The new model shows that production of important metals such as copper will peak over the next few decades, followed by a gradual decline.

　　If electricity is the lifeblood of the modern economy, copper metal acts as the blood vessel. From power plants to sophisticated electronics, copper has always been at the heart of power distribution systems. A small car packs about 20 kilograms of copper, from the engine to the radiator; the copper in a hybrid is double that. However, it has been pointed out that even with copper consumption growing exponentially – reaching 17 million tonnes in 2012 – the mineral will still be able to meet world demand for a long time.

　　But this time may not be too long. A team of resource experts has calculated how much more copper can be extracted from the earth. Models suggest that copper production will peak by the middle of the century, even if copper deposits are more abundant than most geologists thought. And that will drive prices soaring, spur more recycling, and bring sub-substitutes to copper into the market.

　　The research leads to "a very good theory that we may reach a peak around the middle of this century," says Thomas Graedel, an industrial ecologist at Yale University. But techno-optimists disagree. "It's not that it can't happen, but I don't think it will," said John Tilton, a resource economist at Colorado School of Mines. He mentioned that newer and better copper-refining technologies could help to get out of the woods, and he hoped that by stepping up recycling and using copper substitutes to bring about a much-delayed peak in production so that industry and consumers could be more accommodating.

　　The copper debate has spilled over to other minerals as well. The research team also used depletion models to calculate other mineral resources such as oil and lithium. These resources are also facing exponentially increasing consumption.