I spent the early summer of 2006 in India's most remote state, Arunachal Pradesh, a country of great beauty, remoteness and poverty bordering the Brahmaputra River as it descends from Tibet. Green, steamy country, rising up from the Assamese plain, filled with tea plantation and rice paddy at its lower elevations, and dense, tribally controlled jungle up high.

One day, with a few friends, I waded five skeins of a broad river to reach a village called Mang Nang. We'd come to visit a woman trained by a remarkable American foundation, Future Generations, as a "village welfare worker." Her name was Osam Mibang, and she welcomed us to the porch of her bamboo hut.

Like the rest of the villagers she walked three kilometres (two miles) a day to reach the rice fields, where she put in a full day's work, but in the evening, she'd gather other women and tell them about, say, clipping their children's fingernails to reduce worm infestations, or how to use bed nets against malaria, or how to do family planning while handing out contraceptive patches.

She had a medical kit in an aluminum footlocker, containing a notebook she'd filled with impeccable notes on everything from dosages to genetics. (Why genetics? Because with her chart of x and y chromosomes, she could demonstrate to men that it was their sperm that determined the sex of their children, hence it was inappropriate to beat their wives for having girls).

She had another notebook that she used for keeping a register of all the deaths in her village. When she started keeping it, in 2000 and 2001, there were eight deaths a year. By 2004 and 2005, that number had fallen to four, and only one was an infant. She'd cut the death rate in half.

She was too tired to talk for very long, because she had malaria herself, acquired out in the muddy field where she had to work. But she posed for a picture, standing under a portrait of Gandhi that she'd bought to hang on her wall. Like many Indians, she didn't know a great amount about his life, but that didn't matter. "I know he's a person who helped a lot of people, and that's why I bought this instead of a film star for my kids to look at. He said to do good things and to love the people around you, and he looked after a lot of sick people." And so he did.

I came back home to Vermont from that trip with Gandhi on the brain. I'd kept crossing his tracks time and again in village India, and his example kept crossing my mind as I sank into a kind of despair about American inaction on global warming, the great question of our day.

I'd written the first book for a general audience about climate change way back in 1989, and been working on the issue ever since: speaking, producing op-eds, essays and yet more books. After Hurricane Katrina and An Inconvenient Truth, public attention to the problem had indeed soared. But still nothing had happened, not in Washington, which is the center of the problem. No legislation, no real concern, just the choked paralysis of vested interest.

And so, for some reason, the idea of movement had an almost visceral appeal. I'd always loved the story of Gandhi's march to the sea to make salt. It seemed to me that the time had come to march here too, odd as it seemed in an Internet age.

I emailed a few friends, and they emailed a bunch more, and we had some meetings, and three weeks later we started out, leaving from Robert Frost's old summer writing cabin in the Green Mountains.

When we stepped off on the first day of this walk we were perhaps 300 strong, carrying signs with our basic demand: Congress should pledge to cut American carbon emissions 80 percent by 2050. We wound our way in joyful file-it was a gorgeous late summer day-down the shoulder of the Green Mountains and into the broad Champlain Valley, and then for five days we hiked north, often along the shoulder of the two-lane state highway.

At night we'd sleep in fields; in the evening we'd host programs on town greens and in local churches. And by the time we got to the outskirts of Burlington, the state's one small city, there were a thousand of us marching.

That was a lot more than had marched for anything in Vermont in a very long time. It was enough that all the candidates for federal office in Vermont agreed to come meet with us for our final rally on the shore of the lake. And not just meet with us-one by one, liberal Democrat and conservative Republican, they filed up on stage and signed the pledge that they would support our demand: the quite radical pledge to cut carbon emissions by that 80 percent figure. It went way beyond what seemed the politically possible, and yet it was what science demanded.

And that afternoon, by the lake, it suddenly seemed a little less inconceivable. The mere act of marching-of walking side by side, of making ourselves visible and a little vulnerable-seemed to have set something in motion.

We wanted to see if that something could translate beyond Vermont, after all the second-smallest state in the union. And so, a few months later in January, we launched a website: stepitup2007.org. "We" in this case refers to me and my colleagues-six brand-new graduates of Middlebury College, where I teach. We had no money, we had no mailing lists, and so by any normal standard we had no chance. But we did have an idea: We thought there were all sorts of people out there ready to take some action if only they had an idea how to go about it.

Gandhi's great strategic insights all involved figuring out how mass action could focus pressure on an empire at once mighty and fragile. We too wanted to look for weak points, and our sense was that they were all over the country. In Washington, D.C., Exxon Mobil was an invincible lobby; out in the districts, senators and congresspeople could be swayed, once we figured out how to mobilize people to action.

