The largest act of civil disobedience by environmentalists in decades began outside the White House this morning, as more than seventy activists were arrested at the north gates during a protest against the Keystone XL pipeline, which if approved by the administration would carry 900,000 barrels of oil per day from Alberta, Canada to the Gulf of Mexico.

The activists, who sat down at the gates at 11 am holding large banners reading “Climate change is not in our national interest,” were warned three times by US Park Police to move along, and were handcuffed and removed after they refused. More than 2,000 people have pledged to be arrested outside the White House every day until September 3, in daily installments of seventy-five to 100 people.

The Keystone Pipeline would carry oil gouged from the “tar sands” of Alberta—areas where soil is thick with bitumen, which can be refined into synthetic crude oil. The process is environmentally devastating. Parts of Alberta have already been ravaged by the extraction, and the refining process involved creates twice the greenhouse gases as producing a normal barrel of crude.

Since the pipeline would cross an international border, the State Department has jurisdiction and is completing an environmental assessment of the project, which could be released this week. The White House will have ninety days to decide whether to grant a permit for the pipeline. The grassroots group 350.org, which includes many Nation writers, has called for a campaign of nonviolent direct action aimed at persuading the administration to deny the permit.

The Alberta tar sands represent the second-largest repository of oil in the world, and climate scientists are horrified with the prospect of pumping that much carbon into the atmosphere. Environmentalist Bill McKibben, who led today’s action, noted that if all of the oil were extracted overnight it would increase the carbon in the earth’s atmosphere from 393 parts per million to 550 parts per million—a devastating increase. NASA climate scientist James Hansen recently wrote that since phasing existing carbon emissions out is already an enormous task, “if the tar sands are thrown into the mix, it is essentially game over.”

Beyond the climate concerns, there’s the issue of pipeline safety—Keystone XL would traverse the entire country, from Montana to the Gulf of Mexico. Anyone unconcerned with potential pipeline failures should note the recent incident underneath the Yellowstone River, where an Exxon pipeline ruptured and spilled over 1,000 barrels of crude into the river.

There are, of course, massive financial interests behind the construction of Keystone XL. Tar sands commercials are ubiquitous on television, particularly during news programming. The industry, led by the American Petroleum Institute, has launched an enormous advertising and lobbying push.

McKibben rallied the activists in Lafayette Park moments before the action began, and noted the enormous amount of money on the other side of the fight.

“There is enormous pressure coming down on the White House from the fossil fuels industry. These are the richest people. They are the most powerful people on our planet. They usually win,” McKibben said. “We have to find a different currency to work in. Our currency today and for the next two weeks is our bodies and our creativity and our spirit. And that’s all we’ve got to put up against all that money, and we will find out if it’s enough.”

Since Congress is not involved in this decision, the White House is the decisive chokepoint for the Keystone XL project—Obama doesn’t have to tangle with industry-friendly members of Congress. McKibben told reporters in Lafayette Park that “it is really the environmental test for Barack Obama, really in the course of his first term.”

Many of the activists wore buttons from the Obama 2008 presidential campaign, which climaxed in Denver at the Democratic National Convention, where Obama famously marked the moment “when the rise of the oceans began to slow and our planet began to heal.” McKibben predicted that “if Barack Obama mans up and says ‘no’ to this thing, it will send a surge of electricity through all of the people who voted for him three years ago. It’ll be the reminder of why we were so enamored with this guy in 2008.”

When the arrests began, the activists—including McKibben, FireDogLake founder Jane Hamsher, Lt. Dan Choi, and Vermont Law School professor Gus Speth—repeated chants of “Hey hey, ho ho, Keystone XL’s got to go” and “Ain’t no power like the power of the sun, because the power of the sun don’t stop.”

They were handcuffed with zip ties, led one-by-one into a tent set up by the US Park Police, processed and loaded into the back of a large van as tourists watched. The arresting officers gave the activists water over the course of the two-hour process, which took place in the sweltering late-summer heat of Washington. Several activists noted that if Keystone XL isn’t stopped, the hottest weather is surely yet to come.