OTTAWA–Two big U.S. retailers may have written off Alberta's oil sands, but the U.S. ambassador to Canada says the fuel is too important to his country to simply snub the controversial resource.

"If we're looking for long-term safe and secure sources of energy, Canada, and therefore the oil sands, need to be part of it," David Jacobson said in an interview with the Star.

Jacobson praised the "significant progress" being made in cleaning up the environmental impact of the oil sands, though he stressed that more needs to be done.

"I have been to Fort McMurray. I have seen both the mining and the underground extraction of the oil sands. I have met with both representatives of industry and representatives of environmental groups and representatives of the First Nations who are up there. I have learned a lot about the situation. I'm still not expert.

"But I will say this: I think they have made significant progress from what it looked like 10 or 15 years ago, in terms of the environmental impact of the oil sands," Jacobson says.

"But I think they need to make significantly more progress."

On Wednesday, organic food retailer Whole Foods Markets Ltd., as well as the home furnishings giant, Bed Bath and Beyond, announced to fuel suppliers that they would shun gasoline refined from the Alberta oil sands.

There are now concerns in the Alberta petroleum community that the boycott will spread to something larger south of the border.

But Jacobson says he's been learning a lot about American dependence on Canadian oil since he arrived to take up his post here last fall.

There have been a lot of slide presentations, Jacobson says, and two of the slides stand out for him.

"One of them was a list of the countries with the largest proven reserves of petroleum in the world – Canada being two, behind Saudi Arabia. And the other 11 were probably not countries that were typically high on the list of the closest friends of the United States," he said.

"The other slide showed that of the proven reserves of petroleum in the world that are not owned by a government, half of them are in Alberta."

It all means the United States simply can't afford to demonize the oil sands, Jacobson says.

"The other side is that while there has been significant improvement, with respect to air, land, water degradation as a result of oil sands – and there has been – they've got a ways to go."

Oil sands production is condemned by environmental activists because the process used to refine the oil emits significantly more carbon dioxide than the process used in production of other fuels.

The environmental organization ForestEthics says Wednesdy's action by the two major retailers is just the beginning.

"At least 30 large U.S. brands are seriously considering taking action to address the brand risk of being associated with tar sands," said ForestEthics activist Aaron Sanger.