Hannah Scott, 23, works for an environmental charity. She says that even climate activists are in denial about the gravity of the situation, with her own BirthStrike eliciting responses such as “maybe it won’t be so extreme and apocalyptic” and “life is about having children”. She believes it is already too late to claw back the damage done. “That’s why I am not having one – because I feel so desperately that it would be bringing a life into a future that does seem ever more desolate. Every time a friend tells me they’re pregnant, or planning on having children, I have to bite my tongue.”

BirthStrike, she says, “is about saying: ‘It is OK to make this choice, but it’s not OK to have to make this choice.’ We should never be in a situation where we are genuinely scared to bring life into the world.”

BirthStrike is as much a support group as it is a political statement, says spokeswoman Alice Brown, a 25-year-old charitable campaigns manager from Bristol. As a former nanny and support worker, having children of her own had been on Brown’s “to-do list for life” until one of the girls she used to care for developed allergies which, Brown says, was as a result of pollution.