If you really want to cut your carbon footprint, it takes a lot more than recycling. Or switching to LED or compact fluorescent lightbulbs. Or even trading in your SUV for a Prius.
Individuals — especially those in wealthy, developed countries — must make major lifestyle changes to reduce their greenhouse gas emissions in a meaningful way, according to a recent review of emissions-reducing actions.
The four most-impactful things to do: have one fewer child, give up your car, avoid air travel and eat a plant-based diet.
"These actions have much greater potential to reduce emissions than commonly promoted strategies like comprehensive recycling (four times less effective than a plant-based diet) or changing household lightbulbs (eight times less)," researchers Seth Wynes and Kimberly Nicholas wrote in Environmental Research Letters.
Here's a breakdown of annual carbon emission reductions, according to the study, for each of the four most-effective actions:
• Having one fewer child — 58.6 tons
• Being car-free — 2.4 tons
• Avoiding air travel — 1.6 tons for each round-trip transatlantic flight avoided
• Not eating meat — 0.8 tons
(Note: The researchers focused on developed regions, as they're the biggest source of carbon emissions. It's also important to say that recycling does help! It's just not as impactful as other carbon-footprint mitigators.)
Much of this will be unsurprising for most people. Cars and planes are major, obvious polluters, as is animal agriculture.
The part about forgoing a child is what threw people for a loop when this study was published last summer.
Nicholas knew she and Wynes were bringing up a sensitive topic with this research.
"Certainly it's not my place as a scientist to dictate choices for other people," she told NPR. "But I do think it is my place to do the analysis and report it fairly."
In the United States, at least, people are having fewer kids, or none at all.
Right now, the average mother has 2.4 children, according to Pew research. In 1976, 40 percent of moms had four or more kids, with an average of over three kids per mother.
The fertility rate is trending downward in the U.S. And some people are so concerned with climate change that it's making them decide not to have children.
Overall, giant companies are responsible for most carbon emission — not individuals. Last year's Carbon Majors Report found that 100 companies are behind over 70 percent of international greenhouse gas emissions since 1988.
So, a vote for candidates who would support carbon-reducing policies is another effective action individuals can take.
But the researchers note that individual actions like converting to veganism or swapping your car for a bike can happen quicker than government regulations. And the more people who make major behavioural changes, the more it can catalyze other individuals and groups to take action on climate.
Why you may not have heard about this before
Governments don't recommend these four effective climate actions, and education systems don't teach them to kids either, Wynes and Nichols found.
Instead, they found public institutions and school textbooks focus on low-impact climate actions like using reusable grocery bags.
The researchers argue such examples can trivialize the serious nature of climate change. And to them, that's not OK — regardless of how controversial it might be to recommend people have fewer kids, for example.
"Some high-impact actions may be politically unpopular, but this does not justify a focus on moderate or low-impact actions at the expense of high-impact actions," Wynes and Nichols wrote.
For an example on what the government does and does not recommend for climate action, take a look at the Environmental Protection Agency's carbon footprint calculator.
It doesn't mention air travel or diet.
While it appears that number of children is baked into the formula, the webpage explaining methodology for the calculator says it's "being updated." The page links to an archived screenshot from the day before Donald Trump's inauguration, and includes a boilerplate message from EPA administrator Scott Pruitt and the president:
"We are currently updating our website to reflect EPA's priorities under the leadership of President Trump and Administrator Pruitt."