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Small Change

When Words Fail

Climate change activists have chosen a magic number

by Bill McKibben

Published in the July/August 2008 issue of Orion magazine

I ALMOST NEVER write about writing—in my aesthetic, the writing should disappear, the thought linger. But the longer I’ve spent working on global warming—the greatest challenge humans have ever faced—the more I’ve come to see it as essentially a literary problem. A technological and scientific challenge, yes; an economic quandary, yes; a political dilemma, surely. But centrally? A crisis in metaphor, in analogy, in understanding. We haven’t come up with words big enough to communicate the magnitude of what we’re doing. How do you say: the world you know today, the world you were born into, the world that has remained essentially the same for all of human civilization, that has birthed every play and poem and novel and essay, every painting and photograph, every invention and economy, every spiritual system (and every turn of phrase) is about to be . . . something so different? Somehow “global warming” barely hints at it. The same goes for any of the other locutions, including “climate chaos.” And if we do come up with adequate words in one culture, they won’t necessarily translate into all the other languages whose speakers must collaborate to somehow solve this problem.

I’ve done my best, and probably better than some. My first book, The End of Nature, has been published in twenty-four languages, and the essential idea embodied in the title probably came through in most of them. It wasn’t enough, though, nor were any of the other such phrases (like “boiling point” or “climate chaos”) that more skillful authors have used since. So in recent years I’ve found myself grasping, trying to strip the language down further, make it communicate more. This year I find myself playing with numbers.

When the Northwest Passage opened amid the great Arctic melt last summer, many scientists were stunned. James Hansen, our greatest climatologist, was already at work on a paper that would try, for the first time, to assign a real number to global warming, a target that the world could aim at. No more vague plans to reduce carbon dioxide in the atmosphere, or keep it from doubling, or slow the rate of growth—he understood that there was already enough evidence from the planet’s feedback systems, and from the quickly accumulating data about the paleoclimate, to draw a bright line.

In a PowerPoint presentation he gave at the American Geophysical Union meeting in San Francisco last December, he named a number: 350 parts per million carbon dioxide. That, he said, was the absolute upper bound of anything like safety—above it and the planet would be unraveling. Is unraveling, because we’re already at 385 parts per million. And so it’s a daring number, a politically unwelcome one. It means, in shorthand, that this generation of people—politicians especially—can’t pass the problem down to their successors. We’re like patients who’ve been to the doctor and found out that our cholesterol is too high. We’re in the danger zone. Time to cut back now, and hope that we do it fast enough so we don’t have a stroke in the meantime. So that Greenland doesn’t melt in the meantime and raise the ocean twenty-five feet.

For me, the number was a revelation. With a few friends I’d been trying to figure out how to launch a global grassroots climate campaign—a follow-up to the successful Step It Up effort that organized fourteen hundred demonstrations across the U.S. one day last spring and put the demand for an 80 percent cut in America’s carbon emissions at the center of the political debate. We need to apply even more pressure, and to do it on a global scale—it is, after all, global warming. But my friends and I were having a terrible time seeing how to frame this next effort. For one thing, the 180 or so countries that will negotiate a new international treaty over the next eighteen months are pretty much beyond the reach of effective lobbying—we can maybe influence the upcoming American election, but the one in Kenya? In Guatemala? In China? And for another, everyone insists on speaking those different languages. A Babel, this world.

But a number works. And this is a good one. Arcane, yes—parts per million CO2 in the atmosphere. But at least it means the same thing in every tongue, and it even bridges the gap between English and metric. And so we secured the all-important URL: (Easier said than done.) And we settled on our mission: To tattoo that number into every human brain. To make every person on Planet Earth aware of it, in the same way that most of them know the length of a soccer field (even though they call it a football pitch or a voetbal gebied). If we are able to make that happen, then the negotiations now under way, and due to conclude in Copenhagen in December of 2009, will be pulled as if by a kind of rough and opaque magic toward that goal. It will become the definition of success or of failure. It will set the climate for talking about climate.

