Predictions of the demise of the fossil fuel industry are based almost wholly on energy. In future, goes the argument, we are going to use clean energy and so we will be able to leave fossil fuels in the ground as ‘stranded assets’, as Mark Carney would call them.

It is proving hard enough to decarbonise the energy sector, but it tends to be forgotten that at present we rely on coal, gas and oil for many other things, too, such as fertilisers, a reducing agent in the steelmaking process and the manufacture of plastics. While there may be substitutes in theory for some of these uses, the experience of Lego demonstrates how difficult it is to replace oil.

We soon saw during the pandemic how difficult it would be to run the modern world without plastics

Two years ago, as part of its programme to become entirely fossil fuel-free by 2030, Lego proudly announced that it had found a substitute for acrylonitrile butadiene styrene (ABS), the material from which is currently makes its bricks. Instead, it would use recycled polythylene terephthalate (rPET), made from recycled plastic bottles.

However, it has just announced that it has given up. Not only did the material turn out to be unsatisfactory – like ‘trying to make a bike out of wood rather than steel’ according to the company’s head of sustainability – but using it would have led to twice the carbon emissions as compared with the current material, thanks to the large quantities of energy required to process and dry it. Nor is there much hope of an alternative material emerging: the company says it has tested hundreds of materials, all to no avail. Instead, Lego will continue to make its bricks from ABS, although it will use paper packaging rather than plastics in future.

It is yet another demonstration of the myriad of technological issues which will have to be solved if we are to get anywhere near net zero by 2050. These issues have not even occurred to the Panglossian tendency as they fool themselves into thinking achieving net zero is a little more than a formality, and something which is magically going to make us all richer in the process.

Children can always play with wooden bricks, I suppose, as I did as a child. As has been demonstrated with the compulsory levy on single-use shopping bags, we can do without some plastics. But we soon saw during the pandemic how difficult it would be to run the modern world without plastics, when personal protective equipment (PPE) – another form of single-use plastic – became one of the most sought-after commodities in the world.

From hospital equipment to electronics goods, the modern world runs on plastics extracted from oil wells. How to do without them is just one more issue which has hardly been addressed.