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Peak Copper

September 1, 2014

Nearly all of my readers should be familiar with the concept of peak oil. Petroleum does not exist in an infinite supply, so there must be some limit as to how much can be extracted. American geophysicist, M. King Hubbert (1903-1989), developed a model that predicted the rate of petroleum production would be a bell curve as a function of time; thus, it would demonstrate a peak.

Hubert presented his peak theory in 1956, and his theory correctly predicted that petroleum production in the United States would peak in 1970. Later, he predicted that worldwide petroleum production would peak around the turn of the century. Since oil producers have a vested interest in assuring consumers that oil is still plentiful, it's been hard to assess whether peak oil has actually been reached.

Figure captionHubbert's production curve for world oil.

Peak oil was predicted at the year 2000.

(Modified Wikimedia Commons graphic.)

Hubbert's arguments for oil can be applied to all finite resources, so we now have similar theories for the following

 • Peak gas• Peak coal
 • Peak uranium• Peak phosphorus
 • Peak gold• Peak water

It's easy to see how there are limits to the availability of these items, but the applicability of a peak theory to the following two items needs some explanation.

 • Peak wheat• Peak food

If you need more vegetation, you just do more planting, right? Limits on water and arable land, however, will cause wheat and others food to have a production peak. Much of our agriculture depends on chemical fertilizers, and these might have their own peak and become scarce. One other problem is that arable land is being lost to poor land management and pollution. As noted by Malthus, there's a self-correcting feedback mechanism to the problem of peak food, but it's one we would rather not have.

This brings us to the topic of this article, peak copper, which was highlighted in an article, "The Coming Copper Peak," in the February 15, 2014, issue of Science.[1-2] It was written by Richard A. Kerr, a writer for Science magazine. I wrote about the history of copper in a previous article (Antimicrobial Alloys, January 31, 2014)

Copper was an important metal in human history. Copper is too soft a metal for most uses, but dissolving a little tin in copper produces bronze. This addition of tin hardens the copper without changing its crystal structure. Modern bronze generally contains about 10% tin, but bronze exists over a range of tin concentrations. The importance of bronze is signified by the archaeologists' naming of the Bronze Age.

A spool of copper wire (33 AWG)A spool of 0.18 millimeter diameter (33 AWG) copper "magnet" wire.

Although used for other purposes, magnet wire has just a thin coating of a polymer insulation. This allows a high density of turns in magnetic coils.

(Via Wikimedia Commons.)

Copper is used widely in electrical and electronic applications, and seventeen million metric tons were produced in 2012. Our present day is at the end of a nearly exponential rise in copper consumption that's been going on for 10,000 years.[1] We keep finding new uses for this versatile metal. While an automobile might use about twenty kilograms of copper, a hybrid electric vehicle has about twice that amount.[3]

Copper was harvested in antiquity as the free metal; but, after a time, it was extracted from its ores. People always grab the low-hanging fruit at first, so the ores initially mined contained about 10-20% copper. At the end of the 19th century, ores with 2-3% copper were exploited, while now the ores used for copper extraction contain just a percent of copper.[1,4]

Steve Mohr of the University of Technology, Sydney, Australia, modeled mineral peaks for his 2010 dissertation. In 2013, he collaborated with Gavin Mudd, a geologist at Monash University (Clayton, Australia) for a paper on the topic in the International Journal of Sustainable Development. Recently, Mohr and Mudd have teamed with others to model copper production using available data on extractable copper ores combined with models for copper use and world population. When the model matched historical data, they used it to make predictions (see figure).[1]

Peak copper
The projected peak for copper production appears in the next few decades. The interesting thing about this graph is that the world will have figuratively mined its last ounce of copper in 2100. (Graph rendered by author using Inkscape from data in ref. 1.)

Changing the assumptions of the model will shift the peak, but the peak remains. If the recoverable copper is increased by 50%, the model still shows a peak at 2045. If the recoverable copper is doubled, this extends the peak to just 2050. A 400% percent increase gives a peak at 2075.[1,3] On the pessimistic side, decreasing the available copper by 50% shifts the peak to somewhat after 2020.[3]

Whenever a scientific model intersects with finance, there are always deniers. One argument is that economic forces will result in new methods of copper extraction from marginal ores.[5] Recycling of copper is another option, as copper thieves have pointed out. Copper is the third most recycled metal, after iron and aluminum, being recycled at about the 50% level, and this could be increased further. Scarcity will drive up copper prices to make recycling more attractive.[1,3]

Everyone talks about our "oil war," but little is known about the copper war in Papua New Guinea. A ten year civil war raged in that country, sparked by supposed social and environmental disruption caused by the Panguna copper mine in Bougainville.[1]


  1. Richard A. Kerr, "The Coming Copper Peak," Science, vol. 343, no. 6172 (February 14, 2014) pp. 722-724.
  2. Science, vol. 344, no. 6184 (May 9, 2014). The Letters section includes the following: John E. Tilton, Copper Limits: Opportunity Costs; Gustavo Lagos, Copper Limits: Recycling Potential; Alfred J. Cavallo, Copper Limits: Human Agency.
  3. Tommy Humphreys, "Peak copper," mining.com, April 8, 2014.
  4. Gavin M. Mudd, "The limits to growth and 'finite' mineral resources: re-visiting the assumptions and drinking from that half-capacity glass," International Journal of Sustainable Development, vol. 16, nos. 3/4 (2013), pp. 204-220.
  5. Tim Worstall, "Peak Copper: Worldwatch Institute Gets It Wrong Again," Forbes, April 19, 2014.

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