A copy of S.B. 2280, a bill that would have approved the Keystone XL Pipeline, is arranged for a photograph in Washington, D.C.
A copy of S.B. 2280, a bill that would have approved the Keystone XL Pipeline, is arranged for a photograph in Washington, D.C. - 
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UPDATE: The Senate struck down the Keystone XL pipeline in a 59-41 vote Tuesday evening. The original story appears below.

Today’s top political story is, by all appearances, also a top environmental story: a Senate vote to authorize the controversial Keystone XL pipeline, which would carry hundreds of thousands of barrels of crude from the Canadian tar sands to the Gulf of Mexico. The fight against Keystone has been a marquee battle for the U.S. environmental movement for years. However, after all these years, the stakes may have gotten lower. 

The six-year fight against Keystone was primarily about preventing climate change. "Crude oil from the oil sands is a lot more carbon intense," says Jim Krane, an energy-studies fellow at Rice University’s Baker Institute for Public Policy. Just extracting the stuff emits more carbon than extracting other crudes, Krane says, and it throws off extra carbon when burned as well.

The hope was that blocking Keystone could prevent this type of crude from getting to market. But in the years Keystone has been debated, that train has left the station. Literally. Without a pipeline, rail has emerged as the crude's route to market. 

"It’s being transported now by train, down to Vancouver, it’s being put on tankers, and it’s shipped over to Asia," says Keith Brownsey, a political scientist at Mount Royal University in Alberta, Canada. "Bingo, there you go."

The original pro-Keystone argument has also lost a lot of steam. That was “energy independence for North America,” which fracking has made a less-urgent concern.

But for Brownsey, putting the oil in a pipeline now matters for a new reason.

"Rail is exponentially more dangerous than transmitting it by pipeline," he says.  In other words: Pipelines don’t derail.

Opponents say the pipeline remains important, if mostly as a symbol. 

"It’s kind of like the polar bear," says Andrew Weaver, a University of Victoria climate scientist and a Green Party legislator in British Columbia. "Keystone has become that iconic image of: 'If we can’t force change here, where can we force change?'"

Follow Dan Weissmann at @danweissmann