Dear Umbra,

In all sorts of corporate environmental reports, you see claims that compare apples to oranges — “By reducing our emissions by X pounds this year, we’ve saved the equivalent of 17 gazillion trees.” Or “If every person in the U.S. bought our eco-friendly product, we could save all the baby harp seals.” OK, perhaps I exaggerate a little bit. But where do people come up with these eco-unit conversions? I’m making a presentation to our board of directors and I wanted to use a similar easy-to-visualize comparison of our annual energy use. I’ve Googled to no avail. Can you point me in the right direction?

Ronald K.
The Woodlands, Texas

Dearest Ronald,

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Baby harp seals are cute. Did you know that harp seals are true seals — no external ears — and have been around for 20 million years, since the Miocene? Thanks to the incredibly fatty milk of mommy seals, a newborn seal triples its birth weight within two weeks. And is then deserted by its mother. Harp seals give birth and briefly raise their adorable offspring on ice floes, so talking about their survival is not as disconnected from greenhouse-gas emissions as we might think.

Hot fuzz.

I can point you to a handy eco-conversion resource if you, in turn, will help me puzzle over how to make these conversions meaningful. It’s as you say — apples to oranges. Let’s say we save 1,700 trees (a gazillion is too easily convincing). That still leaves us with no context for the greenhouse-gas emissions. Saving a tree doesn’t connote anything globally quantifiable to the average person — who’s ever saved a tree and felt the consequences (other than a warm feeling inside)? In this sort of illustration a tree is just a stand-in for nature, or for the Self-Healing Capacity of Mother Earth in opposition to Industrial Evil. “We will save 1,700 units of natural goodness!” and so on. To compare our emissions to familiar climate change images in a more concrete way, we have to convert the trees into miles driven or flown, or oil burned, or something petroleum-ish.

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Here’s what I think — you tell me if you agree. It would be better to give conservation a context within your company’s own goals: “By reducing our emissions by X, we will cut our carbon footprint by 22 percent.” Or “If we were signatories to Kyoto, we would reduce our annual energy use by Y and slash our greenhouse-gas emissions by Z.” Then we’re comparing numbers to numbers, instead of comparing numbers to trees.

OK, I’m done with my personal digressive interests. You can get your apples to oranges examples from the Environmental Protection Agency over in their greenhouse gas equivalencies calculator. Just enter whatever data you have, which can be in gallons of gasoline, therms of natural gas, kilowatt-hours of electricity, or sundry other categories. The calculator does exactly that which you seek: It gives you evocative equivalencies. I entered 42 gallons of gas consumed, which would emit 0.37 metric tons of CO2. That’s the amount of carbon sequestered annually by 0.08 acres of pine or fir forests! If you seek still more information about this purported coniferous carbon sequestration, click on the footnote and see the calculations and attributed scientific studies (rah rah, Pseudotsuga menziesii!).

The calculator does not provide an equivalency for “saving ice floes so that wittle baby harp seals can nuzzle their fat mamas and grow into big harp seals.” You’ll have to settle for evocative photos and a few moving words about global climate change and the threat to the Arctic. There won’t be a dry eye in the room.


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