Big numbers without context are rife in discussions about climate change (not to mention the state of the nation’s economy). I find it annoying: if you say you will eliminate XX tons of CO2 but don’t provide context or state it as a percentage of what’s possible, it isn’t informative.
But providing context often isn’t easy, as Natalie Angier points out in a N.Y. Times article about Fermi problems.
Fermi problems (named for the physicist, who used them as brain refreshers with his atom bomb team), take a big question and break it down to smaller components to get an estimated answer. One question the article posits is, if you take all the miles Americans drive in a year, how far into space would it go? What’s revealed in the process can be as revealing as the answer itself. Unraveling the question flexes the brain with news ways of thinking, and gives communicators new ways to get the point across, too. It can tell a story of sorts, and make the abstract real.
In answering the miles question, you find out how many miles the average person drives (per Angier’s mechanic, it’s about 12,000). Say there is one car for every two Americans, that’s 150 million times 12,000, or 2 trillion miles. Then note that Pluto, the unplanet, is only 3 billion miles from here, and you’ve got a nice way to make the staggering concept of all those miles driven more concrete.
Angier also looks at a topical problem: how much cropland is needed if we decide to fuel our cars solely with corn-based ethanol? Lawrence Weinstein, co-author of a book* on Fermi problems, uses calories consumed as the starting point. There are 30,000 calories in a gallon of gas, and the average car uses a gallon or two a day. Since a person needs only 2,000 to 3,000 calories a day, Weinstein says, we’d need “20 times more farmland, so this could be a bad idea.”
You can also help people comprehend amorphous figures by translating them into everyday concepts. For instance, to show how much bigger 1 billion is than 1 million, you could point out that 1 million seconds equals 10 days, and 1 billion seconds runs to about 32 years. Neat.
If you’ve made it this far, I’d love to know if anyone has ideas for relating carbon equivalents. I want to see an alternative to “the equivalent of taking XXX cars off the road.” Just how much CO2 does a car produce? Taking it off the road for how long? It muddies the issue, provides no simple, concrete image, and says nothing about the amount of pollution relative to the problem.
*Guesstimation: Solving the Worlds Problems on the Back of a Cocktail Napkin, by John A. Adam and Lawrence Weinstein. We have to love this, given how Thinkshift got started.