Plastics are greener than they seem

Even if the world needs to become much better at managing their waste.

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Michael Phelan, a famous billiards player and supplier, lamented in 1858 that the growing popularity of the game had made the ivory needed for the balls scarce and costly. "If any inventive genius would discover a substitute", he wrote, "he would make a handsome fortune for himself, and earn our sincerest gratitude." Five years later, Phelan's company offered a reward of US$10,000 (about US$250,000 today) for anyone who could do just that. The result, after some tinkering, was celluloid—the world's first major synthetic plastic.

Though he never claimed the prize, John Hyatt, the inventor, was indeed richly rewarded. Ever since, the world has had an almost insatiable hunger for plastics. This is because plastics' structure—made up of repeating molecular units called monomers, which can be combined and arranged in an enormous variety of ways to form polymers—meant that they could be used to replicate the properties of almost any other material. They could also improve on it: becoming lighter, more durable, cheaper or easier to manufacture.

Their impact has been stunning. The ability to ship goods much more efficiently—and perishables more safely—allowed supply chains to stretch across borders, then oceans. In 2000, some 234 million tonnes of plastic were produced. By 2021 annual production had roughly doubled, with the trade in plastics (and goods containing it) estimated to be worth US$1.2 trillion (S$1.6 trillion) each year.

Without plastics the modern world would look decidedly different. Plastic packaging is significantly lighter than other materials—the weight of a one-litre plastic bottle is just 5 per cent that of a glass one; a paper bag is nearly six times heavier than a plastic one (and takes three times as much energy to produce). Using cans or glass bottles for soft drinks results in greenhouse-gas emissions two and three times higher respectively than using plastic, even taking recycling into account.