rate everyone consumed at U.S. rate
Titanium 700,000 7000 31,703
Copper 680,000 17,000 39,798
Nickel 75,000 2100 5014
Tin 4900 230 951
Tungsten 3200 73 369
Antimony 1800 180 519
Silver 540 24 133
Gold 52 2.7 3.37
Data are for 2012, from U.S. Geological Survey, 2013. Mineral commodity summaries 2013. USGS, Washington, D.C. All numbers are in thou-
sands of metric tons. World consumption data are assumed equal to world production data. “Known economic reserves” include extractable
amounts under current economic conditions. Additional reserves exist that could be mined at greater cost.

1. Which of these eight metals will last the longest under 3. In this chart, our calculations of years of supply left do
current economic conditions and at current rates of global not factor in population growth. All else being equal,
consumption? For which of these metals will economic how do you think population growth will affect these
reserves be depleted fastest? numbers?
2. If the average citizen of the world consumed metals at 4. Describe two general ways that we could increase the
the rate that the average U.S. citizen does, the economic years of supply left for these metals. What do you think it
reserves of which of these eight metals would last the will take to accomplish this?
longest? Which would be depleted fastest?

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