This post originally appeared on SierraClub.org and is re-posted with permission.

Photo Credit: tarsandsaction at Flickr.com

President Barack Obama’s rejection of the Keystone XL tar sands pipeline marks one of the biggest victories for the U.S. environmental movement in years. Speaking this morning from the White House, Obama–flanked by Vice President Joe Biden and Secretary of State John Kerry–made one of his most forceful statements to date about the importance of moving the U.S. economy away from fossil fuels.

“Shipping dirtier crude oil into our country would not increase America’s energy security,” the president said. “America is now a global leader when it comes to taking serious action to fight climate change. And frankly, approving this project would have undercut that global leadership.”

Then, in a clear echo of the environmental movement’s overarching message, the president said, “Today, we're continuing to lead by example, because ultimately, if we're going to prevent large parts of this earth from becoming not only inhospitable but uninhabitable in our lifetime, we're going to have to keep some fossil fuels in the ground rather than burn them and release more dangerous pollution into the sky.”

Make no mistake: You never would have heard Obama say “keep some fossil fuels in the ground” had the environmental movement not made Keystone XL one of the defining issues of his presidency.

Coming after years of protests, marches, civil disobedience actions, and nonstop political pressure from both the grassroots and the Democratic party’s major donors, the defeat of the pipeline is a clear win for the environment. The president’s decision removes a potential threat to the Great Plains’ groundwater. It stems the sludgy tide of Canadian tar sands, an especially dirty source of crude oil that would, if fully extracted, accelerate global climate change.

Just as important, the pipeline’s defeat represents a major victory for the ideal of citizen action. “People power” is an overused and almost hackneyed phrase. But in this case, nothing else explains how such a political victory happened.

Just four years ago, many Washington insiders presumed that Keystone XL was a done deal. But Native American tribes, ranchers in the Great Plains, and environmental organizations ignored the conventional wisdom and decided to make Keystone XL a symbol for the choices we face in the era of climate change: Will we continue with the anachronistic fossil fuel economy, or make a pivot toward a society powered by clean energy? As author-activist Bill McKibben got in the habit of saying, Keystone was a “line in the sand.” The cynical “wise men” in Washington said the campaign against Keystone XL was quixotic, if not misguided. (Just see herehere, and here.) In the end, they were proven wonderfully wrong. The president’s decision proves that–even in a money-soaked and lobbyist-chocked political system–ordinary citizens can frustrate the best-laid plans of the powers-that-be.

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