Want to Slow Climate Change? Stop Having Babies, Bioethicist Travis Rieder Says


Carbon dioxide doesn’t kill climates; people do. And the world would be better off with fewer of them.

That’s a glib summary of a serious and seriously provocative book by Travis Rieder, a moral philosophy professor and bioethicist at Johns Hopkins University.

When economists write about climate change, they’ll often bring up something called the Kaya identity—basically a multiplication problem (not an espionage novel) that helps economists estimate how much carbon dioxide may be heading into the atmosphere. The Kaya identity says the pace of climate pollution is more or less the product four things:

  • How carbon-heavy fuels are
  • How much energy the economy needs to produce GDP
  • GDP per capita
  • Population

After years of policymakers’ yammering about carbon-light or carbon-free this-or-that, Rieder basically zeroes in on the fact nobody wants to acknowledge: The number of people in the world—particularly in affluent countries—is literally a part of the equation.

Think of Rieder’s as the argument waiting in the wings should the 195-nation Paris Agreement, which came within a shade of enactment this week, fail to address the problem.

An edited interview transcript of an interview with him follows.

Q: So. What seems to be the problem?

A: There are 19 million adoptable orphans, and there’s catastrophic climate change on the horizon. Contributing a child to the world both makes climate change worse and, if we don’t get our act together, it might actually not be all that great for the child either.

You have two tracks. You could say climate change is a big structural problem, so it requires a structural solution; that’s a policy question. Or you could say a problem like climate change requires that we change our culture of individual obligation, and everybody needs to think about having small families.

Q: That seems like a pretty heavy ask. People don’t even want to think about having small bags of movie popcorn.

A: Well, the argument goes like this: Okay, humans have shown me that they’re just not willing to give up their toys. And so we need another option on the table. You want to continue to live in your 10,000-square-foot house? You know, fly private jets around, and that kind of thing? Well, that would mean a lot fewer people on the Earth.