Diet for a Warm Planet

The secret to cutting carbon? A dieting support group.

Illustration: Katy Lemay

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In 1985 i interviewed James Hansen at his nasa office in New York City about a problem called the greenhouse effect that few outside of science had heard of and fewer would take seriously for another 20 years. He was thoughtful and smart, only 44 years old, though he looked haggard from the battle behind him, as well as the battle he knew lay ahead—one man versus endless rounds of pundits, zealots, oilmen, politicians, journalists, scientists, naysayers, and fools.

The fight that would keep him on the ropes had begun in 1981, when Hansen proposed that the effects of global warming might show up in the real world, instead of just climate models, by 1990—not much later, as many in science were expecting. This early prophecy included uncanny predictions of droughts in North America, melting Antarctic ice sheets, and the opening of the Northwest Passage. More than two decades of bruising battles later, this past spring, Hansen delivered an urgent warning that we must trim atmospheric CO2 concentrations from 385 parts per million to 350 ppm—right now. (See “The Most Important Number on Earth.”)

Hansen’s number presents a staggering challenge. It insists we dramatically reduce emissions at a time when we’re still increasing them by 2 ppm per year, and when little or nothing is happening on the political front. It demands the biggest collaborative effort in the history of our species.

So what can you and I do to set an example for the men who lead the world? How to jump from the Age of Exploitation to the Age of Sustainability and drag the corporate-military-agroindustrial machinery along with us? The path seems paradoxically disconnected—like the business plan of the South Park underpants gnomes: Step One, steal underpants…Step Three, get rich.

Step Two: Embark upon a fossil fuel diet. We need to tighten up, get fit, get agile, smart, and quick. We need to develop a boxer’s stamina if we want to outlast the well-funded heavyweights who will fight us to the death before the referee Nature calls the fight.


In the world of birds, there’s a long-distance traveler without equal, the 15-inch-long bar-tailed godwit. It’s classified as a shorebird, one of those sandpiper species typically found along coastlines. Yet the bar-tailed godwit has a far more impressive curriculum vitae. It manages its hectic calendar and limited resources with a lithe professionalism that enables it to do what no other animal on earth can do—that is, to leave Alaskan shores and strike out over open water to fly nonstop for eight days and 7,200 miles without feeding or drinking before touching down in another hemisphere (New Zealand) during a different season (spring). Six months later, it repeats the feat in reverse, with a five-week feeding stop in China, for an annual round-trip of 16,500 miles. Each bird makes its first migration only three months after hatching, often in flocks composed solely of first-timers.

We don’t know exactly how these pocket Herculeses manage such phenomenal labors. Their skill set includes some form of built-in gps and a meteorological aptitude that enables them to forecast low-pressure fronts a thousand miles away, and then launch in time to intercept their 60 mph tailwinds days later.

We do know that in every stage of their lives these birds are masters of energy management. They breed on the Alaskan tundra, harvesting berries (including, initially, last year’s withered remnants) and seasonal blooms of insects. When their chicks fledge, they move to the shore and overhaul their diet entirely, probing tidal mudflats along Alaskan river deltas, where they transmute marine worms and clams into godwit. Eating is their primary work during these endless summer days, and by the time they launch south they are clinically obese, literally wobbling when they walk, with as much as 55 percent of their 1.5-pound bodies weighing in as fat—the heaviest fat loads recorded in any birds to date.

Yet once airborne they’re sleek and efficient fliers. Somehow, just prior to flight, they shrink their digestive organs, while increasing their heart and breast muscles. They follow intelligent pathways through the air, hopping into the slipstream of useful weather systems, slingshotting around counterproductive ones, often clocking along at speeds of 60 mph. They regulate their energy by optimizing altitude, frequenting the cold, dry air at 15,000 feet in order to minimize energy loss through heat and water loss through evaporative cooling. They probably sleep half of their brains at a time, like migrating mallards.

By the time they arrive on New Zealand’s tidal estuaries, they’re down to half their starting weight, exhausted, bedraggled, and hungry—but just in time for the Southern Hemisphere’s spring bounty. They’ve completed their epic flight without ingesting or combusting a drop of fuel.

They are what we need to be: small of footprint, capable of the long haul.


Our migration from the Profligate to the Sustainable Hemisphere requires us to trim atmospheric CO2 concentrations from 385 to 350 ppm, which we can do by cutting emissions by the same 10 percent. Right? Not quite. Atmospheric CO2 concentrations are rife with long-term feedbacks, both positive and negative, and our current saturation level reflects 250 years of anthropogenic emissions, not just last year’s.

