Q. I’m a graduate student. Most of my peers are taking their notes on a laptop during class lectures, but I prefer to take notes on paper. I used to live near a paper plant, so I have a sense that paper-making has a big environmental impact. When it comes to the environment, is it better to fill 4 sheets of notebook paper (front and back) over the course of a 2.5-hour class? Or to run a laptop for the same amount of time?

Durham, N.C.

Q. I am a college student zeroing in on a zero-waste lifestyle. But there is one part of schooling that is unsustainable, and it’s the necessity to communicate via writing. I have to take tests and do homework with a pen or a pencil. Which is more sustainable: pens or pencils?

Alec H.
Arcata, Calif.

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A. Dearest Sarah and Alec,

By my reckoning, midterms must be coming up. Yet you two scholars both managed to steal a moment for the environment in the same week, which warms my heart. Who says you college kids are just a bunch of beer-swilling ne’er-do-wells, anyway?

Let’s study the notebook computer-versus-actual notebook question first. On your desk, Sarah, we have the quaint college-rule notebook. Pros: doesn’t require electricity, is recyclable, may make you smarter. Cons: made of paper, which necessitates the cutting of trees and, depending on how it’s produced, could also foul up the water supply and use up lots of energy in manufacturing.

Then we have your classmates’ choice, the laptop. Pros: No trees were harmed, extremely reusable. Cons: building it required the not-so-earth-friendly mining of minerals, might end up junking up a landfill in a few years, uses lots of energy in manufacturing too, distracts you with Facebook.

As always with these either-or questions, it’s tough to suss out every variable that tips the environmental scale one way or the other. We can examine the carbon footprint of the note-taking to start: According to the Environmental Paper Network’s calculator, a pound of virgin paper (technically we’re looking at copy paper) emits 4 pounds of carbon dioxide equivalent over its lifetime. If a pound is about 100 sheets, then one piece of paper accounts for .04 pounds of carbon, and one class’s worth is .16 pounds. If you’re using 100-percent recycled paper, though, those numbers dip to .02 pounds of carbon per sheet and .08 pounds per class.

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Laptops vary in terms of energy use, but a ballpark figure gives us .06 kilowatt-hours of electricity used per hour for a 60-watt machine, which translates to .091 pounds of carbon dioxide per hour, or .2275 pounds per class. So at least in this sense, a paper notebook is the better choice — by a factor of almost three for recycled paper.

Naturally, we’ve left a lot out of the equation — the laptop’s total carbon footprint over its life, for one. And (surprise) these vary quite a bit too, from 276 kg for a Dell laptop to 345 kg for a Lenovo to 480 kg for one Macbook Air. Most laptops are similar in one way: You using it accounts for only a small fraction of the overall footprint, as manufacturing and transport are the biggies. And it’s quite difficult to estimate the total environmental impact of one spiral-bound notebook without knowing where the paper came from and how responsible the pulping and paper mills were — suffice it to say, there’s some impact there too.

In short, Sarah, if you like taking paper notes, then take paper notes. For extra credit, use 100 percent recycled paper (the higher the post-consumer recycled content, the better) with Forest Stewardship Council bona fides. And write small. Even better, raid the recycling bin in the computer lab and take notes on the back of all the one-sided printouts you’re sure to find in there. It’s the greenest choice, and you can put the money you’re saving on school supplies toward beer.

Now to Alec’s question: With what to write? This is not what we call a high-priority environmental issue, but it’s worth considering. A visit to the office supplies aisle reveals these options: wooden pencils, mechanical plastic pencils, disposable ballpoint pens, and refillable fountain pens of various compositions. If we follow the eco-principle of using less, then the best bet is the one that lasts the longest. Go for the mechanical pencil or fountain pen, both of which can be refilled. Failing that, look for recycled or biodegradable pens and pencils (this site sells plumes made from plastic bottles, corn plastic, and cardboard, and these pencils used to be newspapers), and use that graphite down to the bitter end.

Good luck this semester to you both — though if you put as much thought into your studies as you do the environmental impact of your classroom choices, I’m convinced you’ll be rolling in the As.