Editor’s Note: This article written by Madeline Ostrander originally appeared online at YesMagazine.org. It is also the cover story for the 2012 Spring edition of YES! Magazine.

In modern life, a David versus Goliath conflict rarely ends as neatly as the story—especially when the Goliath is a $7 billion energy project backed by major oil-industry multinationals.

But this year, a broad coalition of environmental activists, citizens from conservative ranch and farm communities, Obama supporters, and celebrities (such as Daryl Hannah, Julia Louis-Dreyfus, and Mark Ruffalo) shot down the Keystone XL pipeline. The proposed 1,700-mile pipeline would have carried unrefined oil bitumen to the Gulf of Mexico from the tar sands of Alberta. In late summer, in one of the largest civil disobedience actions in the environmental movement’s history, more than 1,200 pipeline opponents got arrested in front of the White House. In the fall, President Barack Obama faced anti-pipeline protesters at stops along his re-election fundraising tour. And several thousand people surrounded the White House at a protest in November, including some major Obama campaign donors.

After months of such pressure, the administration changed course. The State Department announced in November that it would delay a decision on the pipeline until after the 2012 election. Republicans forced matters by attaching a rider to the payroll tax cut extension that required Obama to rule on the pipeline by February. The American Petroleum Institute warned he’d face “huge political consequences” if he didn’t approve Keystone XL. But Obama had already felt enough heat from his base. In January, the verdict was “no”—though TransCanada, the Canadian company that would build the pipeline, is invited to propose a new route, and at time of press, Republicans are pursuing legislative means to take the decision out of the administration’s hands.

Still, the activists’ win is monumental. Oil giants such as ExxonMobil, Koch Industries, and Royal Dutch Shell have major investments in Alberta. According to ­ThinkProgress.org, oil and energy companies spent about 37 times as much on lobbying on Keystone XL as the citizen groups that opposed it.

Moreover, administration officials have close ties to TransCanada. The company’s top lobbyist was once a Hillary Clinton campaign staffer, and this fall, Obama hired a former TransCanada lobbyist for his re-election team. The State Department ran the project through cursory environmental review, which it outsourced to a company that listed TransCanada among its clients. In mid-October, 70 percent of the National Journal’s “energy insiders” thought Obama would approve the pipeline by year’s end.

But then activists and citizens intervened. In the six states that the pipeline would cross, communities grew angry that a Canadian company wanted to seize their land—their frustration drew them to unlikely partnerships with local environmental groups. In Nebraska, rural landowners, concerned citizens, and the state farmers union formed a coalition with advocacy groups and environmentalists to fight the pipeline. Prominent NASA scientist James Hansen also took notice: He observed that Canada’s tar sands were the second largest carbon reserve in the world. He called Keystone XL “game over” for the planet.

His assessment alarmed activist Bill McKibben, founder of 350.org. McKibben led the coalition to fight the pipeline. The oil industry had money and influence, but activists had their own weapons—voting power, legal rights (which allowed them to sue over concerns that the project violated endangered species protections), and the power of numbers. They had a good (and true) story, with something for everyone. Tar sands mining not only has a massive carbon footprint; it is a show-stopping environmental disaster that guzzles city-sized portions of water, annihilates forests, and leaves behind carcinogens and a decimated landscape. 

And a pipeline full of corrosive, toxic tar-sands bitumen is risky business for small communities that rely on irrigation and untreated well water. A major oil spill in the Yellowstone River and a pipeline rupture near Kalamazoo, Mich., left communities doubtful of claims that TransCanada could safely pump bitumen across major rivers and groundwater supplies. The Nebraska Legislature held a special session to pass new environmental regulations in response to heated public debate and polls that showed significant opposition to the pipeline.

“The most precious asset we have out here is our groundwater supply. We don’t take the Ogallala Aquifer for granted,” said Allen Schreiber, a Nebraska Republican who has been active in the anti-pipeline campaign. “And I think TransCanada has this attitude that we’re a bunch of ignorant rubes out here—we won’t know any better.”

The activists focused on the idea that one man—President Obama—had the capacity to halt the pipeline. And the activists made the most of the power of media coverage. Friends of the Earth and other watchdog groups investigated TransCanada and sent the results to the national media, which aired reports on, for instance, incriminating email interactions full of praise, party invitations, and emoticons that suggested State Department insiders were cheering on company lobbyists.

“We know that the money talks, and we see closed-door meetings between TransCanada officials and our [state] lawmakers,” said Ben Gotschall, a fourth-generation rancher and one of the lead organizers for Bold Nebraska, a citizens’ group that spearheaded an anti-pipeline campaign in the state. “A lot of people have come to the conclusion that leaders are not going to lead. They’re not going to take action, and it’s up to the citizens to make them do what is right.”

Obama’s rejection of Keystone XL is, of course, not the end of the road for the anti-pipeline movement forged over the last year. At its best, it could be the beginning of a new chapter in the environmental movement—one that is more populist and cross-partisan, that confronts corporate power head-on, that knows better how to capture and leverage media attention, and that engages citizens in ever more courageous and creative acts of civil disobedience and street protest.

These strategies could set the tone for more climate change struggles to come. According to James Hansen’s predictions, the world has only a few years to begin changing its fossil-fuel-burning ways before greenhouse-gas concentrations in the atmosphere are too high to avoid catastrophic global consequences, such as large-scale water and food shortages. But transforming the energy economy will require not merely facing down the fossil-fuel industry but removing its chokehold on government.

As Bill McKibben wrote to his supporters, “Blocking one pipeline was never going to stop global warming—but it is a real start, one of the first times in the two-decade fight over climate change when the fossil fuel lobby has actually lost.”

The victory reminds the movement that it’s possible to win, even against improbable odds.