So how do we come up with a goal? I’m not a PhD in atmospheric sciences, and neither are you, probably, so this is more in the realm of the hypothetical diet, designed to make a qualitative difference while convincing the world’s leaders that we’re serious about forcing them to join us in the fight. The United States emits 13.1 trillion pounds of CO2 a year, 22 percent of the total annual global emissions—about 43,000 pounds per American. But before we start deconstructing the merits of fluorescent lightbulbs, let’s consider the bigger picture. Yes, China is catching up and by some estimates has already surpassed us. Yet the vast majority of the 385 ppm clogging the atmosphere was emitted by us.

Since America is responsible for 22 percent of annual emissions, I suggest we set a target of shrinking our personal carbon footprint by 22 percent, or 9,606 pounds. If Americans all did this, it would mean we’d take a disproportionate chunk out of that 385 ppm—which China and India would fairly argue that we should. Twenty-two is a hefty number with an alliterative ring to it and is indicative of serious intentions. If enough of us pull it off, 22 percent has the power to fuel a movement our leaders will follow.

So what would a 22 percent diet look like? Step Two is all about losing weight.

Seriously. Body fat. My personal flab is not just a private matter between me and my coronary arteries. Nineteen percent of US energy usage—about as much as is used to fuel our cars—is spent growing and delivering food to the average American who consumes 2,200 pounds of food a year. That’s a whopping 3,747 calories a day—or 1,200 to 1,700 more than needed for personal or planetary health. The skinny truth is that as much as 7.6 percent of total energy in the United States today is used to grow human fat, fat that translates to 3,300 pounds of carbon per person.

Sure, liposuction is an untapped fuel source—and New Zealander Pete Bethune extracted 3.38 ounces of his own fat to add to the biofuel powering his carbon-neutral boat, Earthrace. But a more sustainable strategy would be to avoid growing the fat in the first place. A comprehensive Cornell University study found that we could cut our food energy usage in half by simply eating less, cutting back on meat and junk food, and considering the source of our food.

For starters, half of our food energy use comes from producing and delivering meat and dairy. If we gave up just meat, we could maintain that hefty 3,747-calorie intake but consume 33 percent less in fossil fuels doing it. If Americans cut just one serving of meat a week, it would equal taking 5 million cars off the road.

One-third of those 3,747 daily calories comes from junk food—potato chips, soda, etc. We can save on fossil fuel costs in this area by installing more efficient lighting, heating, and cooling in the plants that make the stuff and by using less packaging materials. But we’d save a lot more if you and I simply bought less of it. A can of diet soda, for instance, delivers only 1 calorie of food energy at a cost of 2,100 calories to make the drink and the can. Transporting the components and the finished product costs even more, and shipping processed food and its packaging accounts for much of the problem of America’s food averaging 1,500 travel miles before it’s eaten.

Ideally, we’d eat our recommended 2,000 to 2,500 daily calories from food grown on smaller, traditional, and organic farms—particularly for dairy and meat, which are extremely energy intensive in their nonorganic forms. To make this work, though, we also need to buy locally, since organic can be grown halfway around the world, and that’s hardly sustainable. True, local produce could find its way to your table via too many polluting pickup trucks, but buying locally from sustainable farms generally produces a smaller carbon footprint than factory farms with their fuel-heavy pesticides, chemical fertilizers, and travel miles.

But wait, you say, it’s too expensive to buy all that local, organic, boutique food. Well, demand drives the market toward affordability. Today nearly 5,000 farmers markets across the US provide fresh neighborhood food to cities, suburbs, and rural areas. The number is growing (up 18 percent between 2004 and 2006) and the farmers are profiting ($1 billion in sales in 2005). The Agriculture Department now provides farmers market vouchers to low-income mothers and seniors—though not yet enough. The next big step in trimming fossil fuel costs is community-sponsored agriculture (csa), where paid subscriptions support a local small farmer, who supplies his subscribers with weekly deliveries of fresh, neighborhood food. There are now 2,000 csas nationwide. What begins as an elite market eventually becomes something common. But it only happens if you and I make it happen.

Our best friend in making it happen is higher fuel costs, which will eventually make some local food cheaper than distant food. Higher gas prices have already prompted Americans to cut back on driving over the last year by just under 5 percent. That’s a bigger decline than during the gas crisis of the 1970s, and it was accomplished without too much pain.

