We've all heard of ways to reduce our carbon footprint: biking to work, eating less meat, recycling.
But there's another way to help the climate. A recent study from Lund University in Sweden shows that the biggest way to reduce climate change is to have fewer children.
"I knew this was a sensitive topic to bring up," says study co-author Kimberly Nicholas on NPR's Morning Edition. "Certainly it's not my place as a scientist to dictate choices for other people. But I do think it is my place to do the analysis and report it fairly."
The study concludes that four high-impact ways to reduce CO2 gas emissions include having fewer children, living without a car, avoiding airplane travel and eating a vegetarian diet.
By the numbers, any of these lifestyle changes drastically reduces carbon emissions compared to more common practices like recycling, using energy-efficient light bulbs and line-drying clothes.
- having one fewer child (an average for developed countries of 58.6 metric ton CO2-equivalent (tCO2e) emission reductions per year;
- living car-free (2.4 tCO2e saved per year);
- avoiding airplane travel (1.6 tCO2e saved per round trip trans-Atlantic flight); and
- eating a plant-based diet (0.8 tCO2e saved per year).
Nicholas says they also found that worldwide, many government resources on climate change did not focus on the top lifestyle changes in order to reduce carbon emissions.
"Something really important we found is that most government recommendations weren't really talking about what makes the biggest difference, and they weren't qualifying how big of a difference it made," Nicholas tells NPR's Steve Inskeep.
Many of the suggested changes need to be made on a large scale in order to have a substantial effect on climate change, but Nicholas says this study isn't meant to tell people how to plan their futures. (To calculate your carbon footprint, try the EPA's calculator.)
"I think the decision to become a parent is a really personal decision," she says. "I think the way people relate to it in terms of climate change depends on their view about climate change. If they don't believe or don't know the science, I feel like it makes them angry. I think if they do know the science and are overwhelmed by it, they feel guilt or despair."
There's already a word for this: climate trauma.
For some activists, climate change isn't only an intellectual problem. It's a "heart problem," says Josephine Ferorelli, co-founder of Conceivable Future. She spoke with NPR's Jennifer Ludden last year on having kids in the age of climate change. That story cited a study from 2010 that came to similar conclusions about the impact of slowing population growth on global carbon emissions.
But what if potential parents know the science and want to raise their child on a healthy planet? Nicholas remains optimistic.
"Having a child in that case is a vote of hope," she says. "It's a vote that the world is going to be a better place and we can actually tackle this challenge."
Nicholas says in her own life, she and her fiancé are deciding whether they want to cast that vote of hope for themselves.
"Because we care so much about climate change, it is a factor we're considering. But it's not the only one."
Tori Whitley (@_toriwhitley) is a producer at Morning Edition.
STEVE INSKEEP, HOST:
Researchers identified a provocative way to fight climate change.
DAVID GREENE, HOST:
Many people want to know what they can do about a vast global problem - maybe switch to an electric car, maybe eat less meat, maybe hang up clothes to dry.
INSKEEP: Well, Kimberly Nicholas of the University of Lund in Sweden wanted to help people make smart choices. And she found many of those efforts we just mentioned make only a slight difference in a family's carbon footprint, as it's called. People make a bigger impact with one thing that they choose to do - or not do.
KIMBERLY NICHOLAS: The single biggest impact that we found was from having a child. The reason for that is because that measure accounts for all the choices that that child would make in their life - and their descendants.
INSKEEP: What did you think and feel when you reached that conclusion?
NICHOLAS: Well, I think - I knew this would be a sensitive topic to bring up. Certainly, it's not my place, as a scientist, to dictate choices for other people. But it is my place to do the analysis and report it fairly. You know, something really important we found is that most government recommendations weren't really talking about what made the biggest difference. And they weren't quantifying how big of a difference it made.
INSKEEP: May I ask a personal question?
NICHOLAS: You may.
INSKEEP: You have kids?
NICHOLAS: I don't. It's a choice I'm thinking about right now and discussing with my fiance.
INSKEEP: Oh, congratulations. You're getting married. That's great.
NICHOLAS: Thank you. Yeah, maybe some people are learning that now. But yes, it is great news. And he is wonderful. And of course, having a child is one of the most personal decisions people can make. And there are many, many factors that go into it for everyone, including us. For us, because we care so much about climate change, it is a factor we're considering. But it's not the only one.
INSKEEP: I'm thinking about the implications here, though, because if a few individuals make a choice to have no children or fewer children than they otherwise would, that's going to make no effective difference. This is something that millions or billions of people would have to decide, I would think, in order to make a significant difference. Do you think that some governments somewhere should be pressing their citizens in some way?
NICHOLAS: No, I really don't think that that's the way to interpret our study. And I think that the decision to become a parent or to have a child is a really personal decision. And I think the way people relate to it in terms of climate change depends on their view about climate change. If they don't believe or they don't know the science, I think it makes them angry because they feel like their rights are being taken away. I think if they do know the science and are overwhelmed by it, they feel guilt or despair.
And I think if they know the science, recognize how serious the risk is and how urgent it is that we reduce emissions but they want a child and they want to raise that child in a safe planet, then having a child in that case is a vote of hope. It's a vote that the world is going to be a better place and that we can actually tackle this challenge. I think making that decision means a big responsibility.
INSKEEP: I can imagine people hearing about your study and being darkly suspicious and thinking, oh, here's somebody who's trying to set the stage intellectually for a one-child policy, like they had in China once upon a time or some kind of forced, government family planning.
NICHOLAS: No (laughter). That's certainly not my secret ambition. You know, I worry about people accusing me of that, but it's not the case. I felt that it's something we really have to look at because we know that how many people there on Earth affects the climate. And if people want to know what they can do to reduce their climate emissions, then we have to look at that question, too.
INSKEEP: You just want us to be conscious of what we're doing, it sounds like.
NICHOLAS: I do. I think there's a huge information gap. I know - I mean, as a scientist, I think in data and numbers and ratios. And I know that it's not information that changes hearts and minds, but information is necessary to start conversations.
INSKEEP: And our conversation with researcher Kimberly Nicholas came via Skype. Transcript provided by NPR, Copyright NPR.