What's the single best decision you can make if you want to decrease the amount of carbon dioxide and other greenhouse gases (GHGs) being released into the atmosphere?

That's the question UBC researcher Seth Wynes and his co-author Kimberly Nicholas set out to answer in a new paper published this week.

Their answer? Have fewer children.

According to the researchers' analysis, having one fewer child outweighed the potential emissions reductions of all other choices more than 20 times. (Tara Carman/CBC)

In the paper, Wynes and Nicholas identify four lifestyle choices individuals in developed countries can make that have the most significant effect on GHG emissions — actions they feel are overlooked by government and educational sources.

The other three choices they identified were eating a plant-based diet, avoiding air travel and giving up personal vehicles. But by their reasoning, having one fewer child overwhelmingly outweighs all other choices, due to all of the GHGs that child would be responsible for emitting over the course of their life.

"To put it simply, adding another person to the planet who uses more resources and produces more carbon dioxide is always going to make a large contribution to climate change," Wynes said.

But Wynes isn't necessarily encouraging people to not have children; rather, it's meant to be a wake-up call.

"The calculations that we did assumed a constant emission scenario [but] if society rapidly reduces our greenhouse gases in the coming years, that number can go down up to 17 times," Wynes said.

"The issue is not having children, but changing this overconsumptive society that the children are born into."

Paper focused on overlooked actions

Wynes and Nicholas arrived at their conclusions by attempting to make their data comparable to the findings of numerous other studies on GHG emissions.

They then analyzed the data with an eye to finding actions they felt were under-promoted by governments and science textbooks, as opposed to solutions like recycling.

"These sources focused their recommendations on incremental actions that were much less effective than the high-impact actions that we found," Wynes said.

They also focused on solutions that weren't just limited to emissions or addressed problems that are not likely to be solved by technology.

Choosing a plant-based diet, for example, is a good solution for Wynes, because it reduces methane emissions from livestock but also addresses the fundamental inefficiency of turning plant calories into animal calories before consuming them.

"It's not like renewable power replacing coal, where we can see an easy or a straightforward path to decarbonization," Wynes said. "No policy changes or scientific advancement can really address that inefficiency."

The paper was published on Wednesday in the journal Environmental Research Letters.