It proved to be as easy as asking. Our emails began circulating, and within days people were coming to the website to register their actions. It was almost magical-day after day, dozens of newfound activists in every corner of the country joined in. They came from every part of society: sorority chapters, evangelical congregations, farm groups. Many were simply people, who had never organized anything of the kind before. But they had been haunted by the coming crisis, and once they were offered the chance to do something about it, something that seemed on the right scale, they poured their energy into the project.

Eleven weeks after we launched the website, our big day of action boasted 1,400 demonstrations in all 50 states. It was the biggest day of grassroots environmental protest since the first Earth Day way back in 1970. And the creativity was as amazing as the commitment.

Just as Gandhi had been so adept at picking symbols that made sense to his countrymen-salt, say-so these new activists managed to find the images that could get through to their neighbours. In lower Manhattan, thousands of people in blue shirts joined arms to form a "sea of people" that showed where the tide would someday reach in the most expensive real estate on Earth. In the mountains of the west, skiers descended in formation down the glaciers already dwindling under the sun's new power. In Jacksonville, Florida, organizers got a crane and winched a yacht 6 metres (20 feet) into the air. "There," they said. "When Greenland slides into the sea, that's where the sea is going to be."

The protests had the effect desired. Before the protests were more than a week in the past, all the leading Democratic presidential candidates had endorsed the 80-percent-by-2050 goal. We did another round of nationwide rallies in November, and this time managed to get almost one-sixth of congresspeople to speak with their constituents about what kind of leadership they planned to provide. The day ended at a great gathering of almost 7,000 college students from around the country. House Speaker Nancy Pelosi was at the podium, leading the throng in a call-and-response: "Eighty percent. By 2050."

We're used to thinking of protest as something from "the '60s," but that's wrong. Martin Luther King, Jr. was a student of Gandhi's-and their techniques work as well now as they did then. New tools change the ways we organize: We couldn't have reached people without the Web, nor uploaded the pictures of their rallies for everyone to see.

But the essential idea-people coming together to shed their fear and despair in the company of their neighbours, to work against concentrated power with the force of hope, to put their bodies on the line if only by marching for a few days-is as powerful as it ever was.

But that's not the only, or perhaps even the main, thing that Gandhi offers a world now driving itself off the edge of a cliff. We tend to forget what he considered the core of his work: re-imagining economic life so it makes human sense.

In his day, the great symbol was the spinning wheel, and the bolt of khadi cloth replacing the suit of clothes imported from the mills of Manchester. (And so infectious was his spirit that the workers in those very mills cheered him when he visited England.) In our time, the symbolic American equivalent is probably the farmers' market, where local food starts to replace the far-flung products of industrial agriculture. That has important environmental benefits-instead of ordering takeout from some thousands of kilometres away, which is essentially what our food system forces us to do now, you can get it from the guy down the road-just as making salt or wearing homespun had serious economic repercussions in India. But in both cases, the chief effect is really psychological.

Gandhi's India needed to feel some confidence-to understand it could stand on its own feet. Our America needs to feel some community-to understand each of us should worry a little less about our individual selves and relax into the pleasure of our neighbours. And that's what happens at a farmers' market. One study found that the average shopper had 10 times as many conversations there than during a visit to the supermarket. That's liberating in the deepest sense of the word.

Our economic lives underpin our sense of who we are-that was one of Gandhi's great insights. Change those daily habits a little and you can change our habits of mind a lot. We are in enormous environmental trouble because we've spent decades trying to meet non-material needs (for status, for affection, for respect, for camaraderie, for security) with material means.

And so we've built ever-bigger houses and driven ever-bigger cars and taken ever-longer vacations and eaten ever-more and ever-finer food. And by every measure we can find, it hasn't made us any happier. Rather the reverse. Americans' satisfaction with their lives peaked in 1956, and our ever-rising standard of living has done nothing to slow our steady decline in happiness.

We need scientists and policy-makers and engineers to help us out of the trouble in which we find ourselves-global warming is the biggest mistake humans have ever made, and it will require many kinds of minds to fix it.

But Gandhi was our scientist of the human spirit, our engineer of political courage. The other advice from the 20th century seems stale now: central planning, endless economic expansion. We've hardly started to explore the possibilities that spring from Gandhi's example. We better get going.

Bill McKibben is Schumann Distinguished Scholar at Middlebury College and co-founder of 350.org. His most recent book is Eaarth: Making a Life on a Tough New Planet.

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