When carbon-neutral was named The New Oxford American Dictionary‘s Word of the Year for 2006, the choice highlighted how recent efforts to combat climate change have brought forth a whole new class of carbon compounds (the lexical kind of compounds, not the chemical kind!). To be carbon-neutral, you can use a carbon calculator to estimate your household’s carbon footprint. Then you can seek to reduce your own carbon emissions, or you can purchase carbon offsets or carbon credits. Countries can institute carbon taxes, while eco-conscious companies can engage in carbon trading on the carbon market. And maybe someday, if we’re all low-carbon or even zero-carbon, we can live in a post-carbon world.
Putting aside the politics of the global warming debate, lexicographers are particularly interested in how the usage of the word carbon has been expanding in recent years. Not everyone is happy about the carbon boom. Salon‘s advice columnist Cary Tennis recently fielded a letter from “Bothered by Bad Buzzwords,” who complained that carbon-neutral and related terms misuse the word carbon. “What I don’t understand is why no one is calling the concept correctly,” the letter-writer grumbled. “Carbon is not carbon dioxide! One is a black solid. One is an odorless, colorless gas. Couldn’t they call it CO2 neutral?”
The column has generated quite a lot of comments from Salon readers. Some have applauded the letter-writer’s questioning of poorly conceived buzzwords and have offered their own pet peeves. Others take issue with the assumption that the carbon in carbon-neutral is a misnomer for carbon dioxide. Some argue that the term could relate to any of the greenhouse gases containing carbon, including methane and chlorofluorocarbons. Decreasing the amount of carbon-containing gases in the atmosphere requires the “sequestration” of carbon in reservoirs like forests and oceans, often called carbon sinks. That’s why carbon offset programs seek to balance the production of greenhouse gases through the planting of trees and other efforts to help natural sequestration.
So the carbon of carbon-neutral and similar buzzwords doesn’t necessarily have to refer to the “black solid” that we recognize as carbon’s elemental form. Instead, it can refer to the carbon that circulates in various molecular forms in and out of the atmosphere. Nonetheless, it’s true that carbon has increasingly been used as a kind of shorthand for carbon dioxide. The forthcoming Sixth Edition of the Shorter Oxford English Dictionary recognizes this new sense of carbon. In addition to providing definitions for the combining forms carbon footprint, carbon-neutral, carbon tax, and carbon trading, the Shorter OED gives an extended sense for the word carbon: “carbon dioxide or other gaseous carbon compounds released into the atmosphere.”
Referring to atmospheric carbon dioxide as carbon is an example of “ellipsis,” the omission of words or parts of words from speech or writing. We’re constantly clipping the language through ellipsis — it’s what allows us to move from “I will see you later” to “See you later” to just plain “Later!” If there’s any potential ambiguity caused by ellipsis, we can usually deal with that by looking at clues from the surrounding context. To take another example involving chemical elements, if a sportscaster says that an Olympic athlete has won gold or silver, we can gather from context that the announcer is talking about medals rather than metals. Similarly, a colloquial reference to someone taking acid is understood to signify LSD (lysergic acid diethylamide) rather than some other acidic substance. And peroxide is the common elliptical term for the form of hydrogen peroxide used to bleach hair.
Elliptical usage can sometimes lead to confusion, however. For instance, does a carbon calculator for your carbon footprint measure the amount of carbon your household produces or the amount of carbon dioxide? There’s a big difference, since the molecular weight of CO2 is about four times that of elemental carbon. As it happens, a carbon footprint typically is calculated in terms of carbon dioxide production, but scientists and government agencies usually measure emissions in terms of carbon units, an estimation that takes into account other organic compounds that contribute to the greenhouse effect. (The New York Times evidently got tripped up by the ambiguity of carbon last year, when it initially reported that a gallon of gasoline emits 11 kilograms of carbon. According to a correction, that’s actually the amount of carbon dioxide produced.)
We can see the word carbon moving in all sorts of new directions these days. The head of environmental markets at Barclays Capital has been quoted as saying, “Carbon will be the world’s biggest commodity market, and it could become the world’s biggest market overall.” That’s carbon in the sense of carbon trading, extended to refer to the emerging “emissions market” in general. Meanwhile, an organization called CarbonSense has issued a “carbon challenge” to foster “carbon leadership,” “carbon literacy,” and the discussion of “carbon issues.” No doubt about it, the semantic explosion of carbon is anything but elemental.
Ben Zimmer is an editor at Oxford University Press and a true word junkie. Once a week he surfaces from his dictionaries to write this column. Check out his “words of the week” on our main page (center column) or by clicking here.