President Barack Obama said the controversial Keystone XL pipeline project could have a “disastrous” impact on climate change by enabling the expansion of Canada’s high-carbon oil sands. During a taped interview Monday on late-night show “The Colbert Report,” the president downplayed the $8 billion project’s benefits and underscored its potential problems, the Washington Post reported Tuesday.

Obama did not indicate to Stephen Colbert, the host of the Comedy Central political satire show, whether he would approve or reject the project. The president has the final word because the 1,200-mile pipeline crosses an international border. In June 2013, Obama said he would approve the project only if it “does not significantly exacerbate the problem of carbon pollution.”

During the interview at George Washington University, he reiterated this requirement. “We’ve got to make sure that it’s not adding to the problem of carbon and climate change. We have to examine that, and we have to weigh that against the amount of jobs that it’s actually going to create, which aren’t a lot,” he said. “We’ve got to measure [the Keystone XL’s benefit] against whether or not it’s going to contribute to an overall warming of the planet -- which could be disastrous.”

If built, the Keystone XL would ship up to 830,000 barrels of oil a day from Alberta, Canada, to Steele City, Nebraska, where it would connect with an existing pipeline to Texas refineries.

The U.S. State Department found earlier this year that building the Keystone XL would not greatly impact global greenhouse gas emissions, since developers of Canada’s oil sands could continue shipping crude oil by rail in the absence of a pipeline. But the agency’s analysis suggested that if oil prices dropped to between $65 and $75 per barrel, shipping Canadian crude by rail would become less profitable -- meaning the Keystone XL would play a greater role in spurring production.

Brent crude oil, an international benchmark, was around $67 a barrel on Tuesday morning, after rebounding from a five-year low of $65.29.

Environmental groups have also argued that the crude oil itself, called diluted bitumen, is more carbon-intensive than conventional sources because it requires more energy to process and extract. Researchers with the Stockholm Environment Institute concluded that the added oil from the pipeline could lower global oil prices even further, which would drive up consumption and in turn produce more greenhouse gas emissions.

TransCanada Corp., the Keystone XL’s builder, said that any emissions that result from the project would be negligible. The Calgary-based company said that the entire North American oil sands industry “contributes less than one-fifth of 1 percent globally. Emissions from Keystone XL in global terms are virtually immeasurable,” according to its website.

In late November, Keystone XL opponents in the U.S. Senate narrowly defeated a bill to approve the oil pipeline. Obama previously said he is delaying a final decision until the State Department wraps up its final environmental impact analysis. He also cited pending legal action in Nebraska as a reason for the continued delay, which might last until early next year.

The Keystone XL hit another snag this summer in South Dakota. In July, a certificate allowing TransCanada to build a pipeline through the state expired, meaning the company has to reapply for permitting. Opponents of the project, including landowners, tribal groups and environmental activists, said they were heading to Pierre on Tuesday to prevent South Dakota regulators from issuing a new permit.   

On the “Colbert” segment, Obama brushed aside claims by the pipeline’s proponents that it would create thousands of quality American jobs and bolster state economies. “The amount of jobs that it’s actually going to create … aren’t a lot,” the president said. “Essentially, this is Canadian oil passing through the United States to be sold on the world market. It’s not going to push down gas prices here in the United States. It’s good for Canada.”