A growing number of Americans are avoiding having kids because of climate concerns.
"I just can't get over the fact I feel like when I if I bring a kid into this world, I'm not going to leave them in a place better than they found it, and I think for me, that is the hardest part," said Kate Swiggett-Craven, who is child-free by choice.
Swiggett-Craven has seen first-hand how climate change and the lack of natural resources impacts global communities because of her job helping resettle refugees.
While she personally also has other reasons to avoid having kids, environmental concerns and climate change has been a top reason for at least 5% of Americans to remain childless, data from the Pew Research Center shows.
Beyond the worry that there won't be a habitable planet left for their children to live on thanks to climate change, many Americans also worry having kids is just bad for the planet. That's because it adds another human to the population whose activities will have an impact on their environment, and also adds to the impact their parents have on the planet. In fact, some studies suggest having kids is one of the biggest contributors to an individual's carbon footprint.
Kimberly Nicholas, an associate professor and sustainability scientist at Lund University's Centre for Sustainability Studies, can help explain how that's calculated.
"If you're talking about the carbon footprint of a hamburger, you would include the carbon cost of raising that beef, everything to produce the cow, to transport the burger from actual consumption and any waste that gets disposed," Nicholas said. "And if you're talking about a person, you can include the entire emissions entailed by creating a new person. There have been studies that look out for an individual on average throughout their lifetime. For a baby, it might include diapers and other kinds of consumption, as we get older and become perhaps homeowners or might fly in planes and drive cars."
In basic terms, the choices one makes in parenting and choices made by their child as they grow in life affect their individual carbon footprints.
Over the past decade, studies have suggested having children and adding to the population of this planet is detrimental to the environment because of this footprint. According to a pivotal study first published in 2008, adding a child to the planet can add up to 9,441 metric tons of carbon dioxide to the environment. That study is commonly cited in the research around this subject that's taken place in the 15 years since, including the work done by Nicholas and her colleagues.
Those 9,441 metric tons are equivalent to adding more than 2,100 gas powered vehicles onto the road for a year, or powering nearly 1,200 homes for the same time period. Compared to catching a flight, if a person were to travel from Washington, D.C. to Paris, France, that travel would increase their carbon footprint by about 1 metric ton.
That's a staggering difference, and it becomes even more concerning when considering the fact that most climate studies name travel, both air and car, as one of the biggest contributors to individual carbon footprints.
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So what makes the apparent footprint from having babies so much higher?
"Individuals will vary from the average, which is what gets used to make these initial estimates," Nicholas said. "If you talk about creating a new person, that impact includes their lifetime emissions and also the emissions of the future generations that they're likely to create, so that's why it added up to be such a big number."
According to the Footprint Thesis, an individual's carbon footprint includes some or all of the emissions of their children and even their children's children.
But individual actions can vary greatly, so this so-called double counting of emissions from the generations to come does not account for any possible individual action or lifestyle choice that would offset the emissions from procreation.
There are certain individual actions climate scientists say can make a great impact on individual carbon footprints.
"Those are reducing flying, driving and meat consumption; that's where your personal emissions will have the biggest bang for the buck," Nicholas said.
Though adding kids to the planet does impact individual emissions, the good news is experts like Nicholas say individual choices can offset emissions, like choosing to have fewer kids. Nicholas' calculations show having one fewer kid per family can save about 58.6 metric tons of carbon each year in developed countries — about the same impact as taking 13 gas powered cars off the road for a year.
Other lifestyle choices like raising your kids as vegetarians and teaching them about environmental conservation must be accounted for as well.
It also matters how and where parents raise their kids. The pivotal study mentioned earlier calculated that under a constant-emission scenario, the average emissions added by having a single child range from 56 tons in a developing country like Bangladesh to the 9,441 ton figure for the U.S.
Americans in general have one of the highest carbon footprints in the world. Data from Michigan University's Center for Sustainable Systems shows that a typical U.S. household's carbon footprint is about 48 metric tons of carbon dioxide a year — the equivalent of putting about 11 gas-powered cars on the road.
Nicholas' research confirms this correlation of wealth with carbon footprint.
"We see both within countries and between countries huge differences in carbon footprints," Nicholas said. "Within the U.S., or I guess if we start globally, the top 10% of people globally cause half of household climate pollution. And actually many of your listeners are probably in that group because to be in that group, you have to earn 38,000 U.S. dollars a year or more."
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The world is already at a critical juncture, and the need for emissions control is more urgent than ever. But that doesn't mean the greater responsibility of climate emissions, or any blame for them, lies on parents or hopeful parents.
"The long-term emissions from having a child are going to outweigh any other individual consumption choice that you make, but I think it's easy to misinterpret what that means because basically what we need to do is cut global emissions in half by 2030. That's just a few years from now," Nicholas said. "Thinking about creating a child has very important long-term impacts on the climate, but it isn't going to prevent or hasten this really narrow window that we have to stabilize the climate and the tolerable limits for humanity to thrive."
Overall, depending on how and where you live, your choice to have or avoid having kids might not affect the climate as much as current blanket calculations suggest.
Broader pro-climate actions — like more robust recycling, transitioning to clean energy, focusing on reforestation and protecting existing greens — can have a big impact on emissions.
Individual actions matter too, and experts like Nicholas say even the little things can go a long way.
"It's also things like voting, supporting climate organizations and being part of demonstrations, writing and contacting your representatives directly, for example, in the citizen sphere and other actions under investor, role model and professional," Nicholas said. "We know what works, and we know what's effective, and we just need more people actually doing those things."
Another thing worth noting is it's not just having kids that's impacting climate change: Climate change is impacting having kids, too.
UCLA researchers who looked at U.S. birth data between 1931 and 2010 showed that births tend to fall in the months after extreme heat and other extreme weather events. They associate the drop to temperature related infertility. Another large study from China also shows how climate change contributors like pollution can increase the likelihood of infertility.
