As of the start of this month, we have consumed as much of the Earth’s natural resources so far in 2018 as we should have done for an entire year.

This includes food, water and carbon, according to research organisation Global Footprint Network, which also estimates that we’d need the equivalent of 1.7 Earths to maintain current consumption levels.

It sounds scary, but statistics like this are unlikely to compel you to leave your car at work this evening and take the bus home. We’re inundated every day with predictions and terrifying data on the damage we’re causing to the planet, but they lose their edge in a world where we have very tangible problems to deal with in our everyday lives, and for a long time, they’ve remained too abstract to scare individuals and governments into enacting enough change to reverse trends. But now the stakes are getting personal and we’re starting to listen.

There’s an argument steadily gaining ground suggesting that – since individuals in developed nations have huge carbon footprints, with all the eating, driving, flying and keeping warm we do – the best way to avoid this damage is to consider having fewer children, or none at all.

And the proliferating organisations arguing we should consider smaller families are being bolstered by recent reports. A major study last year concluded that not having children is one of the most effective ways of cutting our carbon footprint, and that a US family who chooses to have one fewer child would provide the same level of emissions reductions as 684 teenagers who recycle for the rest of their lives.

Last year researchers recommended four ways to contribute to lowering our emissions, including having one fewer child – the equivalent of 58.6 tonnes of CO2 emissions every year. The other three suggestions – avoiding aeroplane travel, ditching the car and eating a plant-based diet – totalled a fraction of the emissions of having a child.

One couple taking this seriously are George Mann and Nir Paldi, artistic directors of theatre company Ad Infinitum. They’re currently touring their play No Kids, based on their own experience of deciding how, and if, to have children. They consider surrogacy, which doesn’t solve the problem of adding to our carbon footprint, and adoption, which they say is a much more complex process than they’d imagined.

As a same-sex couple, Paldi says the extra effort they have to put into having a child makes them question the process even more than a straight, fertile couple.

“We met with adoption recruiters and charities as part of our research for the play and found out how much of a serious undertaking it is. It’s less of an option for us to achieve a happy family than we’d hoped”, Paldi says.

The couple admit they haven’t drawn any conclusions yet, and while the process has made Mann more passionate about the environment, he’s realised how much this is in conflict with his deeper desire to have children.

“It’s brought me face-to-face with this contradiction, with the flaws of human nature that we all have inside,” he says.

If they decide to not have children, Paldi and Mann would be contributing to part of a wider trend of falling birth rates in the UK, as well as in the US. But the UK should still be leading the way, according to Florence Blondel of Population Matters, an organisation that promotes smaller families. She argues it’s crucial to send a message to developing nations, where population growth continues to rise, from countries such as the UK, where she came three years ago to study from her home in Uganda.

“You can’t ignore the UK, because you also have migration here; people come here with their children. You need to be successful here in order to take the message to developing countries, otherwise people would just be suspicious. The UK needs to be an example,” she says.

Blondel, who comes from a family of seven children, says that, while she loves her siblings, she doesn’t think children should be born into inevitable suffering.

“Why have a child to struggle through life? I’m over 30 years old already and I don’t have any children yet – and I come from a country where people start having children aged 15, 16. I’m definitely not going to have more than two children.”

The debate is often narrowed to one of population control, but other organisations argue this is part of a much wider debate. Conceivable Future, a US organisation encouraging conversations around climate change, has grown accustomed to being mentioned in articles arguing the need for population controls.

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Founders Josephine Ferorelli and Meghan Kallman, however, argue that the question shouldn’t be whether people have fewer children because of their future carbon footprint, but why we live on a planet where there is such a carbon cost to having a child.

“It’s preposterous to think a bunch of people deciding not to have children will solve climate change. I could kill myself now, remove myself as one of around seven billion people, and climate change would continue. It’s a socially and morally bankrupt argument,” Kallman says.

“It’s not about individuals choosing to do something or not do something, but about people coming together. If you look at the civil rights movement, the only reason the Montgomery bus boycott worked was because people did it en masse.”

Mann disagrees, and argues individual change is the first step of a bigger political movement.

“You always have to start small,” Mann says. “I’ve encountered couples who’ve decided not to have children for environmental reasons and it does have an impact. When this grows to more people, it will be more impactful.”

Paldi says it’s futile to argue that there’s no point adopting sustainable behaviours when others don’t bother to.

“It’s not unethical to ask someone whether they really need to have a fourth child,” he says. “Not having a child makes a significant impact and, if quite a few people do it, it makes a big difference.”

But Rivka Weinberg, a philosopher and the author of the book The Risk of a Lifetime: How, When, and Why Procreation May Be Permissible, doesn’t think we can do much to improve climate change by having smaller families, and that change can only happen from a policy level.

“Some people are saying you can’t have children and I don’t think that’s at all fair. It’s not that you can’t have a wonderful life as a childless person, but you can’t understate the effects of having children; it’s visceral, it’s a special relationship that no other relationship will substitute,” she says.

Another argument for having fewer children is how dangerous the world will be for future generations, which Weinberg says is the more pressing issue.

“On an individual level, each person has to decide whether it’s morally permissible for them to have children and climate change makes that a harder choice,” she says. “It presents future children with more risks that parents are ill-equipped to do anything about.”

While climate change currently affects those in developing countries the most – in Vietnam, for example, the average temperature has risen by 0.5°C over the past 50 years, and sea levels have risen by about 20cm – she says at some point it will affect us all. But deciding not to have children would be a “premature reaction” now, she adds, because there’s still time to adapt.

“To say someone shouldn’t have children is very premature and unfair – there are other things we can do first, there are less draconian ways of approaching the problem.”

And when it comes to fighting for political change, Josephine says, ironically, having children can help.

“For the most effective activists, their reason for doing this work is because of their children.”

Rebecca Kukla, associate professor of philosophy at Carleton University in Ottawa, says we need clarity around the fact that industry and infrastructural systems are the main threat to the environment, and not individuals.

“Our primary goal, if we want to protect the environment, should be on systems-level reforms, infrastructural development, and strong checks on industry. Even more basically, our goal should be reducing income inequality and poverty, since it is really people in poor and disempowered regions that are under serious threat from climate change,” she says.

“All these discussions about lifestyle choices should be put in perspective. Anyone who chooses not to have a child for environmental reasons should be fully aware of the scientific facts as we know them, including all the facts showing that individual lifestyle choices are not really the main things that need to change.