Science will have the final say on the Keystone XL project, and make U.S. President Barack Obama's rejection of the pipeline a "no-brainer," says American activist and author Bill McKibben.

In an interview with CTV's Question Period, McKibben, a prolific science and environment writer who has organized hundreds of protests against the proposed pipeline, said he believes the anti-Keystone movement is gaining steam.

The $7-billion project would construct a pipeline to carry Alberta bitumen to refineries in the U.S. Gulf Coast. Obama has pushed back his decision on whether to give the project the go-ahead, and final word is not expected until next year.

McKibben said he doesn't know if celebrities like Robert Redford, Neil Young or billionaire Democratic fundraiser Tom Steyer, who have all spoken out against the project, are having an impact in Washington.

But he believes that no matter what lobbying efforts for or against the project occur, "maybe science will actually win this time."

"This is always in the end been about the science and been about the fact that we really can't make global warming manageable if we keep digging up the biggest pools of carbon on earth," McKibben said.

"And what's up there in Alberta is one of those big pools of carbon that needs to stay underground."

Young recently sparked outrage in Alberta when he compared Fort McMurray to the devastation after the atomic bomb was dropped on Hiroshima.

McKibben said he has seen a lot of "bad things" during his reporting career, but he was still surprised by what he saw on a recent trip to survey the oilsands.

"It's really astonishing," he said. "And the effect on the lives of First Nations people is really amazing. Even without the crazy damage to the climate, this thing's a pretty sick project."

Natural Resources Minister Joe Oliver and other government ministers have made several trips to Washington in recent years in an effort to shore up support for the project ahead of Obama's decision.

Oliver says his government has to counter their message with "the facts and the science." He argues that 70 per cent of the U.S. population "is on side in terms of building the Keystone XL pipeline," and says it has the support of lawmakers in states that the pipeline will travel through.

"We have a lot of support, and really it's not surprising because this pipeline will be positive for national security, it will create jobs (and) generate economic growth and significant revenue to governments to support critical social programs like health care and housing," Oliver told Question Period.

Oliver said the Canadian government is "certainly not happy" that Obama is taking so long to make a decision. He said any concerns that the project would increase carbon emissions are allayed by the fact that Alberta oil would be replacing crude from Venezuela in the U.S. supply, and Canada is a more reliable trading partner and "has stringent environmental rules."

"We think the environmental and safety issues have been dealt with," Oliver said.

He also noted that he and other ministers have engaged in ongoing talks with First Nations communities ahead of any development of either the Keystone XL pipeline, or the Northern Gateway project.

"We have to structure these projects so that they will provide real tangible benefits for aboriginal peoples whenever we proceed with development, which of course has to be vetted in any event to make sure that they are safe for Canadians and safe for the environment," Oliver said.

McKibben said he has no indication of which way Obama will go on his Keystone decision, but noted he was concerned about the project leading to an increase in carbon emissions.

"If he follows that standard in good faith, it's a no-brainer," McKibben said. "Because tapping the tarsands is a Rube Goldberg machine for warming up the planet."