It started with the eggs. In the second half of 2020, many of the pulped cardboard boxes that housed supermarket egg supplies were replaced by plastic ones. Just as small bags of flour were replaced by giant, unbranded sacks, the egg situation was a sign that something was awry.

Supermarkets are trying to be more eco-friendly, so ditching cardboard to go back to plastic was a significant move – and one they apologised for. A shortage of the pulp used to make the cardboard, coupled with significant demand for eggs, was to blame.

But the egg box shortage of 2020 was a warning of what was to come. In recent weeks, retailers across the UK have complained that they are unable to source cardboard boxes at all. And Amazon is partly to blame.

Christmas 2020 was a “record-breaking” holiday season for the company, delivering 1.5 billion packages worldwide over the festive period. In the UK, there were an extra 200 million home deliveries over the Christmas period, according to the Recycling Association.

And that has had a knock-on effect on the availability of boxes. Good news for Amazon, bad news for eggs. It’s been widely reported that Amazon and other big retailers have snapped up most of the world's cardboard supply to fulfil online orders, leaving smaller businesses unable to get their hands on boxes of their own. The price of corrugated cardboard, which is old boxes that can be reused to make new ones, has trebled in the last year from $25 a ton to $75.

But the crunch on cardboard could have been much worse if Amazon hadn’t overhauled its box strategy. The retailer has a massive share of the e-commerce market, last estimated at nearly one-third of all sales. While data is hard to come by, analysts estimate that Amazon shipped 415 million packages in July 2020 alone.

Since 2015, Amazon has been eking out more efficiency from its packaging, reducing the weight of boxes in its average shipment by a third. In the last five years the company eliminated more than a million tons of packaging materials, the equivalent of two billion boxes, in part by introducing the concept of “fit to product” boxing: building boxes on demand to better fit the size of the items being delivered. Until the system was introduced, customers could receive a tiny memory stick in an oversized box.