Here's something to watch in 2014: the collective psyche of the green movement.
If President Obama green-lights the Keystone pipeline, the movement will face questions about its tactics and goals at a level unseen since major climate-change legislation collapsed on Capitol Hill in 2010.
"If the pipeline is approved, it's a defeat for 350.org, Sierra Club, et al, with no real strategy for what comes next," said Alex Trembath, a policy analyst with the Breakthrough Institute, an environmental think tank whose founders have often criticized movement tactics.
Whatever the decision, it will be a defining moment for a movement that has had its ups and downs under Obama.
After the 2010 climate-bill defeat, some analysts and activists wondered whether several big green groups, such as the Environmental Defense Fund, had launched a tactically shaky campaign that required too many concessions before failing outright.
Among the criticisms of the cap-and-trade campaign: too much hope that a few Senate Republicans would come along (they didn't); an inside-Congress strategy without enough outside pressure; and too much footsie with big corporate players.
Some of the same kind of soul-searching will occur if (and it's only an "if") Obama approves Keystone, a decision that's likely to come in 2014.
But Dan Becker, a longtime Sierra Club veteran who now directs the Safe Climate Campaign, doesn't think losing on Keystone would be the same kind of demoralizing moment as the collapse of the cap-and-trade bill in 2010.
"This is very different from the cap-and-trade bill, which I personally thought was the wrong approach and was not something the grassroots cared about or supported," he said. "Would I have chosen this?," he said of the Keystone fight. "Maybe not, but it has brought energy into the movement, it has brought new adherents in, it has brought new leadership in."
And to be sure Keystone, however it turns out, is not a rerun of the cap-and-trade fight. The campaigns have been very different. This time, environmentalists have targeted a single White House decision and waged an outside-in mass campaign with a different set of leaders—first and foremost,Bill McKibben of the upstart 350.org.
Others include Sierra Club Executive Director Michael Brune, a veteran of the pugilistic Rainforest Action Network, who has brought some of that rabble-rousing to Sierra since 2010.
A lot of climate activists are all-in, transforming Keystone from a project en route to quiet approval into the highest-profile climate battle in recent years.
"It is not going to be pleasant if it is approved," said Robert J. Brulle, a Drexel University sociologist who studies environmental movements. "I think that one thing we can be pretty sure of is that the marriage between the greens and the Democratic Party will be brought under pretty severe review."
Critics who say climate change is a big problem but that Keystone is the wrong battle are ready to pounce. Some take issue with environmentalists who say Keystone XL would be a major contributor to greenhouse-gas emissions to begin with (it all depends on how much you think it's a linchpin for expansion of carbon-intensive oil-sands development).
Trembath, who calls coal-fired power a much bigger enemy than Keystone, argued that even blocking the pipeline would be a "nominal victory ... without any apparent path forward."
The criticism is well underway even before a decision is rendered.
New York magazine's Jonathan Chait, in late October, agreed with the argument that stopping Keystone would do very little to slow greenhouse-gas emissions, calling EPA plans to regulate existing coal-fired plants as a far more important fight. "The whole crusade increasingly looks like a bizarre misallocation of political attention," he wrote.
But Keystone critics say the fight is both consequential for the climate and a movement-builder. It has included civil disobedience and mass rallies that saw young activists pour into Washington.
"We had not seen that type of in-the-street action for decades," said Bill Snape, senior counsel for the Center for Biological Diversity. "That has rejuvenated the movement. It has rekindled a spirit that was missing."