To get to our goal we need more like a 25 percent decline in driving. That and one less 1,100-mile plane trip per person would save us each an estimated 2,365 pounds of carbon. Assuming we’ve saved 3,300 pounds of carbon by going on an actual diet, we’ve already gotten halfway to that 22 percent reduction in our carbon footprint without sweating. Closing the gap is easy. Even a middling hot water heater produces 3,000 lbs of carbon a year. So when the time comes to replace it, get an on-demand model that doesn’t labor to keep 40 gallons of water hot round the clock. Until then, turn down the temperature to 120° F (carbon saved: 500 lbs). While you’re at it, turn your thermostat down in winter and up in summer (2,000 lbs) and compensate with sweaters and solar shades or glazes. Hang your clothes to dry; you’ll cut 1,440 pounds of carbon, plus gain a few meditative moments with your laundry. My personal favorite: Shop thrift stores. You get to be more of a recycler, less of a consumer, especially if you donate your stuff back when you’re done with it. With almost every decision we make, there’s a carbon way to look at it. (See “Where Carbon Comes From.”) So do an audit. And share your goals with others. Diets work when we support each other. Just as no bar-tailed godwit can make it to New Zealand and back again on its own, neither can we. The secret to Step Two is to learn to flock. Any one of us changing out our lightbulbs is helpful. Many of us acting together becomes a force.


Before their migration, bar-tailed godwits gather on their staging areas to feed, but also to coordinate the group’s intentions, demonstrating what we call migratory restlessness—the massed, circling, erratic flights, the constant kirRUC-kirRUC-kirRUC calls. Our advantage over the birds is that our voices carry beyond our bodies, allowing us to talk effortlessly across miles and languages.

Except that we don’t. On life-and-death matters of sustainability, too many of us remain isolated and silent. A George Mason University study found that while a majority of American health department directors believe their region will suffer serious public health problems from climate change within 20 years, few have made any plans to detect, prevent, or adapt to these health threats—in part because they fear they don’t know enough to speak. The authors conclude that Americans continue to erroneously view climate change as a threat only to species other than our own in part because health professionals remain silent.

When I blogged about this story, angry commenters, some identifying themselves as doctors, complained that health professionals could hardly be expected to solve global warming. That’s not the point. Every one of us has a voice, and every one of us is an expert with our own authority to speak. Since when did we give our power away? A doctor can speak of the troubles in sight from increased heat stress, dehydration, migrating diseases. A mental health professional can speak of the post-traumatic stresses that shadow natural disasters. A computer programmer can speak authoritatively of the need to focus our technological skills on life-saving solutions. Parents can speak of the rights of their children to a functioning planet. Children can speak of their fear and anger at our silence. It’s not about the right to speak, but the obligation.

But free speech is a free-for-all. How do we transition from clamor to consensus? Thomas Malone and Mark Klein of mit suggest we already have the power to harness computer technology and create a “collective intelligence” to address systemic problems, like climate change, that overwhelm our individual intelligence. They propose a Web-mediated discussion and decision-making forum called the Climate Collaboratium—”a kind of Wikipedia for controversial topics, a Sims game for the future of the planet, and an electronic democracy on steroids.”

They suggest four intriguing—and increasingly sophisticated—means to move beyond argument to action: (1) Let online users vote on the issues and run daily simulations of the vote rankings; (2) let users vote within their areas of expertise (scientists within science), except in “values” choices where everyone has a vote, as in “How much economic sacrifice should we make now to reduce sea level rise for our great-grandchildren?”; (3) let users buy and sell predictions about uncertain future events, to be paid only if their predictions are correct; (4) create a “proxy democracy” whereby users could give their voting proxies to others—on scientific issues to the Union of Concerned Scientists, say, or on “values” issues to the Nature Conservancy. Within this cyberflock we might transform our most strident discussions into sound decisions and solid action.

The bar-tailed godwits massing on their staging grounds in Alaska swirl and bunch with elasticized precision. The collective brain of their bodies debates yes and no. On the day of departure, the deliberation rises to 1,500 feet to test the vote up there before descending to the mudflats again. When the decision is finalized, the flocks climb beyond sight, groups of 50 to 100 birds flying in echelons or V shapes, those masterpieces of aerodynamics and communications, each bird gaining lift from the upwash of wings ahead, each bird seeing unimpaired by what lies ahead, all listening to each other’s calls.

“We have used up all slack in the schedule for actions needed to defuse the global warming time bomb,” writes James Hansen, 20 years after telling Congress that climate change was already, certainly, under way. We’re on the mudflats, the tide is rising, the sun is falling, the season is changing, we need to assess those weather systems a thousand miles away. Not one of us can escape the long trip. We still have time—just enough—Hansen says, to tighten up, get fit, get agile, smart, and quick, before the flock is scattered in catastrophic winds that not even the heavyweights will survive.


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