Students at the Lincoln School have a question: should they be using wooden pencils or plastic mechanical ones? This week on Possibly we explain the answer, and how to find it.

Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.

Today, we’re tackling a question from some students at the Lincoln School: is a wooden pencil or a mechanical pencil better for the climate? Meg Talikoff and Nat Hardy checked it out for us.

Hey, guys!

Meg Talikoff: Hi!

Nat Hardy: Hey Megan!

Megan Hall: So, wood pencils versus mechanical ones. Which type creates less emissions?

Meg Talikoff: First, we have to kind of simplify the problem. We’re just going to compare a chunk of wood to a chunk of plastic.

Nat Hardy: That’s not crazy, because mechanical and wooden pencils are basically the same except for the main material that they’re made of.

Meg Talikoff: It’s also as good as we can do, because the way that companies turn plastic and wood into pencils is actually secret information that they don’t want to share.

Megan Hall: Okay, so this is more of a wood versus plastic fight. I instinctively want to say plastic creates more emissions. Is that true?

Meg Talikoff: To figure that out, we have to use something called a life cycle assessment.

Megan Hall: What’s that?

Nat Hardy: It’s a super detailed process that scientists use to analyze the climate impacts of every stage of a product’s existence, from the materials it’s made of, to its time in the landfill.

Meg Talikoff: Whatever you’re imagining, it’s probably five times more meticulous. To look at the impacts of a pencil, you have to know what type of fertilizer was used on the forest where it grew.

Nat Hardy: And how the factory powered its log-debarking machine.

Meg Talikoff: And how long it traveled to the store where you bought it.

Nat Hardy: And how much the wood will decay in the landfill depending on how much oxygen it touches.

Megan Hall: So you guys didn’t try to do this yourself, did you?

Meg Talikoff: No, luckily there were life cycle assessments out there already. And here’s what we found.

Nat Hardy: First, the type of energy used to make the material really matters.

Megan Hall: In what way?

Meg Talikoff: Well, if you think about it, what does it take to turn a living, standing tree into a pencil? A lot of different active steps. And all of those steps require energy.

Nat Hardy: You need to create enough energy to turn oil into plastic or trees into lumber. And since we’re not all using solar power, making energy creates emissions.

Marieke Head: Looking specifically at pencils, that’s probably where we’re going to see a lot of the emissions taking place in terms of the whole life cycle, so that’ll be in the manufacturing process itself.

Meg Talikoff: That’s Dr. Marieke Head, a scientist at a Canadian environmental consulting company named Groupe AGÉCO. She does life cycle assessments for a living.

Megan Hall: Okay. So, does that mean the most important thing is whether a pencil factory uses coal or solar?

Nat Hardy: It’s not the only factor, but you’re right. The type of energy a manufacturer uses is super important.

Meg Talikoff: For wood products, almost all of the emissions come from energy use. You could actually get  down to almost zero emissions if you used renewable energy in the manufacturing process.

Nat Hardy: Plastic is a little different, because the process for making it creates greenhouse gas emissions.

Meg Talikoff: But switching to renewable energy would still cut production emissions by around 60%. 

Nat Hardy: And either option could definitely win depending on who is and isn’t using renewable energy.

Megan Hall: So is the answer that there’s…no answer? We just can’t know?

Meg Talikoff: Technically yes. But there is one important thing about wood that makes it a better choice in a lot of cases.

Megan Hall: What’s that?

Meg Talikoff: Unlike plastic, wood can sometimes be considered a carbon-negative material.

Nat Hardy: That’s because trees absorb carbon dioxide from the air. And then wood doesn’t decay very much in the landfill. So a significant amount of the wood we throw away just becomes a carbon sink.

Meg Talikoff: Marieke looked at the emissions associated with processing lumber from Canadian forests. She found that those emissions were usually outweighed by the carbon dioxide the trees absorbed.

Nat Hardy: So as long as the wood comes from a forest that’s sustainably managed, wooden pencils might be the way to go.

Meg Talikoff: To find out if a pencil came from a sustainably managed forest, you can look for pencils that are certified by the Forest Stewardship Council.

Nat Hardy: But if you want to use a mechanical pencil, that’s fine too. Just refill it as many times as you can to keep its impact as low as possible.

Megan Hall: Sounds good!

That’s it for today. For more information, or to ask a question about the way your choices affect our planet, go to askpossibly.org Or subscribe to us wherever you get your podcasts.

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Possibly is a co-production of The Public’s Radio and Brown University’s Institute for Environment and Society and Brown’s Climate Solutions Initiative.

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