For starters, some resources such as indium – found in computer and smartphone display screens – are byproducts of other mining operations. Almost all of the world’s indium comes from zinc mines; there are no dedicated indium mines, because it occurs in such small amounts mining for it is impractical. So if demand for zinc declines – say, because car manufacturers switch from steel to aluminum bodies, as they have been doing recently – then this would have an impact on indium. “Nature puts deposits where it feels like, without worrying about whether we have the energy or water handy to deal with it,” says Graedel.

In other cases, demand might surpass supply, even if there are dedicated mines for the material. Certain resources are sometimes referred to by the German term Gewürzmetall – “spice metal – because, like a dash of cinnamon or saffron tying a dish’s flavour together, these materials compose only a small proportion of an electronic device’s makeup but are essential for that device to function. Palladium, which is used as a capacitor in cell phones, makes up just 0.015% of those devices’ composition, but the cell phone industry goes through about 15 tonnes of that rare metal each year. Given that palladium is also used by the automotive, jewellery, dental, health and electronics industries, eventually, competition could drive up prices, and supply could fall short.

Politics can come into play, too. Most of the rare-earth-metals supply comes from mines in China. Several years ago, China decided to cut down on its export of those elements. As a result, the price of rare earth metals – and the goods they are used to make – has increased. “It’s not that the rest of the world does not have rare earth metals,” Meinert says. The US, for example, holds around 38% of the world’s deposits, but only one mine in southern California (which was closed for several years due to competition from China) is currently producing them. “It takes a long time to put a mine into production,” Meinert says.

In addition to countries setting their own embargoes on exports, conflicts have an impact on resource availability. Fighting in the Democratic Republic of the Congo could affect the world’s supply of coltan, for example, a metallic ore used to make capacitors.

No substitute

So should we worry about dwindling resources? Historically, the argument that, if one element or another runs dry, the world will find alternatives has worked pretty well. Unfortunately, however, in today’s increasingly complex world, good substitutes are hard to come by. In a recent study, Graedel and his colleagues tried to identify the best substitutes for 62 metals. Twelve of those metals, they found, had no substitute at all for their major uses, and none of the 62 they studied had a substitute available to cover all of their uses. “Because we chose what’s almost always the best from a long list of materials, performance is likely to decrease – computers will get slower, engines will be less efficient and so on – if we start making substitutions,” Graedel says.

Within the next several years Graedel hopes to have a better idea of which metals might soon be in short supply. Product development teams could begin thinking of possible substitutes, and to focus on developing devices using materials with more reliable supplies.