As he begins his second term, President Obama is barreling toward what one Bay Area activist predicts could be "all out warfare" with environmentalists who want him to stop the Keystone XL Pipeline, the transcontinental conduit for tar sands fuel from Canada that many scientists say could expedite climate change.

Obama's political dilemma lies in the pipeline's potential upside: The State Department projects that it could deliver 6,000 temporary jobs to the U.S., where 12.2 million people are unemployed. Bay Area liberals leading the Keystone opposition say Obama has only one choice.

"If he doesn't reject it," said Piedmont attorney Guy Saperstein, a former Sierra Club Foundation president and prominent liberal donor, "then I think it should be all out warfare for the next four years."

Environmentalists are drawing a line in the tar sands with a series of high-profile demonstrations planned this month in Washington.

The timing of the protests is crucial because sometime before April, Obama will receive the State Department's recommendation on whether to green-light the 1,700-mile Canada-to-Texas pipeline, forcing him to make a decision he delayed during last year's presidential campaign to avoid alienating his liberal base.

Liberals who bided their time through four years of little action from the White House on climate change, and who bit their tongues during the 2012 campaign, expect payback.

Civil disobedience

Obama will feel heat from them in the nation's capital, where the Sierra Club, based in San Francisco, plans to participate in civil disobedience for the first time in its history to call attention to the issue.

Saperstein has contributed $50,000 toward the protests, which include a Feb. 17 demonstration on climate change that is expected to be the largest of its kind in U.S. history.

The nonviolent civil disobedience, which will occur on an undisclosed date, will involve only a couple of dozen invited participants, organizers said. The nature of the action hasn't been revealed.

Among those participating will be Sierra Club Executive Director Michael Brune, club board President Allison Chin, and Michael Kieschnick, the president and co-founder of Credo Mobile, the San Francisco cellular phone company that has given more than $75 million to progressive causes over a couple of decades.

Using her clout

This week, San Francisco resident Susie Tompkins Buell - the co-founder of the Esprit clothing company who has given more than $25 million to progressive causes over the past 10 years - wrote a letter to Obama, and to her vast political network, urging the president to take "bold action" on climate change.

"We cannot betray (our children's) future by confining ourselves to small, cautious steps," Buell wrote.

Buell, like many liberals, praised Obama for mentioning climate change more prominently than any other issue during his inaugural address last week.

"We will respond to the threat of climate change," Obama said in his Jan. 21 speech, "knowing that the failure to do so would betray our children and future generations."

The president "made a big commitment and he's got to live up to it," Buell said in an interview.

Saperstein is among the liberals who say that Obama's rhetoric on climate change doesn't match his record. In 2009, during his first inaugural address, Obama said, "With old friends and former foes, we'll work tirelessly to lessen the nuclear threat and roll back the specter of a warming planet."

But little happened. The House, controlled in Obama's first two years by Democrats and led by Rep. Nancy Pelosi, D-San Francisco, passed a climate measure that included a cap-and-trade system to control emissions. But it never got a vote in the Democratic-controlled Senate.

"Obama never pushed for it," Saperstein said, expressing the frustration of many liberals.

'Purest test'

Now, Obama has a chance to redeem himself to environmentalists.

"This is the purest test Obama is ever going to face," said Bill McKibben, a prominent environmentalist and writer who is helping organize the Feb. 17 demonstration as part of a climate-change awareness organization called 350.org. "He doesn't have to ask John Boehner. He doesn't have to ask Mitch McConnell. He just needs to do it."

Even with an unfriendly Congress, activists say, Obama could do more to protect the environment through executive and administrative actions.

The Sierra Club's Brune said Obama could instruct the Department of Energy to stop the approval of liquid natural gas export terminals. Brune said approving those terminals "would intensify fracking (hydraulic fracturing) across the country and intensify greenhouse gases across the country."

"This is among the first biggest tests of (Obama's) commitment to climate change and his willingness to stand up to the oil industry and their toadies in Congress," Brune said.

Brune said his organization's credibility was not compromised after Time magazine reported last year that the Sierra Club accepted $25 million from the gas industry to help fund its "Beyond Coal" campaign from 2007 to 2010.

"We realized that was a mistake," Brune said. "You can't accept funds from industries that need to be reformed."

Now the organization wants Obama to stand up to the oil and gas industry.

"The president has not fully put his muscle behind the effort to combat climate change," Brune said. "That's what needs to change more than anything else."