About four years ago, my wife and I, who are both in our thirties, briefly thought we were having a baby. For the next few nights my dreams were of nuclear flashes lighting up the sky, of the earth cracking open and of waves lapping at the front door. Humans are swiftly making the planet uninhabitable. Why would we want to bring another human being into the world? I’ll admit that my climate anxiety is as melodramatic as it is severe. But polls show that I’m not alone and the figures of declining birth rates speak for themselves. For a population to sustain itself, the average woman has to have 2.1 children in her lifetime. In 2017 that figure was just 1.74 in the UK, and — thanks in part to fears about the future of the planet — it’s now around 1.