So the literary challenge—and the challenge for artists and musicians and everyone else—is how to take a mere number and invest it with meaning. How to make people understand that it means some kind of stability. Not immunity—we’re well past that juncture, and even Hansen says the number is at best the upper bound of safety, but still. Some kind of future. Some kind of hope. That it means kids able to eat enough food, that it means snowcaps on mountains, that it means coral reefs, that it means, you know, penguins. For now 350 is absolutely inert. It means nothing, comes with no associations. But our goal is to fill it up with overtones and shades and flavors. The weekend before we officially launched the campaign, for instance, 350 people on bicycles rode around the center of Salt Lake City. That earned a story in the paper and educated some people about carbon dioxide—but it also started to tint 350 with images of bicycles and the outdoors and good health and pleasure. We need 350 churches ringing their bells 350 times; we need 350 spray-painted across the face of shrinking glaciers (in organic paint!); we need a stack of 350 watermelons on opening day at your farmers’ market; we need songs and videos; we need temporary tattoos for foreheads. We may need 350 people lining up to get arrested in front of a coal train.

It makes sense that we need a number, not a word. All our words come from the old world. They descend from the time before. Their associations have congealed. But the need to communicate has never been greater. We need to draw a line in the sand. Say it out loud: 350. Do everything you can.

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Bill McKibben is editor of American Earth: Environmental Writing Since Thoreau. To learn more about the new campaign and get involved, go to

Article Resources

Scott Walker, 08/04/08:

This is Orion, thanking you all for the lively and interesting discussion.

We are closing the discussion now, and…

Dennis Falgout, 08/04/08:


I have to admit that I find it hard to imagine a context that would make the sentence…

Vittoria, 08/04/08:

I read the part about Prof. Schneider on Discover and I can tell Dennis Falgout he’s guilty of distorting what…

Dennis Falgout, 08/04/08:


This same Stephen Schneider (quoted in your 212) once wrote, “We have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we may have. Each of us has to decide what the right balance is between being effective and being honest.” [Quoted in Jonathan Schell, “Our Fragile Earth,” Discover, October 1989, p. 47].  How refreshing to find a man who has such a devotion to science and truth.  You never have to wonder if such men are telling the truth. 

No, I was not wrong about rising sea level.  The sea level has been rising steadily since the end of the last Ice Age.  Your post confirmed it. 

Your comment 211 requests that I review all of your comments about my inaccuracies.  Insofar as I know, you have not documented any inaccuracy in any statement that I have posted.  If you care to provide conflicting information, as opposed to the unsubstantiated opinion that you have provided, please do so and I will respond. 

In 217, you ask which building codes I meant.  I don’t know.  You cited (in 180) some pollution limits, efficiency standards, and building codes, which if enforced nation wide would have saved a bunch of money in energy costs.  I asked you to provide information about the source of your data, but you declined. 

Your comment (in 218) about carbon dioxide absorbing strongly in the wavelength range from 10 to 12 micrometers is true but misleading.  Water vapor also absorbs in the same wavelength range.  As your graphic shows, the absorption coefficient for water vapor appears to be about half of the carbon dioxide coefficient.  However, the concentration of water vapor at 70 degrees F and 50% relative humidity is approximately 12,300 parts per million.  Therefore, even though carbon dioxide absorbs in that waveband, it can only increase the absorption provided by water vapor by about 3%, which is not significant. 

Carbon dioxide does have an absorption band at about 4.2 micrometers (where water does not absorb), but objects whose temperature is about 500 degrees F emit that wavelength.  The surface of the earth rarely, if ever gets that high.  Your graphic does not show that the total width of the carbon dioxide absorption band is from about 13 to 17 micrometers, because it truncates at about 15 micrometers. 

The data on water vapor concentration and black body emission temperature came from the “Handbook of Chemistry and Physics, 70 ed., Chemical Rubber Company, 1999-1990.